chapter 4shodhganga.inflibnet.ac.in/bitstream/10603/37779/10/10_chapter 4.pdf · crystal violet is...

[187]

Chapter 4

Potential of Anionic Surfactant Modified Alumina in

Removal of Crystal Violet from Aqueous Solution

4.1 Introduction

4.1.1 Crystal Violet

Crystal violet or Gentian violet is triarylmethane dye. The dye is used as a histological stain

and in Gram’s Method of classifying bacteria. Crystal violet has antibacterial, antifungal,

and anthelmintic properties and was formerly important as a topical antiseptic. The medical

use of the dye has been largely superseded by more modern drugs, although it is still listed by

the World Health Organization [1]

.

The name "gentian violet" was originally used for a mixture of methyl pararosaniline dyes

(methyl violet) but is now often considered a synonym for crystal violet. The name refers to

its colour, being like that of the petals of a gentian flower; it is not made from gentians or

from violets. Table 4.1 shows the general detail of Crystal Violet.

Table 4.1: General Detail of Crystal Violet

IUPAC Name

Tris (4-(dimethylamino) phenyl) methylium chloride

Other Names

Aniline violet Basic violet 3 Baszol Violet 57L

Brilliant Violet 58 Hexamethyl-p-rosaniline

chloride

Methylrosanilide chloride

Methyl Violet 10B Methyl Violet 10BNS Pyoktanin

Properties

Molecular Formula: C25N3H30Cl & Molar Mass: 407.979 g/mol

Melting Point: 205 °C, 478 K, 401 °F & Stability: Stable

Solubility : Soluble in cold & hot water, insoluble in diethyl ether

[188]

Figure 4.1: Solid Phase (A), Aqueous Solution (B) & Chemical Structure (C) of Crystal Violet Dye

4.1.2 Production of Crystal Violet:

A number of possible routes can be used to prepare crystal violet [2, 3]

. The original procedure

developed by Kern and Caro involved the reaction of dimethylaniline with phosgene to give

4,4'-bis(dimethylamino)benzophenone (Michler's ketone) as an intermediate [4]

. This was then

reacted with additional dimethylaniline in the presence of phosphorus

oxychloride and hydrochloric acid [5]

.

The dye can also be prepared by the condensation of formaldehyde and dimethylaniline to

give a leuco dye [2, 3, 6]

.

CH2O + 3 C6H5N(CH3)2 → CH(C6H4N(CH3)2)3 + H2O

(A) (B)

(C)

[189]

Second, this colourless compound is oxidized to the coloured cationic form: (A typical

oxidizing agent is manganese dioxide).

CH(C6H4N(CH3)2)3 + HCl + 1/2 O2 → [C(C6H4N(CH3)2)3]Cl + H2O

4.1.3 Synthesis of Crystal Violet:

Crystal violet is one of the components of methyl violet, a dye that was first synthesized by

Charles Lauth in 1861 [7]

. From 1866, methyl violet was manufactured by the Saint-

Denisbased firm of Poirrier et Chappat and marketed under the name "Violet de Paris". It was

a mixture of the tetra-, penta- and hexamethylated pararosanilines [8]

.

Crystal violet itself was first synthesized in 1883 by Alfred Kern (1850–1893) working in

Basel at the firm of Bindschedler and Busch [5]

. To optimize the difficult synthesis which

used the toxic gas phosgene (carbonyl chloride), Kern entered into a collaboration with the

German chemist Heinrich Caro at BASF [4]

.

4.1.4 Dye Colour:

When dissolved in water the dye has a blue-violet colour with an absorbance maximum at

590 nm and an extinction coefficient of 87,000 M−1

cm−1

[7]

. The colour of the dye depends on

the acidity of the solution. At a pH of 1.0 the dye is green with absorption maxima at 420 nm

and 620 nm while in a strongly acidic solution, the dye is yellow with an absorption

maximum at 420 nm.

The different colours are a result of the different charged states of the dye molecule. In the

yellow form all three nitrogen atoms carry a positive charge, of which two are protonated,

while the green colour corresponds to a form of the dye with two of the nitrogen atoms

positively charged. At neutral pH both extra protons are lost to the solution leaving only one

of the nitrogen atoms positive charged. The pKa’s for the loss of the two protons are

approximately 1.15 and 1.8 [7]

.

In alkaline solutions, nucleophilic hydroxyl ions attack the electrophilic central carbon to

produce the colourless triphenylmethanol or carbinol form of the dye. Some

triphenylmethanol is also formed under very acid condition when the positive charges on the

nitrogen atoms lead to an enhancement of the electrophilic character of the central carbon

[190]

which allows the nucleophilic attack by water molecules. This effect produces a slight fading

of the yellow colour.

4.1.5 Toxicological Information:

Hazardous in case of ingestion or inhalation. Slightly hazardous in case of skin

contact (irritant).

Chronic Effect on Human Health:

It may affect genetic material (mutagenic) & may cause adverse reproductive effects

and birth defects (teratogenic) based on animal test data. It may cause cancer based on

animal test data.

Acute Potential Health Effects:

(a) Skin: May cause mild skin irritation. It can stain the area of contacted skin.

(b) Eyes: Causes moderate to severe irritation with immediate severe pain. Eye

contact causes blepharospasm, purple staining of the cornea and conjunctiva cause

permanent corneal/eye damage. Inhalation: May be harmful if inhaled. It may cause

upper respiratory tract and mucous membrane irritration. Ingestion: Harmful if

swallowed. It causes gastrointestinal tract irritation with nausea, vomiting,

hypermotility, diarrhea and abdominal pain. May affect respiration (acute pulmonary

edema), behavior (ataxia) Severe systemic poisonings have not been repeated in

humans, but animal studies have shown blood pressure rise and death from respiratory

paralysis during IV administration. Chronic Potential Health Effects: Ingestion:

Prologned or repeated ingestion may cause peritonitis and may affect metabolism

(weight loss) [8]

.

4.1.6 Application of Crystal Violet:

A. Non - Medical:

Crystal violet is used to dye paper and as a component of navy blue and black inks for

printing, ball-point pens and ink-jet printers. It is also used to colourize diverse products such

as fertilizers, anti-freezes, detergents, and leather jackets.

The dye is also used as a histological stain, particularly in Gram's method for classifying

bacteria.

[191]

When conducting DNA gel electrophoresis, crystal violet can be used as a non-toxic DNA

stain as an alternative to fluorescent, intercalating dyes such as ethidium bromide. Used in

this manner it may be either incorporated into the agar-rose gel or applied after the

electrophoresis process is finished. Used at a 0.001% concentration and allowed to stain a gel

after electrophoresis for 30 minutes, it can detect as little as 16ng of DNA. Through use of

a methyl orange counterstain and a more complex staining method, sensitivity can be

improved further to 8 ng of DNA [6]

. When crystal violet is used as an alternative to

fluorescent stains, it is not necessary to use ultraviolet illumination; this has made crystal

violet popular as a means of avoiding UV-induced DNA destruction when performing DNA

cloning in vitro.

B. Medical:

Gentian violet has antibacterial, antifungal, and anthelmintic properties [9]

. It is used

medically for these properties, in particular for dentistry, and is also known as "pyoctanin"

(or "pyoctanine") [10]

.

It is commonly used for:

Marking the skin for surgery preparation and allergy testing

Tinea; e.g. Athlete's foot, jock itch, and ringworm

Candida albicans and related infections; e.g. thrush, yeast infections

Impetigo, used primarily before the advent of antibiotics, but still useful to persons

who may be allergic to penicillin.

In forensics, gentian violet was used to develop fingerprints. Crystal violet is also used as a

tissue stain in the preparation of light microscopy sections [11]

.

In laboratory, solutions containing crystal violet and formalin are often used to

simultaneously fix and stain cells grown in tissue culture to preserve them and make them

easily visible, since most cells are colourless. It is also sometimes used as a cheap way to put

identification markings on laboratory mice since many strains of lab mice are albino so the

purple colour stays on their fur for several weeks.

[192]

In body piercing, gentian violet is commonly used to mark the location for placing piercings,

including surface piercings.

4.1.7 Source of Dye & Pollution Caused Due to Dye

Color is an important aspect of human world. We like to wear clothes of all kinds of colors

and hues, eat food decorated with colors, even our medicines are colorful. No wonder then,

that a lot of research has gone into the production of color. Today there are more than ten

thousand dyes available commercially and seven lakh tons of dyes are produced annually.

Dyes are colored organic compounds used to impart color onto cloth. The current process for

dyeing textiles is operative, but inefficient and harmful. The primary function of water in the

dyeing process is to rinse excess dye off from the fabrics that have been colored. All of the

current commercial dyeing methods use a significant amount of water, and pollute most of

that water during the process. Dyes can be of many different structural varieties like acidic,

basic, disperse, azo, anthraquinone based and metal complex dyes among others. The textile

industry is the largest consumer of dye stuffs [12]

. Dyeing is the process of adding colour to

the fibres, which normally requires large volumes of water not only in the dye bath, but also

during the rinsing step. Depending on the dyeing process, many chemicals like metals, salts,

surfactants, organic processing aids, sulphide and formaldehyde, may be added to improve

dye adsorption onto the fibres [13]

. During the coloration process a large percentage of the

synthetic dye does not bind and is lost to the waste stream [12]

.

The colour of textile wastewater is mainly due to the presence of textile dyes, pigments and

other coloured compounds. A single dyeing operation can use a number of dyes from

different chemical classes resulting in a complex wastewater. Moreover, the textile dyes have

complex structures, synthetic origin and recalcitrant nature, which makes them obligatory to

remove from industrial effluents before being disposed into hydrological systems [13]

.

Approximately 10-15% dyes are released into the environment during dyeing process making

the effluent highly colored and aesthetically unpleasant.

[193]

Figure 4.2: Colored Effluent Discharge from Industry

The effluent from textile industries thus carries a large number of dyes and other additives

which are added during the colouring process [12]

. Many of the dyes are extremely toxic also.

Among various dyes, crystal violet (CV), a well-known dye has been used for various

purposes such as a biological stain, dermatological agent, veterinary medicine, and an

additive to poultry feed to inhibit propagation of mold, intestinal parasites, fungus, etc. It is

also extensively used in textile dying and paper printing. It is a mutagen and mitotic poison

[14]. These are difficult to remove in conventional water treatment procedures and can be

transported easily through sewers and rivers especially because they are designed to have

high water solubility. They may also undergo degradation to form products that are highly

toxic and carcinogenic. Thus dyes are a potential hazard to living organisms. It is hence

important to safeguard the environment from such contaminants. To prevent contamination of

natural waters by dyes, it is essential to first detect and quantify these chemicals in the waste

waters. Dyes, pigments and heavy metals represent common and dangerous pollutants,

originating in large quantities from dye manufacturing, textile as well as pulp and paper

industries. They are emitted into wastewaters and produce difficult to treat water

contamination, as the colour tends to persist even after the conventional removal processes

[12].

The residual dyes from different sources (e.g., textile industries, paper and pulp industries,

dye and dye intermediates industries, pharmaceutical industries, tannery, and bleaching

industries, etc.) are considered a wide variety of organic pollutants introduced into the natural

[194]

water resources or wastewater treatment systems. One of the main sources with severe

pollution problems worldwide is the textile industry and its dye-containing wastewaters. In

particular, the discharge of dye-containing effluents into the water environment is

undesirable, not only because of their colour, but also because many of dyes released and

their breakdown products are toxic, carcinogenic or mutagenic to life forms mainly because

of carcinogens, such as benzidine, naphthalene and other aromatic compounds. Without

adequate treatment these dyes can remain in the environment for a long period of time. In

addition to the aforementioned problems, the textile industry consumes large amounts of

potable and industrial water as processing water (90-94%) and a relatively low percentage as

cooling water (6-10%) (in comparison with the chemical industry where only 20% is used as

process water and the rest for cooling). The recycling of treated wastewater has been

recommended due to the high levels of contamination in dyeing and finishing processes (i.e.

dyes and their breakdown products, pigments, dye intermediates, auxiliary chemicals and

heavy metals, etc.). Table 4.2 provides the details of textile products responsible for water

pollution [15]

.

Table 4.2: Principal Textile Products Responsible for Water Pollution

Type of Finished Textile Product g/kg of Textile

Product

Polyester Fibres 18

Fabrics from Synthetic Fibres 52

Fabrics from Cotton 18

Dyed Fabrics from Cellulose Fibres 11

Printed Fabrics from Cellulose Fibres 88

4.1.8 Fate and Behavior of Dye in the Environment

It is usually observed that the excess water from dye, now polluted with chemicals and

additives, is often dumped into lakes, rivers, reservoirs, or other water resources. The

environmental issues associated with residual dye content or residual colour in textile

effluents are always a concern for each textile operator that directly discharges commercial

textile operations. Dye concentrations in watercourses higher of 1 mg/L caused by the direct

[195]

discharges of textile effluents, treated or not, can give rise to public complain. High

concentrations of textile dyes in water bodies may stop the reoxygenation capacity of the

receiving water and cutoff sunlight & thereby upset the biological activity in aquatic life and

also the photosynthesis process of aquatic plants or algae [15]

.

The colour in watercourses is accepted as an aesthetic problem rather than an environmental

hazard. The public seems to accept blue, green or brown colour of rivers but the ‘non-natural’

colour as red and purple usually cause most concern. The polluting effects of dyes to the

Aqueous Solution may be also the result of toxic effects due to their long time presence in

environment i.e. half-life time of several years, accumulation in sediments but especially in

fishes or other aquatic life forms, decomposition of pollutants in carcinogenic or mutagenic

compounds but also low aerobic biodegradability. Due to their synthetic nature and structure

mainly aromatic, the most of dyes are non-biodegradable, having carcinogenic action or

causing allergies, dermatitis, skin irritation or different tissular changes. Moreover, various

azo dyes, mainly aromatic compounds, show both acute and chronic toxicity. Dyes are not

biodegradable in aerobic wastewater treatment processes and some of them may be intactly

adsorbed by the sludge at wastewater biological treatment (i.e. bio-elimination by adsorptive

removal of dyes) [15]

.

4.1.9 Toxicity & Carcinogenicity of Dyes

Several dyes cause damage of DNA that can lead to the genesis of malignant tumors.

Electron-donating substituents in ortho and para position can increase the carcinogenic

potential. The toxicity diminished essentially with the protonation of aminic groups (-NH2).

Some of the best known dyes and their breakdown derivatives inducing cancer in humans and

animals are benzidine and its derivatives, and also a large number of anilines. In different

toxicological studies are indicated that 98% of dyes has a lethal concentration value (LC50)

for fishes higher than 1 mg/L, and 59% have an LC50 value higher than 100 mg/L (i.e. 31% of

100-500 mg/L and 28% higher than 500 mg/L) [15]

.

The measurement of BOD and COD offers a good indication of the organic pollution of

water. But these procedures alone are not sufficient to get information about the potential

harmful effects of chemicals. The toxic effects of other unknown and undetermined

substances in complex wastewaters can be estimated only through toxicity studies. Toxicity

[196]

study refers to bio-analytical techniques applied to organisms at various levels to ascertain

the harmful effects of chemicals on them [16]

.

In addition to being toxic, dye effluents also contain chemicals that are carcinogenic,

mutagenic or teratogenic to various organisms. This is especially serious because many

chemicals can cause damage to genetic material without being expressed immediately. Azo

and nitro compounds have been reported to be reduced in sediments of aquatic bodies giving

rise to potentially carcinogenic amines. Many dyes are made from known carcinogens like

benzidine and are also known to accumulate, thus posing a serious threat. Many dyes are also

known to get reduced to toxic substances inside living organisms [16]

.

4.2 Materials & Methodology

4.2.1 Determination of Crystal Violet in Water

a) Method Used to Determine Crystal Violet:

Direct spectrophotometric determination of Crystal Violet colour in the water at 590 nm.

b) Experiment to Determine Crystal Violet in Water & Wastewater by Calibration

Curve Method

Prepare 20 mg/L stock solution of Crystal Violet by weighing 20 mg Crystal Violet

powder & dissolving the same in 1000 ml distilled water.

Prepare standard solutions of 2 mg/L, 4 mg/L, 6 mg/L, 8 mg/L, 10 mg/L & 12 mg/L

from 20 mg/L stock solution. Directly take absorbance at 590 nm.

Take distilled water as a blank. Note down the absorbance & plot the calibration

curve. [18]

[197]

Table 4.3: Experimental Data to Determine Crystal Violet by Calibration Curve Method

Standard Con.

(mg/L) Absorbance

Blank 0.000

2 0.142

4 0.359

6 0.471

8 0.716

10 1.064

12 1.239

Figure 4.3: Calibration Curve for Determination of Crystal Violet in Water & Wastewater

Calculation:

From the calibration curve;

y = 0.10x * Sample Vol. (ml)

Where,

y = Absorbance

x = Concentration of

Monocrotophos in mg/L

[198]

4.2.2 Preparation of Anionic Surfactant Modified Alumina (ASMA)

20,000 mg/L SDS in 500 ml standard measuring flask was prepared.

Volume of the solution was 500 ml.

100 gm/L Alumina was added in the flask.

Adjusted pH 4 with 1N HCl & 1N NaOH.

Flasks were kept on magnetic stirrer for 24 Hrs.

After completion of shaking period, filtered out contents of the flasks through

ordinary filter paper.

Then the filtered solid material (100 gm/L Alumina + surfactant), remaining on the

filter paper, was gently washed first with tap water & then with distilled water.

The washed solid material was then dried in hot air oven at 60 °C for 24 Hrs.

This oven dried solid powder is Anionic surfactant modified alumina (ASMA).

ASMA powder was stored in plastic bottle for its further use in the removal of organic

pollutant like Phenol, Crystal Violet Dye etc. from waste water by adsolubilization

method.

[199]

4.2.3 Factors Affecting Removal of Crystal Violet by ASMA from Aqueous

Solution

4.2.3(A) Experimental Set Up to Study Effects of pH

200 mg/L Crystal Violet stock solution was prepared.

100 ml quantity solution of high initial concentration i.e. 200 mg/L Crystal Violet was

taken in 250 ml beaker.

Such 5 numbers of sets were prepared.

Adsorbent i.e. ASMA dosage was kept 6 gm/L. As here quantity is 100 ml 0.6 gm of

ASMA was added to the previously prepared 200 mg/L Crystal Violet solution.

pH of the 5 beakers were adjusted 2, 4, 6, 8, 10 respectively by adding the required

amount of 1N HCl and 1N NaOH.

Beakers were kept on the magnetic stirrer for 1 Hr.

After completion of shaking, contents in the beakers were allowed to settle down for 5

minutes.

Supernatant was filtered through ordinary filter paper & filtrate was collected to

measure the final concentration of Crystal Violet by using above mentioned direct

spectrophotometric method.

Readings were recorded & Graph was plotted to get equilibrium pH value.

Figure 4.4: Experimental Set up to Study Effects of pH on Removal of CV by ASMA

pH 2

200mg/L CV

+ 6 gm/L ASMA

Contact Time

1 Hr

pH 4

200ppm CV

+ 6 gm/L ASMA

Contact Time

1 Hr

pH 6

200ppm CV

+ 6 gm/L ASMA

Contact Time

1 Hr

pH 8

200ppm CV

+ 6 gm/L ASMA

Contact Time

1 Hr

pH 10

200ppm CV

+ 6 gm/L ASMA

Contact Time

1 Hr

[200]

4.2.3(B) Experimental Set up to Study Effects of Contact Time

100 ml Crystal Violet solution of 500 mg/L high initial concentration was taken in

250 ml beaker.

Such 3 numbers of sets were prepared.

Dosage of the adsorbent was adjusted 6 gm/L.

PH 8 (i.e. equilibrium pH resulted from above experiment 4.2.3(A)) was adjusted for

all the 3 beakers by adding the required amount of 1N HCl & 1N NaOH.

Beakers were kept on the magnetic stirrer for 30 minutes, 1 Hr. & 1.5 Hr.

Beakers were allowed to stay for 5 minutes after shaking time.




Readings were recorded & Graph was plotted to get equilibrium contact time.

Figure 4.5: Experimental Set Up to Study Effects of Contact Time in Removal of CV by ASMA

1.5 Hr.

200 mg/L CV

+ 6 gm/L ASMA

pH 8

1Hr.

200 mg/L CV

+ 6 gm/L ASMA

pH 8

30 min.

200 mg/L CV

+ 6 gm/L ASMA

pH 8

[201]

4.2.3(C) Experimental Set up to Study Effects of Adsorbent i.e. ASMA Dosage

100 ml Crystal Violet solution of 200 mg/L high initial concentration was taken in

250 ml beaker.

Adsorbent dosage was varied in the range 1gm/L, 2gm/L , 3 gm/L , 4 gm/L , 5 gm/L ,

6 gm/L , 7 gm/L , 8 gm/L & 9gm/L.

PH 8 (i.e. equilibrium pH resulted from above experiment 4.2.3(A)) was adjusted &

kept constant for all the beakers by adding the required amount of 1N HCl & 1N

NaOH.

Beakers were kept on the magnetic stirrer for 30 mins. (i.e. equilibrium Contact Time

resulted from above experiment 4.2.3(B))





Readings were recorded & graph was plotted.

Figure 4.6: Experimental Set Up to Study Effects of Adsorbent Dosage in Removal of CV by ASMA

1 gm/L ASMA

200 mg/L CV +

30mins. Contact Time

pH 8

2 gm/L ASMA

200 mg/L CV +


pH 8

3 gm/L ASMA

200 mg/L CV +


pH 8

4 gm/L ASMA

200 mg/L CV +


pH 8

5 gm/L ASMA

200 mg/L CV +


pH 8

6 gm/L ASMA

200 mg/L CV +


pH 8

7 gm/L ASMA

200 mg/L CV +


pH 8

8 gm/L ASMA

200 mg/L CV +


pH 8

9 gm/L ASMA

200 mg/L CV +


pH 8

[202]

4.2.3(D) Experimental Set up to Study Effects of Adsorbate i.e. CV

Concentration

100 ml Crystal Violet solution of various high initial conc. Viz. 100 mg/L, 200 mg/L,

300 mg/L & 400 mg/L were taken in 4 numbers of glass beakers.

Dosage of the ASMA adsorbent was kept 6 gm/L (i.e. equilibrium dosage from above

experiment 4.2.3(C)).

PH 8 (i.e. equilibrium pH from above experiment 4.2.3(A)) was kept constant by

adding the required amount of 1N HCl & 1N NaOH to all the beakers.

Beakers were kept on the magnetic stirrer for 30 mins. (i.e. equilibrium Contact Time

from above experiment 4.2.3(B))





Readings were recorded & Graph was plotted.

Figure 4.7: Experimental Setup to Study Effects of Initial Adsorbate Conc. in Removal of CV by ASMA

100 mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

200 mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

300 mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

400 mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

[203]

4.2.3(E) Effect of Temperature

100 ml Crystal Violet solution of 200 mg/L high initial concentration (i.e. Equilibrium

adsorbate concentration resulted from above experiment 4.2.3(D)) was taken in 250

ml beaker.

Such 3 numbers of sets were prepared to study the effect of temperature (30°C, 40°C

& 50°C) in removal of CV by ASMA.

ASMA dosage of the adsorbent was kept 6 gm/L (i.e. Equilibrium adsorbent dosage

resulted from above experiment 4.2.3(C)).

PH 8 (i.e. equilibrium pH resulted from above experiment 4.2.3(A)) kept constant by

adding the required amount of 1N HCl & 1N NaOH to all the beakers.

Beakers were kept on magnetic stirrer & various range of temperature Viz. 30°C,

40°C & 50°C was adjusted.

Beakers were kept on the magnetic stirrer for 30 min. (i.e. Equilibrium contact time

obtained from above experiment 4.2.3(B)).





Readings were recorded & Graph was plotted to get equilibrium temperature.

Figure 4.8: Experimental Setup to Study Effects of Temperature in Removal of CV by ASMA

30 ºC

200mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

40 ºC

200mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

50 ºC

200mg/L CV

6 gm/L ASMA +

30mins Contact Time

pH 8

[204]

4.2.4 Chemical Kinetic Study

200 ml Crystal Violet dye solution of 200 mg/L high initial concentration was taken

in 250 ml beaker.

Prepare a single set of 200 ml quantity for the study.

Dosage of the adsorbent ASMA was kept 6 gm/L (i.e equilibrium dosage resulted

from experiment 4.2.3 (C)).

PH 8 (i.e. equilibrium pH resulted from above experiment- 4.2.3(A)) kept constant of

all the beakers by adding the required amount of 1N HCl & 1N NaOH.

Beakers were kept on the magnetic stirrer & 10 ml supernatant was taken after every

5 minute interval for 30 minutes (i.e. equilibrium contact time resulted from

experiment 4.2.3 (B)).


measure the final concentration of Crystal Violet by using above mentioned


Readings were recorded & Graphs were plotted.

Following Kinetic Models were studied in detail.

1) Pseudo First Order Model

The pseudo-first order kinetic model based on the adsorbent for sorption analysis is of the

form:

Log (qe - qt) = log qe – (k1/2.303) t

Where,

qe (mg/gm)is the mass of Monocrotophos adsorbed at equilibrium

qt (mg/gm) the mass of Monocrotophos at any time (t) & K1 (min-1

) is the equilibrium rate

constant of pseudo-first order adsorption.

The values of k1 & qe are determined from the slope & intercept of the plot of Log (qe - qt)

versus t, respectively [17]

.

[205]

2) Pseudo Second Order Model

A pseudo-second order rate expression based on the sorption equilibrium capacity may be

represented as:

t / qt = 1/ k2qe2 + (1/ qe) t

Where,

k2 is the pseudo-second order rate constant (g mg-1

min-1

) [17]

.

The value of qe is determined from the slope of the plot of t/ qt versus t.

3) Intra-particle Diffusion

In order to understand the mechanism involved in the sorption process the kinetics

experimental results were fitted to the Weber’s intra-particle diffusion (Weber and Morris,

1963) model. It is reported that if intra-particle diffusion is involved in the process then a plot

of adsorbate uptake vs. the square root of time would result in a linear relationship and the

intra-particle diffusion would be the rate limiting step if this line passes through the origin.

Thus the kinetics results were analyzed by the Intraparticle diffusion model which is

expressed as

qt = kid t1/2

+ C

Where,

C is the intercept

Kid is the intra-particle diffusion rate constant.

The intra-particle diffusion rate constant was determined from the slope of linear gradients of

the plot qt versus t1/2 [17]

.

[206]

4.2.5 Batch Isotherm Studies

Isotherm experiments were conducted to investigate the relationship between the solid phase

concentration of an adsorbate & the solution phase concentration of the adsorbate at an

equilibrium condition. The removal percentage (R %) of CV was calculated for each run by

following equation:

R (%) = [(Ci-Ce)/Ci]*100

Where, Ci and Ce are the initial & final concentration of CV (mg/L) in the solution [15]

. The

adsorption capacity of the adsorbent for each concentration of CV at equilibrium was

calculated using following equation:

qe (mg/g) = [(Ci-Ce)/M]*V

Where, Ci & Ce were the initial & final concentration of CV (mg/L) in the test solution

respectively. V is the volume of solution (in Liter) & M is the mass of adsorbent (gm) [15]

.

4.2.6 Adsorption Isotherm Studies

In the present study, various adsorption isotherm models have been used to study the

adsorption capacity and equilibrium coefficients for adsorption. Four commonly used

isotherms (viz. Langmuir, BET, Freundlich and Temkin isotherm) were studied.

1. The Langmuir Adsorption Isotherm

In the years 1916-1918 Langmuir developed the adsorption theory in its modern form.

Langmuir isotherm equation is derived from simple mass kinetics, assuming chemisorption.

The derivation of the Langmuir adsorption isotherm involves four implicit assumption: a) the

adsorption is at a fixed number of definite, localized sites; b) monolayer adsorption is formed

on the surface of adsorbent; c) the surface is homogenous, that is, the affinity of each binding

site for gas molecules is the same; d) there is no lateral interaction between adsorbate

molecules. Alternatively at higher concentrations, it predicts a monolayer sorption capacity

(Janos et al., 2003). It assumes that the uptake of adsorbate occurs on a homogenous surface

by monolayer adsorption without any interaction between adsorbed ions. The commonly

expressed form is:

[207]

Ce/qe = [1/Q0b + 1/Q0 × Ce]

Where, Ce is the equilibrium concentration of adsorbate (mg/L) and qe is the amount of

adsorbate adsorbed per gram at equilibrium (mg/g), Q0 (mg/g) and b (L/mg) are Langmuir

constants related to adsorption capacity and rate adsorption, respectively. The values of Q0

and b were calculated from the slop and intercept of the Langmuir plot of Ce versus Ce/qe [19]

.

The Langmuir adsorption isotherm has the simplest form and shows reasonable agreements

with a large number of experimental isotherms. Therefore, the Langmuir adsorption model is

probably the most useful one among all isotherms describing adsorption, and often serves as

a basis for more detailed developments [20]

.

2. Freundlich Isotherm

Boedecker proposed in 1895 an empirical adsorption equation known as Freundlich isotherm,

because Freundlich assigned great importance to it and popularized its use. It is frequently

found that data on adsorption from a liquid phase are fitted better by the Freundlich isotherm

equation, provided that the adsorption sites are not identical, and the total adsorbed amount is

the same over all types of sites. The Freundlich isotherm is expressed as:

Log 10 qe = log 10(Kf) + (1/n) log10 (Ce)

Where, qe is the amount of adsorbate adsorbed at equilibrium (mg/g), and Ce is the

equilibrium concentration of adsorbate in solution (mg/L). Kf and n are the constants

incorporating all factors affecting the adsorption process [19]

.

The Freundlich equation is an empirical expression that encompasses the heterogeneity of the

surface and the exponential distribution of sites and their energies. According to Freundlich

equation, the amount adsorbed increases infinitely with increasing concentration or pressure.

This equation is, therefore, unsatisfactory for high coverage. At low concentration, this

equation does not reduce to the linear isotherm. In general, a large number of the

experimental results in the field of van der Walls adsorption can be expressed by means of

the Freundlich equation in the middle concentration range [19]

.

[208]

3. Temkin Isotherm

Temkin isotherm model is given by following equation:

X= a + b ln C

Where, C is the equilibrium concentration of solution (mg/L), X is amount of adsorbate

adsorbed per gram weight of adsorbent (mg/g), a and b are constants related to adsorption

capacity and intensity of adsorption and related to the intercept and slope of the plots of ln C

versus X [21]

.

4. BET Isotherm

BET isotherm was developed by Brunauer, Emmett and Teller as an extension of Langmuir

isotherm, which assumes that first layer of molecules adhere to the surface with energy

comparable to heat of adsorption for monolayer sorption and subsequent layers have equal

energies. Equation in its linearized form expressed as:

Cf/ (Cf-Cs) q = 1/Bqmax – (B-1/Bqmax) (Cf/Cs)

Where, Cs is the saturation concentration (mg/L) of the solute, Cf is solute equilibrium

concentration. B and qmax are two constants and can be evaluated from the slope and intercept

[22].

[209]

4.3 Results & Discussion

4.3.1(A) Effect of pH

pH of an aqueous medium has an important role for the uptake of the adsorbate. The

chemical characteristics of both adsorbate and adsorbent vary with pH. Detail Study was

conducted to observe the effect of pH in the range of 2–10. The pH of the solutions was

maintained by adding 1N HCl or 1N NaOH. In this batch study, initial concentration of

crystal violet was fixed at 200 mg/L & the dose of adsorbent at 6 gm/L. It was observed that

with increase in pH, removal of Crystal Violet increased up to certain pH range & again

gradually decreased. At pH > 9.15 SDS molecules are desorbed from the alumina surface and

cause reduction in the Crystal Violet removal. Here in below figure 4.9, it is shown that

maximum removal of Crystal Violet was obtained from experimental data i.e. 99.8 % and

adsorption capacity (qe i.e. 33.27 mg/gm) at pH 8 [17]

.

Table 4.4 & figure 4.9 show the effect of pH on the removal of Crystal Violet by ASMA

from the Aqueous Solution. Results of % removal of Crystal Violet at various adsorbent

dosages have been given in table 4.5 & it is graphically presented in figure 4.10.

[210]

Table 4.4: Effect of pH on Adsorption of CV by ASMA from Aqueous Solution

High

initial

conc. of

CV (mg/L)

Adsorbent

Dosage

Gm/L

Contact

Time

(Hr.)

pH

Range Absorbance

Final Conc. of CV (mg/L)

from Calibration Curve

(y=0.10x * Sample Vol.)

200 6 1.0

2 1.157 16.3

4 0.090 1.0

6 0.080 0.8

8 0.045 0.4

10 0.074 0.7

Figure 4.9: Effect of pH on Adsorption of CV by ASMA from Aqueous Solution

[211]

Table 4.5: % Removal of CV & Adsorption Capacity of ASMA at Different pH

High initial

conc. of CV

(mg/L)

Adsorbent

Dosage

Gm/L

Contact Time

(Hr) pH Range % Removal

Adsorption

Capacity qe

(mg/gm)

200 6 1.0

2 91.9 30.62

4 99.5 33.17

6 99.6 33.20

8 99.8 33.27

10 99.7 33.22

Figure 4.10: Effect of pH on % Removal of CV by ASMA

[212]

4.3.1(B) Effect of Contact Time

One of the most effective factors affecting adsorption is agitation time or contact time. In the

present study 3 range of contact time was selected to determine the effect of contact time on

CV removal by ASMA which are 30 minutes, 60 minutes & 90 minutes. Among them 60

minutes was found equilibrium for adsorption of Crystal Violet on ASMA. Almost 99.9%

removal was observed at 6 gm/L ASMA dosage and 8 pH. After that % removal efficiency

was decreasing at 90 minutes. As the % removal is almost same at 30 minute & 60 minute we

can consider 30 minute as equilibrium contact time for further studies. This will save both

time & energy.

This decrease in the adsorption rate may be due to a distribution of surface sites that cause

decrease in adsorbent - adsorbate interaction with increasing surface density [23]

. It may be

explained by the fact that optimum adsorption occurs at a particular pH, dose and time.

Gradually adsorption process got slowed because initially a number of vacant surface sites

may be available for adsorption and after some time, the remaining vacant surface site may

be exhausted due to repulsive forces between the adsorbent and counter ion binding at the

surface of the adsorbate [17]

.

Table 4.6 & figure 4.11 show the effect of contact time on the removal of Crystal Violet by

ASMA from the Aqueous Solution. Results of % removal of Crystal Violet at various

adsorbent dosages have been given in table 4.7 & it is graphically presented in figure 4.12.

[213]

Table 4.6: Effect of Contact Time on Adsorption of CV by ASMA from Aqueous Solution

High initial

conc. of CV

(mg/L)

Adsorbent

Dosage

Gm/L

Equilibrium

pH

Contact

Time

(Min.)

Absorbance

Final Conc. of CV

(mg/L)

from Calibration

Curve

y=0.10x * Sample vol.

200 6 8

30 0.057 0.6

60 0.045 0.4

90 0.136 1.6

Figure 4.11: Effect of Contact Time on Adsorption of CV by ASMA from Aqueous Solution

[214]

Table 4.7: % Removal of CV & Adsorption Capacity of ASMA at Different Contact Time

High initial

conc. of CV

(mg/L)

Adsorbent

Dosage

Gm/L

Equilibrium

pH

Contact Time

(Min.) % Removal

Adsorption

Capacity qe

(mg/gm)

200 6 8

30 99.7 33.23

60 99.8 33.27

90 99.2 33.07

Figure 4.12: Effect of Contact Time on % Removal of CV by ASMA

[215]

4.3.1(C) Effect of Adsorbent Dosages

To observe the effect of adsorbent dosage i.e. ASMA dosage various range of the adsorbent

dosage was selected which were between 1 – 9 gm/L. From the experiments it was observed

that adsorption increases with the increase of ASMA dosage. % Removal of crystal violet

increases from 97.6 % to 99.9 % as the ASMA dosage increases from 1 gm/L to 7 gm/L.

Maximum % removal i.e. 99.9% was observed at 7 gm/L ASMA dosage. pH was adjusted 8

& 30 minutes Contact Time was given. But it was also observed that almost 99.8% removal

was observed at 6 gm/L dosage of ASMA. So we can consider 6 gm/L as equilibrium dosage

& can keep that dosage in further studies to save chemical.

After completion of reaction time supernatant was collected & final conc. of crystal violet

was measured spectrophotometrically. After 7 gm/L i.e. at 8 & 9 gm/L, it was observed that

the % removal efficiency decrease slightly & remain almost constant. Higher the dose of

adsorbent in the solution, greater is the availability of exchangeable sites for metal ions and

greater is the surface area [24]

. From the results, the equilibrium adsorbent ASMA dosage is 7

gm/L. Adsorption capacity qe decreases with increase in adsorption dosage due to increase in

dosage surface area will increase & per gram adsorption will decrease [24]

.

Table 4.8 & figure 4.13 show the effect of adsorbent dosage on the removal of Crystal Violet

by ASMA from the Aqueous Solution. Results of % removal of Crystal Violet at various


[216]

Table 4.8: Effect of Adsorbent Dosage on Adsorption of CV by ASMA from Aqueous Solution

High

initial

conc. of

CV

(mg/L)

Equilibrium

Contact

Time (Min.)

Equilibrium

pH

Adsorbent

Dosage

Gm/L

Absorbance

Final Conc. of CV

(mg/L)

from Calibration

Curve

y=0.10x * Sample vol.

200 30 8

2 0.472 4.7

3 0.334 3.3

4 0.142 1.4

5 0.077 0.8

6 0.045 0.4

7 0.026 0.3

8 0.039 0.4

9 0.033 0.3

Figure 4.13: Effect of Adsorbent Dosage on Removal of CV by ASMA from Aqueous Solution

[217]

Table 4.9: %Removal of CV & Adsorption Capacity of ASMA at Different Adsorbent Dosage

High initial

conc. of CV

(mg/L)

Equilibrium

Contact Time

(Min.)

Equilibrium

pH

Adsorbent

Dosage

(Gm/L)

%

Removal

Adsorption

Capacity qe

(mg/gm)

200 30 8

2 97.6 97.6

3 98.3 65.6

4 99.3 49.7

5 99.6 39.8

6 99.8 33.3

7 99.9 28.5

8 99.8 25.0

9 99.8 22.2

Figure 4.14: Effect of Adsorbent Dosage on %Removal of CV by ASMA

[218]

4.3.1(D) Effect of Initial Adsorbate (Crystal Violet) Concentration

The effect of initial concentration of adsorbate Crystal Violet on the adsorption process was

studied. Here, adsorbent dose was kept 6 gm/L, pH 8 was adjusted and contact time was

given 30 minutes. Initial concentration of Crystal Violet was adjusted 100 mg/L, 200 mg/L,

300 mg/L & 400 mg/L. Final conc. of CV was observed 0.3 mg/L, 0.4 mg/L, 1.3 mg/L & 2.2

mg/L respectively for 100 mg/L, 200 mg/L, 300 mg/L & 400 mg/L high initial concentration.

The % removal of CV was observed 99.7%, 99.8%, 99.6% & 99.5% respectively for 100

mg/L, 200 mg/L, 300 mg/L & 400 mg/L high initial concentration. Here, in the present study

% removal efficiency was almost same or near the same for all the high initial concentartion

ranges. Therefore the adsolubilization technique used in present study can be applied to the

waste water or aqueous solution containing higher concentration of Crystal Violet dye. From

the experiment, optimum dosage is 200 mg/L with 99.8% Crystal Violet removal but here

adsorption capacity (qe) increases with increase in concentration of Crystal Violet, due to

availability of higher amount of adsorbate, while in rest of the variables experiments, Crystal

Violet dose was constant.

Table 4.10 & figure 4.15 show the effect of adsorbate concentration on the removal of

Crystal Violet by ASMA from the Aqueous Solution. Results of % removal of Crystal Violet

at various adsorbent dosages have been given in table 4.11 & it is graphically presented in

figure 4.16.

[219]

Table 4.10: Effect of Initial Adsorbate Concentration on Adsorption of Crystal Violet by ASMA from

Aqueous Solution

Equilibrium

Adsorbent

Dosage

(Gm/L)

Equilibrium

Contact

Time

(Min.)

Equilibrium pH

High initial

conc. of

Crystal Violet

(mg/L)

Absorbance

Final Conc. of

CV

from Calibration

Curve (mg/L)

6 30 8

100 0.030 0.3

200 0.045 0.4

300 0.125 1.3

400 0.217 2.2

Figure 4.15: Effect of Adsorbate Conc. on Adsorption of CV by ASMA from Aqueous Solution

[220]

Table 4.11: %Removal of CV & Adsorption Capacity of ASMA at Different Initial Adsorbate Conc.

Equilibrium

Adsorbent

Dosage

(Gm/L)

Equilibrium

Contact Time

(Min.)

Equilibrium

pH

High

initial

conc. of

CV

(mg/L)

Final Conc. of CV

(mg/L)

from Calibration

Curve

%

Removal

Adsorption

Capacity qe

(mg/gm)

6 30 8

100 0.3 99.7 16.6

200 0.4 99.8 33.3

300 1.3 99.6 49.8

400 2.2 99.5 66.3

Figure 4.16: Effect of Initial Adsorbate Conc. on %Removal of CV by ASMA

[221]

4.3.1(E) Effect of Temperature

To observe the effect of temperature on removal of CV from aqueous solution three different

temperature ranges was selected viz. 30 °C, 40 °C & 50 °C. For the study purpose, 3 sets

were prepared. Temperature range was adjusted by the knob of magnetic stirrer. Here

adsorbent dosage & pH were kept 6 gm/L & 8 respectively for all the sets. 30 minutes contact

time was provided. But no change in % removal efficiency was observed at different

temperature. As shown in graph 99.8 % CV removal was observed for all the temperature

range. Thus it can be concluded that temperature has no effect on the CV removal.

Table 4.12 & figure 4.17 show the effect of temperature on the removal of Crystal Violet by

ASMA from the aqueous solution. Results of % removal of Crystal Violet at various


Table 4.12: Effect of Temperature on Adsorption of CV by ASMA from Aqueous Solution

High

initial

conc. of

CV (mg/L)

Equilibrium

Contact

Time

(min.)

Equilibrium

pH

Adsorbent

Dosage

Gm/L

Temp

(°C) Absorbance

Final Conc.

of CV

(mg/L)

from

Graph

200 30 8 6

30 0.045 0.40

40 0.039 0.39

50 0.042 0.42

Figure 4.17: Effect of Temperature on Removal of CV by ASMA

[222]

Table 4.13: %Removal of CV & Adsorption Capacity of ASMA at Different Temperature

High

initial

conc. of

CV

(mg/L)

Equilibrium

Contact Time

(Min.)

Equilibrium

pH

Equilibrium

Adsorbent

Dosage

(Gm/L)

Temp

(°C)

%

Removal

Adsorption

Capacity qe

(mg/gm)

200 30 8 6

30 99.8 33.3

40 99.8 33.3

50 99.8 33.3

Figure 4.18: Effect of Temperature on %Removal of CV by ASMA

[223]

4.3.2 Chemical Kinetic Study

Chemical kinetics is also known as reaction kinetics. It is the study of rates of chemical

processes. It includes investigations of how different experimental conditions can influence

the speed of a chemical reaction. In order to investigate the controlling mechanism of

adsorption process such as mass transfer & chemical reaction, a suitable kinetic model is

needed to analyze the data. In the present study, three kinetic models have been tested in

order to predict the adsorption data of ASMA as a function of time using a Pseudo-First

Order, Pseudo-Second Order Kinetic Models & Intra-Particle Diffusion Model. Table 4.14

shows experimental data of chemical kinetic study.

Table 4.14: Experimental Data of Chemical Kinetic Study

High initial

conc. of

CV (mg/L)

Equilibrium

pH

Adsorbent

Dosage

(Gm/L)

Time

Interval

(min.)

Final Conc. of CV

(mg/L) from

Graph

Adsorption

Capacity qt (mg/gm)

200 8 6

5 8.5 31.91

10 1.7 33.05

15 0.8 33.20

20 0.6 33.24

25 0.5 33.25

30 0.4 33.27 = qe

1) Pseudo-First Order Model

Log (qe - qt) = log qe – (k1/2.303) t

Where, qe (mg/gm)is the mass of CV adsorbed at equilibrium, qt (mg/gm) the mass of CV at

any time (t) & K1 (min-1

) is the equilibrium rate constant of pseudo-first order adsorption. The

values of k1 & qe are determined from the slope & intercept of the plot of Log (qe - qt) versus

t, respectively [23]

. Data required for Pseudo First Order Kinetic Model is given in table 4.15.

[224]

Table 4.15: Data Required for Pseudo First Order Kinetic Model Calculation

Time Interval

(min.)

Final Conc. of CV

(mg/L) from Graph Log (qe – qt) qt (mg/gm)

5 8.5 0.1335 31.91

10 1.7 -0.6576 33.05

15 0.8 -1.1549 33.20

20 0.6 -1.6990 33.24

25 0.5 -1.6990 33.25

30 0.4 0.0 33.27 = qe

Where, qe (mg/gm) = Mass of CV Adsorbed, qt (mg/gm) = Mass of CV at particular time

qe = [(Initial Conc. of CV – Final Conc. of CV)/M) * V

Where, V is the volume of solution (in Liter) & M is the mass of adsorbent (gm) [15]

.

Plot of time interval Vs. Log (qe – qt) is represented in figure 4.19. Calculated values of

constant K1 & correlation coefficient r2 is given in table 4.17.

Table 4.16: Pseudo First Order Kinetic Study

Time Interval (min.) Log (qe – qt)

5 0.1335

10 -0.6576

15 -1.1549

20 -1.6990

25 -1.6990

30 0.0000

[225]

Figure 4.19: Graphical Presentation of Pseudo First Order Kinetic Study

Calculation from Graph

K1/2.303 = Slope

Where, Slope from Graph = -0.024; i.e. K1 = -0.024 * 2.303 = -0.055272

qe (calculated) = Antilog (intercept from graph) = Antilog (-0.412) = 0.3873

Table 4.17: Pseudo-First Order Kinetic Parameters for CV adsorption on ASMA

From the above study it was observed that the present adsolubilization process does not

follow pseudo first order kinetic model. The experimental qe is 33.27 mg/gm & qe value

calculated from graph is 0.3873 mg/gm. As given in the Table 4.17 the experimental &

calculated values of adsorption capacity i.e. qe are not at all in good agreement. From the

figure 4.19, correlation coefficient value i.e. R2 was obtained 0.082 (which is very less)

indicates very poor rate of reaction. From all the above experimental as well calculated data it

was observed that the CV removal by ASMA does not follow pseudo first order kinetic

model.

Adsorbent qe (mg/gm)

(Exp.)

qe (mg/gm)

(Cal.) K1 (min

-1) R

2

ASMA 33.27 0.3873 -0.055272 0.082

[226]

2) Pseudo-Second Order Kinetic Model

t / qt = 1/ k2qe2 + (1/ qe) t

Where, k2 is the pseudo-second order rate constant (g mg-1

min-1

) [17]

. The value of qe is

determined from the slope of the plot of t/ qt versus t (figure 4.20). The calculated value of qe

(34.49 mg/gm) from the pseudo second order kinetic model & it is in good agreement with

experimental qe value (33.27 mg/gm). The obtained correlation coefficient value i.e. R2 =

0.99 indicates very good rate of reaction. This suggests that the sorption system followed the

pseudo second order kinetic model. The value of kinetic constants and qe values of CV

sorption onto ASMA are given in table 4.19.

Table 4.18: Data Required for Pseudo Second Order Kinetic Model Calculation

Time Interval (min.) qt (mg/gm) t/qt

5 31.91 i.e. 5/31.91 = 0.16

10 33.05 i.e. 10/33.05 = 0.30

15 33.20 i.e. 15/33.2 = 0.45

20 33.24 i.e. 20/33.24 = 0.60

25 33.25 i.e. 25/33.25 = 0.75

30 33.27 i.e. 30/33.27 = 0.90

Figure 4.20: Pseudo-Second Order Kinetic Model Study

[227]

Calculation from Graph

qe (Calculated) = 1/Slope from graph = 1/0.029 = 34.49

Intercept = 0.006 = 1/K2qe2

i.e. K2 = 1/ [0.006*(34.49)2] = 1/7.1374 = 0.1401 gm/mg/minute

Table 4.19: Pseudo-Second Order Kinetic Parameters for CV Adsorption on ASMA

Adsorbent qe (mg/gm)

(Exp.)

qe (mg/gm)

(Cal.)

Kinetic Constant

K2 (g mg-1

min-1

) R

2

ASMA 33.27 34.49 0.1401 0.99

3) Intra-Particle Diffusion Model

qt = kid t1/2 + C

Where, C is the intercept & Kid is the intra-particle diffusion rate constant. The intra-particle

diffusion rate constant was determined from the slope of linear gradients of the plot qt versus

t1/2

[17]

as shown in the figure 4.21. Table 4.20 shows parameters of intra-particle diffusion.

Table 4.20: Parameters of Intra-Particle Diffusion

Time Interval (min.) qt (mg/gm) √Time

5 31.91 2.2361

10 33.05 3.1623

15 33.20 3.8730

20 33.24 4.4721

25 33.25 5.0000

30 33.27 5.4772

[228]

Figure 4.21: Intra-Particle Diffusion Study

Table 4.21: Intra-Particle Diffusion Parameters from Graph

Adsorbent Kid C (Graph)

(mg/gm)

qe (Exp.)

(mg/gm) R

2

ASMA 0.36 31.52 32.27 0.67

According to this model, the plot of uptake, qt, versus the square root of time (t1/2

) should be

linear if intra-particle diffusion is involved in the adsorption process & if this line pass

through the origin then intra-particle diffusion is the rate controlling step [25]

. When the plot

does not pass through the origin, this is indicative of some degree of boundary layer control

& this further show that intra-particle diffusion is not only rate-limiting step, but also other

kinetic models may control the rate of adsorption, all of which may be operating

simultaneously [26]

.

The values of rate constant of intra-particle diffusion are given in table 4.21. The values of

the intercept C provide information about the thickness of boundary later i.e. larger the

intercept, larger is the boundary layer effect. Here, intercept C is 31.52 & experimental value

of Adsorption Cpacity (qe) is 33.27 mg/g. Both of them are in good agreement. Calculated

value of adsorption capacity supports the practically obtained adsorption capacity.

[229]

4.3.3 Adsorption Isotherm Studies

1. Langmuir Isotherm

The experimental result of Langmuir isotherm for uptake of CV (Ini. Conc. 200 mg/L) on

ASMA from Aqueous Solution is shown in table 4.22 & Langmuir constant calculated from

graph is shown in table 4.23. Graphical representation of the same is shown in figure 4.22.

Table 4.22: Langmuir Isotherm Data for Uptake of CV (Ini. Conc. 200 mg/L) on ASMA from Aqueous

Solution.

Adsorbent

Dosage (gm)

Langmuir Isotherm

Ce

(Final Conc. of Adsorbate)

(mg/L)

qe

(Adsorption Capacity)

(mg/gm)

Ce/qe

2 4.72 97.6 0.048

3 3.34 65.6 0.051

4 1.42 49.7 0.029

5 0.77 39.8 0.019

6 0.4 33.3 0.012

7 0.26 28.5 0.009

8 0.39 25.0 0.016

9 0.33 22.2 0.015

Figure 4.22: Langmuir Isotherm Plot for Uptake of CV on ASMA from Aqueous Solution

[230]

Table 4.23: Langmuir Constants for Uptake of CV on ASMA from Aqueous Solution

Q0 (mg/gm) b (L/mg) R2

100 1 0.91

The values of coefficient of correlation (R2) for uptake of CV on ASMA obtained is in good

agreement. The value of R2

is 0.91, which is nearer to 1, indicates favorable adsorption. It

indicates first layer of molecules adhere to the surface with energy comparable to heat of

adsorption for monolayer sorption and subsequent layers have equal energies [22, 27]

. Here we

can say that Langmuir isotherm applies to each layer [27, 28]

. The higher values of Q0 i.e. 100

mg/gm & b i.e. 1 L/mg obtained for uptake of CV on ASMA for Langmuir isotherm suggest

better applicability of it. Thus uptake of CV on ASMA has good fit for Langmuir isotherm.

2. Freundlich Isotherm

Results of modeling of the isotherms of CV adsorption by ASMA according to Freundlich

isotherm model is summarized in table 4.24. Graphical presentation of the Freundlich

isotherm is represented in figure 4.23. Table 4.25 shows the Freundlich constants calculated

from graph.

Calculation from Graph:

Langmuir Equation: Ce/qe = [1/Qo b + 1 / Qo × Ce]

Q0 = 1/Slope = 1/0.01 = 100 mg/gm; b = Intercept * Q0 = 0.01 * 100 = 1 (L/mg)

[231]

Table 4.24: Freundlich Isotherm Values for Uptake of CV (Ini. Conc. 200 mg/L) on ASMA from Aqueous

Solution.

Adsorbent

Dosage (gm)

Freundlich Isotherm

Ce

(Final Conc. Of Adsorbate)

(mg/L)

Ce / qe Log Ce Log Ce/qe

2 4.72 0.048 0.6739 -1.3188

3 3.34 0.051 0.5237 -1.2924

4 1.42 0.029 0.1523 -1.5376

5 0.77 0.019 -0.1135 -1.7212

6 0.4 0.012 -0.3979 -1.9208

7 0.26 0.009 -0.585 -2.04576

8 0.39 0.016 -0.4089 -1.7959

9 0.33 0.015 -0.4815 -1.8239

Figure 4.23: Freundlich Isotherm Plot for Uptake of CV on ASMA from Aqueous Solution


Freundlich Equation: Log10 qe = log 10(Kf) + (1/n) log10 (Ce)

n = 1/Slope = 1/0.56 = 1.8 L/mg

Kf = Antilog (Intercept) = Antilog (-1.64) = 0.023

[232]

Table 4.25: Freundlich Constants for Uptake of CV (Ini. Conc. 200 mg/L) on ASMA from Aqueous

Solution.

Kf (mg/gm) n (L/gm) R2

0.023 1.8 0.95

Here the value of Kf i.e. adsorption capacity 0.023 mg/gm & adsorption intensity n (rate of

adsorption) & i.e. 1.8 L/gm is obtained from Freundlich isotherm. The value of n fulfills the

condition (0 < n < 1) of Freundlich isotherm[17, 19, 27]

. The value of n in the range 2-10

represent good, 1-2 moderately difficult and less than 1 poor adsorption characteristics [29]

.

Here the value of intensity i.e. is 1.8 which is almost 2 represents moderately difficult

adsorption characteristics. The values of coefficient of correlation (R2) for uptake of CV on

ASMA obtained is in good agreement. The value of R2

is 0.95 indicates very good

adsorption.

The data obtained from the Freundlich plot indicates that the adsorption sites are not

identical; the total adsorbed amount is the same over all types of sites. It encompasses the

heterogeneity of the surface, exponential distribution of sites and their energies. It reflects

van der walls adsorption in the middle concentration range [30]

.

3. Temkin Isotherm

Results of modeling of the isotherms of CV adsorption by ASMA according to Temkin

isotherm model is summarized in table 4.26. Graphical presentation of the Temkin isotherm

is represented in figure 4.24. Table 4.27 shows the Temkin constants calculated from graph.

[233]

Table 4.26: Temkin Isotherm Values for Uptake of CV (Ini. Conc. 200 mg/L) on ASMA from Aqueous

Solution.

Adsorbent

Dosage (gm)

Temkin Isotherm

Ce

(Final Conc. Of Adsorbate) (mg/L) ln C X (mg/gm)

2 4.72 1.5518 97.6

3 3.34 1.206 65.6

4 1.42 0.3507 49.7

5 0.77 -0.2614 39.8

6 0.4 -0.9163 33.3

7 0.26 -1.3471 28.5

8 0.39 -0.9416 25.0

9 0.33 -1.1087 22.2

Figure 4.24: Temkin Isotherm Plot for Uptake of CV on ASMA from Aqueous Solution


Temkin Equation: X = a + b ln C

b = Slope = 21.8 L/mg & a = Intercept = 49.2 mg/gm

[234]

Table 4.27: Temkin Constants for Uptake of CV on ASMA from Aqueous Solution

a (mg/gm) b (L/mg) R2

49.2 21.8 0.9

The value of correlation coefficient R2 is 0.9 indicates vary good adsorption characteristic

with Temkin isotherm. The uptake of CV on ASMA follows Temkin isotherm as the value of

b is 21.8 which is very high [21]

& value of a i.e. adsorption capacity calculated from graph is nearer

to experimental average qe i.e. 45.2 mg/gm. The Temkin isotherm fits the present data because it

takes into account for the occupation of the more energetic adsorption sites at first [31]

. Value

of the Temkin isotherm fits best for the uptake of CV on ASMA in the present study.

4. BET Isotherm

Result of modeling of the isotherms of CV adsorption by ASMA according to BET isotherm

model is summarized in table 4.28. Graphical presentation of the BET isotherm is represented

in figure 4.25. Table 4.29 shows the BET constants calculated from graph.

Table 4.28: BET Isotherm Values for Uptake of CV (Ini. Conc. 200 mg/L) on ASMA from Aqueous

Solution.

Adsorbent

Dosage (gm)

BET Isotherm

Cf

(Final Conc. of

Adsorbate) (mg/L)

q

(mg/gm) Cf / Cs Cf/(Cs - Cf)*q

2 4.72 97.6 0.0236 2.360

3 3.34 65.6 0.0167 1.114

4 1.42 49.7 0.0071 0.355

5 0.77 39.8 0.0039 0.154

6 0.4 33.3 0.0020 0.067

7 0.26 28.5 0.0013 0.037

8 0.39 25.0 0.0020 0.049

9 0.33 22.2 0.0017 0.037

[235]

Figure 4.25: BET Isotherm Plot for Uptake of CV on ASMA from Aqueous Solution

Table 4.29: BET Constants for Uptake of CV on ASMA from Aqueous Solution

qmax (mg/gm) B (L/mg) R2

0.01 -538.4 0.96


BET Equation: Cf / (Cs-Cf)q = 1/Bqmax – (B – 1/ Bqmax) (Cf/Cs)

1/B*qmax = Intercept i.e. B*qmax = -5.56

i.e. qmax = -5.59 /-538.4 = 0.01 mg/gm

((B – 1)/B*qmax) = Slope = 96.65

i.e. B – 1 = 96.65 * -5.56

i.e. B = -538.4 (L/mg)

[236]

The experimental data for uptake of CV on ASMA have best fit for BET isotherms of

adsorption isotherm. The value of R2 obtained 0.96 for BET isotherm indicates the same.

Here we can say that BET isotherm as an extension of the Langmuir isotherm to account for

multilayer adsorption and Langmuir isotherm applies to each layer [28]

.

4.4 Regeneration Study

After removal of CV from Waste Water, ASMA can be regenerated using Acetone by

following method.

2 gm of exhausted ASMA (i.e. ASMA after CV removal) was taken in a beaker.

8 ml of Acetone was added to it.

The beaker was kept on the magnetic stirrer for 1 Hr at 24°C. The mixture was stirred

well.

Arrange the distillation assembly.

Then after collect the mixture of Acetone & CV in a distillation flask.

Here, boiling points of Acetone & CV are 56°C & 205°C respectively.

Therefore, conduct distillation process at 56°C & distilled out the Acetone in a

collection beaker.

Collect the distillate of Acetone & store it in a glass bottle.

This Acetone can be used further in various processes.

The remaining CV, in a distillation flask, was tested to measure the concentration of

CV desorbed from the ASMA & extracted in Acetone.

After completion of distillation, CV as a solid matter was observed in the distillation

flask.

The final concentration of CV was measured by using above mentioned direct


From the result we found 160 mg/L concentration of extracted CV. The initial high

concentration of CV was 200 mg/L & after adsolubilization by 6 gm/L ASMA it was

0.4 mg/L.

That means 199.6 mg/L of CV was adsolubilized on ASMA.

During Acetone treatment almost 160 mg/L of CV desorbed from the ASMA &

extracted in the Acetone.

[237]

From the results shown in Table 4.30 almost 80% CV can be recovered. Then both

CV as well as ASMA can be reuse for further production or treatment respectively.

But % removal efficiency of ASMA may decrease after regeneration.

% recovery may be extended by using sophisticated instruments & more precise

experimental work.

Then both Crystal Violet as well as ASMA can be reused for further production or

treatment respectively.

Table 4.30: Recovery of Crystal Violet

Initial

Conc.

of CV

(mg/L)

Final

Conc.

of CV

(mg/L)

Quantity

of

Exhausted

ASMA

(gm)

Quantity

of

Acetone

(ml)

Contact

Time for

Recovery

(Hr.)

Temp.

(°C)

Conc. of CV

Adsolubilized

on ASMA

(mg/L)

Conc. of

CV

Extracted

by Acetone

(mg/L)

%

Recovery

of CV

200 0.4 2 8 1 24

=Ini. Conc.

– Final

Conc.

i.e.

200 – 0.4

= 199.6

160 80

4.5 Removal of Mixed Dye from Actual Sample of Textile Industry by ASMA &

DTAC Modified Silica Gel:

The removal of dye from actual textile sample by using anionic surfactant SDS modified

Alumina (i.e. ASMA) & cationic surfactant Dodecyl Trimethyl Ammonium Chloride

(DTAC) Modified Silica Gel (i.e. CSMSG) was also carried out. The sample was containing

mixed dye & its color was brownish red so absorbance was taken at 460 nm. Textile sample

was separately treated with ASMA (Anionic Surfactant Modified Alumina) & CSMSG

(Cationic Surfactant Modified Silica Gel) each. pH 8, contact time 30 min., adsorbent dosage

6 gm/L were adjusted to observe the % removal with ASMA. pH 4, contact time 20 min.,

adsorbent dosage 8 gm/L were adjusted to observe the % removal with CSMSG. Maximum

60% removal was observed with CSMSG for the actual sample & 41% removal was observed

with ASMA.

[238]

The results of % removal have been mentioned in Table 4.31. From the results it was

observed that the CSMSG is an effective adsorbent to remove dyes from industrial waste

water. It may remove more than 60 % of Dyes from the aqueous solution if the sample would

be treated again with fresh adsorbent CSMSG. ASMA showed very less removal efficiency

for actual sample.

Table 4.31: %Removal of Mixed Dyes from Actual Sample

Adsorbent

Used

Adsorbent

Dosage

(Gm/L)

Contact

Time

(Min.)

pH

High Initial

conc. of Dye

(mg/L)

Final Conc. of

Dye (mg/L)

from

Calibration

Curve

% Removal

CSMSG 8 20 4

8168

3338 60

ASMA 6 30 8 4850 41

4.6 Conclusion

In the present study batch experiments were carried out to observe their effect on CV removal

by ASMA. It was observed that the Anionic Surfactant Modified Alumina can be used as an

effective adsorbent in the waste water treatment for the removal of Crystal Violet Dye.

Various factors affecting CV removal were also studied. The variables for pH were decided

2, 4, 6, 8 & 10 to find out optimum pH for further treatment. While studying pH variables;

other parameters such as high initial concentration of Crystal Violet (200 ppm), Contact Time

(1 Hr), & Adsorbent ASMA Dosage (6 gm/L) were kept constant. The variables for contact

time were decided as 1/2 Hr, 1 Hr & 1.5 Hr to find out optimum contact time for further

treatment. While studying Contact Time variables; other parameters such as high initial

concentration of Crystal Violet (200 ppm), pH (8 – optimum pH obtained from previous

study), & Adsorbent ASMA Dosage (6 gm/L) were kept constant. The variables for

Adsorbent ASMA Dosage were decided as 2 gm/L, 3 gm/L, 4 gm/L, 5 gm/L, 6 gm/L, 7

gm/L, 8 gm/L & 9 gm/L to find out optimum adsorbent dosage for further study. While

studying Adsorbent ASMA Dosage variables; other parameters such as high initial

concentration of Crystal Violet (200 ppm), pH (8 – optimum pH obtained from previous

study) & Contact Time (1/2 Hr – optimum contact time obtained from Previous study) were

[239]

kept constant. The variables for adsorbate concentration were decided as 100 ppm, 200 ppm,

300 ppm & 400 ppm to find out optimum adsorbate concentration for further study. While

studying high intial Adsorbate Concentration variables; other parameters such as pH (8 –

optimum pH obtained from previous study) & Contact Time (1/2 Hr – optimum contact time

obtained from Previous study) & Adsorbent ASMA Dosage (6 gm/L) from previous study)

were kept constant. From the batch study pH 8, contact time 30 minutes & ASMA adsorbent

dosage 7 gm/L were found optimum experimental conditions to get maximum 99.9 %

removal of Crystal Violet from aqueous solution. From the adsorbate variable study it was

observed that different adsorbate concentration did not affect Crystal Violet removal by

ASMA from aqueous solution. It shows that the ASMA can be used to remove Crystal Violet

of any high range. From the batch study; pH 8 (99.8% removal of CV), contact time 30 min

(99.7% removal of CV) & adsorbent dosage 7 gm/L (99.9% removal of CV) was found

optimum experimental conditions for maximum % removal of Crystal Violet from aqueous

solution. From the adsorbate variable study it was observed that different adsorbate

concentration did not affect Crystal Violet removal by ASMA from aqueous solution. It

shows that the ASMA can be used to remove Crystal Violet of any high range. The variables

for temperature were decided as 30 ˚C, 40 ˚C & 50 ˚C to find out optimum temperature

range. From the study it was observed that temperature had no effect on % removal efficiency

of ASMA. It was found same i.e. 99.8% for all the temperature range. By maintaining

optimum experimental conditions maximum 99.8% removal of CV was achieved.

The removal efficiency was also checked on actual textile sample & it was found that

CSMSG removed maximum 60% of mixed dye where as ASMA removed 41% of mixed

dye. From the study it is confirmed that CSMSG & ASMA are very good adsorbents & they

can be efficiently used in industries to remove dyes from the effluent.

For the regeneration of ASMA, Acetone was used. In this study it was found that only CV

was desorbed from the ASMA & not surfactant. This is due to pH is less than Zpc of Alumina

i.e. 9.15. During recovery, 2 gm of exhausted ASMA was treated with 8 ml of Acetone for 1

Hr. at 24 °C. Almost 80% recovery of Phenol was observed during extraction.

[240]

4.7 Recommendation

The present study suggested that ASMA can be effectively useful in the treatment plant for

removal of Crystal Violet. These data can be used in designing and fabrication of an

economic treatment plant for the removal of dye from wastewaters generated from textile,

dye manufacturing industries, paint & varnish industries, etc. By implementing this

technology we can prevent the introduction of dye or coloured water into adjacent water

resources. Colored dye effluents pose a major threat to the surrounding ecosystem. Many of

the dyes are extremely toxic. Among various dyes, crystal violet (CV) is a wellknown

cationic dye and has been used as a biological stain, a dermatological agent, a veterinary

medicine, and as an additive to poultry feed to inhibit propagation of mold, intestinal

parasites, and fungus etc. It is also extensively used in textile dying and paper printing. Thus

dyes and surfactants are the two contaminants occurring in many industrial wastes, and in

many cases at a high concentration level. It is thus very important to find ways for the

removal of surfactants and dyes from the water environment when present at high

concentration.

Dyes are very dangerous constituents of waste water of many industries. As they are easily

soluble in water, they can damage public health by running to the drinking water discharge

point. Anionic surfactant modified alumina can adsolubilize basic dyes efficiently from

aqueous media without consuming much energy. Again the CV can be regenerated by using

Acetone – an organic solvent & both can be separated by distillation. Thus separated Acetone

& CV can be re-used as raw materials again in the industries.

[241]

Here in the figure 4.26 probable plant lay out for the treatment of industrial effluent by

ASMA has been given.

Figure 4.26: Treatment Layout for the Industrial Effluent by using Anionic Surfactant Modified

Alumina.

Waste Water

Containing

Dye

Equalization

Tank

Agitation Tank,

Where ASMA

Dosage of 6 gm/L

can be given

pH 8 shall be

Maintained by

Adding 1N HCl or

1N NaOH

30 min. Retention

Time is Provided for

the Reaction

Recycle & Reuse Treated Water

(supernatant) & Regenerate

exhausted ASMA (sludge) by

Acetone to Recycle & Reuse

Regeneration of ASMA &

recovery of CV to recycle

& reuse

[242]

4.8 Reference:

1. Wikipedia, Free Encyclopedia

2. Wikipedia, Free Encyclopedia ,Colour Index 3rd Edition Volume 4, Bradford: Society

of Dyers and Colourists, 4391, (1971)

3. Gessner, T.; Mayer, U., Triarylmethane and Diarylmethane Dyes, Ullmann's

Encyclopedia of Industrial Chemistry, Weinheim: Wiley-

VCH,doi:10.1002/14356007.a27_179, 6 , (2002)

4. Wikipedia, Free Encyclopedia, Reinhardt, C.; Travis, A.S., Heinrich Caro and the

creation of modern chemical industry, Dordrecht, Netherlands: Kluwer Academic,

ISBN 0-7923-6602-6, 208–209, (2000)

5. Wikipedia, Free Encyclopedia, Caro H. & Kern A., Manufacture of dye-stuff or

coloring matter, US 290891, (1883)

6. Wikipedia, Free Encyclopedia, Thetner, D., Triphenylmethane and related dye, Kirk-

Othmer Encyclopedia of Chemical Technology, Wiley (Also available from Scribd),

(2000)

7. Wikipedia, Free Encyclopedia, Lauth C., On the new aniline dye, Violet de Paris,

Laboratory, 1, 138–139, (1867)

8. Wikipedia, Free Encyclopedia, Gardner W., The British coal-tar industry : its origin,

development, and decline, Philadelphia: Lippincott, 173, (1915)

9. Wikipedia, Free Encyclopedia, Adams E., Rosenstein L., The color and ionization of

crystal-violet, J. Amer. Chem. Soc., doi:10.1021/ja02184a014, 36 (7), 1452–1473,

(1914)

10. Material Safety Data Sheet Crystal Violet MSDS

http://www.colour-index.org/help/3121_Triarylmethane.pdf

[243]

11. Wikipedia, Free Encyclopedia, Docampo R., Moreno S., The metabolism and mode

of action of gentian violet, Drug Metab.

Rev., doi:10.3109/03602539009041083,PMID 2272286, 22 (2–3), 161–178, (1990)

12. Wikipedia, Free Encyclopedia, Gorgas, Ferdinand J., Pyoctanin - Methyl-Violet -

Pyoctanine, Dental Medicine. A Manual Of Dental Materia Medica And

Therapeutics, archived from the original on 2011-03-15, retrieved 2011-03-15, 7

(chestofbooks.com), (1901)

13. Wikipedia, Free Encyclopedia, Henneman, Sheila A., Kohn, Frank S., Methylene blue

staining of tissue culture monolayers, Methods in Cell

Science1 , doi:10.1007/BF01352624, (2), 103, (1975)

14. Ratna1., Padhi. B., Pollution due to synthetic dyes toxicity & carcinogenicity studies

and remediation, International Journal of Environmental Sciences © Copyright by

authors – Licensee IPA – Under Creative Commons license 3.0 Research article ISSN

0976 – 4402, doi: 10.6088/ijes.2012030133002, 3 (3), 940, (2012).

15. Carmen Z., Daniela S., Textile Organic Dyes – Characteristics, Polluting Effects and

Separation/Elimination Procedures from Industrial Effluents – A Critical Overview

Zaharia Carmen and Suteu Daniela ‘Gheorghe Asachi’, Technical University of Iasi,

Faculty of Chemical Engineering and Environmental Protection, Romania, (2009).

16. Ratna & Padhi B., Pollution due to synthetic dyes toxicity & carcinogenicity studies

and remediation, International Journal of Environmental Sciences, 3 (3), 940 – 955,

(2012), doi: 10.6088/ijes.2012030133002.

17. Nameni M., Alavi M. R., Arami M., Adsorption of hexavalent chromium from

aqueous solutions by wheat bran, International Journal of Environment Science and

Technology, 5 (2), 161-168, (2008)

[244]

18. Safarik I., Safarikova M., Detection of low concentrations of malachite green and

crystal violet in water, water research, 36, 196-200, (2002).

19. Bansal M., Singh D., Garg V.K., Rose P., Mechanism of Cr+6

removals from synthetic

waste water by low cost adsorbents. Journal of Environmental Research &

Development, 3 (1), 228-243, (2008).

20. Noll K. E et al, Adsorption technology for the air and water pollution control, Lewis

Published Inc., (1992)

21. Abdel-Ghani N. T., El-Nashar R.M., El-Chaghaby G. A., Removal of Cr+3

and Pb+2

from solution by adsorption onto Casuarina glauca tree leaves. Electronic journal of

Environmental Agricultural and Food Chemistry, 7 (7), 3126-3133, (2008),

University of Vigo. Publication.

22. Sharma M., Rani N., Kamra A., Kaushik A., Bala K., Growth, Exopolymer

production and metal bioremoval by Nostoc punctiforme in Na+

and Cr+6

spiked

medium, Journal of Environment Research And Development, 4 (2), 372-379, (2009).

23. Adak A. and Pal A., Removal Kinetics and Mechanism for Crystal Violet Uptake by

Surfactant-Modified Alumina, Journal of Environmental Science and Health Part A,

Copyright C _ Taylor & Francis Group, LLC ISSN: 1093-4529 (Print), 1532-4117

(Online) DOI: 10.1080/10934520600872953, 41, 2283–2297, (2006)

24. Patel N.S., Desai H.H., Potential of Moringa oleifera seeds, leaves and barks for

removal of Hexavalent Chromium from aqueous solution with reference to

adsorption isotherm, International Journal of Water Resources and Environmental

Management, 3 (2), 41-57, (2011)

25. Arami M., Limaaee N., Mahmoodia N., Chem. Eng. J., 139, 2 – 10, (2008).

26. Yakout S. & Elsherif E., Batch Kinetics, isotherms and thermodynamic studies of

adsorption of strontium from aqueous solutions onto low cost rice-straw based

[245]

carbons, Applied Science Innovations Pvt. Ltd., india, Carbon-Sce. Tech., Carbon –

Science and Technology, ISSN 0974 – 0546, artcle, 1, 144 – 153, (2010),

http://www.applied-science-innovations.com.

27. Gholizadeh A., Kermani M. et al., Kinetic & isotherm studies of adsorption &

biosorption processes in the removal of phenolic compounds from aqueous solutions:

comparative stdy, J Environ Health Sci Eng, 11, (2013), doi: 10.1186/2052-336X-11-

29.

28. Sawyer C.N, McCarty P.L, Parkin G.F., Chemistry for Environmental Engineering

and science, Fifth edition, Tata McGraw- Hill Publishing Company Ltd. 52-113,

(2005).

29. Treybal R.E.; Mass Transfer Operations, (3), (1981), McGraw Hill.

30. Hu J., Chen G. and Irene M.C. Lo., Removal and recovery of Cr +6

from wastewater

by maghemite nanoparticles, Water Research, Elsevier, 39 (18), 4528-4536, (2005).

31. Kolasniski, K.W., Surface Science, (2001), Wiley, Chister, UK.

http://www.applied-science-innovations.com/

http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235831%232005%23999609981%23608870%23FLA%23&_cdi=5831&_pubType=J&view=c&_auth=y&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ea00675c0d5d0259e69474911bf1b451

chapter 4shodhganga.inflibnet.ac.in/bitstream/10603/37779/10/10_chapter 4.pdf · crystal violet is...

Documents