11

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

In this chapter the literature available within the purview of the

objectives of the present study is reviewed. The need for the proposed work is

also discussed.

2.2 REMOVAL OF CONTAMINANTS USING ORGANIC

ADSORBENTS

Shokoohi et al (2009) have studied the influence of various

experimental parameters such as initial iron concentration, dosage of biomass

and contact time in removing iron from the aqueous solution by using dried

biomass of activated sludge. From the study it was inferred that when the

concentration was 2 mg/L the removal efficiency was 70% and subsequently

it decreased to 56% when the concentration of the solution was increased.

Shokoohi et al (2009) have concluded that the above influence is due to the

driving force of the concentration gradient, and increase in initial iron

concentration.

Rakhi Gopalan (2007) has investigated the adsorption of hexavalent

Chromium from the chrome plating industry effluent using tapioca peel

carbon. Both batch and column experiments were conducted and the optimum

pH and dosage were found to be 3 and 400 mg respectively. The removal

efficiency was found to be 82% based on the experiments. They have

12

concluded that tapioca peel carbon is more effective in removing Chromium

from wastewater.

Tiwari et al (1995) have investigated the removal of Mercury (II)

from the aqueous solution using the rice husk ash. Both batch and column

experiments were conducted and in the column experiment a circular column

was used and the flow rate was varied from 20-45 mL/min and the pH of the

solution was maintained at 5.5. The study revealed that the adsorption

efficiency decreases with increase in particle size.

Mansour et al (2011) have investigated the removal of Cu (II) ion

from wastewater by adsorption onto polyaniline coated on sawdust. The

concentration of the metal solution was ranged from 5 mg/L to 40 mg/L. The

pH range was 2-8. The adsorption capacity was found to be strongly

dependent on the initial pH of the solution. The adsorption of Cu (II) ions was

significant with the slight increase in pH. The optimum pH was found to be 6

and optimum contact time was 20 minutes. It is found that the sorption

capacity is strongly dependent on the initial concentration and initial pH of

the solution.

Tarek Abdel et al (2000) have carried out a research work on

Fluoride removal from drinking water using activated carbon prepared from

naturally occurring zeolites and molecular sieves. Aqueous solution was

prepared from sodium solution. The initial fluoride concentration was 10mg/l

and the dosage of the adsorbent was 4g/l. It was found that the equilibrium

condition was reached within 48 hours for all combination of adsorbent. It

was found that char fines and bentonite exhibit a removal capacity of 38%

and 40% respectively.

Hameed et al (2009) have studied the effect of pH on the adsorbing

capacity of dye using agricultural waste. pH was varied from 2 to 10 and it

13

was found that the adsorbing capacity increased from 13.29 mg/g to

104.50 mg/g when the pH varied between 2 and 10 .The authors used

pineapple stem for removing cationic dye and studied the potentiality of its

usage. The surface texture of the adsorbent was studied using Scanning

Electron Microscope before and after adsorption and Fourier Transform Infra

Red analysis was applied and the spectra was recorded. From the study, the

results indicate that pineapple stem was very effective in its adsorbent

property.

Danica Barlokova et al (2009) have made studies on the removal

of Iron and Manganese from small water sources by passing the raw water

containing Iron and Manganese through the filtration materials namely

Klinopur-Mn, (activated zeolite), Birm (granulated filter medium) and green

sand. From the study it was found that Kilnopur - Mn was effective in

removing both Iron and Manganese, but the other materials showed lower

efficiency in Manganese removal and found to be effective in Iron removal.

Manjeet Bansal et al (2008) studied the removal of Cr (IV) from

aqueous solution using rice husk. He used two forms of rice husk namely

boiled rice husk and formaldehyde treated rice husk. He conducted batch

studies by varying the parameters such as pH, dosage and agitation speed. The

initial concentration of the solution was taken as 100mg/L, the contact time

was fixed as 180 min, pH of the solution was maintained as 2. The removal

efficiency for boiled rice husk was found to increase from 33.2% to 71% with

increase in dosage from 2 g/L to 4 g/L. Similarly for formaldehyde treated

rice husk the removal efficiency increased from 38% to 78.5% with the

increase in dosage from 5 g/L to 4 g/L. The results indicate that the metal

removal was found to be maximum at pH 2. It is also found that there is no

much difference in adsorption capacity of boiled rice husk and formaldehyde

treated rice husk.

14

Veeraputhiran and Alagumuthu (2011) have investigated the

efficiency of activated carbon prepared from Phyllanthus emblica (Indian

Gooseberry) for fluoride removal from groundwater. It was concluded that the

rate of adsorption of fluoride was increased with increase in contact time.

Also the adsorption capacity decreases with increase in concentration. The

removal efficiency at 2 mg/L concentration was found to be 87.95% and at

10 mg/L it was found to decrease to 47.22%. It was concluded that the

removal efficiency is highly dependent upon contact time, adsorption dose

and concentration and fluoride could be successfully removed from

groundwater using Phyllanthus emblica based activated carbon.

Bhargava et al (2008) have studied the removal of fluoride by

adsorption using fish bone charcoal. The concentration of the solution was

maintained as 6.5 mg/L and pH of the solution was varied from 6 - 9 and the

agitation speed was maintained at 100 rpm to perform batch studies. It was

found that fluoride removal was efficient for pH values less than 9. With

respect to contact time it was found that the fluoride removal increases with

increase in time and it has reached its equilibrium condition in about

540 minutes.

Veeraputhiran and Alagumuthu et al (2011) have studied the

fluoride adsorption capacity using Cynodon dactylon (Bermuda grass) based

activated carbon. The concentration of fluoride solution was varied from

2 mg/L to 10 mg/L with dosage of adsorbent as 1.25 g and the contact time

was maintained at 105 minutes. The adsorption of fluoride decreased from

84% to 51% with increase in fluoride concentration from 2 mg/L to 10 mg/L.

Along with the batch study the effect of coexisting anions such as sulfate,

nitrate, chloride and bicarbonate on fluoride adsorption was studied using

Cynodon dactylon adsorbent. It was found that chloride and nitrate ions did

15

not interfere with fluoride removal upto the concentration of 500 mg/L, while

the sulphate ion showed some adverse effects in the removal process.

Lalhruaitluanga et al (2011) have carried out a research to study the

feasibility of chemically activated raw charcoals of Melacanna baccifera

(bamboo) for the removal of Ni (II) and Zn (II) from aqueous solution. Batch

adsorption studies were conducted by varying the adsorbent quantity from 0.1

g to 0.5 g. The concentration was kept constant at 50 mg/L and 30 mg/L. It

was found that beyond 0.4g, the adsorption capacity decreases which is due to

the overlapping and aggregation of adsorption sites resulting in the decrease

of the surface area available for the metal ions. Lalhruaitluanga et al (2011)

have concluded that chemically activated charcoal of Melacanna baccifera has

higher adsorption capacity than the raw charcoal.

Anjali Gupta et al (2010) have evaluated the effect of novel space

granular chitosin impregnated with molybdate for the removal of arsenite and

arsenate from contaminated water by conducting column studies. Fixed bed

column reactor was employed with a flow rate of 10ml/min. Batch adsorption

experiments were carried out by varying the pH from 4 to 10.The maximum

adsorption was obtained for a pH of 7 for both AS (III) and AS (V). It is

proved that chitosin impregnated with molybdate has been very effective in

both AS (III) and AS (V) in complete removal.

Senthil Kumar et al (2010) have made an attempt to study the

feasibility of Bengal gram husk (BGH) for the removal of ion Fe(III) . The pH

of the aqueous solution was varied from 0.5 to 3 and it was observed that the

removal efficiency increases with increased pH. The dosage of the adsorbent

was varied from 5 to 30 mg/L and significant increase in uptake was observed

when the dosage was increased and the maximum removal of 77.35% was

observed at adsorbent dosage of 20 g/L. The increased contact time raised the

iron adsorption and it remains constant after equilibrium in 30 minutes. From

16

the above results it can be concluded that Bengal gram husk powder has high

potential in removing iron from aqueous solution.

Mohd Rafatullah et al (2010) reviewed the adsorption of methylene

blue on low cost adsorbents such as agricultural wastes, industrial solid

wastes, biomass, clay minerals and Zeolites. Among the various adsorbents

used for removal of methylene blue dye, the fly ash was found to be an

effective adsorbent. The adsorption capacity of fly ash was found to be 6.46

mg/g. The authors have concluded that a number of inexpensive, locally

available materials can be employed in place of commercial activated carbon

in removing the contaminants.

Kailash Daga and Pallav (2009) have made an attempt on the

adsorption of Zinc (II) onto polyvinyl alcohol coated datura stramonium and

by varying the dose from 3-6 g/L. The adsorption capacity was found to be

17.24 mg/g for a pH of 8 for a removal efficiency of 74.3%. Kailash Daga and

Pallav (2009) concluded that polyvinyl alcohol coated with datura

stramonium available cheaply and widely in Thar Desert can be used for

preparation of adsorbent with high adsorption capacity.

Karthikeyan et al (2005) used chitin for iron (III) removal by

adsorption study. The initial concentration of the iron (III) solution was

maintained at 10 mg/L. The dosage was varied from 10 – 30 mg. Maximum

adsorption occurs at the 8th minute after which the adsorption remains

uniform. The time variation curve was smooth with the formation of

monolayer coverage on the outer interface of the absorbent. It was found that

sorption of iron increased at higher concentrations and dosages.

Munavallin et al (2010) have made comparitive studies of

defluoridation techniques. Various adsorbents such as activated alumina,

activated carbon, brick powder of used tea powder were used as absorbents.

17

For all the absorbents it was found that the removal of fluoride increased with

increase in dose of adsorbent till equilibrium is reached. It is also observed

that the adsorption of fluoride increased with time and there is no significant

change beyond a contact time of 60 minutes. The minimum contact time

required for adsorption is independent of initial concentration of fluoride.

Tonni Agustiono Kurniawan et al (2006) compared the effects of

low cost adsorbents for treating waste waters laden with heavy metals, it was

found that low cost adsorbents prepared from agricultural waste have

demonstrated outstanding removal capacity for Cr (VI). The adsorption

capacity was 170 mg/g of hazelnut shell activated carbon, for Ni (II), it was

158mg/g of orange peel, for Cu (II), it was 154.9mg/g of chemically modified

soybean hull, for Cu (II), it was 52.08 mg/g of jackfruit.

Emine Malkoc et al (2006) conducted batch and column studies to

find the adsorption capacity of Chromium (VI) on pomale an olive oil indenty

waste. The effect of pH on the Cr (VI) was investigated by varying the pH

value as 2, 3, 4 and 5 by fixing the contact time as 180 min. The adsorption

capacity of Cr (Vl) at pH 2 was 8.4mg/g which reduced to 2.7 mg/g at pH 5.

In the column study influent flow rate were varied from 5 mL/min to

20 mL/min with bed depth as 10 cm. It was found that breakthrough curve

becomes steeper when the flow rate was increased.

Adeniyi Ogunlaja et al (2010) conducted activity tests using Co-Mo

catalysts prepared from egg shell based activated carbon using silicon dioxide

as supporting element for the hydrogenation of methyl orange. The catalysts

were prepared from leached and unleached carbon. It was found that Co is

more efficient in hydrogenating methyl orange than Mo.

Subramanyan Vasudevan et al (2009) have carried out a research

on the removal of iron from drinking water by electro coagulation. The

18

parameters such as pH, temperature and current density were considered.

Langmuir and Freundlich isotherms were plotted. The results revealed that the

removal efficiency of 98.8% was achieved at pH 6.5.The temperature studies

also showed that the adsorption was endothermic and spontaneous.

Olayinka Kehinde et al (2009) have compared the efficiencies of

two low cost adsorbents in the removal of chromium and nickel from aqueous

solution. Coconut husk and teak tree bark based adsorbents were employed

for the removal of chromium and nickel. The influence of pH, dosage, contact

time and temperature were studied. The coconut husk adsorbents gave better

results the teak tree bark adsorbents at the increased contact time it was also

found that the percentage of adsorption of the adsorbents increased with

increasing adsorbent dosage. From the results it is found that coconut husk

adsorbent was more efficient in removing the metals when compared with

teak tree bark adsorbent.

Kadirvelu and Namasivayam (2001) have made studies on the

removal of Nickel (II) from aqueous solution onto the activated carbon

prepared from coirpith. The batch experiments were conducted and the

concentration of the solution was varied from 10-40 mg/L and the removal

efficiency was found to be 100% for the concentration of 20 mg/L solution.

The results indicate that the removal of metals was strongly dependent on the

pH of the solution. The removal efficiency was increased from 0% to 100%

for a concentration of 20 mg/L and 80% for 40 mg/L with the pH range of

2 to 7. The authors have also made the desorption studies by using HCl, and it

indicated that ion exchange is an important process in the adsorption of metal

ion by carbon.

Vishwanath (1974) has investigated the effect of Lignite in the

removal of Nickel from the aqueous solution and conducted batch

experiments. The effect of the parameters such as sorbent particle size, pH,

19

sorbent/sorbent ratio, retention time, temperature and carbonate ion

concentration was varied. The removal efficiency was found to be 98% at the

retention time of 30 minutes and the optimum pH was found to be 12.6.

Ramesh et al (2009) have prepared activated carbon from green pea

peels for treating dyeing industry wastewater. Wastewaters from textile

industry were collected. 100 ml of the sample was collected and agitated with

0.5 g of adsorbent at 120 rpm. The adsorbent dose was varied from 0.5 g to

3.5 g and pH was varied from 3 to 10. The results revealed that the removal

efficiency increases with agitation time and attains equilibrium after

60 minutes and remains constant thereafter.

Belgin Bayat (2002) has studied the properties of turkish fly ashes

and made a comparative study for the adsorption of copper, nickel and zinc

ashes such as Afsin-Elbistan fly ash and Seyitomer fly ash. The pH was

varied from 3 to 6 and it was found that pH had a greater influence in the

removal efficiency. Equilibrium time was maintained as for minutes. The

effect of concentration, pH and contact time was studied and the results

revealed that the adsorption efficiency for copper was found to be more than

that of zinc and nickel.

Kermit Wilson et al (2006) have carried out research on select

metal adsorption by using activated carbon made from peanut shell. The

metals considered were cadmium, copper, lead, nickel and zinc. The activated

carbon was prepared by different methods such as pyrolysis steam activation,

oxidation and ash removal. It was found that carbons with higher titratable

functional groups are better at binding metal ions than those carbons with

fewer amounts of titratable functional groups.

Ramesh et al (2008) have made studies on COD removal using

cement kiln dust based adsorbents. The adsorbent dose of 4 g was mixed with

20

100 ml sample and it was stirred at 150 rpm in an orbital shaker. It was found

that the removal efficiency of COD increased gradually from 5 minutes and

attained its optimum level at 90 minutes. In this optimum time removal

efficiency of 82% was achieved. Finally it can be concluded that the

maximum adsorption capacity of cement kiln dust based adsorbent was

19.56 mg/g.

Sreenivasulu et al (2010), have conducted experiments on the

adsorption of chromium on acid treated soapnut tree stem bark carbon. The

concentration of chromium was varied from 1.25 mg/L to 50 mg/L. The

stirring speed was maintained as 120 rpm. Equilibrium time was maintained

at 5 hours. The experiment data show 68.4% removal for chromium ion at

pH 3.7 and adsorbent dose of 6 g/L.

Halil Hazar (2003) has investigated the removal of Nickel (II) from

aqueous solution using activated carbon prepared from almond husk and

found that the removal efficiency at 25 mg/L concentration was 97.8% and at

250 mg/L concentration was 68.6%. The data reveal that activated carbon

prepared from almond husk could be used effectively as a potential adsorbent

for the removal of Nickel ions from aqueous solution.

Demirbas (2002) has made equilibrium studies on the removal of

Nickel (II) from aqueous solution by adsorption onto hazelnut shell activated

carbon by varying the parameters such as pH, contact time, temperature,

agitation speed, concentration and the particle size of the adsorbent and pH

was varied from 3 to 8. The studies were carried out at equilibrium contact

time of 180 minutes. Initial metal ion concentration was varied from

15-200 mg/L. It was found that the adsorption efficiency increased as the pH

of the solution was increased.

21

Malathy and Rajkumar (2008) have investigated the use of fly ash

for the removal of colour from the textile factory effluent. The effect of pH,

dosage and concentration of the solution were studied and the maximum

adsorption was found to take place when the pH of the solution was 8. The

retention time was kept for 3 hours. The results showed that fly ash could be

used as an alternative to other adsorbents to reduce the pollution

concentration discharged from dying industries.

Xin Huang et al (2009) have made studies on the adsorption

removal of phosphate in industrial wastewater using metal – loaded skin split

waste taken from the tannery industries. The adsorbent dose taken was 0.1g

and the pH of the solution was adjusted to 7 and the column studies were also

conducted with a constant flow rate of 40 mL/h. Studies revealed that skin

split waste loaded with Fe (III) exhibit good results when compared to skin

split waste loaded with Al (III).

Xiaotian Xu et al (2011) have prepared magnesia loaded fly ash

cenospheres for fluoride removal from aqueous solution. Coal fly ash has

been employed by impregnating it at wet condition with magnesium chloride.

The physiochemical properties were analysed using Scanning Electron

Microscopy and Fourier Transform Infrared Spectrometry. The maximum

adsorption capacity was about 6.0 mg/g with the concentration of the solution

as 100 mg/L with pH 3. It has been concluded that magnesia loaded fly ash is

low cost and found to be more effective in removing fluoride from aqueous

solution.

Raju and Saseetharan (2010) have carried out research on the

removal of lead from metal plating industries using sludge based activated

carbon. The parameters such as pH, contact time and dosage were varied. The

contact time was varied from 0 to 30 minutes with an interval of 5 minutes

and the dosage was varied from 0.25 g to 2g. It was observed that the

22

optimum contact time was 20 minutes with the adsorbent dosage of 1g. The

pH of the solution was varied from 2 to 9. It is clearly understood that the

lead removal was 96% at optimum contact time of 20 minutes and optimum

pH of 5.3, and these results show that sugar mill sludge based carbon can be

an effective alternative to commercial activated carbon for lead removal.

Kalpana et al (2010) have determined the efficiency of eggshell

powder in removing cadmium ions from aqueous solution. Batch studies were

performed to optimize the experimental conditions. The parameters such as

concentration, contact time, dosage and partical size were varied. The results

revealed that percentage biosorption of cadmium decreased with increase in

metal ion concentration. Dosage of the adsorbent was varied from 0.1 g to

0.5 g. At pH 6 and at optimum contact time of 90 minutes the adsorption

capacity of the eggshell powder was found to be 34.38 mg/g.

Ajmal et al (2000) employed orange peel for Ni (II) removal from

simulated wastewater. They found out that the maximum metal removal from

simulated wastewater. They also found out that the maximum metal removal

occurred at pH 6.0 and that the adsorption followed Langmuir isotherm,

indicating that Ni (II) uptake might occur on a homogeneous surface by

mono-layer adsorption. A metal adsorption capacity of 158 mg/g was

achieved at 323 K.

Babel and Kurniawan (2004) investigated the applicability of

Coconut Shell Charcoal (CSC) modified with oxidising agents or chitosan for

Cr (VI) removal. They found out that CSC oxidised with nitric acid had

higher Cr adsorption capacities (10.88 mg/g) than that oxidised with sulphuric

acid (4.05 mg/g) or coated with Citosan (3.65 mg/g). The results suggest that

surface modification of CSC with a strong oxidising agent generated more

adsorption sites on its solid surface for metal adsorption.

23

Bansode et al (2003) made studies on Cu (II) and Zn (II) removal

from real wastewater using pecan shells activated carbon. Some treated pecan

shells used are: PSA (phosphoric acid – activated pecan shell carbon), PSC

(carbon dioxide – activated pecan shell carbon), PSS (steam – activated pecan

shell carbon). PSA and PSS had good removal capacities for both ions. The

Freundlich isotherm was applicable for the equilibrium sorption of PSA,

suggesting that metal uptakes ions took place on a heterogeneous surface by

multilayer adsorption.

Demirbas et al (2002) investigated Ni (II) removal from simulated

solution using hazelnut shell activated carbon. They found out that metal

adsorption improved with an increasing temperature, suggesting that the

adsorption was endothermic as indicated by all thermodynamic parameters.

With an initial metal concentration of 15 mg/L, the optimum Ni (II) removal

took place at pH 3.0 with metal adsorption capacity of 10.11 mg/g.

Bishnoi et al (2003) conducted a study on Cr (VI) removal by rice

husk activated carbon from aqueous solution. They found out that the

maximum metal removal by rice husk took place at pH 2.0 and multilayer

adsorption might occur on the surface of the adsorbent, as indicated by the

applicability of the Freundlich isotherm for the equilibrium data.

Kadirvelu et al (2001) studied the uptake of Cd (II), Ni (II) and Cu

(II) ions from real industrial wastewater using coirpith activated carbon. They

reported that the maximum metal removal occurred at pH ranging from

4.0 – 5.0. Since coirpith was made up of homogeneous adsorption patches,

monolayer adsorption may occur on the surface, as indicated by the

applicability of Langmiur isotherm for equilibrium adsorption.

Halil Hasar (2003) studied Ni (II) adsorption from simulated

solution using almond husk activated carbon. The author found out that the

24

maximum metal removal of 37.17 mg/g occurred at pH 5.0. Monolayer

adsorption might occur on the adsorbent surface as indicated by the

applicability of the Langmuir isotherm for the equilibrium adsorption.

Abia et al (2003) explored thioglycolic acid cassava waste for the

removal of Cd (II), Zn (II) and Cu (II) from simulated solution. After

chemical modification, adsorption kinetics was rapid and equilibrium was

obtained within 20 minutes. The adsorption capacities of the adsorbent were

18.05, 11.06 and 56.82 mg/g for Cd (II), Zn (II) and Cu (II) ions respectively,

thus suggesting that the surface modification of cassava waste with

thio- glycolic acid improved the metal performance.

Periyasami and Namasivayam (1995) investigated the removal of

Ni (II) from synthetic solution using peanut hulls. Maximum Ni (II) removal

of 53.65 mg/g took place at pH ranging from 4 -5. In another column studies,

Periasamy and Namasivayam (1996) explored Cu (II) removal from synthetic

solution using peanut hull. Maximum Cu (II) removal of 65.57 mg/g occurred

at pH ranging from 6 – 10.

Zouboulis and Kydros (1993) investigated red mud, a solid by –

product from alumina production, for Ni (II) removal from wastewater. Red

mud has high cation exchange capacity and cation exchange sites. With an

initial Ni (II) concentration of 400 mg/L, the maximum Ni (II) uptake of

160 mg/g occurred at pH 9.0.

Lee et al (2004) studied green sands, another by – product from the

iron industry, for Zn (II) removal from synthetic solution. Kinetic studies

showed that the adsorbent was effective for the metal removal with an

adsorbent capacity of 32.46 mg/g. Clay and iron in the green sands played

major roles for Zn (II) sorption via sorption and precipitation. The adsorption

reaction was andothermic.

25

Feng et al (2004) investigated Cu (II) and Pb (II) removal from

simulated wastewater using iron slag or steel slag. A pH range from 3.5 to 8.5

for Cu (II) and from 5.2 to 8.5 for Pb (II) was optimum for both iron and

steels slags to maximise metal removal.

Dimitrova (1996) studied the adsorption of Cu (II), Ni (II) and Zn

(II) ions from simulated wastewater using blast – furnace slag. Its sorption

capacities on Cu (II), Ni (II) and Zn (II) were 133.55, 55.76 and 103.33 mg/g,

respectively. The metal sorption was in the form of hydro – oxo complexes

and the high sorption capacity was due to the formation of soluble compounds

on the internal surface of the adsorbent.

Manju and Anirudhan (1997) conducted experiments to determine

the ability of coconut fibre pith carbon to remove Cr+6 from aqueous solution

by adsorption. The extent of removal was found to be dependent on sorbent

dose, initial concentration, pH and temperature. The adsorption process was

exothermic with a maximum adsorption of 99.20% at 30 ºC for an initial

concentration of 50 mg/L at pH 2.0 with an optimum dosage of 2.0 g/L.

The optimum contact time was 3 hours.

Swamy et al (1997) have investigated the possibility of utilizing the

bagasse fly ash and activated carbon for the removal of resorcinol from

aqueous solution. They have concluded that equilibrium data of various

systems at 30 0.5oC and pH 6.5 fit well to the Freundlich equation and the

removal of resorcinol increases with pH of the solution and is maximum at

pH 6.5. The column studies carried out indicate that the absorbed amount of

resorcinol decreased with increasing flow rate and decreasing bed height.

Selvaraj et al (1997) observed the ability of photo film sludge to

adsorb Cr (VI) from synthetic wastewater by adsorption process. Authors

reported that optimal conditions for the maximum removal for Cr(VI) was

26

95% at pH 5.0, adsorbent dosage 750 mg/50 mL, agitation time 90 min,

initial Cr(VI) concentration 10 mg/L, with particle size 0.1 - 0.2 mm.

Selvapathy et al (1998) studied the removal of Cd, Cu, Mn, Ni and

Zn from wastewater using water lettuce a small floating stoliferrous aquatic

herb in its original herbal form. Efficiency of removal has been measured

when the metals were present separately and also in the combined form.

Results indicated that removal efficiency from individual solutions was more

compared to the metals present together. Also it was concluded that water

lettuce plants can be effectively used to remove metal concentration of

10 mg/L or less.

Sulochana et al (1998) conducted a study on the removal efficiency

of Copper and Nickel by wood powder of Phyllanthus embilica (nelli),

Lannea grandis (Odi) and Cicca disticha (Arunelli). It was reported that the

plant substrate of commonly available Indian plant species to be an alternative

for the removal of heavy metal ion.

Samantaroy et al (1998) made a comparative study on the removal

of chromium (VI) by different adsorbents namely Kendu fruit Gum Dust

(KGD), Drumstick Gum Dust (DGD) and Green Peas Skin Dust (GPSD). It

was found that KGD is the most effective one and concluded that the removal

of Cr (VI) upto 100% was observed with KGD, DGD and GPSD whereas

other conventional adsorbents showed lower percentages.

Jayasankar et al (1999) found that tamarind nut, a waste product

from agricultural sector, when processed under suitable conditions to achieve

the required porosity, bulkiness and adsorption capacity, could be used to

remove Lead (II) ions effectively. The results are compared with

commercially available granular activated carbon. The authors discussed the

27

advantages of using this type of locally available activated carbon from

indigenous sources for removal of Lead (II) ions.

Cormick and Fred (1999) studied that Enhanced Copper removal

from Activated Sludge using Bio Ferric / Selectors. Effluent copper

concentrations from a pilot – scale conventional activated – sludge system

(control) was compared with those from a conventional pilot treatment

process that also integrated bio ferric / selector units.

Orhan Altin et al (1999) have studied the effect of pH, flow rate

and concentration on the sorption of Pb and Cd on montmorillonite.

Continuous column adsorption of Lead (II) and Cadmium (II) was studied

using pH adjustment and calcium-saturated montmorillonite in a short

stainless steel column. At intermediate pH (4-6), ionic size played the major

role in adsorption and ion exchange. At low flow rates, sorption of both Lead

(II) and Cadmium (II) increased due to the long retention time in the column.

It was found that, when both Lead (II) and Cadmium (II) ions were present in

the feed, adsorption remained the same while that of Cadmium (II) decreased

compared with single ion experiments.

Rai and Surendrakumar (1999) conducted experiments on

Treatment of Chromium bearing wastewater by adsorption on brick kiln and

fly ash. Suitability of brick kiln ash and fly ash for removing Chromium (VI)

exhibited good sorption at a pH of 1.3 and particle size 124 – 853 µm. The

author reported that fly ash adsorbent was more effective than brick kiln ash

due to smaller particle size.

Reed et al (2000) made investigations on the removal of As(III),

As (V), Hg(II) and Pb(II) by virgin and Fe(III) impregnated Activated

Carbons (FeAC). Observations made indicate that iron oxide impregnation

increased the pH of the carbon from 7.5 to about 8.2 - 8.7, but had no change

28

in the surface area or pore volume. Results indicated that metal removal was a

function of pH with removal increasing with pH for Hg(II) and Pb(II) and

decreasing with pH for As(V). As(III) removal was not a strong function of

pH below 5. It was concluded that As(III) and As(V) removal were about one

and two orders of magnitude higher, respectively, for the FeAC compared

with the non-impregnated carbon, while for Hg(II) and Pb(II) removal, it was

only slightly higher.

Verma et al (2000) investigated the removal of Nickel (II) from

Electro Plating Industry Effluent by Agrowaste Carbons, prepared by using

wheat stem and spent Babul bark as the raw materials and the data were

compared with a commercially available activated carbon. Almost 100 %

removal of Ni (II) was observed at a pH value of 4.0.The Nickel removal

increased with carbon dose, adsorption period, pH and decrease with increase

in Nickel concentration.

In the study made by Ortiz et al (2001) the main component of

converter slag (magnetite) in the steel industry was used as an adsorbent for

the removal of Ni(II) from aqueous solutions over a range of conditions,

initial metal concentration (10 – 100 mg/L), stirring times (2 - 240 min)

adsorbent dosage (1 g for 0.5 L of metal solutions) and temperature (20, 30

and 38oC). The adsorption process was found to obey the Freundlich isotherm

model.

Li et al (2001) developed and studied a mathematical model to

describe the mass transfer kinetics in a fixed – bed adsorber packed with

activated carbon fibers. Experiments were carried out to remove phenolic

compounds from an aqueous solution. A simpler model, based solely on a

liquid phase mass balance and incorporating local equilibrium with axial

dispersion with a good description of the adsorption process.

29

Aksu and Yener (2001) examined a comparative adsorption /

bio sorption study of mono – chlorinated phenols onto various sorbents. The

potential use of dried activated sludge and fly ash as a substitute for granular

activated carbon for removing mono – chlorinated phenols were found out.

The suitability of the Freundlich and Langmuir models to the equilibrium data

were investigated.

Chen et al (2002) studied the removal of phenol and carbon

tetrachloride by activated carbon prepared from sewage sludge. The results

indicate that activated carbon prepared from sewage sludge had remarkable

micropore and mesopore surface areas which aided notable phenol and carbon

tetrachloride removal.

Appel and Ma (2002) focused on the Concentration, pH, and

Surface Charge Effects on Cadmium (II) and Lead (II) sorption in Three

Tropical Soils. Sorption characteristics of two heavy metals, Cd and Pb, in

three tropical soils (Mollisol, Oxisol, and Ultisol) were assessed at varying

metal concentrations and pH values. Sorption appeared to depend more on

soil mineralogy than organic matter content. Metal sorption depended more on

metal type than soil composition. Cadmium (II) sorption displayed greater pH

dependence than Pb. It was concluded that the Lead (II) was adsorbed more

strongly than Cd in the three tropics soils.

Li et al (2009) studied the feasibility of preparation of activated

carbon from coconut shell chars in pilot – scale microwave heating

equipment. Experiments conducted to prepare activated carbon by microwave

heating indicated that microwave energy decreases the reaction temperature,

saving the energy and shortening processing time remarkably compared to the

conventional heating.

30

Wang et al (2008) investigated the removal of Cr (VI) from

aqueous solutions using Alligator weed, a freshwater macrophyte, was

investigated in batch studies. Various factors including solution pH, Cr (VI)

concentrations, agitation time, and temperature were taken into account and

promising results obtained. An initial solution pH of 1.0 was most favorable

for Cr (VI) removal. The results suggested that the Cr (VI) adsorption at all

temperatures was best represented by the pseudo-second-order equation.

Oke et al (2008) investigated that Adsorption kinetics for arsenic

removal from aqueous solutions by untreated powdered eggshell. The batch

removal of arsenic aqueous solution using low – cost adsorbent (powdered

eggshell) under the influences of initial arsenic ion concentration (0.5 to

1.50 mg/L), pH (3.2 to 11.5) and particle size of eggshells (63 to 150 µm)

were investigated.. The study revealed that there was a slight reduction in the

rate of adsorption of arsenic ion onto the larger particle size, but adsorption

capacity and parameters were unaffected. Powdered eggshells with particle

size of 63 µm removed up to 99.6 % of the 1.5 mg/L of arsenic ion in

synthetic water within the first 6 hours but decreased to 98.4 % and 97.4 %

when the powdered eggshell particle sizes were increased to 75 and 150 µm

respectively.

Marin et al (2008) investigated that adsorption of mercury from a

single and multicomponent metal systems on activated carbon developed

from cherry stones. The adsorption of mercury from a single / multi solute

aqueous solution by Activated Carbon (AC) prepared from cherry stones by

chemical activation with H3PO4, ZnCl2 or KOH is studied. Three series of AC

were prepared by controlling the impregnation ratio and carbonization

temperature. The textural characterization of AC was carried out by gas

adsorption, mercury porosimetry and density measurements. Experiments of

31

mercury adsorption were conducted by the batch method, using aqueous

solutions of mercury, cadmium and zinc without pH adjustment.

Lua et al (2007) investigated that adsorption of phenol by oil –

palm – shell activated carbons. The adsorption isotherms could be described

by both the Langmuir Freundlich and the Langmuir equations. A multipore

model is proposed that akes into account of a concentration dependent surface

diffusion coefficient within the particle. This model is an improvement to the

traditional branched pore model. The theoretical concentration versus time

curve generated by the proposed model fitted the experimental data for phenol

adsorption reasonably well.

Babu et al (2008) investigated that adsorption of Cr (VI) using

activated neem leaves using kinetic studies. The adsorption of Cr (VI) is

found to be maximum (99 %) at low values of pH in the range of 1 – 3. A

small amount of the neem leaves adsorbent (10 g/L) could remove as much as

99 % of Cr (VI) from a solution of initial concentration 50 mg/L. The

adsorption process of Cr (VI) is tested with Langmuir isotherm model.

Malik et al (2007) made studies on adsorption of malachite green

by groundnut shell waste based powdered activated carbon. In the study,

groundnut shell an agricultural waste, was used for the preparation of

adsorbent and comparative characterization was conducted with commercially

available powdered activated carbon. It was found that Groundnut shell

Powdered Activated Carbon (GSPAC) has a higher surface area compared to

Commercially Prepared Activated Carbon (CPAC).

Kubilay et al (2007) investigated that the removal of Cu (II), Zn (II)

and Co(II) ions from aqueous solutions by adsorption on to natural bentonite

as a function of initial metal concentration, pH and temperature. Results

showed that bentonitic clay hold great potential to remove the relevant heavy

32

metal cations from industrial waste water. It was evident that the adsorption

phenomena depend on the solution pH.

Konstantinou et al (2007) investigated that Sorption of Cu (II) and

Eu (III) ions from aqueous solution by olive cake. Evaluation of the

potentiometric data obtained from competition experiments indicates on a ion

exchange mechanism. The formation constant of the Eu(III) species sorbed on

olive cake is found to be log = 5.4 ± 0.9. This result of this study are of

particular interest with respect to waste water treatment technologies using

biomass products as adsorbent material and environmental impact

assessments regarding disposal of biomass by products in the geosphere.

Vasanthkumar (2003) investigated the treatment of Dye bearing

waste water by Adsorption Technique using boiler bottom Ash as an

adsorbent. Author carried out the experiments in batch process for removing

color of methylene blue a basic dye, from its aqueous solution and achieved

100% color removal at lower initial concentration of less than 15 mg/L Young

– Sook Shim et al (2003) investigated the adsorption characteristics of heavy

metals by various particle sizes of MSWI bottom ash. The adsorption rate

increased with decreasing particle size and with increasing liquid / solid ratio;

however, the removal efficiency of Cu was higher than that of Ni. In the case

of plating rinse water, the adsorption rate decreased sharply at high liquid /

solid ratio and it showed over 80 % of adsorption rates for Cu and Ni at an

initial pH of 3.

Revathi et al (2005) studied that the removal of Nickel Ions from

Industrial Plating Effluents using activated Alumina as adsorbent. The effect

of various factors, such as initial concentration of nickel, contact time, dose of

adsorbent and pH of the solution were investigated. The results showed that

activated alumina was more efficient in removing nickel ions from aqueous

solution.

33

Ayawei et al (2005) studied the ability of the biomass of

Rhizophora mangle waste in removing Cu2+, Cd2+, Zn2+, Ni2+ and Ag+ from

aqueous solution using batch sorption techniques as a function of pH, contact

time, initial concentration of metal ions and temperature variations. The

optimum pH values for the metal ions Cu2+, Cd2+, Zn2+, Ni2+ and Ag+ were

found. The maximum adsorption capacity of the biomass was evaluated by

the Langmuir adsorption isotherm. Comparative examination of the

adsorption capacity of Rhizophora mangle waste with other biomasses

indicated that, Rhizophora mangle waste is also an excellent sorbent for most

of the metals investigated.

Caramuscio et al (2003) investigated the Preparation of activated

carbons from heavy – oil fly ashes. The use of heavy oil fly ash with high ash

content (45 Wt %) as a precursor for the preparation of activated carbons. The

activated carbons have been characterized with regard to the surface area and

the pore volume.

Ayub et al (2003) evaluated Chromium removal by Adsorption on

coconut Shell. The effect of pH, contact time, adsorbent dose, and

concentration of metal, particle size and temperature were studied. The

coconut shell exhibits good adsorption characteristics and the data follow both

Freundlich and Longmuir models.

Rengaraj et al (2002) made investigations on phenol removal from

aqueous solutions using activated Palm Seed Coat Carbon (PSCC) for varying

experimental condition of contact time, phenol concentration, adsorption dose

and pH. Adsorption equilibrium was reached within 3 h for phenolic

concentration 10 - 60 mg/L. The percent removal remained constant over the

pH range 4-9 for phenolic concentration of 25 mg/L. The adsorption of

phenol on PSCC followed the film diffusion process and the equilibrium data

obeyed Freundlich isotherm equation. Moreover, the comparative study with

34

commercial activated carbon showed that PSCC is two times more effective

than commercial activated carbon.

Altundogam et al (2002) investigated that Arsenic adsorption from

aqueous solutions by activated red mud. Author concluded that red mud an

abundant waste product of the aluminium industry, can be used as an

adsorbent for Arsenic in aqueous solutions. The adsorption data obtained

follow a first order kinetics and fit for Langmuir Isotherm.

Baisakh and Patnaik (2002) studied “Removal of Hexavalent

Chromium from Aqueous Solutions by Adsorption on Coal Char. The effects

of pH, temperature and concentration of hexavalent Chromium were

investigated. Under ambient temperature and pH condition removal efficiency

to the extent of 70 %. The rate process follows first order kinetics.

Rao et al (2003) have conducted experiments on removal of Cr(VI)

and Ni(II) using low – cost adsorbents. In this study, the efficiency of low-

cost materials, namely bagasee and fly ash were assessed. These low cost

adsorbents are used for the removal of Chromium and Nickel (II) from aqua

solution. The effects of pH, contact time, initial concentration of adsorbate

and particle size on the uptake of Chromium and Nickel (II) have been

studied in the experiments. The order of selectivity is PAC > bagasee > fly

ash for Cr (VI) removal and PAC > fly ash > bagasee for Ni (II) removal at

optimum conditions.

Senthilkumar et al (2001) conducted experiments on pollution

studies on Sugar mill effluent – Physico Chemical characteristics and Toxic

metals. The concentration of toxic metals Viz, Cd, Cu, Fe, Hg, Mg, Mn, Pb

and Zn were determined by inductively coupled plasma Atomic Emission

Spectrometry. Author concluded that Fe, Hg, Mg, Mn and Pb content

35

exceeded the permissible limits and Cd, Cu and Zn are within the permissible

limits while Ni is found in traces only.

Singh et al (2001) studied the removal of Chromium (VI), Iron (III)

and mercury (II) from aqueous solutions using activated carbon obtained from

used Tea leaves. Break through and exhaustive capacities, removal and

recovery of Cr (VI), Hg (II) and Fe (III) and effect of diverse ions have been

studied. The experimental results showed that Cr (VI), Fe (III) and Hg (II)

were strongly adsorbed by the adsorbent; Zi (II), Mn (II) and Cu (II) were

adsorbed partially.

Saravanane et al (2002) have conducted experiments for the

removal of heavy metals from wastewater using the chemically modified low

– cost adsorbents. Saw dust and rice husk have the potential of adsorbing

heavy metals, namely Cu(II), Mn(II),Fe(II) ,Cd(II), Pb(II) , Zn(II), Ni(II) and

Cr(VI) either in their natural form or in their chemically activated form, from

synthetic aqueous solution. The extent of removal depends on metal

concentration and pH. Saw dust in its natural form is found to be superior to

rice husk, with respect to the removal efficiency of the above metals from

aqueous solutions, under experimental conditions. The optimum pH for Cd

removal using the rise husk and saw dust is 4 – 6. The efficiency of the Cd

removal for the saw dust and rise husk is 64.81% and 58.62%. For the

chemically activated Carbon with combination of low cost adsorbent the

removal efficiency is increased to 95%.

Verma et al (2000) investigated the removal of Nickel (II) from

Electro Plating Industry Effluent by Agrowaste Carbons, prepared by using

wheat stem and spent Babul bark as the raw materials and data was compared

with a commercially available activated carbon. Almost 100 % removal of Ni

(II) was observed at a pH value of 4.0.The Nickel removal increased with

36

carbon dose, adsorption period, pH and decrease with increase in Nickel

concentration.

Rashed (2001) studied the suitable conditions for using Peach and

Apricot stones, (produced from food industries as solid waste), as adsorbents

for the removal of Lead ions from aqueous solution. Chemical stability of

adsorbents, pH, adsorbent dose, contact time and equilibrium concentration

were studied. The results revealed that adsorption efficiency of Lead ions was

more in the case of Peach stone than Apricot stone.

Rajkumar et al (2001) studied the feasibility of using red mud for

removing trivalent Chromium from wastewater. Experiments were carried out

by batch study at room temperature (27oC) to study the effects of pH, initial

chromium concentration, adsorbent dose and agitation time on the removal of

chromium. The maximum adsorption efficiency of 99.9% was recorded when

1.5 g of red mud was used in test solution containing 150 mg Cr3+ / 100 mL.

The idle pH and agitation time were 6 and 10 h respectively.

Lua et al (2001) investigated adsorption of Sulfur Dioxide on

Activated Carbon from oil – Palm waste. Experimental results showed that

the adsorption temperature and SO2 concentration significantly determined

the amount of SO2 adsorbed and the equilibrium time. Author concluded that

Sample particle size had minimum effect on equilibrium time.

Altin et al (1999) have studied the effect of pH, flow rate and

concentration on the sorption of Pb and Cd on montmorillonite. Continuous

column adsorption of Lead (II) and Cadmium (II) was studied using pH

adjustment and calcium-saturated montmorillonite in a short stainless steel

column. At intermediate pH (4-6), ionic size played the major role in

adsorption and ion exchange. At low flow rates, sorption of both Lead (II) and

Cadmium (II) increased due to the long retention time in the column. It was

37

found that, when both Lead (II) and Cadmium (II) ions were present in the

feed, adsorption remained the same while that of Cadmium (II) decreased

compared with single ion experiments.

Reed et al (2000) made investigations on the removal of As(III),

As(V), Hg(II) and Pb(II) by virgin and Fe(III) impregnated Activated Carbons

(FeAC). Observations made indicate that iron oxide impregnation increased

the pH of the carbon from 7.5 to about 8.2 - 8.7, but had no change in the

surface area or pore volume. Results indicated that metal removal was a

function of pH with removal increasing with pH for Hg(II) and Pb(II) and

decreasing with pH for As(V). As(III) removal was not a strong function of

pH below 5. It was concluded that As(III) and As(V) removal were about one

and two orders of magnitude higher, respectively, for the FeAC compared

with the non-impregnated carbon, while for Hg(II) and Pb(II) removal, it was

only slightly higher.

Jayasankar et al (1999) found that tamarind nut, a waste product

from agricultural sector, when processed under suitable conditions to achieve

the required porosity, bulkiness and adsorption capacity, could be used to

remove Lead (II) ions effectively. The results are compared with

commercially available granular activated carbon. The authors discussed the

advantages of using this type of locally available activated carbon from

indigenous sources for removal of Lead (II) ions.

Cormick and Cannon (1999) studied that Enhanced Copper

removal from Activated Sludge using Bio Ferric / Selectors. Effluent copper

concentrations from a pilot – scale conventional activated – sludge system

(control) was compared with those from a conventional pilot treatment

process that also integrated bio ferric / selector units.

38

Swamy et al (1997) have investigated the possibility of utilizing the

bagasse fly ash and activated carbon for the removal of resorcinol from

aqueous solution. They have concluded that equilibrium data of various

systems at 30 0.5oC and pH 6.5 fit will to the Freundlich equation and the

removal of resorcinol increases with pH of the solution and is maximum at

pH 6.5. The column studies carried out indicate that the absorbed amount of

resorcinol decreased with increasing flow rate and decreasing bed height.

Balasubramaniam and Ahmed (1997) studied the adsorption

technique for the removal of Pb (II) ions from aqueous solutions using lignite

as adsorbent. Authors conducted the batch adsorption tests and found that the

optimum conditions of pH as 3.58, equilibrium contact time as 270 min.,

temperature of effluent as 29.1oC, and initial Pb (II) concentration of

500 mg/L for the maximum removal of Pb (II).

Teik et al (1997) carried out the batch adsorption study to find out

the capability of marine clay to immobilize Zn, Pb, Cd, Cu and Cr under

acidic, neutral and alkaline conditions. The sorption capacity of the heavy

metals in acidic conditions follow the sequence of Cd>Zn>Cu>Pb>Cr.

Raji et al (1997) investigated the use of chemically modified saw

dust in the removal of Lead (II) ions from aqueous media. The sorption of

Lead (II) on polymerized saw dust has been found to be dependent on contact

time, concentration, temperature, particle size and pH. Maximum removal of

Lead (II) ions was 98.6% with sorbent concentration of 10 mg/L and

adsorbent dosage of 2.0 g/L with pH 6.0 at 60ºC. The equilibrium data fit well

with the Langmuir and Freundlich isotherms.

Periasamy and Namasivayam (1994) studied the removal and

recovery of Cadmium (II) from wastewater by a Low-Cost adsorbent, peanut

hull. It was reported that carbon derived from peanut hull, a waste agricultural

39

by-product, removed Cd(II) efficiently from aqueous solution. The

investigation also details a comparative study of peanut hull carbon and

commercial activated for the removal of Cd(II) from aqueous solution.

Prasad et al (1995) investigated the sorption of Arsenic on partially

activated crushed coconut shell under sorption kinetics. The removal

efficiency was found to be 72% when 1 mg/L of Arsenic (III) was taken with

5 g/L of sorbent of pH 6.2 and sorbent size 548 µm. The equilibrium sorption

data fitted to both Langmuir isotherm and Freundlich isotherm. The

adsorption found to increase when the pH is below 7 and decreases as the pH

increases.

Gajghate and Saxena (1991) have studied the removal of Lead (II)

from aqueous solution using Commercial Carbon. Different grades of

activated carbon were used and claimed that adsorption does not increase

with decrease in size alone.

Vaishya and Agarwal (1993) conducted the batch adsorption

studies for the removal of Arsenic (III) from contaminated ground water using

Ganga sand at Arsenic concentrations ranging from 0.1 to 1.6 mg/L at

different adsorption doses of 5-40 g/L .The equilibrium data followed the

Langmuir Isotherm. The maximum removal occurred between pH range of 7

and 9.

2.3 NEED FOR THE PRESENT STUDY

From the above observations it is found that the conventional

approaches are much costly for the removal of metal ions and salts from

effluent. This strongly necessitates the alternative treatment to remove such

contaminants. Hence in the present work an alternative method using agro-

based waste materials is proposed for the removal of metal ions and salts.

40

2.4 SUMMARY

In this chapter a literature review relating to the treatment of

aqueous solutions using agro - based waste materials is presented. Further the

need for the present study is set out.