prof. dhiraj sud dean academic department of chemistry, sant longowal institute of engineering and...

SYNTHESIZED DOPED TIO2 PHOTOCATALYSTS FOR MINERALIZATION OF QUINALPHOS

FROM AQUEOUS STREAMS

Prof. Dhiraj SudDean Academic

Department of Chemistry, Sant Longowal Institute of Engineering and Technology, (Deemed to be University), Longowal 148106, India

E-mail address: [email protected]

An influx of anthropogenic substances in environmental matrix is an issue of National & Global concerns

Nature does not have any mechanism to deal

Emergence of Recalcitrant, Xenobiotic chemicals - resistant towards Biological degradation, Bioaccumulation tendency

Xenobiotic Chemicals commonly present in Wastewater streams are: Dyes , Phenols ,Pesticides Detergents and Surfactants Agrochemicals Pharmaceutical Compounds(ug /l to ng/l) >>>>>>>>>>>>

Synthesized Doped TiO2 Photocatalysts ……………

Organophosphate pesticides are of great significance in pest control as compared to other types. These cover the 70% of the total pesticides used.

Commonly used Pesticides

Commonly used Pesticides

organophosphate pesticides

pyrethoid miscellaneous compounds urea

anilides

Organochlorine Pesticides

carbamates

Pesticides are the synthetic compounds or mixtures intended for preventing, destroying or controlling pest including vectors of human or animal disease, unwanted species of plants and animals causing harm during or otherwise interfering with the production, storage, processing and transportation or marketing of food, agricultural commodities.


Pesticide???

SunDegradation

Persistence

Desorption/

Leaching Ground water

Adsorption

Micro-organism

s

Hydrolysis

FATE AND BEHAVIOUR OF PESTICIDE IN ENVIRONMENT


5

Mainly used for control a variety of sucking, chewing

and boring insects and spider mites on vegetables, fruits, cotton, groundnut,

cereals and rice.

The EPA classifies Quinalphos as a class II toxicity - moderate

toxic.

Solubility in water- 20mg/l

Acute oral LD50 for rats- 14 to 37 mg/kg

Mode of Action- By inhibiting acetylcholinesterase

PSO

OOH5C2

H5C2

N

N

QUINALPHOS (Organophosphate Pesticide)


235 255 275 295 315 335 355 375 3950

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

QP

Soil C

Soil D

Soil A

Soil B

Wavelength

Absorb

ance

Soil %age adsorption (QP)

A 43.4

B 44.o3

C 47.9

D 62.8

Paramjeet Kaur and Dhiraj Sud, Clean – Soil, Air, Water 2011, 39 (12), 1060–1067

ADSORPTION OF QUINALPHOS ON VARIOUS SOILS


7

Mainly used for control a variety of sucking, chewing

and boring insects and spider mites on vegetables, fruits, cotton, groundnut,

cereals and rice.

The EPA classifies Quinalphos as a class II toxicity - moderate

toxic.

Solubility in water- 20mg/l

Acute oral LD50 for rats- 14 to 37 mg/kg

Mode of Action- By inhibiting acetylcholinesterase

PSO

OOH5C2

H5C2

N

N

QUINALPHOS (Organophosphate Pesticide)


PERSISTENCE IN WATER AFTER 10 DAYS

PERSISTENCE IN WATER AFTER 105 DAYS

0 5 10 15 20 250

5

10

15

20

25

30

35

40

45

Retention time

Inte

nsit

y

0 2 4 6 8 10 12 14 16 180

5

10

15

20

25

30

35

After 105 days

Retention Time

Inte

nsit

y

After 10 days


9

Conventional methods for Waste water

treatment

Advanced

Oxidation

Systems

Heterogeneous(UV,Catalyst and oxidant)

Homogeneous

(UV,Ozone or H2O2)

Emerging trendAdvanced oxidation

processes (AOP’s) as potential destructive technology

Titanium dioxide (TiO 2) is

found to be most efficient catalyst

• Organic Pollutant + O2 → CO2+ H2O + mineral acid

• Oxidation of pollutant in ppb range

•Capable of destroying the organics without harmful byproducts.

Potential to utilize sunlight instead of artificial light as a UV source

Adsorption Filtration Aeration

Aerobic Anaerob

ic

Ion exchange Membrane

sepn Precipitation


PHOTOCATALYTIC MECHANISM

TiO2 + hυ → e- TiO2 (CB) + h + TiO2 (VB)

O2 +e- (CB) → O▪ -

2

O▪ -2 + H2O →▪ OH + OH-

h+ (VB) + OH- → ▪ OH ▪ OH + C6H5ClO → Intermediate → CO2 +

H2O


NANOSIZED SEMICONDUCTOR PARTICLES

Nanosized semiconductor particles exhibit unique size and shape dependent photophysical (Optical, Electronic, Catalytic and magnetic and photocatalytic properties) distinct from their bulk counterparts .

They can possess enhanced photo redox chemistries and reduction reactions that might not otherwise occur using bulk materials .

Higher catalytic activities Smaller a semiconductor particle becomes, the more the

number of atoms located at the surface and the surface area to volume ratio increase - enhance available surface active sites and interfacial charge-carrier transfer

Inner sphere absorption mechanism


Photocatalyst

Extension of excitationwavelength using Photosensitizers

Band-gap tuning

promoting forward reaction andreactant absorbance by providing adequate quality and quantity of active sites

Extending charge-carrier

recombination times

Doping

Sensitization


NON-METAL ION DOPING METAL ION DOPINGSubstitutional doping of nitrogen into the TiO2 lattice causes a significant shift of the absorption edge in the visible region because the N 2p states con-tribute to the band-gap narrowing by mixing with the O 2p states.

Metal ion traps the holes

and electrons and prevents recombination of e– h+ pairs. This helps maintain electro neutrality while degrading organic compounds.

R. Asahi, T. Morikawa, T. Ohwaki, K. Aoki, Y. Taga, Science, 293 (2001) 269-271.


Dopant + Ethanol TTIP + Ethanol

Ppts. With NH3

Ultrasonicated

Calc

inat

ed

Filtered

Different temperatures 350, 450, 550 and 750°C

Prepararation Method


Non-metal doped

Photocatalyst

N-doped TiO2

S-doped TiO2

Mn-N-doped TiO2

Metal co doped Photocatalyst


XRD analysis of N-doped TiO2

Position [°2Theta] (Copper (Cu))

10 20 30 40 50 60 70

Counts

0

200

400

0

1000

2000

0

500

1000

0

200

400

600

800

NS4-550

F-RB-750

450

350

N-doped TiO2 calcinated at different temperature

S. no.

Calcination treatment (°C)

Lattice parameters

d-spacing (A°)

Crystalline phase

a b

1. Pure TiO2

3.776

9.486 3.54 Anatase

2. 350 3.765

9.454 3.5067

Anatase

3. 450 3.765

9.454 3.5072

Anatase

4. 550 3.765

9.454 3.5066

Anatase

5. 750 3.765

9.454 3.5073

Rutile+ Anatase

Crystal phase, interplanar distance and d- spacing value of pure TiO2 and N-doped TiO2 calcinated at

different temperatures

S.No

Pos. [°2Th.]350°C

Pos. [°2Th.]

450°C

Pos. [°2Th.]550°C

hkl Rel. Int. [%]

1 25.37

25.38 25.40 101 100.00

2 37.89

37.93 37.76 004 16.70

3 48.33

48.23 48.01 200 18.78

4 54.11

54.21 54.03 105 13.70

5 62.82

62.77 62.85 204 10.10

6 75.38

75.26 75.33 215 5.47

S.No

Pos. [°2Th.]750°C

hkl

Rel. Int. [%]

1 25.35 101

100.00

2 27.49 110

22.12

3 37.86 101

18.56

4 38.64 210

4.78

5 48.13 200

23.60

6 54.39 105

9.85

7 55.12 220

12.77

8 62.75 310

9.00

9 70.38 202

3.98

Anatase phase at 350°, 450°, 550°C

Rutile phase

at 750°C

Phase transformati

on

2θ, hkl and relative intensity of peaks appeared in XRD

SEM Results of N-doped TiO2S.No. Sonicatio

n time (min)

yield (mg)

1. 10 1815.66

2. 20 2042.38

3. 40 2586.15

4. 60 1906.33

Surface morphology at different calcination temperatures Optimization of Sonication conditions

UV-Vis Spectra

FT-IR Raman Crystallite size

Band gap

576 nm

1019 cm-1 143, 397, 519 and 638 cm-1

10.13 2.10

Spectroscopic studies of N-doped TiO2

RC SAIF PU, Chandigarh

Spectrum Name: Nidhi SLIET-13.sp Description: S-4

Date Created: fri mar 01 12:35:05 2013 India Standard Time (GMT+5:30)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 450.0

42.543

44

45

46

47

48

49

50

51

52

53

54

55

55.8

cm-1

%T

3365

2925

1628

1019

763

465

anatase is predominant phase

structure

TEM OF N-doped TiO2 calcinated at 450°C

XRD Results of S-doped TiO2

S-doped TiO2 calcinated at different temperatures

Sample

S/TiO2

(molar ratio)

EDS (wt %)

Phase composition at 750 ˚C

S-750 1:0.1 .43%

11.9 (A) + 88.1 (R)

S-750 1:0.5 .57%

58.2 (A) + 41.8 (R)

S-750 1:1 .76%

89.5 (A) + 10.5 (R)

1:0.1 1:0.5 1:1

Sample Phase composition

Axial distance(edge lengths)

Axial angles Volume of the cell Lattice strain

S-550 Anatase a= b= 3.7760c= 9.4860

α = β = γ = 90° 135.25 0.0039

Phase composition, lattice parameter, cell volume and lattice strain of S-550 Nidhi Sharotri and Dhiraj Sud, New Journal of Chemistry,

2015,39, 2217- 2223

SEM Results of S-doped TiO2

S-doped TiO2 calcinated at different temperatures

S-doped TiO2 synthesized at different molar ratio’s

Nidhi Sharotri and Dhiraj Sud, New Journal of Chemistry, 2015,39, 2217- 2223

TEM of S-doped TiO2 calcinated at 350, 450, 550 and 750ºC

Calcinated at 350°C





UV-Vis Spectra

FT-IR Raman Crystallite size

Band gap

500 nm

1400.63 cm-1 (S=O stretching ),1142.61 cm-1 (S-O stretching ) 1051.62 cm-1 (Ti-S stretching vibration)

197, 397, 512 and 637 cm-1

10.13 2.47 eV

Spectroscopic studies of S-doped TiO2


Nidhi SLIET-28.sp - 2/18/2014 - S-3

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0

45.0

48

50

52

54

56

58

60

62

64

66

68

70

72

75.0

cm-1

%T

3368,52

2342,56

1627,58

1400,63

1142,611051,62

668,48

200 400 600 800 1000 1200

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

Abso

rban

ce

Wavelength (nm)

S-550 S-350 S-750 S-450

200 400 600 800

10000

20000

30000

40000

50000

60000

70000

80000

Inte

nsity

(a.u

.)Raman shift (cm-1)

(143)

(197)

(397) (512)(637)


XRD data of Mn- N co-doped TiO2

Position [°2Theta] (Copper (Cu))

30 40 50 60 70

Counts

0

1000

0

500

0

200

400

0

200

400

600

24

23

22

21

S.No 2θ350°C

2θ450°C

2θ550°C

2θ750°C

Rel. Int. [%]

1 25.15 25.41 27.55 27.55 77.38

2 28.96 27.59 31.14 28.97 27.36

3 31.05 28.95 32.42 31.11 10.90

4 32.42 31.08 36.14 32.40 51.41

5 36.13 32.41 38.16 36.19 100.00

6 37.23 36.17 41.83 36.56 10.18

7 38.13 38.10 44.44 38.06 12.56

8 44.49 39.28 50.01 39.32 4.67

9 50.95 41.45 50.87 41.36 16.46

10 53.94 44.51 55.13 44.16 5.33

11 54.97 48.06 58.61 44.53 13.60

12 56.11 49.95 59.96 49.93 3.35

13 58.55 50.84 64.63 50.78 12.07

Sample Phase composition Axial distance (edge length)

Axial angles Volume of the cell

Lattice strain

Crystallite size (nm)

Mn-N - 350 Anatase + Wurtzite a= b= 3.7760, c= 9.4860

α = β = γ = 90°

135.25 .0031 66.9

Mn-N - 450 Anatase + Wurtzite a= b= 3.7760, c= 9.4860

α = β = γ = 90°

135.25 0.0022 38.3

Mn-N - 550 Anatase + Rutile + Wurtzite a= b= 3.7760, c= 9.4860

α = β = γ = 90°

135.25 0.0027 33.4

Mn-N - 750 Rutile + Wurtzite a= 3.765, b= 9.454 α = β = γ = 90°

135.25 0.0018 53.1

Mn-N-doped TiO2 calcinated at different temperatures 2θ, hkl and relative intensity of peaks appeared in XRD

TEM of Mn-N co-doped TiO2 calcinated at 350, 450, 550 and 750ºC





UV-Vis Spectra

FT-IR EPR Crystallite size

Band gap

700 nm 1466.62, 1149.62 and 1086.62 cm-1 (N-H mode)550 and 620 cm-1 ( Mn-O-Ti and O-Ti-O resp.)

280- 350mT (Mn2+)125-175mT ( Mn4+ )

33.43 2.4 eV

Spectroscopic studies of S-doped TiO2


Nidhi SLIET-26.sp - 2/18/2014 - S-1

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0

40.0

42

44

46

48

50

52

54

56

58

60

62

64

66

67.8

cm-1

%T

3369,52

2922,56

2852,58

1729,62

1629,59

1466,62 1149,621086,62

629,42

530,47

416,63

nm.190.00 400.00 600.00 800.00 1000.00 1100.00

Abs

.

3.000

2.000

1.000

0.000

2

1

2

1

2

1

2

1

0 50 100 150 200 250 300 350 400 450-200

-100

0

100

200

300

Inten

sity (

a.u.)

Magnetic field (mT)

Photocatalytic degradation of Quinalphos

Percentage Degradation/Degradation Efficiency % Degradation = {(C0 –C) /C0} x100

HPLC

RESPONSE PARAMETERS

Photocatalytic Chamber Jacketed Wall Reactor UV Lamp (30 W Philips,

05 Nos.) Millipore 0.45 µm Filter Magnetic Bead Magnetic Stirrer Lab Jack

100 ml of sample solution of various

concentrations

Fixed amount of Photo catalyst

UV light

At different time interval aliquot was taken with the help of syringe

Aqueous suspension was

magnetically stirred and

aerated

Absorption spectra were recorded at

λmax

Rate of degradation was studied in terms of change

in absorption spectra.

Filtered (Millipore syringe filter of 0.45 µm)

Photocatalytic Degradation Experiment

Experimental setup for photocatalytic process

TIME DEPENDANT UV-VIS SPECTRA OF QUINALPHOS (OPTIMAL CONDITION-: N-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

EFFECT OF VARIOUS WAVELENGTH REGION (490 NM, 565 NM AND 660 NM) ON THE PERCENTAGE DEGRADATION OF QP (OPTIMAL CONDITION-: N-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L

220 240 260 280 300 320 340 360 380 400

0.0

0.2

0.4

0.6

0.8

1.0

% d

egra

datio

n

Wavelength (nm)

0 min 30 min 60 min 90 min 240 min

60 90 1500

20

40

60

80

100

79.870

57.7

660 nm565 nm490 nm

Time (min)

% d

eg

rad

ati

on


Photocatalytic activity of NT-450

COMPARISON OF DEGRADATION EFFICIENCY OF DEGUSSA P25 AND N-DOPED TIO2 (OPTIMAL CONDITION-: N-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

EFFECT OF VARIATION IN pH (2-10) FOR DEGRADATION OF QP

0 20 40 60 80 100 120 140 1600

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

% d

egra

datio

n

Time (min)

Degussa P25 N-doped TiO2

2 4 6 8 10

0

10

20

30

40

50

60

70

80

50.7 53.3

68.1

79.8

64.6

pH

% d

egra

dati

on


Photocatalytic activity of NT-450

TIME DEPENDANT UV-VIS SPECTRA OF QUINALPHOS (OPTIMAL CONDITION-: S-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

% REMOVAL EFFICIENCY AT DIFFERENT WAVELENGTHS % REMOVAL EFFICIENCY AT DIFFERENT WAVELENGTHS (OPTIMAL CONDITION-: S-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

220 240 260 280 300 320 340 360 380 4000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Abso

rban

ce

Wavelength (nm)

0 min 30 min 60 min 120 min 180 min 240 min

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

70

80

90

490 nm 565 nm 660 nm

Per

cent

age

degr

adat

ion

Time (min)


Photocatalytic activity of S-doped TiO2

COMPARATIVE DEGRADATION EFFICIENCY OF S-DOPED TIO2, TIO2 (MERCK) AND DEGUSSA P25 FOR DEGRADATION OF QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

EFFECT OF VARIATION IN pH (2-10) FOR DEGRADATION OF QP

S-550TiO2 (Merck)

TiO2 (Degussa)

0

10

20

30

40

50

60

70

80

9086.7

50.1

37.7

Catalyst

% d

egra

dat

ion

2 4 6 8 100

102030405060708090

100

60.669.6

86.475.9

63.1

pH

% d

eg

rad

ati

on


EFFECT OF CALCINATION TEMPERATURE ON THE PERCENTAGE DEGRADATION OF QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

EFFECT OF VARIATION OF WAVELENGTH ON THE PERCENTAGE DEGRADATION OF QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L)

250 300 350 400 450 500 550 600 650 700 750 80060

75

90

% d

egra

datio

n

Effect of calcination

Quinalphos

480 500 520 540 560 580 600 620 640 660 680

65

70

75

80

85

90

Quinalphos

% d

egra

datio

n

Effect of wavelength (nm)


Photocatalytic activity of Mn-N-doped TiO2

TIME DEPENDANT UV-VIS SPECTRA OF QUINALPHOS QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

KINETIC ANALYSIS OF QUINALPHOS UNDER CONDITION(MN-N-550–50 mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)

220 240 260 280 300 320 340 360 380 4000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Abs

orba

nce

Wavelength (nm)

0 min 30 min 60 min 120 min 180 min 240 min

0 50 100 150 200 2501.5

1.6

1.7

1.8

1.9

2.0

2.1

lnC

0/C

Time (min)


HPLC CHROMATOGRAPH OF QP AT 0 MIN AND 8 HR

N-DOPED

Mn-N-CO-DOPED


Proposed mechanism of Photocatalysis


Conclusions

Ultrasonication process , an ecofriendly technique can be applied effectively for synthesis of nanophotocatalysts in lesser span of time.

The particle size of the synthesized photocatalysts catalysts varies from 10- 100 nm.

Anion doped, cation doping and double doping resulted in excellent visible light activity of TiO2.

Mn2+ codoped N-TiO2 shows higher activity probably due to early phase transformation.

Photocatalytic degradation of the synthesized catalysts resulted in almost complete mineralization of quinalphos after 8 hr without the formation of intermediates.

The synthesized visible light responsive photocatlysts offers an opportunity to make this technique commercially viable using solar light.


SLIET, Longowal Panjab University, Chandigarh AIIMS, New Delhi IIT, Ropar

Acknowledgement

Thanks!

prof. dhiraj sud dean academic department of chemistry, sant longowal institute of engineering and...

Documents

classes of pesticides

pesticides detergents

total pesticides

mineralization of quinalphos

adsorption of quinalphos

pest control purposes

toxicity moderate toxic

aqueous streams