Room Temperature Synthesis of Surface Modified ZnO Nanoparticles and its Application in Dye Degradation J. Mishra1, N. Kaur2, A. K. Ganguli3,4* 1 Centre for Nanoscience and Nanotechnology, Panjab University, Chandigarh, India, 160014 2 Department of Chemistry, Panjab University, Chandigarh, India, 160014 3Indian Institute of Technology, Hauz Khas, Delhi, India, 110016 4Institute of Nano Science and Technology, Habitat centre, Phase 10, Sector 64, Mohali, India, 160062 Corresponding author: ashokganguliiitd@gmail.com
Introduction: • Water
pollution is a major environmental issue in the present scenario.
• Dyes are one of the dreadful agents which cause water pollution. • Several semiconductors like ZnO, CdSe etc. are well known materials [1-5] reported for dye degradation in the presence of light. But high temperature, pressure and rigorous reaction conditions are required for the synthesis of suitable photocatalyst which can be used for dye degradation. • We have synthesized an organic surface directing agent by a simple single step reaction which is used further for insitu ZnO nanoparticle synthesis at room temperature. • These surface modified ZnO nanoparticles were then used as photocatalyst for Rhodamine B dye degradation from dye solution. O2N
NCS
Synthesis:
R S
H2N NH2 N
HN NO2
N
HN
HN
HN
Zn(NO3)2.6H2O
NO2
ZnO
HN HN
Dry chloroform, Reflux at 50-60oC
H2N
R
R
S
S
R
NaOH, 30-40oC
R R
O2N
R
Tren
Scheme 1
Characterization: (a)
( b)
(d)
(c) o
Figure 2. (a) NMR spectrum of R; (b) MASS spectrum of R; (c) IR spectrum of R and R-ZnO; (d) TEM image of R-ZnO
Photocatalytic study of Rhodamine B dye degradation by surface modified ZnO nanoparticles: 1.0
0.4
(Cn/Co) Exponential fit of (Cn/Co)
(b)
1.0
Equation
5
(c)
y = A1*exp(-x/t1) + y0
Adj. R-Square
0.99894
0.8
Value
4
Standard Error
Cn/Co
y0
0.02494
0.00405
Cn/Co
A1
0.97496
0.01124
Cn/Co
t1
5.5883
0.35252
0.6
3
ln Co/Cn
0.6
(a)
Cn/Co
Absorbance
0.8
Blank 30 min in dark 15 min in light 30 min in light 45 min in light 1 hour in light 1 hour 15 min in light 1 hour 30 min in light 1 hour 45 min in light 2 hours in light
0.4
2
ln Co/Cn Linear fit of ln Co/Cn
0.2
0.2
1
Equation
y = a + b*x
Adj. R-Square
0.6035
0.0
0.0 450
500
550
600
Wavelength (nm)
Value
0
20
40
60
80
100
120
Irradiation time (min)
0 0
20
40
60
Standard Error
lnCoCn
Intercept
1.61659
0.50852
lnCoCn
Slope
0.02585
0.00712
80
100
120
Irradiation time (min)
Figure 3. (a) Photocatalytic degradation of Rhodamine B dye by surface modified ZnO; (b) Plot of Cn/Co vs. Irradiation time (min); (c) Plot of ln Co/Cn vs. Irradiation time (min)
Conclusions: • An organic compound was synthesized which was characterized by NMR, MASS and IR spectroscopy. • This compound was further used as surface directing agent for the synthesis of ZnO nanoparticles which was characterized by PXRD and IR spectroscopy and TEM technique . • These surface modified ZnO nanoparticles were then used as a photocatalyst for Rhodamine B dye degradation. • The efficiency of the surface modified ZnO nanoparticles was 94% when kept in the dark for 30 min which increases upto 98% after 1 hour of Hg lamp illumination. • The reaction kinetics was studied by the exponential and linear fit of the plot of Cn/Co vs. time and ln(Co/Cn) vs. time respectively. The degradation followed the first order reaction kinetics with coefficient of determination for exponential fit of Cn/Co vs. time as 99.9%. The rate constant determined by the linear fit of ln(Co/Cn) vs. time was 2.58x10-2 min-1.
References: [1] Ren et al., ACS Appl. Mater. Interfaces 2014, 6, 1608- 1615
Acknowledgement: Authors thank DST for financial assistance.
[2] Ganguli et al., ACS Appl. Mater. Interfaces 2014, 6, 13221- 13233 [3] Ganguli et al., J. Phys. Chem. C 2013, 117, 5558- 5567 [4] Shi and Yan et al.,Cryst Eng Comm, 2015, 17, 1701-1709 [5] Li et al., Phys. Chem. Chem. Phys., 2013, 15, 19545- 19549