∑
that the PL emission results from the recombination of the excited
electrons and holes. Hence the lower PL intensity indicates a
lower recombination rate.58 Fig. 10 shows that the PL spectra
of Al2O3–MCM-41 and 5 Cu/Al2O3–MCM-41. It is observed
that the PL intensity of 5 Cu/Al2O3–MCM-41 sample is lower
than the Al2O3–MCM-41. This indicated that the recombination
of charges decreased after doping of Cu onto the surface of
Al2O3–MCM-41. But in case of Al2O3–MCM-41, PL intensity
is more, resulted more electron-hole recombination. As a result
photocatalytic dye degradation in some extends led to less dye
degradation as compared to 5 Cu/Al2O3–MCM-41.
and generation of OH are the key properties of 5 Cu/Al2O3–
MCM-41 which aid degradation of highly concentrated 500 mg
L-1 dyes within 30 min. 5 Cu/Al2O3–MCM-41 is not only an
efficient catalyst for single dye degradation process but also treated
as an excellent catalyst for mixed dyes degradation. Thus, 5
Cu/Al2O3–MCM-41 act as an efficient photocatalyst/adsorbent
for photocatalytic degradation and adsorption of dyes and will act
as a futuristic material to control the industrial pollution.
Acknowledgements
We acknowledge Prof. B. K. Mishra, Director, IMMT,
Bhubaneswar, Orissa, India, for his constant encouragement and
permission to publish the paper. One of the authors, Amaresh
Chandra Pradhan (CSIR-SRF) is extremely thankful to CSIR
New Delhi, India, for the award of SRF. We are thankful to DST,
Govt. of India for the financial support.
References
1 H. Kyung, J. Lee and W. Choi, Environ. Sci. Technol., 2005, 39, 2376–
2382.
2 C. Peter, Color in dye house effluent, Society of Dyers and Colourists,
Alden Press, Oxford, U.K., 1995.
3 V. K. Gupta, I. Ali and V. K. Saini, Environ. Sci. Technol., 2004, 38,
4012–4018.
4 I. Ali and V. K. Gupta, Nat. Protoc., 2007, 1, 2661–2667.
5 K. M. Parida and A. C. Pradhan, J. Hazard. Mater., 2010, 173, 758–764.
6 H. Zhang, D. Chen, X. Lv, Y. Wang, H. Chang and J. Li, Environ. Sci.
Technol., 2010, 44, 1107–1111.
Fig. 9 Type-1 = mixed dyes adsorption/degradation without sunlight
at pH 3.5, Type-2 = mixed dyes adsorption/degradation at pH 11 and
Type-3 = mixed dyes degradation at pH 11 in presence of sunlight.
7 T. Aarthi and G. Madras, Ind. Eng. Chem. Res., 2007, 46, 7–14.
8 C. Guo, M. Ge, L. Liu, G. Gao, Y. Feng and Y. Wang, Environ. Sci.
Technol., 2010, 44, 419–425.
9 C. Hu, X. Hu, L. Wang, J. Qu and A. Wang, Environ. Sci. Technol.,
2006, 40, 7903–7907.
10 V. K. Gupta, P. J. M. Carrott, M. M. L. Ribeiro Carrott and Suhas,
Crit. Rev. Environ. Sci. Technol., 2009, 39, 783–842.
11 V. K. Gupta and Suhas, J. Environ. Manage., 2009, 90, 2313–2342.
12 V. K. Gupta and I. Ali, Environ. Sci. Technol., 2008, 42, 766–770.
13 V. K. Gupta, A. Mittal, R. Jain, M. Mathur and S. Sikarwar, J. Colloid
Interface Sci., 2006, 303, 80–86.
14 V. K. Gupta, A. Mittal, V. Gajbe and J. Mittal, Ind. Eng. Chem. Res.,
2006, 45, 1446–1453.
15 V. K. Gupta, A. Mittal, V. Gajbe and J. Mittal, J. Colloid Interface Sci.,
2008, 319, 30–39.
16 V. K. Gupta, R. Jain, S. Varshney and V. K. Saini, J. Colloid Interface
Sci., 2007, 307, 326–332.
17 V. K. Gupta, A. Mittal, L. Krishnan and J. Mittal, J. Colloid Interface
Sci., 2006, 293, 16–26.
18 V. K. Gupta, I. Ali and V. K. Saini, J. Colloid Interface Sci., 2007, 315,
87–93.
Fig. 10 Photoluminescence spectra of Al2O3–MCM-41 and 5 Cu/
Al2O3–MCM-41.
19 M. A. Fox and M. T. Dulay, Chem. Rev., 1993, 93, 341–357.
20 O. Carp, C. L. Huisman and A. Reller, Prog. Solid State Chem., 2004,
32, 33–177.
21 V. K. Gupta, R. Jain, S. Agarwal and M. Shrivastava, Colloid Surf. A:
Physicochem. Eng. Aspects, 2011, 378, 22–26.
Conclusions
The mesoporous 5 Cu/Al2O3–MCM-41 composites is found to
behave just like a semiconducting material and showed excellent
activity for photocatalytic dyes degradation in presence of sun-
light. The high texture MA has been synthesized using starch
as template and incorporated in situ into the framework MCM-
41. This process forms a high surface area mesoporous support
Al2O3–MCM-41 which converted to 5 Cu/Al2O3–MCM-41 by
impregnation of copper. The 5 Cu/Al2O3–MCM-41 and Al2O3–
MCM-41 showed intra-particle mesoporosity and high textural
properties such as high surface area, narrow pore diameter and
wide pore volume which gives platform to adsorb MB, MV, MG
and Rd 6G. The intra-particle mesoporosity, electron transfer
22 V. K. Gupta, R. Jain, A. Mittal, M. Mathur and S. Sikarwar, J. Colloid
Interface Sci., 2007, 309, 464–469.
23 A. Matsumoto, H. Misran and K. Tsutsumi, Langmuir, 2004, 20, 7139–
7145.
24 Z. Yan, S. Tao, J. Yin and G. Li, J. Mater. Chem., 2006, 16, 2347–
2353.
25 A. Walcarius and L. Mercier, J. Mater. Chem., 2010, 20, 4478–4511.
26 Z. Yan, G. Li, L. Muab and S. Taoa, J. Mater. Chem., 2006, 16, 1717–
1725.
27 F. N. Gu, F. Wei, J. Y. Yang, Y. Wang and J. H. Zhu, J. Phys. Chem. C,
2010, 114, 8431–8439.
28 K. Y. Ho, G. McKay and K. L. Yeung, Langmuir, 2003, 19, 3019–3024.
29 X. Zhuang, Y. Wan, C. Feng, Y. Shen and D. Zhao, Chem. Mater.,
2009, 21, 706–716.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 7348–7356 | 7355
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