Photocatalytic Degradation of Chlorobenzene in Aqueous Solutions–Comparison of Tio2 with Periwinkle and Snail Shells’ Powder as Photo Catalyst

Aim: The goal of the study is to determine the efficiency of periwinkle shell powder and snail shell powder – two locally prepared photocatalysts in comparison with TiO2 in the treatment of wastewater polluted with chlorobenzene.
Place and Duration of Study: The present study was conducted between January and October 2011 at the Department of Chemical Engineering, University of Benin-Nigeria as part of a Master of Engineering Degree research project.
Methodology: The obtained periwinkle (PSA) and snail (SSA) shells were crushed to powder, sieved and then analysed for the functional group (especially the transition metals) using Fourier Transform Infra-red (FTIR) analysis. The catalytic activity of the unmodified PSA, SSA as well as their modification with H2O2 were then compared with commercial grade TiO2 (Degussa P25) for the degradation of chlorobenzene in wastewater both under laboratory condition (dark) and solar irradiation using sets of special boron-silica glass reactors. UV/VIS spectrophotometer model T70 installed with printer was used for the determination of chlorobenzene concentration while BET surface area of the catalysts was determined by means of nitrogen adsorption/desorption isotherm.
Results: The result show that the photocatalytic activity of pure PSA and SSA were very poor when compared with TiO2. However, PSA and SSA modified with H2O2 showed greater promise as their degradation efficiency increased by 87.98% and 41.72% respectively.
Conclusion: PSA and SSA cannot be used as photocatalyst for the degradation of organic pollutants in aqueous solution without being modified or doped with appropriate metal or non metal dopants.