Photodegradation study of Congo Red in Aqueous Solution using ZnO/ UV-A: Effect of pH And Band Gap of other Semiconductor Groups

Laouedj Nadjia, Elaziouti A

Abstract

The photocatalytic degradation of Congo red in aqueous solution was investigated under UVA light at different operating conditions, including irradiation time, pH solution and band gap of MO2 (M=Ti+4 and Ce+4) and M’2O3 (M’=Al+3 and Fe+3) semiconductor groups by UV-spectrophotometric monitoring. The results showed slight stability of 597nm band of CR over the pH range of 6-7, while, it almost completely disappeared at pH higher than 7. Maximum photo degradation was obtained at pH 8 as a result of 95.02% degradation efficiency of CR for 60 min of irradiation time. The photo decomposition efficiency of MO2 (M=Ti+4 and Ce+4) semiconductor group was higher, compared to that of M’2O3 (M’=Al+3 and Fe+3). Photodecomposition reactions correlated with pseudo-first-order kinetic model. These findings can support the design of remediation processes and also assist in predict their fate in the environment.

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