Effective photocatalytic degradation of rhodamine-B over Zn-doped BaO2 and SrO2 composites under UV and sunlight irradiation

Abstract

Environmental pollution due to dye industries is a major concern as it affects both aquatic and human life. Among various processes, photocatalysis involving the advanced oxidation process (AOP) that employs semi-conductor based photocatalysis is popular and this process degrades dyes into CO₂ and H₂O. The currently used TiO₂ based photocatalysis requires ultra-violet (UV) light irradiation for activation. There is always a need for a catalyst that works under natural sunlight so that the dye degradation process is economical. Towards this objective, we have developed Zn doped metal peroxides as efficient photocatalysts towards rhodamine B (RhB) dye degradation. A new family of zinc-doped barium peroxide (Ba_1-xZn_xO₂x = 0, 0.2, 0.4, 0.6, and 0.8) and zinc-doped strontium peroxide (Sr_1−xZn_xO₂x = 0, 0.2, 0.4, 0.6, and 0.8) photocatalysts were prepared by the co-precipitation technique for the photocatalytic degradation of RhB under UV and natural sunlight irradiation. In particular, Ba_0.4Zn_0.6O₂ (x = 0.6) and Sr_0.6Zn_0.4O₂ (x = 0.4) photocatalysts exhibit higher photodegradation efficiency than the pure peroxides both under UV and sunlight irradiation. Ba_0.4Zn_0.6O₂ and Sr_0.6Zn_0.4O₂ photocatalysts show a degradation efficiency of 99.9% and 99.8% within 15 min and 10 min under UV light, respectively. The rate constants of degradation by doped peroxides, in particular Ba_0.4Zn_0.6O₂ and Sr_0.6Zn_0.4O_2, are 100 times higher than those of the parent peroxides.