The semiconductor metal oxides based photocatalysis is one of the efficient techniques used for eradication of pollutants from wastewater. The plants mediated biosynthesis of metal oxides have got much interest due to environmentally friendly and cost‐effective nature. This article reports the Calotropis gigantea mediated biosynthesis of ZnO and Ag@ZnO as effective catalysts for degradation of rhodamine B (RhB) dye. After characterization with advanced techniques, the biosynthesized ZnO and Ag@ZnO were tested as photocatalysts on degradation of RhB dye under irradiation. The catalytic activity of ZnO and Ag@ZnO was estimated in terms of decolorization, COD, and TOC removal. Results showed that 50.4 and 90.2% decolorization, 41.3 and 74.8% removal of COD, and 45.3 and 83.5% removal of TOC were measured over ZnO and Ag@ZnO as photocatalysts in 120 min, respectively. The biosynthesized Ag@ZnO was a stable and reusable catalyst in degradation experiments.

中文翻译：

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Calotropis gigantea叶片辅助ZnO和Ag @ ZnO催化剂的生物合成，用于在水性介质中降解罗丹明B染料

基于半导体金属氧化物的光催化是用于消除废水中污染物的有效技术之一。由于环境友好和具有成本效益的性质，植物介导的金属氧化物的生物合成引起了人们的极大兴趣。本文报道了Calotropis gigantea介导的ZnO和Ag @ ZnO的生物合成作为降解罗丹明B（RhB）染料的有效催化剂。通过先进的技术表征后，将生物合成的ZnO和Ag @ ZnO作为光催化剂测试了RhB染料在辐射下的降解。ZnO和Ag @ ZnO的催化活性通过脱色，COD和TOC去除来估算。结果表明，在120min内，分别以ZnO和Ag @ ZnO作为光催化剂，测得的脱色率为50.4％和90.2％，COD的去除率为41.3％和74.8％，TOC的去除率为45.3％和83.5％。在降解实验中，生物合成的Ag @ ZnO是一种稳定且可重复使用的催化剂。