Abstract

This study has focused on the applications of newly prepared zinc oxide (ZnO) composite with polyvinyl pyrrolidone (PVP) for adsorption and photocatalytic removal of methyl orange and congo red. Both the surface area and pore size of ZnO–PVP composite are relatively higher than the simple of unmodified ZnO. This finding signifies the role of PVP in the composites of metal oxide–PVP. The FT-IR analysis showed the chemical interactions of zinc oxide and different functional groups of polyvinyl pyrrolidone, which contribute significantly in removing the azo dyes from the aqueous system. A detailed kinetic study of the sorption used to remove methyl orange and congo red from aqueous solutions by ZnO–PVP composite was undertaken. Pseudo second order kinetic model was found to be best applicable for both the dyes. The mechanism governing the adsorption kinetics was examined by employing the Boyd and intraparticle diffusion models. The results confirmed that the adsorption of dyes by ZnO–PVP composite is mainly controlled by film diffusion (external diffusion) and internal transport of dye is inferior to the external transport. The obtained adsorption capacity for methyl orange is higher than that for congo red due to the presence of an additional functional group and size of the dye. The photocatalytic degradation of dyes with UV light was found to increase significantly with the addition of H₂O₂.

中文翻译：

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PVP功能化ZnO对甲基橙和刚果红的吸附和光催化降解动力学

摘要

这项研究集中在新制备的具有聚乙烯吡咯烷酮（PVP）的氧化锌（ZnO）复合材料在吸附和光催化去除甲基橙和刚果红方面的应用。ZnO-PVP复合材料的表面积和孔径均比未改性的ZnO简单要高。这一发现表明PVP在金属氧化物-PVP复合材料中的作用。FT-IR分析表明，氧化锌与聚乙烯吡咯烷酮的不同官能团之间存在化学相互作用，这对从水性体系中去除偶氮染料起着重要作用。进行了详细的动力学研究，研究了用ZnO-PVP复合材料从水溶液中去除甲基橙和刚果红的吸附过程。发现伪二阶动力学模型最适用于两种染料。通过使用博伊德和粒子内扩散模型检查控制吸附动力学的机制。结果证实，ZnO-PVP复合材料对染料的吸附主要受膜扩散（外部扩散）的控制，染料的内部迁移不如外部迁移。由于存在附加的官能团和染料的尺寸，因此获得的对甲基橙的吸附能力高于对刚果红的吸附能力。研究发现，添加H可以显着增加紫外线对染料的光催化降解。结果证实，ZnO-PVP复合材料对染料的吸附主要受膜扩散（外部扩散）的控制，染料的内部迁移不如外部迁移。由于存在附加的官能团和染料的尺寸，因此获得的对甲基橙的吸附能力高于对刚果红的吸附能力。研究发现，添加H可以显着增加紫外线对染料的光催化降解。结果证实，ZnO-PVP复合材料对染料的吸附主要受膜扩散（外部扩散）的控制，染料的内部迁移不如外部迁移。由于存在附加的官能团和染料的尺寸，因此获得的对甲基橙的吸附能力高于对刚果红的吸附能力。研究发现，添加H可以显着增加染料在紫外光下的光催化降解。₂ O ₂。