Photocatalytic reduction of Cr(VI) and Ni(II) in aqueous solution by synthesized nanoparticle ZnO under ultraviolet light irradiation: a kinetic study

• Published in: Environmental technology Vol. 32; no. 14; pp. 1573 - 1579
• Main Authors: Shirzad Siboni, M, Samadi, M.T, Yang, J.K, Lee, S.M
• Format: Journal Article
• Language: English
• Published: Abingdon TF 01-10-2011; Taylor & Francis Group; Taylor & Francis; Taylor & Francis Ltd
• Subjects: Applied sciences; Aqueous solutions; Atmospheric pollution; Catalysis; catalysts; Catalytic reactions; Chemical engineering; Chemistry; chromium; Chromium - chemistry; Chromium - isolation & purification; Chromium - radiation effects; corrosion; Corrosion inhibitors; Cr(VI); environmental technology; Exact sciences and technology; General and physical chemistry; Inhibition; irradiation; Nanocomposites; Nanomaterials; nanoparticle; nanoparticles; Nanoparticles - chemistry; Nanoparticles - radiation effects; Nanostructure; Ni(II); nickel; Nickel - chemistry; Nickel - isolation & purification; Nickel - radiation effects; Organic chemicals; Oxidation-Reduction - radiation effects; Photocatalysis; Photochemistry - methods; Pollution; Reactors; Solutions; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Titanium - chemistry; Titanium - radiation effects; ultraviolet radiation; Ultraviolet Rays; Water - chemistry; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water Pollutants, Chemical - radiation effects; Water Purification - methods; Water treatment; zinc; Zinc oxide; Zinc Oxide - chemistry; Zinc Oxide - radiation effects; ZnO; British Isles; Pollutant behavior; Nanoparticle; Chemical method; Photocatalysis; Ni(II); Ultrafine particle; Chemical reduction; Ultraviolet radiation; Cr(VI); Corrosion; Aerosols; pH; Air pollution; ZnO; Kinetics; Aqueous solution; Catalyst; Photochemical degradation; Passivation
• ISSN: 1479-487X; 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2010.543933

Photocatalytic removal of Cr(VI) and Ni(II) from aqueous solution using synthesized nanoparticle ZnO under ultraviolet (UV) light irradiation was studied in this work. Firstly, nanoparticle ZnO was prepared by the chemical method with an organic chemical inhibitor. Then removal efficiency of Cr(VI) and Ni(II) by nanoparticle ZnO was investigated with variation of the solution pH, ZnO dosage, contact time and initial Cr(VI) and Ni(II) concentration. Maximum removal of Cr(VI) and Ni(II) was observed at near‐neutral pH because the reduced photocatalytic activity of ZnO at exceedingly low and high pH values originates from either acidic/photochemical corrosion of the catalyst and/or surface passivation with Zn(OH)₂. As the ZnO dosage increased, the removal efficiency of Cr(VI) and Ni(II) was continuously enhanced, but was gradually decreased above 1.25 g/l due to the increased blockage of the incident UV light used for the photocatalytic reaction. The optimum ZnO dosage was determined as 1 g/l. Removal efficiencies of Cr(VI) and Ni(II) decreased as initial Cr(VI) and Ni(II) concentration increased, due to an increased inhibition effect on the surface of ZnO resulting from the decreased reaction sites on the surface of ZnO required for the further photocatalytic reaction.