Environmental Health Research Centre, Kurdistan University of Medical Sciences, Sanandaj, Kurdistan, Iran.
Environ Technol. 2011 Oct;32(13-14):1573-9. 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.
本工作研究了在紫外 (UV) 光照射下使用合成的纳米 ZnO 光催化去除水溶液中的 Cr(VI) 和 Ni(II)。首先，通过化学方法用有机化学抑制剂制备了纳米 ZnO。然后，通过改变溶液 pH 值、ZnO 用量、接触时间和初始 Cr(VI)和 Ni(II)浓度来研究纳米 ZnO 对 Cr(VI)和 Ni(II)的去除效率。在近中性 pH 值下观察到最大的 Cr(VI)和 Ni(II)去除效率，因为 ZnO 在极低和高 pH 值下的光催化活性降低源于催化剂的酸性/光化学腐蚀和/或 Zn(OH)2 的表面钝化。随着 ZnO 用量的增加，Cr(VI)和 Ni(II)的去除效率不断提高，但超过 1.25 g/l 后逐渐降低，这是由于用于光催化反应的入射 UV 光的阻挡增加。最佳 ZnO 用量确定为 1 g/l。随着初始 Cr(VI)和 Ni(II)浓度的增加，Cr(VI)和 Ni(II)的去除效率降低，这是由于表面 ZnO 的反应位点减少，对 ZnO 表面的抑制作用增强，从而进一步抑制了光催化反应。
