Samarghandi Mohammad-Reza, Yang Jae-Kyu, Giahi Omid, Shirzad-Siboni Mehdi
a Department of Environmental Health and Research Center for Health Sciences , Hamadan University of Medical Sciences , Hamadan , Iran.
Environ Technol. 2015 May-Jun;36(9-12):1132-40. doi: 10.1080/09593330.2014.982718. Epub 2014 Dec 9.
In this study, photocatalytic reduction of hexavalent chromium [Cr(VI)] by amorphous FeOOH was investigated with variations in FeOOH dosage, pH, initial Cr(VI) concentration, purging gas, organic compounds and initial hydrogen peroxide concentration. Reduction and adsorption were identified as important processes for the removal of Cr(VI). FeOOH dosage was also an important parameter for the removal of Cr(VI). As the FeOOH dosage increased up to 0.5 g/L, the removal of Cr(VI) was continuously enhanced and then decreased above 0.5 g/L due to increased blockage of the incident UV light. The removal efficiency of Cr(VI) decreased with increasing pH, initial Cr(VI) concentration and initial hydrogen peroxide concentration. While the removal efficiency of Cr(VI) increased with purging of nitrogen gas compared to that of oxygen gas because of less competition between dissolved oxygen and Cr(VI) with the electron in the conduction band of FeOOH. The photocatalytic reduction of Cr(VI) was increased in the presence of citric acid and phenol, while it was decreased in the presence of EDTA and oxalic acid. The reaction rate constant (kobs) was decreased from 0.2141 to 0.0026 1/min and the value of electrical energy per order (EEo) was increased from 22.41 to 1846.15 (kWh/m3) with increasing initial Cr(VI) concentration from 10 to 50 mg/L, respectively. Finally, proper photocatalytic activity was maintained even after five successive cycles.
在本研究中，研究了非晶态FeOOH对六价铬[Cr(VI)]的光催化还原作用，考察了FeOOH用量、pH值、初始Cr(VI)浓度、吹扫气体、有机化合物和初始过氧化氢浓度的变化。还原和吸附被确定为去除Cr(VI)的重要过程。FeOOH用量也是去除Cr(VI)的一个重要参数。随着FeOOH用量增加至0.5 g/L，Cr(VI)的去除率持续提高，而在0.5 g/L以上时由于入射紫外光的阻挡增加而下降。Cr(VI)的去除效率随pH值、初始Cr(VI)浓度和初始过氧化氢浓度的增加而降低。与氧气吹扫相比，氮气吹扫时Cr(VI)的去除效率更高，这是因为溶解氧与Cr(VI)在FeOOH导带中对电子的竞争较小。在柠檬酸和苯酚存在下，Cr(VI)的光催化还原作用增强，而在EDTA和草酸存在下则减弱。随着初始Cr(VI)浓度从10 mg/L增加到50 mg/L，反应速率常数(kobs)从0.2141降至0.0026 1/min，单位电能(EEo)值从22.41增加到1846.15(kWh/m3)。最后，即使经过连续五个循环，仍能保持适当的光催化活性。
