紫外强化铜循环催化过硫酸盐降解甲基橙

摘要

为增强Cu(Ⅱ)∕PMS(PMS为活化过硫酸盐)体系的氧化能力,加速Cu(Ⅰ)和Cu(Ⅱ)之间的循环转化,以MO(甲基橙)为目标污染物,研究了Cu(Ⅱ)∕PMS∕UV(UV为紫外线)体系氧化降解MO的效果和反应机理,以及UV在Cu(Ⅱ)∕PMS体系中的作用.结果表明:反应20 min时,Cu(Ⅱ)∕PMS体系中MO的降解率为41.13％,Cu(Ⅱ)∕PMS∕UV体系中MO的降解率达到100％;通过投加TBA(叔丁醇)和EA(乙醇)发现,在酸性条件下体系的主要氧化物种是SO4-?(硫酸根自由基)和少量的?OH(羟基自由基);MO的降解率随pH的增大而减小;提高紫外灯功率和PMS投加量均有利于MO的降解;最佳Cu(Ⅱ)投加量为10.0μmol∕L,超过Cu(Ⅱ)的最佳投量会抑制MO的降解;MO的降解过程符合假一级动力学;紫外可见光谱图分析结果表明,MO最终被降解为共轭二烯类物质.研究显示,在Cu(Ⅱ)∕PMS∕UV体系中,UV可以有效促进Cu(Ⅱ)向Cu(Ⅰ)的转化,从而显著增强Cu(Ⅱ)∕PMS体系的氧化能力,有效降解水中污染物.%In order to enhance the oxidative capacity of the Cu( Ⅱ)∕PMS process and accelerate copper-redox cycle, methyl orange ( MO) was selected as a target compound to investigate the efficiency and the mechanism of MO degradation, and the role of UV in Cu( Ⅱ)∕PMS∕UV process. The results showed that MO was degraded for 41. 13％ and 100％ after 20 min during Cu(Ⅱ)∕PMS and Cu(Ⅱ)∕PMS∕UV processes, respectively, indicating that UV could effectively promote the reduction from Cu ( Ⅱ ) to Cu ( Ⅰ ) . The addition of radical scavengers, tert-butyl alcohol ( TBA ) and ethyl alcohol ( EA ) , inhibited MO degradation, which demonstrated that sulfate radical ( SO4-?) and a small amount of hydroxyl radical (?OH) were primary oxygen species of this process. MO degradation was reduced with the increasing pH. The high power of UV light and dosage of PMS were favorable for the degradation of MO. The optimal dosage of Cu( Ⅱ) was 10. 0 μmol∕L, while exceeding this dosage, MO degradation would be inhibited. Besides, the degradation of MO followed the pseudo-first-order kinetics, and the UV-vis absorption spectra of MO showed that MO was removed to conjugated diene finally. This study revealed that the addition of UV irradiation could strongly enhance the oxidative capacity of the Cu ( Ⅱ )∕PMS process via accelerating the transformation from Cu( Ⅱ) to Cu( Ⅰ) , which further removed the contaminants in the aqueous solution.