中间价态锰强化KMnO_4氧化降解三氯生

Oxidative removal of triclosan by potassium permanganate enhanced with manganese intermediates

为验证中间价态锰在KMn O4氧化降解广谱杀菌剂三氯生过程中的强化作用,在不同p H假一级动力学实验条件下,研究KMn O4氧化降解三氯生的动力学规律,考察外加络合剂对KMn O4氧化降解三氯生的影响,评价还原剂Mn(II)在KMn O4氧化降解三氯生过程中的作用.结果表明,KMn O4氧化降解三氯生符合假一级动力学规律,且假一级速率常数Kobs(s-1)随KMn O4浓度的增加呈线性增加.通过KMn O4浓度与Kobs得到的二级反应速率常数k(L·mol-1·s-1)随p H先升高后降低,在三氯生p Ka=8.1附近时最大.络合剂和天然水体的背景成分通过其配位作用,使得KMn O4氧化过程中产生的中间价态锰稳定性增强,强化KMn O4氧化降解三氯生.紫外-可见光谱扫描结果进一步表明,络合剂的强化作用主要是KMn O4氧化过程中生成具有强氧化性Mn(III)的贡献,同时络合剂存在条件下,Mn(II)能够催化KMn O4氧化降解三氯生.

To investigate the effect of manganese intermediates in situ formed on the oxidation of anti-biocide triclosan by potassium permanganate,experiments were conducted to examine the effects of some ligands as well as Mn（ II） on the oxidation of triclosan by potassium permanganate under the condition with potassium permanganate in excess over a wide p H range. The results showed that the degradation of triclosan followed the second-order kinetics and the rate constants increased with the increase of p H and reached the maximum near the p Ka（ 8. 1） of triclosan,after which they decreased gradually. Both selected ligands and the background matrices of nature waters could significantly enhance the oxidation dynamics of triclosan by potassium permanganate via the involvement of stabilized manganese intermediates. The analysis by the UV-vis spectrophotometer scanning confirmed the formation of soluble Mn（ III） in the presence of ligands,which would otherwise disproportionate spontaneously to yield solid Mn O2. Also,these results suggested a catalytic role of Mn（ II） in the oxidation of triclosan by potassium permanganate.