亚硫酸氢盐强化微量Fe^(2+)活化过二硫酸盐降解扑热息痛

Bisulfite Promoted Minute Fe^(2+)-Activated Peroxydisulfate for Paracetamol Degradation

Fe^(2+)可激活过二硫酸盐(PDS)快速产生硫酸根自由基(SO_(4)^(-)·),但Fe^(2+)会快速转化为低活性的Fe^(3+),且Fe^(2+)的投加量普遍较大,限制了该体系的广泛应用.采用亚硫酸氢盐(BS)强化微量Fe^(2+)-PDS体系降解水中的扑热息痛(APAP).结果表明,投加BS可促进Fe^(2+)-Fe^(3+)的循环,明显改善Fe^(2+)-PDS体系对APAP的降解效果,在最优条件下(PDS=0.6 mmol·L^(-1);BS=0.4 mmol·L^(-1);Fe^(2+)=10μmol·L^(-1);pH=4)下,APAP(4μmol·L^(-1))可在180 s内被完全降解.同时,APAP的降解速率随BS(0~0.6 mmol·L^(-1))和PDS(0.2~1.5 mmol·L^(-1))浓度的增大而升高,适量提高Fe^(2+)浓度可促进APAP的降解,但增加BS的投加次数对降解速率影响不大.HCO_(3)^(-)与HPO_(4)^(2-)明显抑制了体系降解APAP的效率,Cl^(-)和NO_(3)^(-)有轻微抑制作用,腐殖酸(HA)则影响不大.通过淬灭实验和电子顺磁共振波谱检测,证实了体系中SO_(4)^(-)·、·OH和单线态氧的产生,其中SO_(4)^(-)·是降解APAP的主要活性物种.利用三维荧光光谱技术对APAP降解过程进行了表征,表明APAP降解产物具有荧光特性.此外,还鉴定出5种中间产物,并提出了3种可能的降解途径.体系在实际水体中的效能低于超纯水中的表现,但延长反应时间可明显增强降解效果,表明BS-Fe^(2+)-PDS体系是一种有前景的有机污染物降解方法.

Fe^(2+)has been commonly selected to activate peroxydisulfate(PDS)for sulfate radical(SO_(4)^(-)·)generation because of its eco-friendly,cost-effective,and high activity characteristics.However,Fe^(2+)can be rapidly oxidized to Fe^(3+)in the reaction,leading to poor utilization of iron for PDS activation.Further,a fairly high concentration of Fe^(2+)is generally required and may cause iron sludge production and secondary pollution.In this study,a minute Fe^(2+)-activated PDS system induced by bisulfite(BS)was used to degrade paracetamol(APAP)in water.The results showed that the Fe^(2+)-PDS system could be enhanced by the circulation of Fe^(2+)-Fe^(3+)with the injection of BS and by keeping Fe^(2+)at a high concentration.Under the optimal conditions(PDS=0.6 mol·L^(-1);BS=0.4 mol·L^(-1);Fe^(2+)=10μmol·L^(-1);pH=4),100% APAP(4μmol·L^(-1))was removed within 180 s.The degradation rate of APAP increased with the increase in BS(0-0.6 mmol·L^(-1))and PDS(0.2-1.5 mmol·L^(-1))concentration,and a modest Fe^(2+)concentration could accelerate APAP removal.Co-existing substances inhibited the APAP removal and followed the order of HCO_(3)^(-)>HPO_(4)^(2-)>Cl^(-)>NO_(3)^(-)>humic acid(HA).Based on the quenching experiments and electron paramagnetic resonance spectroscopy test,SO_(4)^(-)·was shown to be the primary reactive species for APAP decomposition in the BS-Fe^(2+)-PDS process.Three-dimensional fluorescence spectroscopy revealed that APAP intermediates had fluorescence characteristics.Moreover,five intermediates were identified,and the probable APAP degradation pathways were proposed.The removal efficiencies of APAP were lower in real waters than that in ultrapure water.Nevertheless,the removal effect was greatly improved after a prolonged reaction time.All results indicated that the BS-Fe^(2+)-PDS system could be a promising method for organic pollutant treatment.