可见光下苯醌类化合物诱导磷酸铁芬顿反应的铁离子源汇机制

Iron-ion source and sink mechanism for Fenton reaction based on iron phosphate induced by benzoquinones under visible light

构建了可见光下苯醌类化合物诱导磷酸铁产生芬顿反应的体系,分析了苯醌类化合物对磷酸铁释放亚铁离子的影响,比较了苯醌类化合物诱导磷酸铁芬顿反应降解橙Ⅱ的效率,研究了橙Ⅱ降解过程中铁离子和亚铁离子之间的转化以及羟基自由基浓度的变化,讨论了可见光下苯醌类化合物诱导磷酸铁芬顿反应铁离子的源汇机制.结果表明,可见光下苯醌类化合物诱导的磷酸铁是芬顿反应铁离子的间接铁源和直接铁汇.当可见光-磷酸铁-过氧化氢体系分别添加2-氯-1,4-苯醌、苯醌和对二甲基醌,溶液中亚铁离子浓度峰值(对应时间)从基础实验的0.86 mg·L^(-1)(120 min)分别提高到2.06 mg·L^(-1)(40 min)、1.61 mg·L^(-1)(40 min)和1.04 mg·L^(-1)(120 min);铁离子引发的芬顿反应能极大提高橙Ⅱ的脱色率和矿化率:反应60 min时,橙Ⅱ脱色率分别是99.5%、98.1%和77.7%;反应180 min时,橙Ⅱ矿化率分别为78.8%、77.6%和52.4%;反应结束时,总铁离子的浓度会大幅降低至0.2 mg·L^(-1)左右,能避免铁离子的二次污染.另外,可见光下苯醌诱导磷酸铁芬顿反应循环降解橙Ⅱ的结果表明,铁离子释放和回收过程具有较高的重现性;FT-IR和XPS图谱表明,磷酸铁在循环使用后具有较高的结构和化学重现性.本研究开发了磷酸铁用于有机废水处理高值化利用的途径,为废旧磷酸铁锂电池的资源化利用提供理论依据.

A new Fenton system was constructed based on iron phosphate induced by benzoquinones(2-Chloro-1,4-benzoquinone,1,4-Benzoquinone or 2,5-Dimethylquinone)under visible light.The effects of benzoquinones on ferrous ion release from iron phosphate and degradation efficiency of OrangeⅡthrough Fenton process were analyzed in detail.During OrangeⅡdegradation,the transformation between iron and ferrous ions and the change concentration of hydroxyl radical were detected.The iron-ion source and sink mechanism for Fenton reaction was further investigated.The results showed that iron phosphate was the indirect source and direct sink of iron ions induced by benzoquinones under visible light.When 2-Chloro-1,4-benzoquinone,1,4-Benzoquinone and 2,5-Dimethylquinone were added to the visible light-iron phosphate-hydrogen peroxide system,the peak values of ferrous ion concentration(corresponding time)was increased from 0.86 mg·L^(-1)(120 min)to 2.06 mg·L^(-1)(40 min),1.61 mg·L^(-1)(40 min)and 1.04 mg·L^(-1)(120min),respectively.Then the decolorization and mineralization rates of OrangeⅡcould be greatly enhanced through Fenton process using iron ion as catalyst.After 60 min treatment,the decolorization rates of OrangeⅡwere increased to 99.5%,98.1%and 77.7%,respectively;after 180min treatment,the mineralization rates of OrangeⅡwere up to 78.8%,77.6%and 52.4%,respectively.In addition,the concentration of total iron ions was decreased to about 0.2 mg·L^(-1)after treatment,therefor the secondary contamination of iron ions could be avoided.Furthermore,the iron release and recovery process has high reproducibility.Importantly,Fourier transform infrared and Xray photoelectron spectroscopy showed that iron phosphate had high structural and chemical reproducibility after reaction.This study developed a way of high-value utilization of iron phosphate for organic wastewater treatment,which provided a theoretical support for comprehensive utilization of waste lithium iron phosphate batteries.