光芬顿法处理次磷酸盐同步回收磷性能及参数研究

The influencing factors for the treatment of hypophosphite and simultaneous recovery of phosphorus via photo-Fenton

本研究构建了以模拟太阳光(AM 1.5,100 mW·cm^(−2))为光源的光芬顿体系,研究了对化学镀镍废水中次磷酸盐(H_(2)PO_(2)^(-))的氧化且同步回收磷(P),比较了单独H_(2)O_(2)、模拟太阳光和H_(2)O_(2)联用、H_(2)O_(2)与FeSO_(4)联用(芬顿法)、模拟太阳光和芬顿法联用(光芬顿法)对H_(2)PO_(2)^(-)的氧化效果.结果表明光芬顿法效果最优,能够高效氧化H_(2)PO_(2)^(-)为PO_(4)^(−)的同时在一定条件下以磷酸铁(FePO_(4))沉淀形式回收P.考察了不同H_(2)O_(2)浓度、H_(2)O_(2)投加次数、溶液初始pH值、共存无机阴离子次氯酸根(ClO^(−))、共存有机阴离子柠檬酸根(C_(6)H_(5)O_(7)^(3−))对总磷(TP)去除效果的影响.结果表明,初始pH为3,浓度为1 mmol·L^(-1)的H_(2)PO_(2)^(-)在光芬顿体系中,Fe^(2+)投加量为3 mmol·L^(-1),H_(2)O_(2)投加量为9 mmol·L^(-1),H_(2)O_(2)分5次投加反应60 min后,TP去除率可达99%.体系中ClO^(−)和低浓度C_(6)H_(5)O_(7)^(3−)(1 mmol·L^(-1))能促进TP去除,高浓度C_(6)H_(5)O_(7)^(3−)会抑制TP去除.淬灭实验和电子自旋共振波谱测试(ESR)表明体系中氧化H_(2)PO_(2)^(-)的主要活性物种为羟基自由基(·OH).通过对实际废水处理进一步证实了该体系的可行性,为含H_(2)PO_(2)^(-)废水的资源化处理提供了参考.

In this study,the hypophosphite(H_(2)PO_(2)^(-))in electroless nickel plating effluents was treated by photo−Fenton method under simulated sunlight(AM 1.5,100 mW·cm^(−2))irradiation and simultaneously recovering phosphorus(P).The performance of the oxidation of H_(2)PO_(2)^(-)to PO_(4)^(3−)with varies methods including hydrogen peroxide(H_(2)O_(2)),light combined with H_(2)O_(2),Fenton,and photo−Fenton were compared.It was found that photo−Fenton method could effectively achieved the oxidation of H_(2)PO_(2)^(-)to PO_(4)^(3−),and P could be successfully recovered in the form of ferric phosphate(FePO_(4))precipitates under certain conditions.The effects of different operating parameters including H_(2)O_(2) concentration,H_(2)O_(2) feeding mode,initial solution pH,coexisting inorganic anions hypochlorite(ClO^(−))and organic anions citrate(C_(6)H_(5)O_(7)^(3−))concentrations on the removal efficiency of total phosphorus(TP)in the constructed photo−Fenton system was investigated.The results indicated that the removal efficiency of TP was 99%and P was recovered in the form of FePO_(4) precipitates at 60 min under sunlight with the initial concentration of H_(2)PO^(2−)at 1 mmol·L^(-1),a dosage of Fe^(2+) at 3 mmol·L^(-1) and H_(2)O_(2) at 9 mmol·L^(-1),the feeding mode of H_(2)O_(2) in five steps,and pH_(3).The removal of TP was obviously enhanced in the presence of ClO^(−) or low concentration of C_(6)H_(5)O_(7)^(3−)(1 mmol·L^(-1)).However,the removal of TP was obviously inhibited at higher C_(6)H_(5)O_(7)^(3−)concentration.The radical quenching experiments and electron spin resonance(ESR)spectroscopy results indicated that hydroxyl radical(•OH)was the main reactive species for H_(2)PO_(2)^(-)oxidation in the photo-Fenton system.The applicability of this method was confirmed for the treatment of actual electroless nickel plating effluents.This study will provide reference for the resource recovery for P from wastewater containing H_(2)PO_(2)^(-).