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环境化学

基金项目：中国博士后科学基金资助项目(No.20070410970);南京大学污染控制与资源化研究国家重点实验室开放课题资助项目(No.PCRRF07013);中国地质大学(武汉)优秀青年教师资助计划重点项目(No.CUGQNL0702)

摘要：为了控制UV/Fenton方法中铁元素的用量,合理利用溶解态铁的催化反应过程并提高其降解效率,研究以难生物降解性染料罗丹明B为目标物,通过正交实验和单因素实验确定了UV/Fenton体系的最佳反应条件,并利用一元线性方程模拟了罗丹明B退色反应的的动力学方程.结果显示,当体系的最初pH为3.00,溶液中[Fe²⁺]=0.180mmol·L^-1、[H₂O₂]=124.022mmol·L^-1时,UV/Fenton氧化罗丹明B退色符合一级反应动力学方程.研究了总铁含量维持在0.180mmol·L^-1、保持紫外光照射、4次向同一UV/Fenton体系中添加1.7mLH₂O₂,每次反应后Fe²⁺/Fe³⁺的循环转化规律和溶液的脱色效果.研究结果表明,每次反应结束阶段(30min),Fe²⁺浓度均高于Fe³⁺浓度,残余液仍具有较强的催化能力,溶液的脱色率达到99.9%;退色反应速率常数始终维持在较高水平,最后一次循环反应结束后,反应速率常数达到0.2547,相对于初始反应速率常数只下降了17%左右.

Abstract：In order to reduce the over usage of dissolved Fe in the UV/Fenton system and enhance the catalytic oxidation involving Fe ions,the kinetics of oxidation of the refractory dyestuff Rhodamine B were studied through orthogonal experiments,individual factor experiments and unitary linear regression equation simulation.The results show that high degradation efficiency occurs at initial pH=3,Fe²⁺ concentration of 0.180 mmol·L^-1 and H₂O₂ concentration of 124.022 mmol·L^-1.The UV/Fenton degradation obeys first-order kinetics.Furthermore,cyclic transformation of Fe²⁺ with Fe³⁺ as well as degradation of Rhodamine B in the UV/Fenton system were investigated,by maintaining 0.180 mmol L^-1 dissolved total Fe and ordinary UV irradiation throughout the whole reaction,while adding 1.7 mL 30% H₂O₂ into the residual solution four times in sequence.The Fe²⁺ concentration in the residual after each recycle is still higher than that of Fe³⁺,which implies that the system still has a high catalytic oxidation ability.It was also found that 99.9% of decoloration is observed at 30 min in each of the five cycles.The reaction rate constant for the last cycle was 0.2547 s^-1,a decrease of only 17% compared to the initial rate constant.