摘要
二价铁离子活化过硫酸盐(PS)产生自由基可降解有机污染物,但体系中Fe(Ⅲ)/Fe(Ⅱ)循环速率较慢,成为制约降解效率的关键因素之一.为提高反应体系效率,制备向日葵秸秆生物炭(SFBC),以苯甲酸(BA)为目标污染物,探究SFBC强化Fe(Ⅲ)/S2O8^2-体系降解BA的效果.SFBC表征结果说明其具有孔隙结构,由无定形炭组成,表面有丰富的官能团及持久性自由基(PFRs).考察了反应条件(pH、PS浓度和SFBC投加量)对降解的影响,结果表明,SFBC/Fe(Ⅲ)/S2O8^2-体系对BA降解效率明显高于Fe(Ⅲ)/S2O8^2-及SFBC体系,在SFBC=2.0 g·L^-1、BA=10.0mg·L^-1、PS=2.0mmol·L^-1、Fe(Ⅲ)=1.0mmol·L^-1和pH=3.0条件下, 90 min时BA降解率达100.00%;自由基猝灭实验及电子顺磁共振光谱(EPR)实验表明,SO4^-·和·OH共同参与BA降解并以SO4^-·为主导;循环实验及实际水体影响说明SFBC具有较好地循环稳定性及实际应用性.机制分析阐明PFRs和-OH给出电子还原Fe(Ⅲ)生成Fe(Ⅱ),进而由Fe(Ⅱ)活化PS高效降解BA.
Fe(Ⅱ) activation persulfate(PS) is an effective method of degradation of organic pollutants, but the undesirable Fe(Ⅲ)/Fe(Ⅱ) cycle has become a restrictive factor in the Fe(Ⅱ)/PS system. The effects of sunflower-straw-derived biochar(SFBC) on an Fe(Ⅲ)/S2O2-8 system and the subsequent degradation of benzoic acid(BA) in water were systematically investigated. The characterization results of SFBC showed that it has a porous structure, consists of amorphous carbon, and has an abundance of surface functional groups and persistent free radicals(PFRs). The effects of critical parameters, including the initial pH, PS concentration, and dose of SFBC were also investigated. The results indicated that the degradation rate of BA in the SFBC/Fe(Ⅲ)/S2O2-8 system was significantly higher than that in the Fe(Ⅲ)/S2O8^2- system and SFBC system. The degradation efficiency of BA reached 100.00% with SFBC, BA, PS, and Fe(Ⅲ) concentrations of 2.0 g·L^-1, 10.0 mg·L^-1, 2.0 mmol·L^-1, and 1.0 mmol·L^-1, respectively, an initial pH of 3.0, and a reaction time of 90 min. Free radical quenching experiments and EPR studies demonstrated that SO4^-· and ·OH were involved in the SFBC/Fe(Ⅲ)/S2O8^2- system, and the SO4^-· was the main radical for the BA degradation. Reuse and real water matrix effects experiments suggested that SFBC had good stability and practical applicability. Mechanism analysis revealed that PFRs and-OH as the electron donor reacted with Fe(Ⅲ) to generate Fe(Ⅱ), which then activated PS for highly efficient oxidation of BA.
作者
孙鹏
张凯凯
张玉
张延荣
SUN Peng;ZHANG Kai-kai;ZHANG Yu;ZHANG Yan-rong(School of Environmental Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China;School of Energy and Environment,Inner Mongolia University of Science and Technology,Baotou 014010,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2020年第5期2301-2309,共9页
Environmental Science
基金
国际科技合作项目(2016YFE0126300)。
