阴极材质对电活化过硫酸盐降解盐酸四环素的影响

Effects of cathode materials on degradation of tetracycline hydrochloride by electro-activated persulfates

通过分槽实验研究了石墨、铜(Cu)和泡沫镍(NF)3种不同阴极电活化过硫酸盐(PDS)降解盐酸四环素(Tetracycline Hydrochloride,TCH),考察了操作条件对降解TCH的影响,并通过自由基猝灭实验、电化学行为等表征手段分析了降解TCH机理。结果表明,PDS在阴极表面活化后产生的活性物质显著提高了TCH的降解效率,且TCH降解结果符合伪二阶动力学反应。阴极电活化体系中,PDS主要通过在电极表面获得电子完成活化;溶液体系内的主要活性物质为·SO_(4)^(-)和·OH,其中·OH占主导地位。在电流密度为20 mA/cm^(2)、PDS浓度为5 mmol/L、初始pH=7的条件下反应120 min,石墨阴极电活化体系中获得了56.7%的TCH降解率和14.2%的矿化率,表现优于Cu和NF阴极。材料的反应电荷转移能力不同是造成3种阴极电活化降解TCH存在差异的主因。

Three kinds of cathodes,including copper,nickel foam and graphite,are respectively employed for the degradation of tetracycline hydrochloride by electro-activated persulfate through divided cell experiments.The effects of operating conditions on the degradation of tetracycline hydrochloride are investigated,and the degradation mechanism is analyzed through radical quenching experiments and electrochemical characterization.The results show that the active substances generated after activation of persulfate on the cathode’s surface significantly improve the degradation efficiency of tetracycline hydrochloride,and the degradation result of tetracycline hydrochloride conforms to the pseudo-second-order kinetic reaction.In cathodic electro-activation system,persulfate is mainly directly activated by obtaining electrons on the surface of cathode.Main active substances in the solution system are·SO_(4)^(-)and·OH,of which·OH plays a major role for the degradation of tetracycline hydrochloride.The removal efficiencies of tetracycline hydrochloride and total organic carbon are 56.7%and 14.2%,respectively in a graphite cathode activated persulfate system when the current density is 20 mA·cm^(-2),the concentration of sulfate is 5 mmol·L^(-1),initial pH=7,and the reaction has performed for 120 min.The results are better than that by Cu and NF cathodes.The differences in degradation of tetracycline hydrochloride by electro-activated sulfate in three different cathodes are mainly due to different reactive charge transfer abilities of cathodes.