牺牲阳极活化过硫酸盐耦合电渗析修复石油-镉复合污染土壤研究

Study on the Remediation of Petroleum-cadmium Co-contaminated Soilby Sacrificial iron Anode Activated Persulfate Coupled Electroosmosis

针对石油-镉复合污染土壤,提出以牺牲阳极释放Fe^(2+)原位活化阴极注入S_(2)O_(8)^(2-)降解石油,同时利用电渗析作用实现解吸附Cd^(2+)的高效迁出。研究结果表明,碳酸钠和柠檬酸作为阳极和阴极电解液可有效避免土壤pH降至/升至较低/较高水平。提高电压梯度并未显著提高累积电渗析流的量,但Fe^(2+)释放量在10 d以后显著增长,可保证S_(2)O_(8)^(2-)的高效活化与石油的有效去除。然而,随着阴极附近土壤pH不断升高,Cd^(2+)逐渐沉淀累积,难于迁出土体。每5 d切换一次电极极性可有效避免土壤镉累积,电压梯度1 V/cm、S_(2)O_(8)^(2-)注入浓度10 g/L条件下处理20 d后,修复土体pH维持在4.8~5.5之间,残留镉含量15.4~19.7 mg/kg,残留石油含量664.1~703.25 mg/kg,且均呈现出两端高、中间低现象。

For the remediation of petroleum-cadmium co-contaminated soil,sacrificial iron anode was used for in-situ activated of S_(2)O_(8)^(2-)injected by cathode to degrade petroleum,and the deposited Cd^(2+)would be moved out the soil by electroosmosis at the meanwhile.The research results indicated that,the sodium carbonate and citric acid could prevented the soil pH falling/rising to a relatively low/high level when used as anolyte and catholyte,respectively.Although the increased of voltage gradiant did not obviously increased the cumulative electroosmosis flow,the release amount of was significantly increased after 10 d treatment,and the efficient activation of S_(2)O_(8)^(2-)and efficient removal of petroleum could be guaranteed.However,the cadmium would be accumulated near the cathode with the increased of soil pH,which was difficult to migration out of the soil.The electrode polarity switched every 5 days could effectively avoid the accumulation of cadmium in soil,and the soil pH was in the range of 4.8~5.5 when the applied voltage gradiant was 1 V/cm and the concentration of S_(2)O_(8)^(2-)was 10 g/L.The residual concentration of cadmium and petroleum was in the range of 15.4~19.7 mg/kg and 664.1~703.25 mg/kg,severally,and showed high at both ends and low in the middle.