以松针提取液为阴极电解液对电动修复重金属土壤的影响研究

Effect of pine needle extract as catholyte on electrokinetic remediation of heavy metals in soil

采用模拟试验方法,选择不同料液比的呈天然酸性的新型有机电解液(松针提取液)及常规化学有机电解液(草酸、醋酸、柠檬酸)分别作为阴极电解液,通过分析电流密度、p H值、总溶解性固体、迁移情况的变化来探究其对土壤重金属去除率的影响,同时采用改进的BCR法分析重金属形态变化。结果表明,松针提取液料液比越高,电流密度越大,对抑制阴极p H值突跃效果越好,溶解出的金属离子越多;料液比越高,去除率越高,1∶1的试验组镉、铜、镍的去除率较对照组提高25.83%~38.95%;常规有机电解液的去除效果从大到小为柠檬酸、醋酸、草酸,1∶1的试验组对镉、铜、镍去除率较草酸试验组分别提升13.76%、10.01%、21.14%。镉、镍的酸可提取态和可还原态的百分比随料液比的增高而降低,较化学有机电解液极大地降低了生物有效性和环境风险。

In order to avoid the potential environmental risks,it was taken by traditional chemical electrolytes on electrokinetic remediation of soil field,three new kinds of electrolyte solutions(pine needle extract)with different material-liquid ratio(1∶15,1∶5,1∶1)and three conventional chemical electrolytes(oxalic acid,acetic acid,citric acid)were respectively selected as a catholyte to explore its effect on heavy metal removal in this study.The experiment used an electric field gradient of 1 V/cm,the remediation time was 7 d,carbon felt was used as the electrode piece,and the anolyte was selected from tap water.The results showed that the pine needle extract was naturally acidic and could effectively control the p H increasing of the cathode.It contained organic acids such as amino acids and shikimic acid,which could chelae heavy metal ions.The experimental group of material-liquid ratio 1∶1 removes heavy metal cadmium,copper and nickel,its removal rate can be increased by 25.83%-38.95%compared with the control group;Compared with the conventional chemical electrolyte(0.1 mol/L oxalic acid),the removal rate of heavy metal cadmium,copper and nickel is respectively increased by 13.76%,10.01%,21.14%.The higher the material-liquid ratio,the lower the percentage content of heavy metal cadmium and nickel migration forms(acid extractable and reducible);Compared with the conventional chemical electrolyte,cadmium and nickel’s migration forms of materialliquid ratio 1∶1 is significantly reduced,which indicates that the pine needle extract as a catholyte to repair the soil can reduce the bioavailability of heavy metals and thus reduce the risk of entering the environment.And,as is well known,the pine needles’extract can help to effectively remove the heavy metal chips,with their green efficient electrolyte,in addition to their priceless cost and natural non-toxic advantage.And,moreover,their introducing into the soil can help to increase the content of organic content of the soil,all of which can help to promote the electrokinetic remediation of the sediment.