采用铁钛复合材料固定土壤中的砷

ARENIC IMMOBILIZATION IN SOIL USING IRON/TITANIUM COMPOSITE

固定化修复是常见的含砷土壤修复方法,合理选择固化剂至关重要。根据土壤中砷的特性,分别合成了铁钛复合材料和生物炭改性的铁钛复合材料,探究2种材料对土壤中砷固化的效果,并采用吸附等温模型、吸附动力学模型等对其吸附特性进行研究。结果表明:生物炭改性的铁钛复合材料的吸附效果优于铁钛复合材料;通过吸附动力学模型拟合发现最佳模型为Elovich模型,说明2种材料对三价砷[As(Ⅲ)]的吸附机制主要为化学吸附;吸附等温实验中最佳模型为Freundlich等温吸附模型,表明As(Ⅲ)在2种材料表面的吸附为非均相多分子吸附和单层吸附,同时包括物理和化学吸附。上述2种吸附材料均能较好地吸附土壤中的As,最大吸附量分别为48.63,61.09 mg/g。通过添加生物炭可有效提高材料的吸附速率,实现短期内快速稳定土壤中As的效果,且在不同含水率条件下均具有较高的As固定化效果。研究结果可为探索新型的复合材料用以固定土壤中的As提供借鉴。

At present,immobilization is one of the most common remediation methods for arsenic-contained soil.Reasonable selection of immobilization reagents is very important in soil immobilization remediation.According to the characteristics of arsenic in soil,this study synthesized Fe/Ti composite material and the modified Fe/Ti composite material by biochar,to explore the effect of immobilization of arsenic in soil,respectively.The adsorption isothermal model and adsorption kinetics model was used to study the adsorption characteristics.The experimental results showed that the adsorption effect of biochar-modified Fe-Ti composite material was better than that of Fe-Ti composite material.The Elovich model was found to be the best kinetics model in fitting the adsorption process,indicating that the adsorption of trivalent arsenic by the two materials was mainly chemical adsorption.The Freundlich isothermal adsorption model was the best model in the adsorption isothermal experiment,which showed that the adsorption of trivalent arsenic on the surface of the two materials was heterogeneous multimolecular adsorption and monolayer adsorption,including physical and chemical adsorption.These two adsorbents can effectively adsorb arsenic in soil,and the maximum adsorption amount is 48.63 and 61.09 mg/g,respectively.By adding biochar,the adsorption rate of the material can be effectively improved,rapid stabilization of arsenic in soil can be achieved,and the immobilization effect of arsenic is higher under different water contents in soil.It can provide a reference for arsenic removal from soil by biochar-modified iron titanium composite.