硅藻土对污染土壤中铅的固定效果及机制

为了有效地将硅藻土应用于土壤铅污染修复，并加以推广，逐步恢复受污染土壤的生产能力，研究了硅藻土对污染土壤中铅的固定效果、吸附过程、等温吸附和吸附动力学。结果表明：硅藻土能充分将土壤中交换态的铅转化为残渣态，硅藻土的施加不会对土壤pH值和有机质等理化性质造成较大改变；硅藻土对Pb2+的吸附过程控制步骤是孔道内的化学反应；硅藻土对Pb2+的吸附动力学属性符合伪2级动力学模型，等温吸附符合Langmuir模型，最大吸附量qm为10.428 mg/g。硅藻土可以有效固定土壤中的铅，并降低其生物有效性，可作为铅污染土壤的有效改良剂。

Fixation Effects and Mechanisms of Diatomite on Pb in Contaminated Soil

In order to apply and extend diatomite to repair the soil polluted by lead effectively,and recover production capacity of contaminated soil step by step,fixation effect,adsorption process,isothermal adsorption and adsorption kinetics of Pb on diatomite were investigated and revealed.The results showed that,diatomite could change Pb from exchange state to residual state adequately,addition of diatomite wouldn’t change pH and organic matter of soil,the adsorption process of Pb2 ＋ on diatomite was mainly governed by chemical reaction in channels,the kinetic of Pb2＋ adsorption on diatomite was consistent with Pseudo-second-order,the equilibrium adsorption data of Pb2 ＋ on diatomite fitted to Langmuir isotherm,qm of Pb2 ＋ on diatomite was 10.428 mg/g.The diatomite could fix lead in the soil effectively,and decrease its bioavailability,and was an available improver for contaminated soil.