改良黏土对重金属离子的吸附特性及防渗性能

Adsorption Characteristics of Heavy Metal and Permeability by Sludge Activated Carbon Modified Clay

为了评价污泥活性炭(SAC)改良黏土作为垃圾卫生填埋场衬垫防渗材料的可行性,该文通过吸附动力学试验、等温吸附平衡试验、柔性壁渗透试验,分别研究了掺量为0%、1%、3%、5%的SAC改良黏土对Cd(Ⅱ)、Cu(Ⅱ)的吸附特性以及渗透性能。试验结果表明,改良黏土对Cd(Ⅱ)或Cu(Ⅱ)的吸附以30 min内的颗粒表面吸附为主,吸附平衡时间分别为120 min或90 min。改良黏土对Cd(Ⅱ)或Cu(Ⅱ)的吸附符合Langmuir等温吸附模式。随SAC掺量由0%增加至5%,在S/L=120 g/L,Cd(Ⅱ)、Cu(Ⅱ)最大吸附量qm分别增加了25%、47%;当固液比增加到200 g/L,Cd(Ⅱ)、Cu(Ⅱ)最大吸附量qm分别增加了32%、48%。水、垃圾渗滤液2种渗透媒介下SAC改良黏土的渗透系数为1.8×10^-9~1.2×10^-8cm/s,均<1×10^-7cm/s的防渗要求。因此,SAC改良黏土可以作为垃圾填埋场的衬垫防渗材料使用,可以有效阻滞渗滤液中重金属离子的迁移。

In order to evaluate the feasibility of sludge activated carbon modified clay as an anti-seepage material for garbage sanitary landfill liners,adsorption kinetics test,isothermal adsorption equilibrium test and flexible wall penetration test were carried out,aiming to analyze the adsorption properties of Cd(Ⅱ),Cu(Ⅱ)and permeability by modified clay with0%,1%,3%,5%of sludge activated carbon.The results indicated that adsorption properties of sludge activated carbon modified clay to Cd(Ⅱ)and Cu(Ⅱ)were dominated by surface adsorption within 30 min,and the adsorption equilibrium time were 120,90 min,moreover,the adsorption of Cd(Ⅱ)or Cu(Ⅱ)by sludge activated carbon modified clay conformed to the Langmuir isothermal adsorption model.With the content of sludge activated carbon increasing from 0%to 5%in clay,at S/L=120 g/L,the maximum adsorption capacity qmof Cd(Ⅱ)and Cu(Ⅱ)increased by 25%,47%.When the solid-liquid ratio increased to 200 g/L,the maximum adsorption capacity qmof Cd(Ⅱ)and Cu(Ⅱ)increased by 32%,48%respectively.The permeability coefficient of sludge activated carbon modified clay under the infiltration media of water and landfill leachate was 1.8×10^-9~1.2×10^-8 cm/s,both of which were less than 1×10^-7 cm/s.Therefore,sludge activated carbon modified clay can be used as an impervious material in landfills,which can effectively block the migration of heavy metals.