全球土壤镉(Cd(II))污染威胁着土壤环境,食品安全,和人类健康。传统的电动修复(EKR)和增强方法通常在强电场中运行,导致强烈的副反应和不均匀的去除。在这项工作中,为了在低压电场下有效去除土壤中的Cd(II),开发了一种新型的电动吸附修复方法,该方法使用双组电极和壳聚糖-活性炭复合膜(DE-EKR-CAC)。为了易于回收和重复使用吸附剂,合成了壳聚糖-活性炭(CAC)复合膜。pH的影响,接触时间,初始浓度,并测定了外源离子对CAC复合膜去除Cd(Ⅱ)的影响。除了在强酸性环境(pH=2.0)中,CAC复合膜表现良好。DE-EKR-CAC中的土壤pH在3.4和5.0之间变化,其中CAC复合膜是适用的。高浓度的Ca2+干扰了Cd(Ⅱ)的吸附,说明CAC复合膜对Cd(Ⅱ)的选择性不够高。Langmuir(R2=0.999)和伪二级动力学(R2=1.0)模型揭示了单层覆盖和化学吸附机制,最大吸附量为40.81mg/g。此外,SEM,FTIR,和XPS分析表明物理吸附,含氧官能团的络合,氨基的螯合,和离子交换是CAC吸附Cd(II)的潜在机制。DE-EKR-CAC的表现优于使用一组电极修复的组,具有更高的去除效率和更均匀的去除。最低能耗为3.33kWh/m3,低于其他增强方法。从土壤中分离CAC复合膜很容易,和重用性能良好。DE-EKR-CAC提供了从土壤中去除Cd(II)的潜在选择,因为它使用低压直流电具有更好的性能,低能耗,和易于回收的吸附剂。
Global soil cadmium (Cd(II)) contamination threatens the soil environment, food safety, and human health. Conventional electrokinetic remediation (EKR) and enhancement methods usually operate in strong electric fields, leading to strong side reactions and uneven removal. In this work, to remove Cd(II) from soil effectively in a low-voltage electric field, a new-style electrokinetic-adsorption remediation using double-group electrodes coupled with chitosan-activated carbon composite membranes (DE-EKR-CAC) was developed. Chitosan-activated carbon (CAC) composite membranes were synthesized for easy recovery and reuse of adsorbents. The effects of pH, contact time, initial concentration, and foreign ions on the removal of Cd(II) by the CAC composite membranes were determined. The CAC composite membranes performed well except in a strongly acidic environment (pH = 2.0). The soil pH varied between 3.4 and 5.0 in DE-EKR-CAC, where the CAC composite membranes were applicable. High concentrations of Ca2+ interfered with the adsorption of Cd(II), which means that the selectivity of CAC composite membranes for Cd(II) is not high enough. The Langmuir (R2 = 0.999) and pseudo-second-order kinetic (R2 = 1.0) models revealed the monolayer coverage and chemisorption mechanism, and the maximum adsorption capacity was 40.81 mg/g. Furthermore, SEM, FTIR, and XPS analyses suggest that physical adsorption, complexation of oxygen-containing functional groups, chelation of amino groups, and ion exchange are potential mechanisms for the adsorption of Cd(II) on CAC. DE-EKR-CAC performed better than the group remediated with one set of electrodes, with higher removal efficiencies and more uniform removal. The lowest energy consumption was 3.33 kWh/m3, which is lower than other enhancement methods. Separation of CAC composite membranes from soil is easy, and reuse performance is good. DE-EKR-CAC provides a potential option for Cd(II) removal from soil because of its better performance using low-voltage direct current, low energy consumption, and ease of recycling the adsorbent.