Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, China.
Chemosphere. 2017 Aug;181:461-467. doi: 10.1016/j.chemosphere.2017.04.127. Epub 2017 Apr 25.
Cost-effective and eco-friendly washing agents are in demand for Cd contaminated soils. Here, we used leonardite-derived humic substances to wash different types of Cd-contaminated soils, namely, a silty loam (Soil 1), a silty clay loam (Soil 2), and a sandy loam (Soil 3). Washing conditions were investigated for their effects on Cd removal efficiency. Cadmium removal was enhanced by a high humic substance concentration, long washing time, near neutral pH, and large solution/soil ratio. Based on the tradeoff between efficiency and cost, an optimum working condition was established as follows: humic substance concentration (3150 mg C/L), solution pH (6.0), washing time (2 h) and a washing solution/soil ratio (5). A single washing removed 0.55 mg Cd/kg from Soil 1 (1.33 mg Cd/kg), 2.32 mg Cd/kg from Soil 2 (6.57 mg Cd/kg), and 1.97 mg Cd/kg from Soil 3 (2.63 mg Cd/kg). Cd in effluents was effectively treated by adding a small dose of calcium hydroxide, reducing its concentration below the discharge limit of 0.1 mg/L in China. Being cost-effective and safe, humic substances have a great potential to replace common washing agents for the remediation of Cd-contaminated soils. Besides being environmentally benign, humic substances can improve soil physical, chemical, and biological properties.
具有成本效益和环保效益的洗涤剂是受 Cd 污染土壤所需求的。在这里，我们使用风化煤衍生的腐殖质来洗涤不同类型的 Cd 污染土壤，即粉质壤土（土壤 1）、粉质黏土壤土（土壤 2）和砂壤土（土壤 3）。研究了洗涤条件对 Cd 去除效率的影响。腐殖质浓度高、洗涤时间长、接近中性 pH 值和大的溶液/土壤比都能提高 Cd 的去除率。基于效率和成本之间的权衡，建立了一个最佳的工作条件，如下：腐殖质浓度（3150mgC/L）、溶液 pH 值（6.0）、洗涤时间（2 小时）和洗涤液/土壤比（5）。单次洗涤可从土壤 1 中去除 0.55mg Cd/kg（1.33mg Cd/kg），从土壤 2 中去除 2.32mg Cd/kg（6.57mg Cd/kg），从土壤 3 中去除 1.97mg Cd/kg（2.63mg Cd/kg）。通过添加少量的氢氧化钙处理流出物中的 Cd，将其浓度降低到中国规定的 0.1mg/L 排放限值以下。腐殖质具有成本效益和安全性，有望替代普通洗涤剂用于修复 Cd 污染土壤。腐殖质不仅环保，还可以改善土壤的物理、化学和生物特性。
