Abstract: Effects of natural sepiolite amendment on a heavy metals polluted soil and the sorption behaviour of sepiolite with respect to cadmium and zinc were studied by means of batch extractions. Using sepiolite as stabilizing agent, the soluble amount of both metals as well as their readily-extractable fractions are substantially decreased, when a sepiolite dose of 4% is applied, sepiolite has significant stabilizing efect on soluble amount of Cd and Zn as evidenced by a decline of 57. 3% and 41. 4% respectively, while the readily-extractable fractions of Cd and Zn as evidenced by a decline of 42. 8% and 24. 7% for Cd and Zn. The sorption processes of Cd and Pb by sepiolite can be described by Langmuir and Freundlich model. The sorption capacities are pH dependent undergoing a decrease with H⁺ concentration increase. The maximum sorption capacities shown at pH 6 are 12. 3 mg/ g and 6. 80 mg/ g for cadmium and zinc, respectively.

Key words: sepiolite, cadmium, zinc, soil pollution, in situ remediation

摘要： 通过土壤原位钝化与等温吸附试验, 研究了海泡石黏土矿物对污染土壤中镉、锌有效态及 pH 对海泡石吸附镉、锌的影响。结果表明: 海泡石黏土矿物加入土壤后, 显著降低了土壤中水溶态镉、锌和可提取态镉、锌含量。在海泡石最大施用量( 土重的4%) 时, 水溶态镉、锌含量分别比对照下降了57. 3% 和41. 4% ; 而可提取态镉、锌含量分别比对照下降42. 8% 和24. 7% 。海泡石对 Cd²⁺ 和 Zn²⁺ 的吸附过程符合 Langmuir 和 Freundich 等温吸附方程所描述的规律。随着体系 pH 升高, 海泡石对镉、锌的吸附能力增强, 在 pH 为 6, 海泡石对 Cd²⁺和 Zn²⁺ 的最大吸附量分别为 12. 3 mg/ g和6. 80 mg/g, 海泡石对2种金属离子的吸附能力为 Cd²⁺ > Zn²⁺ 。海泡石作为土壤重金属钝化剂,施入土壤后能有效地降低土壤中 Cd²⁺ 和Zn²⁺的活性;而pH是控制海泡石的钝化能力强弱的关键因素。

关键词: 海泡石, 镉, 锌, 土壤污染, 原位修复