ABSTRACT

The aim of this study was to evaluate the capacity for Hg adsorption, understand the mechanisms of Hg sorption in tropical soils, and study the potential for Hg sorption by a natural zeolite for possible application in remediation of soils contaminated with Hg. The soil samples used in this study were collected from the 0 to 20 cm layer in areas of native vegetation in the state of Minas Gerais, Brazil. The experiment was conducted in a completely randomized design in a 5 × 8 factorial arrangement, with five soils of contrasting characteristics and eight Hg concentrations (0, 0.05, 0.1, 0.2, 0.4, 0.8, 1.2, and 2.4 mg L⁻¹). A zeolite material was also added in the sorption study for purposes of comparison. Samples of the five soils under study and the zeolite before and after Hg adsorption were characterized by Fourier-transform infrared spectroscopy (FTIR). The species HgOH₂, HgClOH, and HgCl₂ predominates in the contaminating solutions. Analysis through FTIR showed that the oxygenated functional groups (Al-O, Si-O, Fe-O) of the clay minerals and oxides present in the soil are responsible for the high Hg adsorption capacity. The zeolite clinoptilolite has the potential for remediation of soils contaminated with Hg.

摘要

本研究的目的是评估汞的吸附能力，了解热带土壤中汞的吸附机制，并研究天然沸石吸附汞的潜力，以用于修复受汞污染的土壤。本研究中使用的土壤样品采集自巴西米纳斯吉拉斯州原生植被区 0 至 20 厘米层。该实验采用完全随机设计，采用 5 × 8 因子排列，有 5 种不同特征的土壤和 8 种 Hg 浓度（0、0.05、0.1、0.2、0.4、0.8、1.2 和 2.4 mg L ^-1）。为了比较，还在吸附研究中添加了沸石材料。采用傅里叶变换红外光谱 (FTIR) 对所研究的五种土壤样品和吸附汞前后的沸石进行了表征。HgOH ₂、HgClOH 和 HgCl ₂在污染溶液中占主导地位。通过 FTIR 分析表明，土壤中存在的粘土矿物和氧化物的含氧官能团（Al-O、Si-O、Fe-O）是高汞吸附能力的原因。沸石斜发沸石具有修复受汞污染的土壤的潜力。