Study of methylmercury uptake by Mongolian natural zeolite
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Methylmercury
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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.
Clinoptilolite
Mercury
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Abstract The uptake of inorganic Hg 2+ and organometallic CH 3 Hg + from aqueous solutions by 11 different natural zeolites has been investigated using a batch distribution coefficient (K d ) method and supported by a preliminary voltammetric study. The effect of mercury concentration on the K d response is shown over an environmentally appropriate concentration range of 0.1–5 ppm inorganic and organometallic Hg using a batch factor of 100 ml g -1 and 20 h equilibration. Analcime and a Na-chabazite displayed the greatest methylmercury uptakes (K d values at 1.5 ppm of 4023 and 3456, respectively), with mordenite as the smallest at 578. All uptake responses were greater for methylmercury than for the inorganic mercuric nitrate solutions, suggesting a distinctive sensitivity of zeolites to reaction with different types of solute species. It is likely that this sensitivity is attributable to the precise nature of the resultant Hg-zeolite bonds. Additionally, both the Si-Al ratio and the Na content of the initial natural zeolite samples are shown to influence the K d responses, with positive correlations between K d and Na content for all zeolites excluding mordenite.
Chabazite
Mordenite
Analcime
Mercury
Methylmercury
Silanol
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