Abstract:

Thallium is highly toxic to mammals. Tl(Ⅰ) is a common stable and migratory form in water, and hard to remove. In this study, Fe-Mn binary oxide composite active aluminosilicate mineral (FMAAM) was prepared via coprecipitation method by loading Fe and Mn oxides on active aluminosilicate mineral (AAM) and applied to Tl(Ⅰ) removal in water. The effects of the initial pH, ionic strength and FMAAM dosage as well as the removal mechanism of Tl(Ⅰ) were studied. The results showed that the adsorption of Tl(Ⅰ) by FMAAM reached its equilibrium at 120 min, and the removal rate was more than 89.0% at the solution pH range of 3-9. The adsorption process of Tl(Ⅰ) by FMAAM was more consistent with Langmuir model. The maximum adsorption capacity of Tl(Ⅰ) by FMAAM was 61.50 mg/g at 293 K (pH=7, a dosage of 1.00 g/L). The specific surface area (SBET), average pore size and total pore volume of FMAAM were tested, which showed that the SBET of FMAAM (36.830 m²/g) was significantly higher than that of AMM(0.165 m²/g), with a difference of more than 200 times. According to the analyses of energy-dispersive X-ray spectroscope (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the adsorption mechanism of Tl(Ⅰ) by FMAAM is related to ion exchange, complexation reaction, and oxidation precipitation.

Key words: Fe-Mn binary dioxide, aluminosilicate mineral, thallium, compound