Adsorption of Pb2+ by ameliorated alum plasma in water and soil.

Four methods, including hot acid treatment, hot alkali treatment, calcination treatment and sulfhydrylation treatment, were applied to activate alum plasma in order to obtain new Pb²⁺ adsorbents. The corresponding adsorption isotherm satisfies the Langmuir equation, and the maximum adsorption of the alum plasma after hot acid treatment, hot alkali treatment and high-temperature calcination were 18.9, 57.3 and 10.9 mg·g⁻¹, respectively, and in the range of 1.23–6.57 times greater than the adsorption capacity of the original alum plasma. The soil culture experiments indicated that the effective Pb content in the soils treated with hot alkali ameliorated alum plasma was significantly lower (p < 0.05) than those treated with the other three types of alum plasma. For example, if the additive content is 5.0%, after a storage period of 16 weeks, the effective Pb content becomes 19.87 mg·kg⁻¹, which corresponds to a reduction of 60.9% in comparison with the control sample. In addition, Specific surface area (BET), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FIR) were used to characterize the microstructure of alum plasma before and after amelioration. It was evident that hot alkali treatment of alum plasma resulted in smaller particles, a significantly higher specific area and lower mineral crystallinity, which improved the adsorption performance of Pb²⁺. In conclusion, hot alkali treatment of alum plasma indicates relatively good Pb²⁺ adsorption ability, and is a promising novel adsorbents that could ameliorate soils that have been polluted by heavy metal Pb. [ABSTRACT FROM AUTHOR]