Shi Mingyan, Zhang Yali, Hong Weibin, Liu Jiayu, Zhu Huijie, Liu Xu, Geng Yuxin, Cai Zhenyin, Lin Shaonan, Ni Chengzhi
School of Civil Engineering, Guangzhou University, Guangzhou, 510006, China.
Guangzhou Zhiqinglan Environmental Technology Company Ltd, Guangzhou, 510006, China.
Environ Sci Pollut Res Int. 2022 Dec;29(56):85364-85375. doi: 10.1007/s11356-022-21312-9. Epub 2022 Jul 6.
In this study, a schwertmannite-like mineral was synthesized for the removal of lead (Pb) and chromium (Cr) from contaminated wastewater. A shaking flask test was performed (150 r/min, 1 h) with FeSO·7HO, HO, NaSiO, and CaCl added for the mineral synthesis reaction. Results show that optimal performance was achieved with the addition of 1.24 g/L FeSO·7HO, 0.75 g/L HO, 1.27 g/L NaSiO, and 0.44 g/L CaCl at a water temperature of 28 °C, with coexisting ion (Na, K, Mg) concentrations of 1.50 mmol/L and 0.50 mmol/L EDTA as a complexing agent. Under these optimal conditions, maximum Pb and Cr removal rates of 95.08% and 97.99%, respectively, were achieved within the first 1 min of the mineral synthesis reaction, with the synthesis reaction completed by 6 min. The simultaneous removal of Pb and Cr during the schwertmannite-like material synthesis process occurred via electrostatic adsorption and coprecipitation. When the concentration of the complexing agent was increased from 0.75 to 6.03 mmol/L, the Pb removal rate decreased from 71.88 to 35.45%, and the Cr removal rate decreased from 95.13 to 75.07%, showing that Pb and Cr removal exhibited significant levels of inhibition. In contrast, varying reaction temperatures induced no significant differences. The Pb and Cr dissolution rates from Pb/Cr-containing schwertmannite-like minerals were 8.18% and 2.86% after 40 days, respectively. Therefore, the risk of secondary dissolution of heavy metals is small.
