Application and adsorption characteristics of scoria for removing sulfate from a low-temperature groundwater environment in Longdong area, China

Bai, Xue; Zhang, Yuling; Chen, Bangxian; Liu, Ting; Li, Shuo

Application and adsorption characteristics of scoria for removing sulfate from a low-temperature groundwater environment in Longdong area, China

2021

Bai, Xue | Zhang, Yuling | Chen, Bangxian | Liu, Ting | Li, Shuo

Removal of excessive sulfate from the low-temperature groundwater environment in the Longdong area is important for protecting human health. The effects of naturally occurring hydrochemical ions and pH on sulfate adsorption were examined to verify the applicability of magma-derived scoria and determine whether scoria could be reused. Hydrochemical ions and pH of the natural groundwater environment in the study area improved the adsorption capabilities of scoria for sulfate. Additionally, 2% AlCl₃ was sufficiently stable for use as a high-efficiency regenerant for sulfate desorption from the scoria. The adsorption characteristics of scoria were determined using a continuous dynamic column system. The effects of flow rate, initial sulfate concentration, and column height on breakthrough curves were investigated at low temperatures. The scoria adsorption capacity increased with increasing sulfate initial concentrations and decreased with increasing flow rates and column heights. The maximum adsorption capacity was 10.14 mg/g at a flow rate of 5 mL/min, initial concentration of 500 mg/L, and column height of 10 cm. The breakthrough time increased with increasing column heights and decreased with increasing flow rates and initial concentrations. Model comparison to analyze adsorption kinetics showed that the Bohart–Adams model is an excellent fit for the dynamic experimental data. Electron microscopy and spectroscopy methods confirmed the surface changes before and after adsorption. Thus, scoria is a highly efficient, economical, and environmentally friendly adsorbent for removing sulfate from groundwater, providing a foundation for the application of scoria for groundwater environment restoration in cold regions in China.

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