Influence of inherent iron and oxygen concentrations on selenite sorption process using bentonite

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2017,（9）
• 页码范围: 1258-1264
• 页数: 7页
• 语种: 英文
• DOI: 10.1007/s11426-017-9091-4

摘要

The oxygen concentration and inherent Fe in bentonite have a significant influence on the Se(Ⅳ) sorption process.In this study,the sorption of selenite on natural bentonite was investigated using a batch experiment method,and the distribution coefficient (Kd) values were obtained in the pH range from 2.0 to 10.0 under oxic/anoxic conditions.The Kd values always reached a maximum value at a pH of 4 under oxic conditions and at a pH of 8 under anoxic conditions;meanwhile,the Kd value under anoxic conditions was larger than the value under oxic conditions,especially in regard to the maximum Kd values.The oxygen conditions have a significant influence on the ratio of redox-sensitive Fe2+/Fe3+,which was closely related to the difference in the Kd values under both oxic/anoxic conditions.Ferric selenite and green rust could be responsible for the maximum Kd values under oxic/anoxic conditions.In the leaching experiments,we found that the Fe2+ in bentonite could replace Mg2+ and A13+ in the octahedral sheet.Spectroscopy methods,such as Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were used to characterize the surface properties of the samples after reaction.Overall,this study shows that the addition of Fe2+-containing materials into backfill/buffer materials under anoxic condition could enhance the sorption of 79Se(Ⅳ).