Chromate and phosphate adsorption on schwertmannite: Competition, mobilization and mechanisms
Chromate and phosphate adsorption on schwertmannite: Competition, mobilization and mechanisms
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DOI：
10.1016/j.colsurfa.2022.130691
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发表时间：
2023-02
期刊：
影响因子：
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通讯作者：
Cong Fan;C. Guo;Wei Chen;Lu Tao;Qianjing Yao;G. Lu;Yueling Shen;Z. Dang
中科院分区：
文献类型：
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作者：
Cong Fan;C. Guo;Wei Chen;Lu Tao;Qianjing Yao;G. Lu;Yueling Shen;Z. Dang
铬酸盐与磷酸盐在自然界中竞争施韦特曼石上的吸附位点，这是由于它们与硫酸盐具有相似的性质。该竞赛对铬、磷污染土壤和水体的环境修复具有重要意义。在这项研究中，铬酸盐（CrO 42 −）和磷酸盐（PO 43 −）在施韦特曼石上的吸附分别和组合进行了研究，以独特的视角与各种添加顺序。在单独的吸附实验中，磷酸盐（1.9 mmol g−1）比铬酸盐（0.4 mmol g−1）更大量地吸附在施氏石上，显示施氏石对磷酸盐的吸附性能更好。磷的吸附以0.5h为界，表现为快、慢两个阶段。结果表明，在两种阴离子共存的体系中，铬酸根和磷酸根在施氏石上存在明显的竞争吸附，且吸附顺序对竞争吸附有影响。磷酸盐的加入导致了铬酸盐吸附量的下降，反之亦然。磷酸盐与铬酸盐竞争吸附位的能力更强，磷酸盐可以很容易地移动和置换预先吸附的铬酸盐，但铬酸盐的加入不会导致磷酸盐的释放。对于铬酸盐，施氏石的吸附主要通过SO 42 −-交换进行，而对于磷酸盐，吸附涉及SO 42 −-交换和与表面羟基的配体交换。这些研究结果提供了一个更好的理解，在竞争吸附的含氧阴离子上的施威特曼石，从而提高战略，使用施威特曼石作为一个潜在的吸附剂修复污染的含氧阴离子。
Chromate competes with phosphate in nature for sorption sites on schwertmannite due to their similar properties to sulfate. The competition has implications for the environmental remediation for chromate and phosphate contaminated soil and water. In this study, the adsorption of chromate (CrO42−) and phosphate (PO43−) on schwertmannite was investigated individually and in combination, in a unique insight with various addition order. In individual adsorption experiments, a larger amount of phosphate (1.9 mmol g−1) was adsorbed on schwertmannite than chromate (0.4 mmol g−1), showing better adsorption property of schwertmannite for phosphate. Phosphate exhibited fast and slow adsorption stages with the boundary of 0.5 h. In systems with both anions, results showed obvious competitive adsorption between chromate and phosphate on schwertmannite, which was affected by addition order. Phosphate addition induced greater decrease of chromate adsorption than vice versa. Phosphate competed more effectively with chromate for sorption sites, and could easily mobilize and replace the pre-adsorbed chromate, but chromate addition could not cause release of phosphate. For chromate, adsorption on schwertmannite mainly occurred through SO42−-exchange, while for phosphate, adsorption involved both SO42−-exchange and ligand exchange with surface hydroxyl groups. These findings provided a better understanding in competitive adsorption of oxyanions on schwertmannite, and thereby improve the strategy to use schwertmannite as a potential adsorbent for the remediation of polluted oxyanions.