School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China.
School of Environment, Jinan University, Guangzhou, 510632, China.
Chemosphere. 2023 Nov;341:140066. doi: 10.1016/j.chemosphere.2023.140066. Epub 2023 Sep 4.
Zero-valent iron (Fe) is restricted in phosphate removal due to the formation of a passive P-Fe layer on its surface. A micro-electric field (0.20 mA cm) was employed in Fe column to facilitate iron corrosion for enhanced phosphate removal with a Fe column as the control. The performance of two columns was compared by batch experiment at a Fe filling rate of 10 vol% with quartz sand as dispersing media. The stability and reusability of micro-electric field driven Fe (MFD-Fe) column was estimated by cyclic test. Solid phase analysis showed promoted iron corrosion, iron ion generation, and secondary mineral production such as lepidocrocite and magnetite in the MFD-Fe column. Since iron ions tended to precipitate with phosphate, and iron minerals provided reaction sites for phosphate adsorption, the MFD-Fe column achieved an enhanced phosphate removal of 94.1%, 2.8 times higher than that of the Fe column. The increase of current density from 0 to 0.20 mA cm significantly improved phosphate removal from 24.5% to 94.1%, further demonstrating the promoting effect of micro-electric field on iron corrosion. The MFD-Fe column also possessed excellent stability and reusability. It only showed a slight decrease of phosphate removal from 94.1% to 89.7% in eight cycles. It restored a phosphate removal capacity of 97.4% as compared to the initial MFD-Fe column by eluting iron (hydro)oxides on Fe and quartz sand surfaces with sulfuric acid. This study indicated that MFD-Fe is a promising method to remove phosphate from water and an alternative strategy for overcoming Fe passivation.
零价铁（Fe）由于其表面形成的钝化 P-Fe 层而在磷酸盐去除中受到限制。在 Fe 柱中施加 0.20 mA cm 的微电场以促进铁的腐蚀，从而增强磷酸盐的去除效果，以 Fe 柱作为对照。在 Fe 填充率为 10 vol%的条件下，通过批式实验比较了两个柱的性能，石英砂作为分散介质。通过循环试验评估了微电场驱动 Fe（MFD-Fe）柱的稳定性和可重复使用性。固相分析表明，在 MFD-Fe 柱中促进了铁的腐蚀、铁离子的生成以及次生矿物如纤铁矿和磁铁矿的生成。由于铁离子容易与磷酸盐沉淀，并且铁矿物为磷酸盐吸附提供了反应位点，因此 MFD-Fe 柱实现了增强的磷酸盐去除率 94.1%，比 Fe 柱高 2.8 倍。电流密度从 0 增加到 0.20 mA cm 时，磷酸盐去除率从 24.5%显著提高到 94.1%，进一步证明了微电场对铁腐蚀的促进作用。MFD-Fe 柱还具有出色的稳定性和可重复使用性。在八个循环中，磷酸盐去除率仅从 94.1%略微下降到 89.7%。通过用硫酸洗脱 Fe 和石英砂表面的铁（氢）氧化物，MFD-Fe 柱恢复了初始 MFD-Fe 柱 97.4%的磷酸盐去除能力。本研究表明，MFD-Fe 是一种从水中去除磷酸盐的有前途的方法，也是克服 Fe 钝化的替代策略。
