电活性镍钴双金属氧化物高选择性去除/回收水中磷酸盐离子

磷是植物体生长的重要营养素, 也是引发水体富营养化的重要因素, 因此废水中磷酸盐的去除与回收均至关重要。本研究采用单极脉冲电沉积法在炭布上制备镍钴双氢氧化物, 并于管式炉中原位焙烧制得镍钴双金属氧化物(NiCo-Layered Double Oxide, NiCo-LDO), 将其用于电控离子交换(Electrochemically Switched Ion Exchange, ESIX)过程实现PO₄ ^3-的去除与回收。实验对比了ESIX与离子交换(Ion Exchange, IX)过程中NiCo-LDO对PO₄ ^3-的去除性能, 并考察了其选择性及循环稳定性。结果表明, 在(10.00±0.05) mg/L的PO₄ ^3-溶液中, ESIX过程中膜对PO₄ ^3-的离子交换量约为IX的2倍; NiCo-LDO对PO₄ ^3-具有高选择性, 且经过5次循环后, 离子交换量仍可达到初始值的92%以上; 结合XPS分析, 发现NiCo-LDO对PO₄ ^3-的ESIX过程包括一个不可逆的“记忆效应”结构恢复过程及两个可逆的层板金属离子氧化/还原和PO₄ ^3-与O-H基团的配体交换过程。

Potential Induced Reversible Removal/Recovery of Phosphate Anions with High Selectivity Using an Electroactive NiCo-layered Double Oxide Film

Phosphorus is an essential nutrient for organisms growth and a major cause of eutrophication in water bodies.Thus,it is crucial for both of the removal and recovery of phosphate from wastewater.In this work,the NiCo-layered double oxide(NiCo-LDO)was successfully fabricated on carbon cloth conductive substrate via the in-situ calcination of the NiCo-layered double hydroxide(NiCo-LDH)and served as the electrochemically switched ion exchange(ESIX)film electrode for the removal and recovery of PO₄^3-.The performance of NiCo-LDO for PO₄^3-removal by ESIX and ion exchange(IX)was compared,while the selectivity and stability of NiCo-LDO for PO₄^3-removal were also investigated.The results revealed that,in(10.00±0.05)mg/L PO₄^3-solution,the ion exchange quantity of the NiCo-LDO for PO₄^3-removal by ESIX process was about twice over that by IX.Moreover,compared with Cl-,NO₃-,SO₄2-and I-,the NiCo-LDO exhibited much higher selectivity towards PO₄^3-.In addition,the ion exchange quantity still retained 92%of its initial value after 5 uptake and release cycles.Coupled with XPS analysis,it was found that ESIX process of NiCo-LDO film electrode for PO₄^3-removal and recovery mainly consisted of 3 steps,which were an irreversible"memory effect"structure recovery process,the redox reaction of metal ion in lamellar and the ligand exchange between PO₄^3-and O-H groups.