温州大学化学与材料工程学院

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祝贺张伟明和陈庆老师指导研究生程欢在Journal of Membrane Science上发表学术论文

发布时间:2018-11-30    来源:化学与材料工程学院    作者:    点击次    [点击关闭]

标题(中文):通过扩散透析显著提高脱卤的选择性从近中性硫酸锌电解液中

标题(英文):Significantly enhanced dehalogenation selectivity in near-neutral zinc sulfate electrolytes by diffusion dialysis

刊物名称及期号、页码:Journal of Membrane Science, 2018, 563:142-148

作者姓名(中文):程欢、肖慧芳、陈庆、李秀敏、秦文梦、陈宝生、肖东、张伟明

作者姓名(英文):Huan Cheng, Hui-Fang Xiao, Qing Chen, Xiu-Min Li, Wen-Meng Qin, Bao-Sheng Chen, Dong Xiao, Wei-Ming Zhang,Dong Xiao, Wei-Ming Zhang

摘要(英文):

For industries around the world, the hydrometallurgical roast–leach–electrowin process is the most common means of producing zinc metal. Dechlorination from the highly-concentrated zinc sulfate electrolyte is of vital importance to the zinc industry. In a recently published work, we innovatively employed diffusion dialysis (DD) to selectively remove Cl- and F- from a highly-acidic spent electrolyte, which extended the application of DD from acid recovery to selective ion separation. In the current paper, we greatly enhance the dechlorination selectivity by adjusting the acidity of feed electrolytes. The Cl-/SO42- permselectivity increases from 2.56 to 42.8 when the acidity is reduced from 160 to 0 g/L as free H2SO4, and meanwhile the removal ratio of Cl- impurity is basically retained (from 55.1% to 46.6%). The competitive permeation of different ions and the interplay between anions and cations are carefully investigated. It is believed that the distinct diffusivity of anions (Cl-, F-,HSO4- and SO42-) originates from their different hydrated sizes. This excellent selectivity observed here is unprecedented and has never been observed in any practical DD processes. It not only remarkably improves the cost-effectiveness of the dechlorination process in zinc production, but also puts forward a new possibility to regulate the permselectivities between ions with the same charge sign and provides new insights into the DD process in the selective ion separation.

研究现状(中文):全球有将近80%的金属锌由湿法冶锌工艺生产。在此过程中由于硫酸电解液反复循环使用,有害杂质特别是微量氯离子逐渐累积,对整个冶锌工艺及最终锌产品的品质均会造成严重影响。如何从极高浓度的硫酸锌电解液(SO42- >320g/L)中选择性去除微量的氯离子杂质(Cl-~200-700 mg/L),迄今没有令人满意的解决方案,成为了制约湿法冶锌行业发展的瓶颈之一。我们前期工作利用传统扩散渗析技术(DD)对酸性硫酸锌电解液中游离H2SO4进行回收的过程中,首次在常规离子交换膜(IEMs)中观察到显著的同号(甚至同价态)离子之间的选择性。提出了一种新的纯化酸性电解液的方法,通过常规的扩散渗析过程从酸性电解液中选择性去除卤化物杂质。研究结果表面,卤化物(Cl-和F-)相对HSO4-更容易透过阴离子交换膜,在最佳流速下(4L/h.m2),氯离子的去除率达到55.1%.硫酸的损失率仅为21.54%。 前期工作中Cl-相对于HSO4-表现出优先透膜扩散特性的原因可能在于两种离子水合半径的不同。由于HSO4-水合半径较大,其跨膜传输较Cl-更为困难。在该工作的基础上我们猜测由于水合半径更大,二价的SO42-离子的跨膜传输可能更为困难,将酸性硫酸锌电解液中的HSO4-转化为SO42-或许能进一步提高去除Cl-的选择性,大大减小硫酸根的损失。通过调节DD进料硫酸锌电解液的酸度,其脱氯的选择性确实会大大提高。当电解液酸度从160降至0 g/L时,Cl-/SO42-选择性从2.56增加到了42.8,而Cl-的去除率基本得到了保持。这种优异的选择性在常规IEM中是从未被观察到的。基于在近中性电解液中取得的结果,本小组对电解液除氯工艺开展了进一步的优化。

创新点(中文):

  1. 通过调节电解的酸度极大的提高去除氯离子的选择性;

  2. 将扩散渗析的应用从酸/碱回收扩展到中性溶液当中离子的选择性分离;

  3. Cl-相对SO42-的选择性分离从最初的2.6增加至42.8;

  4. 讨论了竞争性渗透的潜在机理;

原文链接: https://doi.org/10.1016/j.memsci.2018.05.053