Department of Environmental Engineering Sciences, University of Florida, P.O. Box 116450, Gainesville, FL 32611-6450, USA.
Water Res. 2011 Jan;45(3):1329-37. doi: 10.1016/j.watres.2010.10.018. Epub 2010 Oct 21.
Magnetic ion exchange (MIEX) is an effective process for removing dissolved organic carbon (DOC) from natural waters, but its implementation has been limited due to production of waste sodium chloride solution (i.e., brine) from the regeneration process. Chloride is of concern because elevated concentrations can have adverse effects on engineered and natural systems. The goal of this research was to explore the efficacy of using anion exchange resin with bicarbonate as the mobile counter ion, which would produce a non-chloride regeneration solution. It was found that bicarbonate-form MIEX resin had a similar affinity as chloride-form MIEX resin for sulfate, nitrate, DOC, and ultraviolet-absorbing substances. Both bicarbonate-form and chloride-form MIEX resins showed the greatest removal efficiencies as fresh resin, and removal efficiency decreased with multiple regeneration cycles. Nevertheless, sodium bicarbonate solution was as effective as sodium chloride solution at regenerating MIEX resin. Regeneration of the bicarbonate-form MIEX resin was illustrated by sparging carbon dioxide gas in a water/resin slurry. This regeneration process would eliminate the need for the addition of salts such as sodium chloride or sodium bicarbonate. The stoichiometry of the bicarbonate-form resin revealed that the bicarbonate was deprotonating within the resin matrix leading to a mixture of both carbonate and bicarbonate mobile counter ions. This work makes an important contribution to ion exchange applications for water treatment by evaluating the affinity, regeneration, and stoichiometry of bicarbonate-form anion exchange.
磁离子交换（MIEX）是一种从天然水中去除溶解有机碳（DOC）的有效方法，但由于再生过程会产生废氯化钠溶液（即盐水），其应用受到限制。氯是令人关注的，因为高浓度的氯会对工程和自然系统产生不利影响。本研究的目的是探索使用带碳酸氢根作为移动抗衡离子的阴离子交换树脂的效果，这将产生非氯化物再生溶液。研究发现，碳酸氢盐形式的 MIEX 树脂对硫酸盐、硝酸盐、DOC 和紫外吸收物质的亲和力与氯化物形式的 MIEX 树脂相似。碳酸氢盐形式和氯化物形式的 MIEX 树脂作为新鲜树脂时都表现出最高的去除效率，随着多次再生循环，去除效率下降。尽管如此，碳酸氢钠溶液在再生 MIEX 树脂方面与氯化钠溶液一样有效。通过在水/树脂浆料中鼓入二氧化碳气体来演示碳酸氢盐形式的 MIEX 树脂的再生过程。这种再生过程将不需要添加氯化钠或碳酸氢钠等盐。碳酸氢盐形式树脂的化学计量揭示了碳酸氢盐在树脂基质中脱质子，导致碳酸根和碳酸氢根移动抗衡离子的混合物。这项工作通过评估碳酸氢盐形式阴离子交换的亲和力、再生和化学计量，为水处理中的离子交换应用做出了重要贡献。
