Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611-6450, USA.
Water Res. 2011 Apr;45(9):2875-86. doi: 10.1016/j.watres.2011.03.004. Epub 2011 Mar 10.
The goal of this research was to evaluate the long-term performance of magnetic ion exchange (MIEX) treatment using bicarbonate as the mobile counter ion (i.e., MIEX-HCO(3)) and sodium bicarbonate for regeneration. This work is important because there are many unknowns concerning the affinity and regeneration efficiency of bicarbonate-form anion exchange, whereas chloride-form anion exchange (i.e., MIEX-Cl resin) is well-studied. Raw water samples were collected approximately two times per month for one year from a single location on the St. Johns River (SJR), FL, USA. The SJR is characterized by high concentrations of dissolved organic carbon (DOC; 12-26 mg C/L) and bromide (550-1100 μg/L), and is being considered as an alternative drinking water supply. Jar tests were conducted using MIEX-HCO(3) resin, and MIEX-Cl resin was used as a baseline for comparison. The same batch of MIEX-HCO(3) and MIEX-Cl resin was used for the entire study, which was accomplished by regenerating the resins after each jar test in concentrated solutions of sodium bicarbonate and sodium chloride, respectively, and resulted in 21 regeneration cycles. Maximum removal efficiency was achieved with fresh MIEX-HCO(3) resin and virgin MIEX-Cl resin. Both forms of fresh/virgin MIEX resin also had the same affinity sequence with sulfate ≈ UV-absorbing substance > DOC > bromide. The removal efficiency of both forms of MIEX resin decreased as the number of regeneration cycles increased, with MIEX-HCO(3) resin showing 7-18% lower removals than MIEX-Cl resin after 21 regeneration cycles. The affinity sequence of regenerated MIEX-HCO(3) and MIEX-Cl resins differed from fresh resin with UV-absorbing substances > DOC > sulfate > bromide. Scanning electron microscopy and simulated MIEX-HCO(3) treatment under rapidly changing water quality were also used to improve the understanding of bicarbonate-form anion exchange. The major contribution of this research is a systematic study of the extended use of bicarbonate-form anion exchange resin in the context of affinity, regeneration efficiency, and changing water quality.
本研究的目的是评估使用碳酸氢盐作为移动抗衡离子（即 MIEX-HCO(3)）和碳酸氢钠进行再生的磁离子交换（MIEX）处理的长期性能。这项工作很重要，因为关于碳酸氢盐形式阴离子交换的亲和力和再生效率有许多未知之处，而氯化物形式阴离子交换（即 MIEX-Cl 树脂）则研究得很好。水样是从美国佛罗里达州圣约翰河（SJR）的一个单一地点每月大约采集两次，持续一年。SJR 的特点是溶解有机碳（DOC；12-26mg C/L）和溴化物（550-1100μg/L）浓度高，正被考虑作为替代饮用水供应。使用 MIEX-HCO(3)树脂进行了 jar 测试，并将 MIEX-Cl 树脂作为基线进行了比较。整个研究过程中使用的是同一批次的 MIEX-HCO(3)和 MIEX-Cl 树脂，具体做法是在每次 jar 测试后分别在浓碳酸氢钠和氯化钠溶液中对树脂进行再生，总共进行了 21 次再生循环。使用新鲜的 MIEX-HCO(3)树脂和原始的 MIEX-Cl 树脂可实现最大去除效率。新鲜/原始的两种 MIEX 树脂也具有相同的亲和力顺序，硫酸盐≈紫外吸收物质>DOC>溴化物。随着再生循环次数的增加，两种 MIEX 树脂的去除效率都降低了，21 次再生循环后，MIEX-HCO(3)树脂的去除率比 MIEX-Cl 树脂低 7-18%。再生的 MIEX-HCO(3)和 MIEX-Cl 树脂的亲和力顺序与新鲜树脂不同，顺序为紫外吸收物质>DOC>硫酸盐>溴化物。扫描电子显微镜和模拟快速变化水质下的 MIEX-HCO(3)处理也用于提高对碳酸氢盐形式阴离子交换的理解。本研究的主要贡献是系统研究了在亲和力、再生效率和水质变化的背景下，碳酸氢盐形式阴离子交换树脂的扩展使用。
