ABSTRACT

Micelle enhanced ultrafiltration (MEUF) is a surfactant-based membrane separation process that may be used to separate target ions from mixed metal aqueous solutions, such as leachates of coal ash and other geological wastewaters. The ability of MEUF to separate rare earth elements (REEs) was evaluated using sodium dodecyl sulfate (SDS) as the sorbent in surfactant micelle phase, which was subsequently separated using ultrafiltration, acidification, and ferricyanide precipitation. Separation experiments were performed with a synthetic coal ash leachate feedstock as an example mixed-metal feedstock. Experiments tested the influence of surfactant concentration, pH, and co-existing competitive ions on REE recoveries, and also tested methods for SDS recovery and reuse. Membrane rejection efficiencies of REEs were 97% and 71% respectively for synthetic and real leachate under optimized operating conditions. A two-step process of precipitation with CaCl₂ and Na₂CO₃ following membrane separation was the best for recovering SDS with a yield of 99.7%.

摘要

胶束增强超滤 (MEUF) 是一种基于表面活性剂的膜分离工艺，可用于从混合金属水溶液中分离目标离子，例如煤灰和其他地质废水的渗滤液。使用十二烷基硫酸钠 (SDS) 作为表面活性剂胶束相中的吸附剂，评估了 MEUF 分离稀土元素 (REE) 的能力，随后使用超滤、酸化和铁氰化物沉淀将其分离。以合成煤灰浸出液原料作为示例混合金属原料进行分离实验。实验测试了表面活性剂浓度、pH 和共存竞争离子对 REE 回收率的影响，并测试了 SDS 回收和再利用的方法。在优化的操作条件下，合成和真实渗滤液的 REE 膜去除率分别为 97% 和 71%。用氯化钙沉淀的两步法_{膜分离后的2}和 Na ₂ CO ₃对 SDS 的回收效果最好，收率为 99.7%。