正渗透脉冲电场电敏凝胶汲水行为分析及优化调控

Water scarcity is occurring globally, while extracting drinking water from wastewater may seem to be an excellent method. Unlike pressure-driven processes, FO is environmentally friendly and can be operated at a low cost due to the absence of hydraulic pressures. However, its development is still hindered by some factors such as reverse diffusion of draw solutions, and high energy consumption during the process of draw solutions regeneration. In this study, electric-sensitive hydrogels, which show swelling and deswelling behavior when exposed to water and electric fields respectively, were employed as draw agents in the FO process to design a novel forward osmosis reactor with pulsed electric fields. This reactor can absolutely avoid the draw agents to contaminate the feed solution and product water and ensure easy recycle of draw agents, which can effectively solve the aforementioned problems. We intend to synthesize the most appropriate electric-sensitive hydrogels used in wastewater treatment, which possess high swelling pressure, high electric sensitive and steady mechanical performance, and thus to explore the swelling/deswelling behavior and mechanism of the hydrogels under different pulsed electric fields. Besides, coupling electrolytic flocculation together with electrophoresis, the pulsed electric fields will be optimized. Through the study of FO in these aspects, the safe and effective drinking water regeneration can be expected.

水资源短缺已经上升为全球性危机，从污水中直接提取饮用水是解决缺水问题的重要途径之一。正渗透无压操作，节能且环境友好。但其汲取液存在反向扩散、再生能耗高等问题，桎梏了正渗透技术的更广泛应用。本研究基于正渗透汲水原理和电敏凝胶水中溶胀、接触电场刺激下消溶胀的功能，设计以电敏凝胶作为汲取物的脉冲电场正渗透反应器，目的在于完全避免汲取物污染原料液及产水的发生，体现安全性的同时，方便、低耗地完成汲取物再生，有效解决正渗透技术面临难题。研究方法为以高膨胀压、高电场灵敏度、稳定机械性能为目标优化电敏凝胶合成方法，分析不同工况脉冲电场电敏凝胶汲水/脱水行为和机制，筛选污水提纯适宜电敏凝胶，耦合电絮凝除污染和电泳减缓膜污染效能，优化设计正渗透反应器脉冲电场，从而更安全、高效完成饮用水再生。

水资源短缺已经上升为全球性危机，从污水中直接提取饮用水是解决缺水问题的重要途径之一。正渗透无压操作，节能且环境友好。但其汲取液存在反向扩散、再生能耗高等问题，桎梏了正渗透技术的更广泛应用。本研究基于正渗透汲水原理和电敏凝胶水中溶胀、接触电场刺激下消溶胀的功能，设计了以电敏凝胶作为汲取物的脉冲电场正渗透反应器，目的在于完全避免汲取物污染原料液及产水的发生，体现安全性的同时，方便、低耗地完成汲取物再生，有效解决正渗透技术面临难题。研究结果表明，附加电压为6 V，以冻融5次的透明质酸-聚乙烯醇电敏水凝胶运行60 h，间歇运行所产生总过水量分别为50.84与62.39 L•m-2，单位产水量能耗为3.2×105 J。证明了电敏凝胶可以反复利用，切实解决正渗透技术汲取液反向渗透和再生困难的难题。.基于以上研究基础，更提出新的思路，以具有超强吸水和重复压缩性能的气凝胶作为正渗透汲取物，则不仅可以继续保持水凝胶汲取物产水水质高、完全不存在反向渗透的优点外，还可能实现简易快速的释水和汲取物再生。本研究以简单温和的方法合成了亲水耐压气凝胶并以其作为汲取物用于汲取净水。在正渗透测试中，测定SA-GO-3干气凝胶纯水通量（15.25±0.65 LMH）为1 M NaCl（10.44±0.99 LMH）的1.46倍。连续反复压缩再生测试表明，SA-GO-3气凝胶水通量恢复性能良好，水通量保持在4-6 LMH之间，没有明显的通量衰减，即该型气凝胶可通过简单压缩反复汲水/释水无需其它再生手段。同时，SA-GO-3干气凝胶对模拟海水的脱盐能力优良（水通量为6.7 LMH）。由此，可以看出气凝胶汲取物具有优良的正渗透性能，可以完全避免汲取液反向渗透，且仅依靠人力简单压缩即可完成从污水中反复提取，净水过程操作简便，产水无受众范围限制，特别适合用于军事和应急救灾等领域所用应急正渗透汲水装置的汲取液革新。