College of Environment and Resources, Fuzhou University, Fujian 350116, China.
Water Desalination & Reuse (WDR) Center King Abdullah University of Science and Technology, 23955-6900, Saudi Arabia.
Water Res. 2017 Oct 1;122:580-590. doi: 10.1016/j.watres.2017.06.025. Epub 2017 Jun 10.
Forward osmosis (FO) has demonstrated its merits in hybrid FO seawater desalination. However, FO may have a potential for other applications if suitable draw solutes are available. In this study, a series of novel draw solutes based on oxalic acid (OA)-transitional metal complexes are presented. Influential factors of FO performance have been systematically investigated by varying the transitional metals, cations of the complex draw solutes as well as the experimental conditions. Compared to NaCl and other recently synthesized draw solutes, the OA complexes show superior FO performance in terms of high water fluxes up to 27.5 and 89.1 LMH under the respective FO and PRO (pressure retarded osmosis) modes, both with negligible reverse solute fluxes. The features of octahedral geometry, abundant hydrophilic groups and ionic species are crucial for the OA complexes as appropriate draw solutes with satisfactory FO performance. Among the synthesized OA complexes, the ammonium salt of chromic complex (NH-Cr-OA) outperforms others due to the presence of more ionic species in its complex system. NH-Cr-OA also performs better than the typical NaCl draw solute in FO oily wastewater treatment with higher water recovery and negligible reverse fluxes. Dilute solutions of OA complexes have been reconcentrated through membrane distillation (MD) and reused to new round of FO processes. The OA complexes have demonstrated their suitability and superiority as a novel class of draw solutes for the FO process in this study.
正向渗透（FO）在混合 FO 海水淡化中表现出了其优势。然而，如果有合适的汲取剂，FO 可能会有其他应用的潜力。在这项研究中，提出了一系列基于草酸（OA）-过渡金属配合物的新型汲取剂。通过改变过渡金属、配合物汲取剂的阳离子以及实验条件，系统地研究了 FO 性能的影响因素。与 NaCl 和其他最近合成的汲取剂相比，OA 配合物在 FO 和 PRO（压力延迟渗透）模式下具有高达 27.5 和 89.1 LMH 的高水通量，且反向溶质通量可忽略不计，表现出了优异的 FO 性能。八面体几何形状、丰富的亲水基团和离子种类的特点对 OA 配合物作为具有令人满意 FO 性能的合适汲取剂至关重要。在所合成的 OA 配合物中，由于其配合物体系中含有更多的离子种类，六价铬的铵盐（NH-Cr-OA）表现优于其他配合物。与典型的 NaCl 汲取剂相比，NH-Cr-OA 还在 FO 含油废水处理中表现出了更高的水回收率和可忽略的反向通量，性能更好。通过膜蒸馏（MD）对 OA 配合物的稀溶液进行浓缩，并重新用于新的 FO 过程。在这项研究中，OA 配合物已被证明适合且优于 FO 过程中的新型汲取剂。
