Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Singapore.
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Singapore; Water Desalination & Reuse (WDR) Center, King Abdullah University of Science and Technology, 23955-6900, Saudi Arabia.
Water Res. 2014 Jul 1;58:230-8. doi: 10.1016/j.watres.2014.03.024. Epub 2014 Apr 3.
Cupric and ferric hydroacid complexes have proven their advantages as draw solutes in forward osmosis in terms of high water fluxes, negligible reverse solute fluxes and easy recovery (Ge and Chung, 2013. Hydroacid complexes: A new class of draw solutes to promote forward osmosis (FO) processes. Chemical Communications 49, 8471-8473.). In this study, cobaltous hydroacid complexes were explored as draw solutes and compared with the ferric hydroacid complex to study the factors influencing their FO performance. The solutions of the cobaltous complexes produce high osmotic pressures due to the presence of abundant hydrophilic groups. These solutes are able to dissociate and form a multi-charged anion and Na(+) cations in water. In addition, these complexes have expanded structures which lead to negligible reverse solute fluxes and provide relatively easy approaches in regeneration. These characteristics make the newly synthesized cobaltous complexes appropriate as draw solutes. The FO performance of the cobaltous and ferric-citric acid (Fe-CA) complexes were evaluated respectively through cellulose acetate membranes, thin-film composite membranes fabricated on polyethersulfone supports (referred as TFC-PES), and polybenzimidazole and PES dual-layer (referred as PBI/PES) hollow fiber membranes. Under the conditions of DI water as the feed and facing the support layer of TFC-PES FO membranes (PRO mode), draw solutions at 2.0 M produced relatively high water fluxes of 39-48 LMH (L m(-2) hr(-1)) with negligible reverse solute fluxes. A water flux of 17.4 LMH was achieved when model seawater of 3.5 wt.% NaCl replaced DI water as the feed and 2.0 M Fe-CA as the draw solution under the same conditions. The performance of these hydroacid complexes surpasses those of the synthetic draw solutes developed in recent years. This observation, along with the relatively easy regeneration, makes these complexes very promising as a novel class of draw solutes.
铜和铁的氢酸配合物已被证明在正向渗透中作为汲取溶质具有优势，因为它们具有高水通量、可忽略的反向溶质通量和易于回收的特点（Ge 和 Chung，2013. Hydroacid complexes: A new class of draw solutes to promote forward osmosis (FO) processes. Chemical Communications 49, 8471-8473.）。在这项研究中，探索了钴氢酸配合物作为汲取溶质，并将其与铁氢酸配合物进行了比较，以研究影响其正向渗透性能的因素。钴配合物溶液由于存在大量亲水基团而产生高渗透压。这些溶质能够在水中离解并形成多电荷阴离子和 Na(+)阳离子。此外，这些配合物具有扩展的结构，导致可忽略的反向溶质通量，并提供相对容易的再生途径。这些特性使新合成的钴配合物适合作为汲取溶质。通过醋酸纤维素膜、聚醚砜支撑的薄膜复合膜（简称 TFC-PES）和聚亚苯并咪唑和 PES 双层（简称 PBI/PES）中空纤维膜分别评估了钴和铁-柠檬酸（Fe-CA）配合物的正向渗透性能。在 DI 水作为进料和面对 TFC-PES FO 膜的支撑层（PRO 模式）的条件下，2.0 M 的汲取溶液产生了相对较高的水通量 39-48 LMH（L m(-2) hr(-1)），可忽略的反向溶质通量。当模型海水（3.5 wt.% NaCl）代替 DI 水作为进料，在相同条件下使用 2.0 M Fe-CA 作为汲取溶液时，水通量达到 17.4 LMH。这些氢酸配合物的性能超过了近年来开发的合成汲取溶质。这种观察结果，以及相对容易的再生，使得这些配合物作为一种新型的汲取溶质非常有前途。
