Qingwu Long,Jiaqi Huang,Shu Xiong,Liang Shen,Yan Wang
FO technology has attracted growing attention in water treatment and desalination applications recently. The development of a suitable draw solute with high performance and low cost is therefore in high demand to facilitate practical FO applications. In this study, two oligomeric carboxylates — poly maleic acid sodium (PMAS) and poly(itaconate-co-acrylate) sodium [P(IA-co-AA)] with controllable molecular weights of 400–1000 Da, are synthesized via one-step polymerization and employed as novel draw solutes for FO applications. The successful synthesis is confirmed via by various characterization techniques. The osmotic pressure, relative viscosity and FO performance of PMAS and P(IA-co-AA) draw solutions with different concentrations are studied systematically. Two types of FO membranes are employed, and their performance is compared using PMAS draw solution. With 0.5 mol/kg PMAS draw solution and DI water feed solution, high water fluxes of 30.6 and 62.4 LMH can be achieved using HTI-TFC and homemade PSf-TFC membrane in the FO tests, respectively. 0.5 mol/kg PMAS draw solution is further studied for the desalination of 0.6 mol/kg NaCl solution via FO, with a water flux of 6.63 LMH obtained. The diluted PMAS solution after FO test can be recovered by nanofiltration with a high rejection rate. The excellent performance and available recovery route of the developed oligomeric carboxylates imply their great potential as promising draw solutes for FO applications.
Li Bin,Hao Wenrui,Xu Xiaojia,Liu Jizhen,Fu Dandan,Zhou Mengjing,Hu Zhigang
Choline chloride (ChCl) was used as the hydrogen bond acceptor (HBA) and acrylic acid (AA) and acrylamide (AM) as the hydrogen bond donor (HBD), and the three materials were mixed in a certain molar ratio to obtain deep eutectic solvent (DES). Subsequently, P(IA-co-AA-co-AM) composite hydrogels were prepared by adding itaconic acid (IA) to DES using the frontal polymerization (FP) method. The hydrogels were characterized by Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the influence patterns of IA content on the mechanical properties, swelling properties, and pH responsiveness of the composite hydrogels were investigated. The results showed that the composite hydrogel exhibited a homogeneous porous structure. The elongation at the break of the composite hydrogel gradually increased with the increase of IA content, and the elongation of the FP4 sample reached 167%. The addition of IA increased the number of hydrophilic groups, resulting in a 2.14-fold increase in the equilibrium swelling of the composite hydrogel in distilled water. P(IA-co-AA-co-AM) composite hydrogels exhibit different swelling patterns in acidic and alkaline environments, making them promising for acid–base indicators, biosensors, and other applications. In this study, a simpler and greener method was proposed to prepare P(IA-co-AA-co-AM) composite hydrogels with pH responsiveness.
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