In this study, a facile method has been developed to prepare high performance thin film composite (TFC) forward osmosis (FO) membranes, which was conducted by coating the surface of a polysulfone (PSf) substrate with polydopamine (PDA) prior to the interfacial polymerization of trimesoyl chloride and m-phenylenediamine. The PDA coating layer was investigated by ATR-FTIR, XPS, FESEM and contact angle measurements. Results showed that the PDA layer played the following roles: (1) endowing the PSf substrate with catechol and ethylamino groups to enhance the hydrophilicity, which resulted in a significant increase in water flux; (2) facilitating the formation of a denser selective polydopamine layer during the interfacial polymerization process to enhance salt rejection. The TFC membrane based on PDA coated dual PSf surfaces showed a water flux of 43.4 LMH and a salt flux of 6.46 gMH in pressure retarded osmosis (PRO) mode using 2 M NaCl as draw solution.

In this study, polyamide thin-film nanocomposite (TFN) membranes were prepared on nanosilica-modified polysulfone (PSf) support layers for forward osmosis (FO) applications. Different contents of SiO₂ nanoparticles (1, 3, and 5 wt%) were added to a dope solution to develop FO membranes with improved performance. The effects of SiO₂ on the membranes were investigated by attenuated total reflectance-Fourier transform infrared spectrometry, scanning electron microscope, hydrophilicity measurement, and mechanical property tests. The results showed that the wettability of PSf substrates was improved with increasing concentrations of SiO₂. The resulting TFN membranes had smaller structural parameters, which meant lower internal concentration polarization effects compared to typical thin-film composite membranes. However, SiO₂ nanoparticle is a good modifying agent to enhance water permeability, but it could not improve the selectivity of TFN membranes. The FO performance was evaluated using deionized water as feed solution and either 1 or 2 M NaCl as draw solution in both membrane orientations. The FO water flux of the fabricated membranes increased from 9.1 to 22.3 LMH when the active layer faced the feed solution (AL-FS) and 18.2 to 41.9 LMH when the active layer was placed towards the draw solution (AL-DS), mainly due to the improvement of PSf substrate with an addition of SiO₂.

The porous Ti/Sb-SnO₂/Ni-Ce-PbO₂ electrode was prepared by using a porous Ti plate as a substrate, an Sb-doped SnO₂ as an intermediate, and a PbO₂ doped with Ni and Ce as an active layer. The surface morphology and crystal structure of the electrode were characterized by scanning electron microscope(SEM), energy dispersive spectrometer(EDS), and X-Ray diffraction(XRD). The electrochemical performance of the electrodes was tested by linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and electrode life test. The results show that the novel porous Ni-Ce-PbO₂ electrodes with larger active surface area have better electrochemical activity and longer electrode life than porous undoped PbO₂ electrodes and flat Ni-Ce-PbO₂ electrodes. In this work, the removal of Cl⁻ in simulated wastewater on three electrodes was also studied. The results show that the removal effect of the porous Ni-Ce-PbO₂ electrode is obviously better than the other two electrodes, and the removal rate is 87.4%, while the removal rates of the other two electrodes were 72.90% and 80.20%, respectively. In addition, the mechanism of electrochemical dechlorinating was also studied. With the progress of electrolysis, we find that the increase of OH^- inhibits the degradation of Cl⁻, however, the porous Ni-Ce-PbO₂ electrode can effectively improve the removal of Cl⁻.

Novel modified cellulose acetate (CA) membranes using functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized by phase inversion via immersion precipitation technique. Carboxylated functionalized MWCNTs (F-MWCNTs) were used as additives into the casting solution of CA, 1, 4-dioxane, acetone, lactic acid, and methanol to enhance the forward osmosis (FO) membranes performance. Different contents of F-MWCNTs (0.01, 0.05, and 0.1 wt.%) were added into the casting solution. The novel synthesized CA/F-MWCNTs membranes were characterized by various methods in terms of membranes structure and surface properties, as well as FO performance, and then compared with traditional CA membrane and commercial FO membrane. The surface hydrophilicity, porosity, and tensile strength of CA/F-MWCNTs membranes were improved with the increment of the content of F-MWCNTs in the casting solution. The morphological studies showed that the addition of F-MWCNTs significantly changed the surface properties of the modified CA membranes. The FO performance was evaluated using purified water as feed solution and 1 M NaCl solution as draw solution. The CA/F-MWCNTs membranes showed higher water permeability and salt rejection in the range of 0.01–0.1 wt.% F-MWCNTs content than CA membrane and the commercial FO membrane. These encouraging results suggested that CA/F-MWCNTs membranes showed superior potential to be further developed for FO applications.