No abstract

We modified poly(vinylidene fluoride) (PVDF) membranes with a polydopamine (PDA) coating for photocatalytic membrane reactor application with appropriate UV resistance and studied the effects of the PDA coating conditions (i.e., coating time and dopamine concentration) and UV irradiation time on the modified PVDF membrane properties. The PVDF membrane that was surface‐coated with the appropriate dopamine solution concentration and coating time played a key role in controlling the membrane properties and in protecting the modified membrane against UV radiation. The optimization of the coating condition not only completely protected the modified membrane from free‐radical attack initiated through UV irradiation but also improved the membrane hydrophilicity, antifouling properties, filtration performance, and mechanical strength of the membrane. UV irradiation of the membrane that was surface‐coated with a high‐concentration dopamine solution for a long coating time resulted in a higher mechanical strength than that of the membrane without the application of UV irradiation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47312.

Composite ultrafiltration membranes were successfully fabricated by blending a nonionic surfactant and inorganic nanoparticles via a nonsolvent‐induced phase separation (NIPS) method. Brij35 was used as the nonionic surfactant and silica (SiO2) nanoparticles from rice husk ash, a low cost and widely available material, were used as the inorganic nanoparticles. The synergetic effect of both additives was used to tailor the membrane structure and properties because the selected additives showed completely different or, in some cases, the opposite effect on the membrane properties and structure. The combined effects of Brij and SiO2 resulted in a membrane with a noticeable improvement in membrane overall performance including pure water permeability, hydrophilicity, antifouling properties, long‐term stability, tensile strength, on the cost of a slight decrease in membrane elongation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47737.

This paper discusses about the influence of polydopamine layer in enhancing UV resistance of PVDF membrane for membrane photocatalytic reactor application. The PVDF membrane was prepared by common NIPS method using DMAc as a solvent and PEG as a pore-forming additive. The polydopamine layer was deposited on the membrane surface by the facile dip-coating method through Tris-buffered dopamine polymerization. The UV-shielding effect of PDA layer was studied by comparing the changes in pure and PDA coated membrane coating before and after UV irradiation. The studied effects are in terms of changes in chemical, morphological structure and mechanical properties which observed by means of ATR-FTIR, FESEM instrumental analysis, and tensile measurement, respectively. The IR analysis showed that after PDA coating, the membrane surface is rich of catecholamine groups which greatly contributed as free radical scavengers. The change in chemical structure was seen on pure membrane which attributed to the rearrangement of polymer chemical structure caused by UV-induced photodegradation. FESEM imaging results showed that with PDA coating the membrane surface showed minimal damage in comparison to that of non-coated PVDF membrane. These results altogether confirmed, that the PDA layer can protect the membrane surface from UV-initiated free radicals attack.

Selection of the appropriate solvent plays an important role in the characteristics of the membrane formation. Flat-sheet polyethersulfone (PES) membranes were formation via non-solvents induced phase separation (NIPS) technique. PES as a polymer, Brij58 as hydrophilic surfactant and three types of solvent were used to prepare the dope solution. This paper attempts to show the effects of three different solvents there are; dimethylsulfoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMAc) on characterizations and performance of fabricated membranes. The fabricated membranes in this study were characterized by measuring water contact angle and mechanical properties. The performance of fabricated membranes was carried out using a dead-end ultrafiltration module. Solubility between solvent and non-solvent is an essential factor in the membrane formation process. The porosity of membrane fabricated from the system of PES/Brij/DMAc was higher than membrane made from another system, so that the water permeability of this membrane was higher than others. The membrane fabricated with DMAc as solvent had a tensile strength of 12.42 kgf/mm2.

Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane. The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m .hr.atm with the addition of 7% PF127 additive. PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

Surface water is commonly used as a source of clean water, but increasingly, surface water is contaminated with various foulants. Humic acids (HAs) are a natural organic matter predominant in ground and surface waters. HAs can reduce the quality of water. This study aims to investigate the results adding magnesium hydroxide, or Mg(OH)2, to modify polyethersulfone (PES) membranes by determining the characteristics and performance of the membranes. The mixed-matrix membranes were prepared using PES and various amounts of modified Mg(OH)2 (0%, 1%, and 1.5% wt) as nanoparticle additives. A scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and water contact-angle analysis were used to characterize the membranes, followed by a membrane performance test (flux, permeability, and selectivity of the membrane) using a dead end ultrafiltration module. It can be concluded that Mg(OH)2 can improve the hydrophilicity of PES membrane with decreasing the water contact angle from 84.2° (pure PES membrane) to 68° (modified membrane), where ultrafiltration membranes with the highest permeability coefficient are obtained at 1.5% wt of Mg(OH)2 with a value of 41.94 L/m2.h.bar and a rejection percentage of 67.72%.

Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane.  Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m 2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.