Polyethersulfone composite hollow-fiber membrane prepared by in-situ growth of silica with highly improved oily wastewater separation performance

In order to reduce surface aggregation and enhance the performance of PES membranes, a hydrophilic PES/TEOS HF membrane was developed for the treatment of wastewater containing oil. PES/TEOS was prepared via a sol-gel self assembly and dry–wet spinning method. Silicon dioxide sol was prepared from a mixture of tetraethoxysilane, ethanol, water, and acetic acid (acting as the catalyst). HF hybrid membranes were produced from dope solutions containing polyethersulfone, polyethylene glycol, silicon sol, and NMP. The membranes were characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), porosity, fourier transform infrared spectroscopy (FTIR), and contact angle measurements. The composite membranes were successfully used to treat wastewater containing oil and their separation performance were evaluated. The PES/TEOS-2 membrane displayed the best performance, with a permeate flux of 90.937 L/m² h and an oil retention of 99.98%. In addition, this membrane showed a higher pure water flux of 102.43 L/m² h as compared to PES-0 and PES/SiO₂–1 membranes (87.347 L/m² h and 91.949 L/m² h, respectively). The PES/TEOS-2 membrane also presented enhanced antifouling behavior with a FRR and a RFR of 93.33% and 11.22%, respectively. In addition, this membrane displayed excellent long-term recycling properties, making it a desirable candidate for oily wastewater separation applications.     

Fouling evaluation of polyethersulfone (PES)/sulfonated cation exchange resin (SCER) membrane for BSA separation

In this study, antifouling membranes were prepared through dry wet‐phase inversion method. The incorporation of electrostatistically charged group of sulfonate cation exchange resins (SCER) into polyethersulfone membrane matrix attempts to give a synergistic combination of properties for bovine serum albumin (BSA) removal. The effect of different composition of SCER into the blend membranes were characterized using scanning electron microscopy, atomic force microscopy, porosimeter, attenuated total reflectance Fourier transform infrared spectroscopy, and goniometer. All the prepared membranes were evaluated for BSA separation. The membrane resistance of all membranes decreases with increase in SCER loading. Among all membranes, P3 membrane shows a better fouling, reversible and irreversible resistance for BSA, signifying that the attached BSA on the membrane surface can be easily removed by physical cleaning. The improvement in hydrophilicity of P3 membrane was found to be the dominant factor in mitigating BSA fouling. The results demonstrated that BSA fouling could be alleviated by varying SCER concentration in the polyethersulfone matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45854.     

Influence of ethanol as bore fluid component on the morphological structure and performance of PES hollow fiber membrane for oil in water separation

The relationships among varying bore fluid compositions containing ethanol/water were studied. The ethanol composition was varied in the ratio of 0%, 25%, 50%, 75% and 100%. The membrane dope solutions were prepared from 17.25 wt% polyethersulfone (PES), 0.75 wt% polyethylene glycol (PEG), 3 wt% silicon dioxide sol and 78.25 wt% of 1-methyl-2-pyrrolidone (NMP) via dry-jet spinning process. The membranes’ morphology as a result of varying ethanol ratio in the bore fluid composition was characterized and their effects on crude oil/water emulsion separation were evaluated. Results show that the membrane pore size and porosity decreased with increasing ethanol content in the bore fluid mixture, whereas the inner wall thickness of fibers increased. Furthermore, an increase in ethanol concentration also resulted in a slight increase in water contact angle. The use of 100/0 of ethanol/water resulted in UF membranes with the lowest performance. On the other hand, bore fluid mixture containing 25/75 ethanol/water produced membrane with the best performance for crude oil/water separation. Overall, the use of bore fluid mixture containing 25/75 ethanol/water mixture was found to be a powerful way to tune the morphological properties and performance of HF membrane.     

Sand-Fixation Model for Interface Engineering of Layered Titania and N/O-Doped Carbon Composites to Enhance Potassium/Sodium Storage

Layered titania (L-TiO₂) holds great potential for potassium-ion batteries (PIBs) and sodium-ion batteries (SIBs) due to their high specific capacity. Synthesizing L-TiO₂ functional materials for high-capacity and long cyclability battery remains challenging due to the unstable and poor conductivity of bare L-TiO₂. In nature, plant growth can stabilize land by preventing sands from dispersing following desertification. Inspired by nature's “sand-fixation model,” Al³⁺ “seeds” are in situ grown on layered Ti₃C₂T_x “land.” Subsequently, NH₂-MIL-101(Al) “plants” with Al as metal nodes are grown on the Ti₃C₂T_x “land” by self-assembly. After annealing and etching processes (similar to desertification), NH₂-MIL-101(Al) is transformed into interconnected N/O-doped carbon (MOF-NOC), which not only acts as a plant-like function to prevent the pulverization of L-TiO₂ transformed from Ti₃C₂T_x but also improves the conductivity and stability of MOF-NOC@L-TiO₂. Al species are selected as seeds to improve interfacial compatibility and form intimate interface heterojunction. Systematic ex situ analysis discloses that the ions storage mechanism can be endowed by mixed contribution of non-Faradaic and Faradaic capacitance. Consequently, the MOF-NOC@L-TiO₂ electrodes exhibit high interfacial capacitive charge storage and outstanding cycling performance. The interface engineering strategy inspired by “sand-fixation model” provides a reference for designing stable layered composites.