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International audience

The use of pore forming agents has been notable for improving the water flux in a water-based separation membrane but are rarely being studied as a methodology to influence the substrate's surface architectures for composite membrane fabrication in gas separation. In this study, the influence of lithium chloride (LiCl) on the surface pore architectures and hence, the gas permeance, has been studied in both bare and composite forms with poly(dimethylsiloxane) (PDMS). 1–4 wt% of LiCl was mixed with the dope solution of PES/NMP in the ratio 0.19 and was casted via the dry–wet phase inversion method. Bare substrates were noted to possess increasingly larger surface pore sizes but at a diminishing surface pore density with maximum surface porosity at 2 wt% LiCl. The permeances were, however, significantly reduced with the increase in the LiCl content from 105 300 to 4300 GPU for N2 gas, presumably due to the thicker skin layer. Nevertheless, the porous surface morphology was confirmed and exhibited Knudsen selectivity with a CO2/N2 selectivity of about 0.8, signifying minimal gas flow resistance by the substrates. Upon coating with a similar amount of thin PDMS layer, the composite permeances retain the same trend with values from 361.9 GPU for 0 wt% LiCl substrates to 68.8 GPU for 4 wt% LiCl substrates for CO2 gas at a consistent selectivity of about 14. As the PDMS layer of the same volumes were used and no significant difference in the coating thickness was noted, the mixed influence of pore intrusion and lateral diffusion is hypothesised at the substrate–coating interface owing to the different surface pore architectures of the substrates.

New dope formulation was synthesized to fabricate an antibacterial and antifouling hollow fiber (HF) membrane using polyvinyl alcohol (PVA)–zinc oxide (ZnO) blend, mediated by lithium chloride (LiCl). Study was done between neat polyethersulfone (PES), PES–ZnO, PES–PVA, and PES–PVA–ZnO membrane samples. The addition of PVA improved the antifouling properties with the lowest recorded relative humic acid flux (HAF) above 0.95. On the other hand, PVA–ZnO incorporation improved the humic acid rejection up to 96.03 ± 1.07%. Minimal bacterial formation was found on ZnO present sample surfaces, suggesting superior antibacterial properties.

The aim of this study is to develop an Emulsion Liquid Membrane (ELM) system for the extraction of acetaminophen (ACTP). Firstly, ELM was formulated by the screening of liquid membrane components where the compatibility of diluent with other membrane phase components was investigated. The chosen carrier, diluent and stripping solution must comply with the reaction at the interface of the membrane to support the simultaneous processes of extraction and stripping. Therefore, parameters such as stripping agent concentration, volume ratio, initial concentration of feed phase and HCl concentration were investigated. A stable emulsion and maximum acetaminophen removal efficiency of 85% was achieved.

The aim of this study is to analyse the fouling behaviour of polyethersulfone (PES) / polyvinyl pyrrolidone (PVP) / titanium oxide (TiO2) mixed matrix (MM) hollow fiber (HF) membrane with varying TiO2 loadings for humic acid (HA) treatment. The MM HF membrane was fabricated using dry jet – wet phase inversion method by blending varying amount of TiO2 nanoparticles (1, 2, 3, and 4 wt. %) into the PES dope solution. The fabricated HF membrane was characterised in terms of their surface and cross section morphology, contact angle, pore size, and porosity. These characteristics can highly affect the membrane antifouling behaviour as well as membrane flux. The membrane was tested using 50 mg/L of HA solution adjusted to pH 7.7. All MM HF membranes suggested better antifouling with S2 sample at 2 wt.% TiO2 having optimal antifouling and flux performance with the lowest value for resistance by fouling and less than 5% difference from the best permeate flux and rejection values. Under this formulation, HA permeation test has registered an improved membrane flux at 23.851 kg/m2 h and HA rejection of 97.89%; an improvement of 28.9% and 3.8% respectively as compared to the neat PES membrane. HA rejection increased drastically due to higher surface hydrophilicity of TiO2 blended membranes, which repels the hydrophobic HA and prevented the adsorption of HA onto the membrane surface. This also minimize the formation of reversible and irreversible fouling by HA, which increases its antifouling abilities.