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Several efforts to produce mechanically robust polymeric hollow fiber membranes have led to the use of polyethylene terephthalate (PET) hollow braided tubes, which offer rigidity to hollow fiber membranes. However, a compensation of flux exists with increased filtration pathway occasioned by braid substrate and thick polymer coating. It is often difficult to control the fabrication parameters to achieve uniformly coated and thin separation layer. In this work, we report a modification of the erstwhile dry-jet wet spinning process for braided hollow fiber by introducing a loop-system to increase resident time in the coagulation bath for effective solvent exchange and leaching of pore former additive. A combination of air gap (5, 15 and 25 cm), polymer concentration (15%, 17% and 19%) and take-up speed (1.2, 2.4 and 3.6 m/min) were varied to produce membranes with optimum filtration performance against crude oil emulsion feed. BRP-HM8 spun with 15 wt% PVDF, 15 cm air gap and take-up speed of 2 rpm exhibited thin and uniform coating outside of braid, well-developed pore structure resulting in high flux up to 620 L/m2h, good hydrophilic/oleophobic characteristics with > 98% rejection of crude oil as well high mechanical properties against harsh feed and elevated pressure. [Display omitted] • Loop-system for improved spinning of braided hollow fiber membranes. • Thin and uniform polymer coating reducing filtration pathway with well-developed finger-like pores. • Excellent rejection properties occasioned by good underwater oleophobicity. • High-strength reusable membranes with simple flushing. [ABSTRACT FROM AUTHOR]

In this study, thin-film composite (TFC) hollow fibers (HFs) were fabricated by an in-situ coating of polyamide layer on the lumen side of PVC/PC blend substrates for desalination by forward osmosis (FO). Particularly, the substrate HFs were spun at two air gap distances of 2 and 6 cm, to investigate the effect of the air-gap distance on the FO performance. The substrate HFs were characterized by pure water flux measurement, FESEM, and gas permeability test. The Interfacial polymerization (IP) method was then utilized for coating polyamide (PA) layer on the lumen surface of the substrate to fabricate TFC HFs. The TFC HFs so fabricated were also characterized by FESEM, before their FO performance was tested. Furthermore, the effect of HF length on the FO flux was investigated. The results showed that the novel TFC HFs exhibited good FO performance. The longer the air gap distance, the better becomes the FO performance in terms of simultaneous water flux and alginate fouling resistance, while the effect of the HF length remains a controversial issue. • Higher surface porosity resulted defect free active layer. • Higher surface porosity enhanced mass transfer coefficient, by reducing CP. • Irreversible fouling is suppressed when HF spun with longer air gap distance. • Water flux decreased with the fiber length, contrary to the model simulation. • In high flux mode increasing number of the fibers can increase productivity. [ABSTRACT FROM AUTHOR]

In this study, hollow fiber PVC/ZnO-nanocomposite in an MBR was investigated for municipal wastewater treatment. The following parameter were evaluated: BOD, COD, TSS, NTU, TP, TKN. ZnO nanoparticles caused to decrease the contact angle from 78° to 67° for the neat PVC and 0.5 wt% ZNO-nanocomposite membrane, respectively. The majority of the neat membrane resistance was due to irreversible resistance. Because of the antibacterial properties of zinc oxide nanoparticles, with increasing nanoparticles loading, the resistance of irreversible part compared to the reversible resistance experienced a significant decrease. This confirm that the fabricated nanocomposite membranes did not show affinity toward adsorption of the sludge inside the pores hence substantially limited the membrane fouling. The FTIR results showed the reduction of proteins and polysaccharides onto the surface of the nanoparticle-incorporated membranes, approaching the clean PVC membrane. This was most likely due to the antibacterial properties of ZnO NPs. Nitrogen and phosphor removal for PVC0.5 membrane was 99% and 79% and TSS removal up to 100% was achieved. The findings of this study showed that modification of PVC polymer using ZnO nanoparticles with the presence of ferric chloride coagulant is a very effective technique for municipal wastewater treatment to meet the well-known standard levels. [Display omitted] [ABSTRACT FROM AUTHOR]