Fabrication of high performance PVDF hollow fiber membrane using less toxic solvent at different additive loading and air gap

Existing toxic solvents in the manufacturing of polymeric membranes have been raising concerns due to the risks of exposure to health and the environment. Furthermore, the lower tensile strength of the membrane renders these membranes unable to endure greater pressure during water treatment. To sustain a healthier ecosystem, fabrication of polyvinylidene fluoride (PVDF) hollow fiber membrane using a less toxic solvent, triethyl phosphate (TEP), with a lower molecular weight polyethylene glycol (PEG 400) (0–3 wt.%) additive were experimentally demonstrated via a phase inversion-based spinning technique at various air gap (10, 20 and 30 cm). Membrane with 2 wt.% of PEG 400 exhibited the desired ultrafiltration asymmetric morphology, while 3 wt.% PEG 400 resulting microfiltration. The surface roughness, porosity, and water flux performance increased as the loading of PEG 400 increased. The mechanical properties and contact angle of the fabricated membrane were influenced by the air gap where 20 cm indicate 2.91 MPa and 84.72◦, respectively, leading to a stronger tensile and hydrophilicity surface. Lower toxicity TEP as a solvent helped in increasing the tensile properties of the membrane as well as producing an eco-friendly membrane towards creating a sustainable environment. The comprehensive investigation in this study may present a novel composition for the robust structure of polymeric hollow fiber membrane that is suitable in membrane technology

Facile and economical, single-step single-chemical method for conversion of palm oil fuel ash waste into graphene nanosheets

Palm oil fuel ash (POFA) is a waste material generated in large quantities by palm oil industry worldwide. To avoid the rising disposal costs and environmental issues, its positive and cost-effective utilization is the urgent requirement. An economical, single-step, and green chemical method has been adopted in this study to convert as received waste byproduct, POFA, from oil palm mills to produce precious "POFA derived graphene (PDG) nanosheets." The results analyses from different latest instrumental techniques like Raman, High-resolution transmission electron microscopy (HRTEM) and Atomic force microscopy (AFM) confirmed the successful synthesis of 1–8 layer PDG nanosheets with high yield (> 25 wt%). Parameters like temperature, the ratio of KOH: POFA, and reaction time were optimized to get the maximum yield and removal of all inorganic impurities up to < 0.5 wt.% in the final sample. Clean and smooth edges of PDG with hexagonal rings were also observed using HRTEM. In addition, the surface area of PDG was improved up to 1506.60 m2/g along with a high degree of porosity. Waste POFA ash as the cheapest carbon precursor used for the first time to synthesize economical graphene using a single-step, single chemical method. As a low cost carbon source, POFA, proves to be economical for scalable and sustainable production of PDG and presents an environment-friendly approach towards a green environment, besides promoting the circular economy concept

Immobilization techniques of a photocatalyst into and onto a polymer membrane for photocatalytic activity

This article reviews the various techniques of immobilizing a photocatalyst into and onto the polymer membrane for pollutant removal and as a problem solver in handling suspended photocatalyst issues from the previous literature. A particular focus is given to the preparation of mixed matrix membranes and deposition techniques for photocatalytic degradation in applications for wastewater treatment. Advantages and disadvantages in this application are evaluated. Various operating conditions during the process are presented. About 90 recently published studies (2008-2020) are reviewed. From the literature, it was found that TiO2is the most favoured photocatalyst that is frequently used in photocatalytic water treatment. Dry-wet co-spinning and sputtering techniques emerged as the promising technique for immobilizing a uniformly distributed photocatalyst within the polymeric membrane, and exhibited excellence pollutant removal. In general, the technical applicability is the key factor in selecting the best photocatalyst immobilizing technique for water treatment. Finally, the scope of various techniques that have been reviewed may provide potential for future photocatalytic study

Bisphenol A Removal Using Visible Light Driven Cu₂O/PVDF Photocatalytic Dual Layer Hollow Fiber Membrane

Bisphenol A (BPA) is amongst the endocrine disrupting compounds (EDCs) that cause illness to humans and in this work was removed using copper (I) oxide (Cu2O) visible light photocatalyst which has a narrow bandgap of 2.2 eV. This was done by embedding Cu2O into polyvinylidene fluoride (PVDF) membranes to generate a Cu2O/PVDF dual layer hollow fiber (DLHF) membrane using a co-extrusion technique. The initial ratio of 0.25 Cu2O/PVDF was used to study variation of the outer dope extrusion flowrate for 3 mL/min, 6 mL/min and 9 mL/min. Subsequently, the best flowrate was used to vary Cu2O/PVDF for 0.25, 0.50 and 0.75 with fixed outer dope extrusion flowrate. Under visible light irradiation, 10 mg/L of BPA was used to assess the membranes performance. The results show that the outer and inner layers of the membrane have finger-like structures, whereas the intermediate section of the membrane has a sponge-like structure. With high porosity up to 63.13%, the membrane is hydrophilic and exhibited high flux up to 13,891 L/m2h. The optimum photocatalytic membrane configuration is 0.50 Cu2O/PVDF DLHF membrane with 6 mL/min outer dope flowrate, which was able to remove 75% of 10 ppm BPA under visible light irradiation without copper leaching into the water sample