Composite membranes comprising of polyvinylamine-poly(vinyl alcohol) incorporated with carbon nanotubes for dehydration of ethylene glycol by pervaporation

Polymeric Nanocomposite Membranes for Next Generation Pervaporation Process: Strategies, Challenges and Future Prospects

Pervaporation (PV) has been considered as one of the most active and promising areas in membrane technologies in separating close boiling or azeotropic liquid mixtures, heat sensitive biomaterials, water or organics from its mixtures that are indispensable constituents for various important chemical and bio-separations. In the PV process, the membrane plays the most pivotal role and is of paramount importance in governing the overall efficiency. This article evaluates and collaborates the current research towards the development of next generation nanomaterials (NMs) and embedded polymeric membranes with regard to its synthesis, fabrication and application strategies, challenges and future prospects.

Polyurethane membrane with a cyclodextrin-modified carbon nanotube for pervaporation of phenol/water mixture

Polyurethane (PU) membrane has great potential in pervaporation recovery of phenol from water. In order to improve the permeability of the membrane, cyclodextrin was attached onto carboxylic and hydroxylate carbon nanotubes (CNTs) by physical and chemical methods, with which modified CNTs/PU membranes were prepared. The results showed that the addition of modified CNTs greatly increases the permeability and comprehensive performance of PU membranes in the pervaporation separation of a phenol/water mixture. With 0.5% phenol content in feed at 80°C, the flux and pervaporation separation index of blank PU are 6.10 and 324 kg·μm·m−2·h−1, while those of chemically modified carboxylic CNTs/PU membranes are 156.1 and 655.8 kg·μm·m−2·h−1, respectively.

Functionalized carbon nanotube (CNT) membrane: progress and challenges

Various approaches have been investigated to functionalize CNT for achieving a high dispersion of CNT as well as high compatibility between CNT and polymer matrix which lead to improvement of membrane properties and performances.

Novel reverse osmosis membranes composed of modified PVA/Gum Arabic conjugates: Biofouling mitigation and chlorine resistance enhancement

A novel crosslinked Poly (vinyl alcohol) (PVA) reverse osmosis (RO) thin film membrane conjugated with Gum Arabic (GA) with superb performance and features was synthesized for water desalination. RO membrane desalination parameters, such as hydrophilicity, surface roughness, water permeability, salt rejection, Chlorine resistance and biofouling resistance were evaluated using a dead end RO filtration unit. The incorporation of Pluronic F127 and the conjugation of Gum Arabic improved the overall RO performance of the membranes. This study has shown that the membrane PVA-GA-5 that contains 0.9wt% Gum Arabic provided excellent permeation, salt rejection, Chlorine and biofouling resistance and mechanical strength. The most remarkable result to arise from this research is that the overall RO performance enhancement has been achieved while utilizing PVA/Gum Arabic as a separation layer without the use of a substrate, which eliminates negative effects associated with the use of a substrate like internal concentration polarization.

Pervaporation dehydration of an acetone/water mixture by hybrid membranes incorporated with sulfonated carbon molecular sieves

Sulfonated carbon molecular sieves (SCMS) were incorporated into a chitosan (CS) matrix. The sulfonic acid groups hydrophilic sites can preferentially interact with water, while the ordered channels facilitate water transport.

Desalination of simulated seawater by purge-air pervaporation using an innovative fabricated membrane

An innovative polymeric membrane has been invented, which presents a breakthrough in the field of desalination membranes. It can desalinate simulated seawater of exceptionally high concentration to produce a high flux of potable water with over 99.7% salt rejection (%SR) in a once-through purge-air pervaporation (PV) process. A set-up was constructed for conducting the desalination experiments and the effect of initial salt solution concentration (Ci) and pervaporation temperature (Tpv) on the water flux (J), %SR, separation factor, and pervaporation separation index were determined. The membrane was prepared by the phase-inversion technique, of a specially formulated casting solution consisting of five ingredients, after which the membrane was subjected to a post-treatment by which certain properties were conferred. The results confirmed that the salinity of the pervaporate was independent of Ci (all %SR above 99.7). The best result was at Tpv=70 °C, where J varied from 5.97 to 3.45 l/m2 h for Ci=40-140 g NaCl/l, respectively. The membrane morphology was confirmed to be asymmetric. The contact angle was immeasurable, indicating the membrane to be super-hydrophilic. Activation energies computed using Arrhenius law were, under all conditions investigated, less than 20 kJ/mol K.

Introduction and demonstration of a novel Pb(II)-imprinted polymeric membrane with high selectivity and reusability for treatment of lead contaminated water

Lead contaminant in water has become an issue of great concern due to its high toxicity and easy accumulation in human body. In this study, a novel Pb(II)-imprinted polyvinyl alcohol (PVA)/polyacrylic acid (PAA) membrane (Pb-IM) was prepared based on semi-interpenetrating polymer network for selective lead removal. The chemical stability and lead adsorption performance of the Pb-IM were evaluated. The results revealed that the Pb-IM exhibited high adsorption capacity of 1.003mmol/g for lead, fast adsorption equilibrium within 1.5h, and the adsorption process obeyed Langmuir isotherm model and intraparticle pore diffusion model. The Pb-IM retained high adsorption of lead in the presence of competitive factor, i.e. cadmium. In comparison with non-imprinted PVA/PAA membrane, the Pb-IM possessed a much higher selectivity toward lead versus cadmium, with selectivity coefficient of 70.7. Furthermore, the Pb-IM displayed a high reusability for lead uptake and could maintain 96.32% of the adsorption capacity of virgin Pb-IM after six adsorption/desorption cycles. The FTIR and XPS analyses indicated that carboxyl groups in PAA and hydroxyl groups in PVA were mainly associated with the lead adsorption. Finally, the stability study showed that Pb-IM was quite stable and suitable for water treatment. It can be concluded that the Pb-IM can be provided as a powerful material for the selective removal of lead from aqueous solution.