Characterization and Separation Performance of a Novel Polyethersulfone Membrane Blended with Acacia Gum

Novel polyethersulfone (PES) membranes blended with 0.1–3.0 wt. % of Acacia gum (AG) as a pore-former and antifouling agent were fabricated using phase inversion technique. The effect of AG on the pore-size, porosity, surface morphology, surface charge, hydrophilicity, and mechanical properties of PES/AG membranes was studied by scanning electron microscopy (SEM), Raman spectroscopy, contact angle and zeta potential measurements. The antifouling -properties of PES/AG membranes were evaluated using Escherichia coli bacteria and bovine serum albumine (BSA). The use of AG as an additive to PES membranes was found to increase the surface charge, hydrophilicity (by 20%), porosity (by 77%) and permeate flux (by about 130%). Moreover, PES/AG membranes demonstrated higher antifouling and tensile stress (by 31%) when compared to pure PES membranes. It was shown that the prepared PES/AG membranes efficiently removed lead ions from aqueous solutions. Both the sieving mechanism of the membrane and chelation of lead with AG macromolecules incorporated in the membrane matrix contributed to lead removal. The obtained results indicated that AG can be used as a novel pore-former, hydrophilizing and antifouling agent, as well as an enhancer to the mechanical and rejection properties of the PES membranes

Preparation and characterization of emulsion poly(vinyl chloride) (EPVC)/TiO(2) nanocomposite ultrafiltration membrane

Emulsion poly(vinyl chloride)/titanium dioxide (EPVC/TiO2) nanocomposite ultrafiltration membranes were prepared using the phase inversion method with different TiO2 contents. Pure water flux through the membranes was investigated at a operating pressure of 2 bar and its antifouling properties were studied using bovine serum albumin (BSA) as a foulant. The results showed an increment in pure water flux with increasing content of TiO2 up to 2 wt%, and then it slightly decreased by addition of 4 wt% TiO2 due to agglomeration of the nanoparticles at this content. The static water contact angle test showed improvement in membrane hydrophilicity, due to hydrophilic behavior of the nanoparticles, which led to higher water flux. SEM and EDAX analyses were applied to investigate membrane morphological changes. EDAX analysis indicated that the nanoparticles are homogeneously dispersed in membrane structure at low concentrations. However, at high loading, the nanoparticles have a propensity to aggregate. SEM images showed that with TiO2 addition, initially finger-like structures change to macro-voids and after 1 wt% TiO2 loading, they return to finger-like construction with elongated finger-like pores. TiO2 addition also enhanced BSA rejection properties. BSA ultrafiltration experiments showed that the antifouling ability of nano-TiO2 embedded membranes was better than the unfilled EPVC membrane.Hesamoddin Rabiee, Mohammad Hossein Davood Abadi Farahani, Vahid Vatanpou

Improvement in flux and antifouling properties of PVC ultrafiltration membranes by incorporation of zinc oxide (ZnO) nanoparticles

In this study, modification of polyvinyl chloride (PVC) ultrafiltration membranes with zinc oxide (ZnO) nanoparticle addition was taken into consideration. The ZnO at five different weights was added to the polymeric solution, and the membranes were fabricated by the phase inversion method using water as a nonsolvent and PEG 6 kDa as a pore former additive. The results showed that the pure water flux of the modified membranes increased up to 3 wt% ZnO addition, which was the optimized amount of the nanoparticle addition in this study. Also, at 3 wt% ZnO addition, flux recovery ratio reached from 69% to above 90%, indicated that the nanocomposite membranes were less susceptible to be fouled. BSA rejection of the membranes also enhanced up to 97% by 3 wt% ZnO addition. The membranes were further characterized by SEM images and remarkable changes in their morphologies were observed, and they became more porous with higher interconnectivity between the pores. Furthermore, EDAX analysis was applied to study ZnO dispersion in the membrane structure and except for 4 wt% ZnO addition which particles aggregation was noticeable, ZnO was dispersed finely in the membrane structure. In addition, the modified membranes had higher hydrophilicity and lower contact angle that was effective to obtain higher water flux.Hesamoddin Rabiee, Vahid Vatanpour, Mohammad Hossein Davood Abadi Farahani, Hamed Zarrab

Ball-milled Cu2S nanoparticles as an efficient additive for modification of the PVDF ultrafiltration membranes: Application to separation of protein and dyes

This study reports the fabrication and application of polyvinylidene fluoride (PVDF) ultrafiltration membranes embedded with various concentrations of the Cu2S nanoparticles. The Cu2S nanoparticles were generated from natural chalcocite applying a high energy planetary ball-milling technique. Non-solvent induced phase separation method was used for the fabrication of the membranes and characterized with scanning electron microscopy (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM), porosity and static water contact angle measurements. The results of the contact angle and porosity revealed the increased hydrophilicity and porosity of the nanocomposite membranes as a result of the addition of Cu2S leads to water permeation improvement. The nanocomposite membrane with 0.2 wt% of Cu2S nanoparticles exhibited a maximum water flux of 248.25 Lm-2 h-1 and flux recovery ratio (FRR) value of 92.4%, which showed 65% and 19% increase compared with the control PVDF membrane. Meanwhile, the nanocomposite membranes were able to highly reject the anionic dyes such as reactive blue 21 (RB21), direct black 38 (DB38), and direct yellow 12 (DY12). © 2021 Elsevier Ltd

Ball-milled Cu₂S nanoparticles as an efficient additive for modification of the PVDF ultrafiltration membranes: Application to separation of protein and dyes

This study reports the fabrication and application of polyvinylidene fluoride (PVDF) ultrafiltration membranes embedded with various concentrations of the Cu2S nanoparticles. The Cu2S nanoparticles were generated from natural chalcocite applying a high energy planetary ball-milling technique. Non-solvent induced phase separation method was used for the fabrication of the membranes and characterized with scanning electron microscopy (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM), porosity and static water contact angle measurements. The results of the contact angle and porosity revealed the increased hydrophilicity and porosity of the nanocomposite membranes as a result of the addition of Cu2S leads to water permeation improvement. The nanocomposite membrane with 0.2 wt% of Cu2S nanoparticles exhibited a maximum water flux of 248.25 Lm-2 h-1 and flux recovery ratio (FRR) value of 92.4%, which showed 65% and 19% increase compared with the control PVDF membrane. Meanwhile, the nanocomposite membranes were able to highly reject the anionic dyes such as reactive blue 21 (RB21), direct black 38 (DB38), and direct yellow 12 (DY12)

Novel polymeric additives in the preparation and modification of polymeric membranes: A comprehensive review

One of the basic challenges in polymeric membrane fabrication is the control of pore size and the porosity of the membranes. In this review paper, the role of polymeric additives is overviewed in membrane fabrication processes, such as the formation of pores in membranes, increasing permeability, hydrophilicity and even the creation of a desirable property such as antifouling and antibacterial properties. The polymeric additives could dissolve in water during the phase inversion process (a pore forming agent) or remain in the membrane matrix (hydrophilic and antifouling agent) or could have both roles. The additives could also act as proton exchanger and gas transport facilitating agents. This review concentrates on the introduction of new polymeric additives. In the blended membranes, the miscibility of chosen polymeric additives at the molecular levels make it a challenge to use the modification method. Molecular interactions between polymers such as hydrogen bonding and charge transfer play the main roles of the quality of blending. Different methods of polymer/co-polymer addition to the polymeric matrix of membranes are investigated to identify the best polymeric additives in various types of polymeric membranes including: pervaporation, contactor membrane, distillation membrane, etc. Moreover, the mixability of the additive polymer with the matrix polymer solution and the effectiveness of some functional additives are described in this review. © 2022 The Korean Society of Industrial and Engineering Chemistr

An in vitro comparison of internally versus externally mounted leaflets in surgical aortic bioprostheses

OBJECTIVES: To improve haemodynamic performance, design modifications of prosthetic valves have been proposed with each new generation of valves. These different designs also impact the amount of mechanical wear, because mechanical stresses are distributed differently. Because long-term evidence for new prosthetic valves is lacking, this in vitro study compared hydrodynamic performance and durability among 3 currently available bioprosthetic valves with internally (IMLV) or externally mounted leaflets (EMLV).METHODS: Prostheses of the internally mounted Medtronic Avalus and Carpentier-Edwards Perimount Magna Ease valves were compared to prostheses of the externally mounted Abbott Trifecta valve. For each labelled size (e.g. 19, 21 and 23) of the 3 types, 3 valves underwent accelerated wear testing for up to 600 million cycles, corresponding to similar to 15 years of simulated wear. The valves underwent hydrodynamic testing and visual inspection.RESULTS: EMLV had the largest effective orifice area and lowest pressure gradient for each labelled size at baseline and 600 million cycles; the effective orifice area and the pressure gradient were equivalent for the 2 types of IMLV. Five of 9 EMLVs had at least 1 hole or tear in the leaflet tissue around the stent posts, which resulted in severe regurgitation at 500 million cycles in 2 cases. All IMLVs were intact at 600 million cycles with minimal tissue wear.CONCLUSIONS: EMLV showed superior hydrodynamic performance but inferior mechanical durability compared to IMLV after 600 million cycles of testing. The primary failures were because of significant mechanical abrasion in the commissural region, which may warrant close monitoring of EMLV during long-term follow-up.Thoracic Surger