The performance of membranes for a specific application can be determined with the help of structural properties such as molecular weight cut-off (MWCO), morphology, and pore statistics. Heavy metal ions from aqueous streams can be separated with the help of ultrafiltration membranes. In the presence and absence of the various components of the additive poly (ethylene glycol) 600, MWCOs and pore statistics of polyurethane (PU) and carboxylated polysulfone (CPSf) blend ultrafiltration (Total Polymer Concentration = 17.5 wt %) were studied with the help of dextran of different molecular weights ranging from 19 kDa to 150 kDa. The derived pore size, porosity, and the number of pores have a remarkable relationship with the MWCO, morphology, and the flux performance of the membranes. The blend membranes rejected certain toxic divalent heavy metal ions such as copper, cadmium, nickel, and zinc by complexing them into a polymeric ligand, poly(ethyleneimine) (PEI). The effect of polymer blend compositions and additive concentrations on metal ions' rejection and permeate flux are discussed

Tailored polyacrylonitrile (PAN) ultrafiltration (UF) membranes are fabricated with Pluronic-F127 and polyethylene glycol phosphate decorated calcium carbonate (PGP-CaCO3) additives with the aim of high water permeation, macromolecular rejection and antifouling properties. The nanoscale CaCO3 synthesis is carried out via a single step carbonization route using PGP as a hydrophilic modifier to introduce hydroxyl groups onto its surface. The topographies of the nanoparticles are investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). PAN/PGP-CaCO3 mixed matrix membranes (MMMs) are fabricated via phase inversion method and examined by attenuated total reflectance-Fourier infra-red spectroscopy (ATR-FTIR), mechanical stability, thermo-gravimetric analysis (TGA) and scanning electron microscopy (SEM) to explore the changes in membrane properties due to the well-dispersed PGP-CaCO3 in the PAN membrane matrix. The UF performance of the membranes is investigated in terms of pure water flux, macromolecular rejection and antifouling property. The fouling resistance of membranes is assessed using bovine serum albumin (BSA) and humic acid (HA) as model foulants. The membrane loaded with 0.75wt.% (M3) of PGP-CaCO3 manifested increased wettability with reduced surface free energy leading to a higher pure water flux of 366L/m2h. M3 also displayed a rejection of 93.9% for BSA and 93.2% for HA. The success of the modification can be confirmed as the membrane M3 exhibited lower flux decline and displayed a flux recovery ratio of 90.98% during HA filtration. The results demonstrated the potential use of PAN/PGP-CaCO3 membranes in water treatment.

MnO2 nanospheres are prepared by simple hydrothermal technique, and their influence on the permeation, antifouling and contaminant removal properties of poly (ether imide) (PEI) ultrafiltration (UF) membranes is investigated by adding them at three different concentrations such as 0.5, 1.0 and 2.0 wt.% (designated as PEI-0.5, PEI-1 and PEI-2). The hydrophilic property of PEI/MnO2 membranes is investigated using contact angle and pure water flux measurements. The addition of MnO2 nanospheres reduces the contact angle to 60.8 degrees and enhances the pure water flux to 129.8 Lm(-2)h(-1) for PEI-1 membrane due to the increased surface hydrophilicity. SEM and AFM characterization revealed that the custom-made membranes showed noticeable changes in the formation of macrovoid, porosity and roughness parameters. During the separation of contaminants such as bovine serum albumin (BSA), humic acid (HA) and oil, the tailored membranes show enhanced rejection (between 96.8 and 99%) and flux recovery ratio (FRR) (between 95.5 and 99.5%) due to the improvement in hydrophilicity and formation of the water layer on the membrane surface proved their better rejection and antifouling capacity. Hydraulic resistance (14.7 kPa/Lm(-2)h(-1)) and tensile strength (5.58 MPa) results suggested that, the PEI-1 membrane showed better resistance to pressure and mechanical stress compared to the standard PEI membrane, due to the changes occurred in their morphologies. However, the additive loading limited at 2 wt.%, in order to avoid the negative effects of MnO2 nanospheres at higher concentrations.

Recently utilization of nanoparticle incorporated polymer membranes for water treatment is in significant consideration. Herein we present the individual effect of graphene oxide (GO) and molybdenum disulfide (MoS2) nanosheets in altering the poly (amide imide) (PAI) membrane's hydrophilicity and thereby its separation efficiency and antifouling ability. The GO was characterized by Field Emission Scanning Electron Microscope (FESEM) and Raman spectroscopy. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction spectroscopy (XRD) were used to probe the existence of GO and MoS2 in PAI nanocomposite membranes. Contact angle (CA), pure water flux (PWF), water uptake, and porosity were measured to evaluate the enhancement in hydrophilicity of nanocomposite membranes. Top surface and cross-section morphology of the membranes were investigated by scanning electron microscopy (SEM). Antifouling capacity of the membranes was evaluated by fouling experiments using bovine serum albumin (BSA) and humic acid (HA) fouling agents. PAI-MoS2 nanocomposite membranes demonstrated better results in enhancing the membrane performance viz., superior PWF (105.6 Lm−2h−1), water uptake (80%) and porosity (21.2%), BSA and HA rejection (95.8 and 93.2%), FRR (90.5%), and slightly reduced hydraulic resistance (Rm) and more reduced CA (64.8°) than that of PAI-GO nanocomposite membranes. The highly flexible and ultrathin MoS2 nanosheets with greater interaction between Mo and S atoms causes larger macrovoids in the bulk, and the sandwiched structure of MoS2 causes greater permeation. GO also improved PAI matrix to some extent due to its oxygen containing functional groups however several desirable and versatile characteristics of the MoS2 makes the PAI-MoS2 UF membranes as superior performer.

A dendritic-benzimidazole (D-BI) has been prepared using polyphosphoric acid (PPA) as a condensing medium with diaminobenzidine (DAB), 1,3,5-benzene tricarboxylic acid, and isophthalic acid as monomers. The structure of D-BI was ascertained by elemental analysis, FTIR, 1H NMR, and solid-state 13C-NMR. The D-BI was incorporated into polysulphone (PSf) by blending with polyvinylpyrrolidone (PVP K-30) as a macromolecular additive. The membranes were cast by phase inversion technique. The physical properties such as surface morphology and the chemical properties such as contact angle and the performance attributes, such as NOM rejection, salt rejection, and pure water flux were studied. It is imperative that the infusibility of rigid polymeric backbone is overcome by the introduction of polar moieties with no compromise on thermal stability. The membranes displayed substantial increase in thermal stability with D-BI content. The marginal increase in flux has been attributed to the branching and steric effect of D-BI. This is because the introduction of polar group efficiently affords to stabilize the adjacent aromatic rings. The salt rejection shows the order of MgSO4 ≈ Na2SO4 > MgCl2 > NaCl, which follows that the divalent ions are rejected more than monovalent ions. The antifouling behaviour was also significant as the irreversible fouling (RIr 9%), which was found to be minimal for D-BI-incorporated membrane. The blended membranes exhibited good hydrophilicity, antifouling, and fairly good rejection of salts.

Poly (m-phenylene isophthalamide) (PMIA) ultrafiltration (UF) membranes has been prepared using lithium chloride (LiCl) and poly (ethylene glycol) of average molecular weight 600 Da (PEG 600) as additives by phase inversion technique. Membranes were characterized by FTIR, TGA, DTG and UTM. Surface characteristics are probed by SEM, AFM and water contact Angle. It was evidenced from SEM analysis that all membranes have macrovoids in its structure and hence possess high water permeability. Accordingly, all membranes were highly hydrophilic in nature which can be predicted from water wettability and work of adhesion measurement using contact angle. Further, membranes were subjected for protein rejection study using bovine serum albumin (BSA) as a model foulant and its fouling ability was analyzed. It has been found that the 10 wt.% PMIA membrane with 2 wt% of PEG 600 and 4 wt.% of LiCl has high water permeability and better reversible and irreversible anti-fouling capability than any other prepared membranes. Flux recovery ratio (FRR) of 91% was obtained for the 10 wt.% PMIA also confirmed it is one of the promising UF membrane materials.

Materials undergo enhanced corrosion in the presence of oxidants in aqueous media. Usually, hydrogen gas or water soluble reducing agents are used for inhibiting corrosion. In the present study, the feasibility of using alternate reducing agents such as hydrazine, aqueous ammonia, and hydroxylamine that can stay in the liquid phase was investigated. A comparative study of corrosion behavior of the structural materials of the nuclear reactor viz. carbon steel (CS), stainless steel (SS-304 LN), monel-400 and incoloy-800 in the oxidizing and reducing conditions was also made. In nuclear industry, the presence of radiation field adds to the corrosion problems. The radiolysis products of water such as oxygen and hydrogen peroxide create an oxidizing environment that enhances the corrosion. Electrochemical studies at 90 degrees C showed that the reducing agents investigated were efficient in controlling corrosion processes in the presence of oxygen and hydrogen peroxide. Evaluation of thermal stability of hydrazine and its effect on corrosion potential of SS-304 LN were also investigated in the temperature range of 200-280 degrees C. The results showed that the thermal decomposition of hydrazine followed a first order kinetics. Besides, a change in electrochemical corrosion potential (ECP) was observed from -0.4 V (Vs SHE) to -0.67 V (Vs SHE) on addition of 5 ppm of hydrazine at 240 degrees C. Investigations were also made to understand the distribution behavior of hydrogen peroxide and hydrazine in water-steam phases and it was found that both the phases showed identical behavior. (C) 2016 Elsevier B.V. All rights reserved.

In this work, an attempt has been made for protein rejection from aqueous solution using ultrafiltration blend membrane based on poly(phenylene ether ether sulfone) (PEES) and polyetherimide (PEI) was prepared in various blend compositions. Prepared membranes were characterized in terms of pure water flux, water content, membrane hydraulic resistance, porosity, contact angle, scanning electron microscopy, thermogravimetric analysis, and attenuated total reflectance-Fourier transform infrared spectroscopy. Studies were carried out to find out the rejection of proteins such as trypsin, pepsin, egg albumin, and bovine serum albumin. The extent of protein separation is directly proportional to molecular weight of protein. Pristine PEES membrane exhibited high-percentage protein rejection of BSA (92.7%), EA (88.2%), pepsin (85.8%), and trypsin (82.2%) compared to PEES/PEI blend membranes. PEES/PEI blend membranes have better hydrophilic property compared to pristine PEES membrane. Pristine PEES has a contact angle of 97.8°, embedded with PEI and reduced to 67.9°. The thermal stability of the membrane was slightly decreased when the percentage of PEI composition into the PEES/PEI blend increased and observed that the pure PEES membrane has superior thermal stability than PEES/PEI blend membranes

In this work the graphene oxide prepared by the modified Hummers' method was effectively carboxylated. These carboxylated graphene oxide (c-GO) microsheets was characterized by X-ray diffraction analysis, Raman shift, zeta potential, and their morphology was observed using a high resolution scanning/transmission electron microscopy. Polyetherimide mixed matrix membranes (MMMs) were fabricated by the non-solvent induced phase separation technique with varying concentration of this microsheet. The presence of these microsheets on the membrane surface was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and could also be confirmed visually by optical images. The membranes were further characterized; they showed a greater water flux, higher porosity, and sufficient thermal stability. Incorporation of these microsheets improved the hydrophilicity of the membrane confirmed by the lower contact angle values, which in turn explained the lower interfacial free energy, the increase in work of adhesion, the higher solid-vapor free energy and the spreading coefficient. Membranes loaded with 0.3 wt% of c-GO showed a flux recovery of 94% and only a small flux decline even after 180 min of filtration of humic acid (HA) solution. The efficiency of these membranes in removal of HA, toxic metal ions was also investigated. The bacterial anti-adhesion property of c-GO in the membranes was also explored using Escherichia coli, as a model bio-foulant. The charge of the micro sheets and their unique architecture imparts higher hydrophilicity and greater fouling resistance along with improved permeation flux when incorporated into the polymer matrix. (C) 2016 Published by Elsevier B.V.

In this work, flat sheet polyacrylonitrile (PAN) based ultrafiltration (UF) membranes were fabricated by blending with amphiphilic copolymer Pluronic F127 (PF127) and inorganic calcium carbonate (CaCO3) nanoparticles by nonsolvent induced phase inversion process which was employed as fouling resistant membranes for the separation of oil-water emulsion mixture. CaCO3 nanoparticle was synthesized by controlled precipitation of saturated carbonate and calcium nitrate aqueous solution and was then confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HR-TEM). The fabricated membranes were characterized by attenuated total reflectance infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA), mechanical analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) analysis to study the effect on the addition of PF127 together with varying amount of CaCO3 nanoparticle dosage on the membrane property. The filtration performances of the membranes were evaluated by measuring pure water flux, molecular weight cut off (MWCO), porosity and water content. The membrane hydrophilicity/hydrophobicity was examined through water contact angle measurement and separation efficacy was measured through ultrafiltration of oily feed solution. Membrane properties such as wettability, pure water permeability, mechanical strength, thermal stability, oil removal efficiency of the modified membrane was found to increase high upon addition of 0.75 wt% of CaCO3 nanoparticle.Flux recovery was found to elevate from around 63% to 90% after a simple hydraulic wash indicating that the modified hybrid membranes were less susceptible to fouling. The increase in water permeability and antifouling property is ascribed the presence of large number of hydroxyl functional groups coupled with large number of small pores on the modified membrane surface. (C) 2016 Elsevier B.V. All rights reserved.

Polyvinyl chloride (PVC) was treated with aqueous solution of ethylenediamine to obtain aminated polyvinyl chloride (APVC). PVC/APVC blends ultrafiltration membranes, by phase inversion technique. Different polymer blend compositions with and without an additive, like Poly (ethylene glycol) of molecular weight 600Da were also prepared. The blend membranes were characterized and evaluated by scanning electron microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), water contact angle, water content, pure water flux, and membrane porosity to investigate the influence of APVC on the final properties of the membranes. The presence of amine functional group was confirmed by FTIR spectrum. SEM analysis showed that the blend PVC membranes have thinner top layer and higher porosity in the sublayer. The blend membranes showed an increase in overall porosity, hydrophilicity, and water content, with increase in APVC content and in the presence of additive. The fouling resistant capability of the membranes was studied by Bovine serum albumin as the model foulant and flux recovery ratio (FRR) of the membranes was calculated. The blend membrane showed an increase in FRR indicating more fouling resistance than the pure PVC membrane

ABSTRACTOxidizing environment prevailing in water coolant systems aggravates the corrosion of structural materials. Reducing agents are added to the reactor coolant systems to control the oxidants and mitigate material corrosion. Maintenance of required concentration of the reducing agents in the system and their removal after completing the processes can be done using ion exchange resins as well as ion exchange membranes. In this article, a comparative study on the efficacy in removing the reducing agents from aqueous solutions by the cation exchange resin and membranes such as sulfonated polysulfone and nafion is evaluated. Some of the membranes were synthesized in the laboratory and characterized by SEM, FTIR and pure water flux studies. Nitrogen containing reducing agents such as hydrazine, hydroxylamine, and ammonium hydroxide have been chosen for the study. Results indicate that strong acid cation exchange (SAC) resin taken in a column and sulfonated polysulfone (SPSf) membrane as a stack are found to be equally efficient in purification of coolant system from the added reducing agents. Uptake of metal ions was observed to be higher on SAC resin column in presence of reducing agent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44588.

Functionalized multi-walled carbon nanotube incorporated polyetherimide mixed matrix membranes for blood purification application.

Hemodialysis is one of the most commonly used treatments for patients suffering from irrecoverable kidney damage. In our present work, we investigate poly(ether imide) (PEI) mixed matrix membranes (MMMs) as a potential candidate for hemodialysis applications due to their efficient clearance and high biocompatibility. Graphene oxide (GO) was synthesized by the modified Hummers' method and was then confirmed by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy. The GO-polyvinylpyrrolidone nanocomposite incorporated PEI MMMs were fabricated by a semiautomatic casting unit using the nonsolvent induced phase separation technique. The effect of the nanocomposite loading ratio was evaluated by water content, ultrafiltration rate, and porosity, which were all found to increase as the nanocomposite content increased. Cross-sectional and top surface morphology was visualized using scanning electron microscopy and atomic force microscopy. The hydrophilicity of these membranes was in consonance with contact angle values. These MMMs demonstrated an increase in biocompatibility: reduced protein adsorption, suppressed platelet adhesion, and lower complement activation. Furthermore, the prolonged blood clotting time is an indication of the heparin mimic anticoagulant properties of these membranes. The cytocompatibility results by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-tetrazolium bromide assay and live cell/dead cell staining indicated that there was an increase in cell viability. The membranes with 0.1 wt % GO showed an excellent clearance of the model uremic toxins, namely urea, vitamin B-12, and cytochrome-c in vitro. The diffusive permeability of these membranes could be comparable to the existing commercial hemodialysis membranes. Thus, it can be concluded that these membranes containing a composite of both functional nanosheets and bioactive polymers have a tremendous potential to be utilized commercially in hemodialysis modules if shown successful in further in vivo studies with an animal model.

In this work, we evaluate the properties of solution casted polysulfone (PSf)/sulfonated polyethersulfone (SPES) blend membranes prepared by non-solvent induced phase inversion technique. The morphologies of these blend membranes, observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging, indicated a smoother skin layer and an increased number of highly interconnected pores in the sub layer. The efficacy of the prepared membranes was evaluated in terms of porosity, ultrafiltration rate (UFR), molecular weight cut-off (MWCO) and mean pore size. The hydrophilicity of these membranes was in consonance with contact angle values. It was observed that the selectivity and the UFR of the blend membranes were higher when compared to pristine membranes. Furthermore, these blend membranes demonstrated an increase in biocompatibility — prolonged blood clotting time, suppressed platelet adhesion, reduced protein adsorption and lower complement activation. These membranes were also investigated for uremic solute removal. Diffusive permeability of middle molecular weight cytochrome-c revealed an increase from 8 × 10− 4 cm·s− 1 to 18 × 10− 4 cm·s− 1 and illustrates the possibility that these sulfonated PES/PSf blend membranes can be used to prepare membrane modules for hemodialysis applications.

Separation of toxic metals from industrial effluents and protein removal from food and bio-related industrial waste are gaining ground due to environmental concerns and recovery of value added materials. In this work, an attempt has been made to remove the valuable proteins and metal ions by using blend of poly((vinyl chloride) (PVC) and sulfonated poly((vinyl chloride) (SPVC) membranes prepared in absence and presence of polymeric additive such as poly ethylene glycol (PEG 600) in various composition. The prepared membranes were used to find the rejection and permeate flux of proteins such as bovine serum albumin (BSA), egg albumin, pepsin and trypsin and metal ions such as Cu(II), Zn(II), Ni(II), and Cd(II) using polyethyleneimine (PEI) as chelating ligand. On increasing SPVC concentrations, rejection of proteins and metal ions decreases, whereas permeate flux has an increasing trend. These effects are due to the increase pore formation in the PVC membranes because of functionalization by sulfonation and presence of additives. In general, it was found that PVC/SPVC blend membranes displayed better performance compared to the membranes prepared from pure poly vinyl chloride. The extent of separations of proteins was found to be directly proportional to the molecular weight of proteins while the extent of metal ions removal depends on the affinity of metal ions to PEI to form macromolecular complexes and the stability of the formed complexes.

•Synthesis of poly 3-methyl 2-vinyl pyridinium nitrate (P3M2VPN).•Preparation of P3M2VPN incorporated membrane (PVDF/P3M2VPN).•Increase in membrane porosity, hydrophilicity and decrease in mean surface-pore size.•Removal of metal ions such as Cu(II), Pb(II) and Cd(II) by modified PVDF membranes.

Poly(isophthalamide) based copolymer, poly(isophthalamide)-graft-methacrylamide (PIPA-g-MAA) has been prepared and used to modify the surface and fouling liable properties of the cellulose acetate (CA) membranes. Grafting facilitated the solubility of PIPA in common aprotic solvents and made it available as a potential membrane material for the modification of CA membrane. Compatibility between CA and PIPA-g-MAA in blend membranes was confirmed by a single glass transition temperature, and improved hydrophilicity of the membranes was illustrated by the lower contact angle values. The thermal and mechanical stability of the CA membrane was also improved by the blending with PIPA-g-MAA. The separation efficiency of various commercial proteins by these CA/PIPA-g-MAA blend membranes was studied and found to have improved significantly. The fouling propensity of the membranes was studied using BSA as a model foulant and the resistance arising during different stages of filtration was evaluated using resistance in series model. From the AFM images it could be observed that protein uniformly covers the blend membrane surfaces and non-uniform protein clusters are formed in the CA membranes due to preferential adsorption at specific sites. The irreversible fouling resistance (Rir) could be greatly reduced by the incorporation of the synthesized PIPA-g-MAA in the CA matrix.