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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 0.75 wt.% (M3) of PGP-CaCO3 manifested increased wettability with reduced surface free energy leading to a higher pure water flux of 366 L/m2 h. 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.

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 ( R m ) 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.

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 antifouling 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.

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.

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 (CaCO 3 ) nanoparticles by nonsolvent induced phase inversion process which was employed as fouling resistant membranes for the separation of oil-water emulsion mixture. CaCO 3 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 CaCO 3 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 CaCO 3 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.