Rajesh Sahadevan

Fresenius Medical Care North America | FMCNA · Fiber Development Group

The objective of this study was to develop highly efficient and cost-effective ultrafiltration (UF) media/membranes from electrospun nanofibers alone without using expensive/complicated chemical modification methods. The hypothesis was that, during hot-pressing hybrid electrospun nanofiber membranes (ENMs) consisting of a thermoplastic polymer (e.g...

Development of bioseparation media that can perform separations based on both ion-exchange and size exclusion provide a transformative technology to purify therapeutic proteins with fewer operations in downstream processing. Thus, in this study we have developed cellulose-graft-polyethyleneamidoamine (CL-g-PEAA) anion-exchange nanofiber membrane ad...

Fabrication of membrane adsorbers with elevated binding capacity and high-throughput is highly desired for simplifying and improving purification efficiencies of bioproducts (biotherapeutics, vaccines, etc.) in the biotechnological and biopharmaceutical industries. Here we demonstrate the preparation of a novel class of self-supported, cellulose-gr...

Graphene oxide (GO) sheets can be readily surface-overlaid on hot-pressed electrospun polyacrylonitrile (PAN) nanofiber membrane to form a continuous and crack-free layer; upon thermal reduction at 150 oC for 12 h, the resulting reduced GO (rGO) layer can reject ~90% MgSO4 with high water flux (due to the size exclusion mechanism), making the prepa...

Despite the excellent potential of molecular layer-by-layer assembly (mLbL) in tuning the nanostructure and chemical functionality of the polyamide selective layer of thin film composite (TFC) membranes, practical application of mLbL is limited due to its slow film growth, low permeability and poor chlorine stability. Herein, we demonstrate the pre...

Electrospun nanofiber membranes (with varied fiber diameters and different membrane porosities and thicknesses) have been explored as innovative microfiltration media for the highly efficient and cost-effective removal of contaminations with particle sizes of 0.2 μm (even 0.1 μm) from water. For the first time, the membrane porosity has been judici...

Electrospun nanofiber membranes (ENMs) have demonstrated promising applications for water purification primarily due to high water flux and low degree of fouling. However, the equivalent/apparent pore sizes of as-electrospun ENMs are in microns/sub-microns; therefore, the ENMs can only be directly utilized for microfiltration applications. To make...

Nanofiltration membranes were prepared by forming multilayers of branched polyethylenimine (BPEI) and polyacrylic acid (PAA) on a polyacrylonitrile (PAN) nanofibrous mat by layer-by-layer (LbL) assembly. The degree of ionization (DI) of PAA, estimated using FTIR spectra both in the absence and presence of added salt, was shown to have a strong infl...

Charge mosaic membranes, which possess distinct cationic and anionic domains that transverse the membrane thickness, are capable of selectively separating dissolved salts from similarly-sized neutral solutes. Here, the generation of charge mosaic membranes using facile layer-by-layer assembly methodologies is reported. Polymeric nanotubes with pore...

Solute-solute interactions can have a dramatic impact on the permeation of solutes through dense polymeric membranes. In particular, understanding how solute-solute interactions can affect the design of osmotically driven membrane processes (ODMPs) is critical to the successful development of these emerging water treatment and energy generation pro...

Poly (ether-imide) (PEI) was carboxylated and used as the hydrophilic modification agent for the preparation of polyacrylonitrile (PAN) membranes. Membranes were prepared with different blend compositions of PAN and CPEI by diffusion induced precipitation. The modified membranes were characterized by thermo gravimetric analysis (TGA), mechanical an...

Methacrylamide was grafted on to poly (isophthalamide) (PIPA-g-MAA) to improve its solubility and hydrophilicity. Then, PIPA-g-MAA incorporated high performance cellulose acetate ultrafiltration (CA) membranes were prepared by phase inversion technique and physical properties of the membranes were studied by various analytical methods. The efficien...

Poly (amide–imide) (PAI) and TiO2 nanoparticles impregnated polysulfone (PSf) nanofiltration membranes with integral dense layer were prepared by phase inversion technique from a dope solution containing N-methyl-2-pyrrolidone as solvent and 1,4-dioxane as co-solvent. The prepared membranes were characterized using attenuated total reflectance-four...

Epoxidated polyethersulfone (EPES) incorporated cellulose acetate (CA) ultrafiltration membranes were prepared by diffusion induced precipitation technique in the absence and presence of pore former polyethyleneglycol-600. Effect of blend ratio on the compatibility, thermal stability, mechanical strength, hydrophilicity, morphology, pure water flux...

Poly(amide-imide) (PAI) and TiO2 nanoparticle-incorporated poly(ether-sulfone) (PES) asymmetric nanofiltration membranes with an integrally dense skin layer were prepared by diffusion induced phase separation. The prepared membranes were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffract...

Biocompatible Polysulfone (PSf) hemodialysis membranes were prepared by phase inversion technique using poly (ether-imide) (PEI) as the modification agent and Polyethylene glycol (PEG-200) as the pore former. The effect of PSf/PEI blend ratio on the morphology, hydrophilicity, water content, porosity, glass transition temperature, mechanical streng...

Epoxy functionalized poly(ether-sulfone) (PES) was prepared and it was utilized as the hydrophilic modification agent for the preparation of high performance cellulose acetate (CA) membranes by phase inversion technique. The prepared membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-r...

High performance Cellulose Acetate (CA) ultrafiltration membranes were prepared by phase inversion technique using poly (ether-imide) (PEI) as the modification agent and Polyethylene Glycol (PEG-200) as pore former for hemodialysis. The morphology, hydrophilicity, water content, porosity and ultrafiltration permeation rate of the prepared membranes...

Polymeric membranes intended to use in industrial separations must maintain excellent thermal and mechanical properties over their targeted operating conditions. Therefore, cellulose acetate (CA) membranes with superior properties were prepared by phase inversion technique using high performance thermoplastic poly (amide-imide) (PAI) as the modific...

Fouling-resistant cellulose acetate (CA) membranes were prepared by the phase inversion technique using hydrophilic poly(amide-imide) (PAI) as the modification agent. The prepared membranes were characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy...

Polysulfone membranes possess excellent mechanical, biological and chemical stability but they suffer from fouling which leads to flux decline. Fouling can be minimised by functionalisation. In an attempt to overcome this limitation, the polysulfone was both sulphonated and carboxylated. The presence of sulphonic and carboxylic groups was confirmed...