Hydrophilized Ultrafiltration Membranes Synthesized from Acrylic Acid Grafted Polyethersulfone for Downstream Processing of Therapeutic Insulin and Cobalamin.

The present study focuses on synthesis of novel high-performance acrylic acid (AA) grafted polyethersulfone (PES) ultrafiltration (UF) membranes for purification of small therapeutic biomolecules such as urea, insulin, and cobalamin. The membranes were indigenously synthesized by adding polyethylene glycol (PEG) of 6 kDa M.Wt. as a pore former and subsequent grafting of AA using 2 to 6 wt.% concentrations under UV-induced photo grafting. Scanning electron microscopy reveals that the PEG additive profoundly influences the pore density on the membrane surface. FTIR spectra confirm the graft polymerization of AA with the PES substrate. Separation performance of the grafted membranes was evaluated to establish the trade-off between the degree of grafting and MWCO. From the experimental results, the pure water flux (PWF) of 6% grafted PES membrane was enhanced from 8.5 (PES [0] [6]) to 18.20 l m-2 h-1 (PES [6 +] [6]) in the presence of PEG pore former, respectively. The grafting concentration window of 2-6% resulted in selective membranes to altogether remove uremic toxins into the permeate with retention of high molecular size proteins. Hence, 5 and 6 wt.% AA grafted membranes exhibited > 90% rejection for insulin and cobalamin biomolecules along with 24.5 and 23.8 l m-2 h-1 bar-1 permeability towards urea, respectively. The process results correlate well with the MWCO values of membranes ranging from 1 to 10 kDa. This work provides the efficacy of these grafted membranes for potential application in the downstream processing of therapeutic biomolecules such as insulin and cobalamin.

Solvent resistant chitosan/poly(ether-block-amide) composite membranes for pervaporation of n-methyl-2-pyrrolidone/water mixtures.

A novel composite barrier comprising of hydrophilic and solvent resistant chitosan (CS) membrane on porous solvent resistant poly(ether-block-amide) (PEBA-2533) substrate was synthesized for pervaporation (PV) based dehydration of the polar aprotic n-methyl-2-pyrolidone (NMP) green solvent. The composite barrier was crosslinked with tetraethyl orthosilicate (TEOS) to control swelling and enhance selectivity. Operating parameters such as feed water concentration, permeate pressure and membrane thickness were varied to assess membrane flux and selectivity. A two-dimensional finite element method (FEM) model was developed to predict the concentration profile within the membrane through computational fluid dynamics (CFD). On the basis of complete mixing experiments, a numerical simulation was performed to predict membrane area requirement and exit streams' compositions for commercial pervaporation units operated in plug flow mode. Both unmodified chitosan and tetraethyl orthosilicate crosslinked composite membranes successfully separated feed mixture containing 4.6 wt% water by exhibiting water fluxes of 0.024 and 0.019 kg/m(2)h, whereas the corresponding selectivities were found to be as high as 182 and 225, respectively.