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.

Performance of chemically resistant polyurea reverse osmosis membrane in the treatment of highly alkaline industrial wastewater containing sodium aluminate.

The goal of the present study is to treat industrial wastewater containing sodium aluminate using a chemically inert polyurea (PU) based thin film composite (TFC) reverse osmosis (RO) membrane to promote water reclamation and zero liquid discharge (ZLD). Pretreatment was carried out to reduce the pH of the effluent from 12.5 to 7.1. The TFC RO membrane was fabricated by coating PU on Polyethersulfone (PES) substrate by interfacial polymerization (IP). The surface and cross-sectional morphologies of the membrane were characterized using scanning electron microscopy (SEM). The indigenously synthesized membrane was effective in the removal of total dissolved solids (TDS), chemical oxygen demand (COD), colour and electrical conductivity. The experiments were conducted by varying the feed composition of the wastewater. The maximum water recovery and flux were found to be 74% and 73.9 L/m2·h. RO process using PU membrane exhibited significant potential for cost effective, safe and pollution-free treatment of sodium aluminate industrial effluent.

Pervaporation performance of PPO membranes in dehydration of highly hazardous mmh and udmh liquid propellants.

Polyphenylene oxide (PPO) membranes synthesized from 2,6-dimethyl phenol monomer were subjected to pervaporation-based dehydration of the highly hazardous and hypergolic monomethyl hydrazine (MMH) and unsymmetrical dimethyl hydrazine (UDMH) liquid propellants. Membranes were characterized by TGA, DSC and SEM to study the effect of temperature besides morphologies of surface and cross-section of the films, respectively. Molecular dynamics (MD) simulation was used to study the diffusion behavior of solutions within the membrane. CFD method was employed to solve the governing mass transfer equations by considering the flux coupling. The modeling results were highlighted by the experimental data and were in good agreement. High separation factors (35-70) and reasonable water fluxes (0.1-0.2 kg/m(2)h) were observed for separation of the aqueous azeotropes of MMH (35 wt%) and UDMH (20 wt%) and their further enrichment to >90% purity. Effect of feed composition, membrane thickness and permeate pressure on separation performance of PPO membranes were investigated to determine optimum operating conditions.