Positively charged organic–inorganic hybrid ultrafiltration membranes for selective protein separation were fabricated from blends of PVA, functionalized600 dpi in TIF format)??> chitosan and tetraethylorthosilicate.

Low fouling novel positively charged hybrid ultrafiltration membranes with adjustable charge density were fabricated from blends of polysulfone (PSf) and quaternized polysulfone (QPSf) in combination with varied fractions of graphene oxide (GO) nanosheets by a non-solvent induced phase separation method. Fourier transform infrared spectroscopy in the attenuated total reflection mode, scanning electron microscopy, outer surface zeta potential and contact angle studies were conducted to characterize the morphologies of hybrid membranes, structures, charge and surface properties. Results confirmed the fabrication of porous, hydrophilic and positively charged membranes. The water permeabilities (flux) andantifouling ability of membranes with protein solution were dependent on the fraction of quaternary ammonium groups and GO nanosheets in the membranes matrix. Antifouling ability of membranes was improved after the incorporation of GO nanosheets. In addition, 2 irreversible protein fouling of membranes was substantially decreased with increasing fraction of GO nanosheets (%). The transmission of protein as a function of solution pH and the fraction of GO nanosheets (%) in the membranes was studied for two model proteins (bovine serum albumin; BSA or lysozyme; LYZ). The transmission of BSA or LYZ was controlled by size exclusion and the fraction of GO nanosheets in the membranes matrix. The highest transmission of proteins at their isoelectric points was obtained for membrane containing 2 wt% of GO nanosheets to total weight of polymers.

The remarkable adsorption capacity of graphene-derived materials has prompted their examination in composite materials suitable for deployment in treatment of contaminated waters. In this study, crosslinked calcium alginate–graphene oxide beads were prepared and activated by exposure to pH 4 by using 0.1M HCl. The activated beads were investigated as novel adsorbents for the removal of organic pollutants (methylene blue dye and the pharmaceuticals famotidine and diclofenac) with a range of physicochemical properties. The effects of initial pollutant concentration, temperature, pH, and adsorbent dose were investigated, and kinetic models were examined for fit to the data. The maximum adsorption capacities qmax obtained were 1334, 35.50 and 36.35 mg g−1 for the uptake of methylene blue, famotidine and diclofenac, respectively. The equilibrium adsorption had an alignment with Langmuir isotherms, while the kinetics were most accurately modelled using pseudo- first-order and second order models according to the regression analysis. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated and the adsorption process was determined to be exothermic and spontaneous.

No abstract