Graphene Oxide Membranes For Separation Research Articles

Retraction Note to: Novel Branched Polyamide/Poly(acrylonitrile)/Graphene Oxide Membranes for Separation of Chlorinated Volatile Organic Compounds from Water via Pervaporation

Retraction Note to: Novel Branched Polyamide/Poly(acrylonitrile)/Graphene Oxide Membranes for Separation of Chlorinated Volatile Organic Compounds from Water via Pervaporation

Surface modified and functionalized graphene oxide membranes for separation of strontium from aqueous solutions

Graphene oxide-strontium (GO-Sr) composites prepared under different ambient conditions were characterized using morphological and spectroscopic techniques to optimize the uptake of Sr from aqueous solutions. These studies indicated that interactions among GO and Sr2+ ions are highly sensitive to size and aging of GO sheets, as well as pH of the ambience. Further, the extent of Sr uptake on GO sheets was found to be largely influenced by relative fractions of the associated –COOH, –OH, C–O–C functional groups and sp2-C domains. Membranes prepared using various forms of GO were evaluated for their Sr separation ability and, a window of parameters for optimum separation of Sr has been proposed. Among the variety of membranes studied, those made up of fresh and large GO sheets were found to exhibit superior Sr adsorption capacity (~296 mg/g) at limited GO mass. Further, adsorption efficiency of these GO membranes was observed to deteriorate with aging of GO sheets and rise of GO mass on membrane. The membrane based filtration procedure introduced in present work facilitates to provide a lamellar structure of GO sheets with abundant surface area, diverse and accessible sites for Sr2+ ion uptake and offer high Sr adsorption efficiencies.

RETRACTED ARTICLE: Novel Branched Polyamide/Poly(acrylonitrile)/Graphene Oxide Membranes for Separation of Chlorinated Volatile Organic Compounds from Water via Pervaporation

Branched polyamides (BPAs) were prepared through a polycondensation method and then blended with poly(acrylonitrile) (PAN; 3:1) to construct the nanocomposite membranes having various concentrations of graphene oxide (GO) (2 and 5 wt%). The BPA/PAN and BPA/PAN/GO membranes were applied for selective removal of chlorinated volatile organic compounds (Cl-VOCs) from water by pervaporation. Impacts of feed composition, GO content and distinct feed types were investigated on pervaporation performance. Membranes were water selective and the permeation rate incremented with GO elevation. The highest permeation rate (203 g/m2 h) and separation factor (10) were detected for BPA/PAN/GO-5 nanocomposite membrane containing 5 wt% GO for separating the pentachloroethane/water mixtures at 30 °C for 0.1 wt% pentachloroethane in feed. Separation of pentachloroethane/water mixture proceeded easier than those of 1,1,1,2-tetrachloroethane/water, trichloroethylene/water, and 1,2-dichloroethylene/water mixtures because of the larger molecular size of pentachloroethane.

Fundamental Transport Mechanisms and Advancements of Graphene Oxide Membranes for Molecular Separation

Graphene shows excellent mechanical, electrical, and optical properties. Its unique structure and attributes have made it and its derivatives (e.g., graphene oxide (GO) and reduced graphene oxide (rGO)) promising candidates in molecular separation. Excellent molecular separation performance, including permeability and selectivity, has been demonstrated by GO membranes recently. In this review, the mechanisms, i.e., in-plane pores (defects), interlayer spacing, and functional group assisted molecular separation, of selective molecular transport through GO membranes are summarized. In addition, preparation and interlayer spacing tuning strategies of GO membranes are provided. This timely review aims to present the latest advancements in both the theoretical and experimental demonstration of GO membranes for molecular separation. Moreover, current challenges and emerging perspectives of GO membranes for separation are also discussed.