Fabrication of Graphene-Based Xerogels for Removal of Heavy Metal Ions and Capacitive Deionization

Abstract

With a rapid increase of population, delivering clean and potable water to humans has been an impending challenge. Here, we report a green method for the preparation of graphene–chitosan–Mn3O4 (Gr–Cs–Mn3O4) composites, where Gr–Cs hydrogels are first prepared from the self-assembly of chitosan with graphene oxide (GO) nanosheets; then Gr–Cs–Mn3O4 composites are obtained by oxidizing Mn­(II) ions which are adsorbed by Gr–Cs hydrogels. The effects of pH and mass ratio of GO to Cs on sorption of different ions are investigated. Enhanced capacitive deionization performance of Gr–Cs–Mn3O4 composites was also demonstrated. The resultant Gr–Cs–Mn3O4 composites exhibit a hierarchical porous structure with a specific surface area of 240 m2/g and excellent specific capacity of 190 F/g, much higher than those of pristine reduced graphene oxide electrodes. Distinguished electrochemical capacity and low inner resistance endow Gr–Cs–Mn3O4 composites with outstanding specific electrosorptive capacity of 12.7 mg/g.

Site-specific functionalization for chemical speciation of Cr(III) and Cr(VI) using polyaniline impregnated nanocellulose composite: equilibrium, kinetic, and thermodynamic modeling

“…As is obvious from Fig. 4a, the isotherm is related with the characteristic of type IV isotherm with a type H 3 hysteresis, representing that PANI-NCC is mesoporous in nature (Zargoosh et al 2013;Gu et al 2015). The surface area of PANI-NCC was found to be 112.26 m 2 g -1 .…”

Mn-Containing N-Doped Monolithic Carbon Aerogels with Enhanced Macroporosity as Electrodes for Capacitive Deionization

“…All the materials displayed high porous features, confirming that the incorporation of the additive (either B or D) does not hinder the polycondensation of the reactants. [29][30][31] All the materials displayed type IV isotherms according to IUPAC classification 32 with relatively high adsorbed volume at relative pressures below 0.2 (corresponding to micropore range) and well-defined hysteresis loop in the desorption branches at relative pressures higher than 0.7, evidencing their mesoporous character. The large pore volumes and hysteresis loops in the gas adsorption data suggest that the polycondensation of the monomers is slowed down in the presence of the additives (either B or D).…”

Carbon nanotubes, graphene, and their derivatives for heavy metal removal

“…A favorable adsorption has an n between 1 and 10; a normal L-type isotherm is represented when 1/n < 1, which means an effective interaction between the adsorbent and adsorbate; if 1/n > 1, a co-adsorption is implied [174][175][176][177]. Zhou et al [164] prepared sponge-like polysiloxane-GO gel via a simple one-step sol-gel method to remove Pb(II) and Cd(II) from wastewater.…”