Ojha, AbhijeetAbhijeetOjhaThareja, PrachiPrachiThareja2025-08-302025-08-302018-03-3010.1016/j.apsusc.2017.11.1572-s2.0-85034866751http://repository.iitgn.ac.in/handle/IITG2025/22314In this study, we report the microstructure, rheology and adsorption characteristics of aqueous suspensions of Graphene Oxide (GO) at a volume fraction (ϕ <inf>GO</inf> ) = 0.018, which can be transformed into gels by cation induced charge shielding and cross-linking between GO nanosheets. GO nanosheets of average thickness ∼1.5 nm and a lateral dimension of ∼750 nm are synthesized by Hummer's process. At ϕ <inf>GO</inf> = 0.018, cations of varying size and valence are systematically introduced with electrolytes NH <inf>4</inf> Cl, LiCl, NaCl, KCl, MgCl <inf>2</inf> and FeCl <inf>3</inf> at concentrations ranging from 10 ^-5 –10 ^-1 M to investigate their effect on the rheology of GO suspensions. Our results suggest that depending on the electrolyte concentration, size and the valence of the cation: low viscosity suspensions, fragile gels and solid-like GO-electrolyte gels are formed. The storage modulus (G') of all GO-electrolyte gels increases with the increase in electrolyte concentration and G' follows the order GO-FeCl <inf>3</inf> > GO-MgCl <inf>2</inf> > GO-KCl > GO-NaCl > GO-LiCl > GO-NH <inf>4</inf> Cl. FESEM analysis shows that lyophilized GO-electrolyte gels with 10 ^-1 M electrolytes have a porous morphology resulting from the aggregation of GO nanosheets. The GO-electrolyte gels are shown to adsorb high quantities of oils, with GO-FeCl <inf>3</inf> gels showing a higher adsorption capacity. The GO-NaCl and GO-FeCl <inf>3</inf> lyophilized gels are also shown to adsorb methylene blue dye and follow the pseudo-second-order kinetics of adsorption. Along with higher oil and dye adsorption efficiency, GO-electrolyte gels are easy to recollect after the adsorption, thus avoiding the potential toxicity for bio-organisms in water caused by GO nanosheets.falseAggregation | Nanosheets | Rheology | SuspensionsArticle786-79830 March 201821arJournal21WOS:000424247500096