Reduction of graphene oxide/alginate composite hydrogels for enhanced adsorption of hydrophobic compounds

Abstract

Carbon-based materials, consisting of graphene oxide (GO) or reduced GO (rGO), possess unique abilities to interact with various molecules. In particular, rGO materials hold great promise for adsorption and delivery applications of hydrophobic molecules. However, conventional production and/or usage of rGO in aqueous solution often causes severe aggregation due to its low water solubility and thus difficulties in handling and applications. In our study, to prevent the severe aggregation of GO during reduction and to achieve a high adsorption capacity with hydrophobic compounds, GO/alginate composite hydrogels were first prepared and then reduced in an aqueous ascorbic acid solution at 37 °C. Adsorption studies with a model hydrophobic substance, rhodamine B, revealed that the reduced composite hydrogels are more highly absorbent than the unreduced hydrogels. In addition, the adsorption properties of the composite hydrogels, which are consequences of hydrophobic and ionic interactions, could be modulated by controlling the degree of reduction for the adsorption of different molecules. The composite hydrogels embedding rGO can be very useful in applications related to drug delivery, waste treatment, and biosensing.

Characterization and in vitro release kinetics of antimalarials from whey protein-based hydrogel biocomposites

“…WPI and rGO contain hydrophilic groups which contribute to the enhanced water sorption ability of the hydrogels. Some researchers reported similar findings in which the addition of rGO to hydrogel enhanced the swelling capacity of hydrogels [31,32]. However, it is important to mention that the hydrogel GW4 containing only rGO exhibited low swelling ability at pH 7.4 and at a temperature of 24 °C, indicating suppressed swelling ability and suggesting good mechanical property that is not easily destroyed by swelling forces.…”

Facile one-pot synthesis of nickel-incorporated titanium dioxide/graphene oxide composites: Enhancement of photodegradation under visible-irradiation

“…Moreover, Raman spectra showed that the reduction degree of GO increased with increasing Ni content. This was one of the key factors to enhance the adsorption capacity in the removal of organic contaminants [58,59]. …”

Graphene derivatives in responsive hydrogels: Effect of concentration and surface chemistry

“…Several chemical and physical routes are available for partially restoring the honeycomb structure and removing the functional groups [16]. The resulted reduced graphene oxide (RGO) can have great potential in hydrogel nanocomposites as its properties are close to that of the graphene, but its hydrophobicity is decreased [17]. Nowadays GO containing systems are in the focus of attention [18][19][20][21] and few attempts have been already made to prepare various RGO containing composite materials [22][23][24][25][26] as well.…”

“…reduction agent added to the initial precursor mixture) may be used [28,29]. An effective way to make RGO containing gel composites is to reduce the already incorporated GO inside the gel matrix [30,31], however the circumstances of the reduction (e.g. reducing agent, temperature) should be chosen with great care in order not to affect the physical/chemical properties of the gel.…”