Gellan gum/graphene oxide aerogels for methylene blue purification.

ABSTRACT

Stable gellan gum (GG)/graphene oxide (GO) aerogels were prepared by freeze-drying a mixture of GG and GO. On introduction of GO, the GG/GO aerogels had different level pore structures due to the different freezing temperatures. The volume per gram (1/ρ) of GG/GO aerogels ranges from 76.80 ± 1.54-158.30 ± 2.30 cm3/g. The porosity of GG/GO-3 (-80 °C) and GG/GO-6 (-20 °C) was 45.53 % and 61.30 %, respectively. The resulting three-dimensional GG/GO aerogels exhibited excellent performance in methylene blue (MB) adsorption. The pseudo-first-order and Freundlich isotherm models produced the best fits for the adsorption kinetics and adsorption equilibrium, respectively. The Gibbs free energy, enthalpy, and entropy of adsorption indicated that the adsorption was a spontaneous, exothermic, and entropy-increasing process. It is illustrated that the GG/GO aerogels exhibited faster adsorption kinetics and adsorption capacity. These GG/GO aerogels can remove MB from aqueous solutions.