Graphene oxide-montmorillonite/sodium alginate aerogel beads for selective adsorption of methylene blue in wastewater

A porous three-dimensional (3D) graphene oxide-montmorillonite/sodium alginate (GO-MMT/SA) aerogel beads have been prepared by a simple method of cross-linking and freeze-drying, which is used to selectively adsorb methylene blue (MB) in aqueous solution. In addition, the properties of GO-MMT/SA aerogel beads are characterized by FTIR, Raman, TG, BET, SEM and XPS. Characterization results show that GO-MMT/SA aerogel beads obtain an integral porous structure and a larger specific surface area. The three-dimensional network of as-prepared aerogel beads is formed by the strong interaction between the –COO– in SA and Ca2+ ions. Interestingly, it is found there are chemical crosslinking and hydrogen bonds among MMT, GO and SA under our experiment condition. In different conditions, a series of adsorption experiments on the GO-MMT/SA aerogel beads for the removal of MB are carried out. GO-MMT/SA aerogel beads show better adsorption capacities toward MB, and poor adsorption capacities for rhodamineB and methyl orange. The pseudo-second-order kinetic equation and Freundlich equation can appropriately describe the adsorption process. Furthermore, the possible adsorption mechanism of GO-MMT/SA aerogel beads for MB is also proposed based on the experimental results.