Alginate-graphene oxide hybrid gel beads: an efficient copper adsorbent material

Here we report on the adsorption performance of calcium alginate (Ca-Alg2) and Ca-Alg2 with encapsulated graphene oxide (Ca-Alg2/GO) gel bead adsorbents for the successful removal of Cu(2+) ions from aqueous solution. Different adsorbent doses, Cu(2+) concentrations and contact times were investigated using equilibrium and kinetic studies. The adsorbents were characterized using Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and focussed ion beam scanning electron microscopy (FIB/SEM). The equilibrium adsorption data were fitted to Langmuir isotherms and the maximum adsorption capacities of the Ca-Alg2 and Ca-Alg2/GO gel beads were found to be 42.7 mg g(-1) and 60.2 mg g(-1), respectively. The equilibrium adsorption data were fitted to a pseudo-second-order kinetic equation showing that the Ca-Alg2 gel beads had a higher kinetic adsorption rate at 0.0425 g mg(-1)min(-1) compared to Ca-Alg2/GO at 0.0179 g mg(-1)min(-1).