Evaluation of magnetic nano adsorbent produced from graphene oxide with iron and cobalt nanoparticles for caffeine removal from aqueous medium

In recent years, there is an increase of emerging pollutants, such as pharmaceuticals, which are recognized as emerging micro-pollutants that negatively influence the environment, human health and are difficult to biode-grade. Several of these compounds remain in the environment even after water treatment processes, requiring more effective removal methods. The present study proposes the development of new adsorbent materials consisting of the combination of graphene oxide (GO) with iron oxide nanoparticles (alpha gamma-Fe2O3) and cobalt oxide (Co3O4) to intensify the efficiency of the batch adsorption process. The results of the caffeine adsorption tests in GO#alpha gamma-Fe2O3Co3O4 demonstrated removal of 80% and maximum adsorption capacity of 28.94 mg g(-1). The study of caffeine adsorption kinetics demonstrated a better fit for the pseudo-second order model. The analysis of the adsorption isotherm model showed that the Langmuir and Temkin models fit well the experimental data. The thermodynamic parameters showed that caffeine adsorption in GO#alpha gamma-Fe2O3Co3O4 was exothermic, sponta-neous and thermodynamically favorable. Through the competition of ions, it was found that ions of Na+, K+, Ca2+ and Mg2+ do not interfere in the adsorptive process. In addition, the adsorbent material showed excellent regenerative capacity and ease of separation, exhibiting high efficiency in removing caffeine from water.