Evaluation of adsorptive efficiency of activated carbon obtained from algaroba pod (Prosopis juliflora) as adsorbent in removal of gasoline present in water

Abstract

One of main environmental concerns is contamination of water by harmful organic substances, which represent a significant threat to the environment. In an attempt to solve this problem, adsorption appears as an effective purification and separation solution. In this work, performance of physically activated carbon (PAC) and physically and chemically activated carbon (PCAC) derived from mesquite pods (Prosopis juliflora) in adsorption of gasoline present in water was evaluated. This work aimed to analyze if increasing contact time would provide more satisfactory and complete results. The same methodology was used as proposed by Lima et al. (2014). For production of activated carbon, Morais (2014) methodology was used for obtaining physically activated carbon. In second stage, chemical activation was followed using potassium hydroxide to obtain physically and chemically activated carbon. It was followed by study of adsorption kinetics, in which times 5 to 120 minutes were evaluated. Equilibrium study, whose concentrations varied from 5% to 50%, was also carried out. As a result, it was observed that adsorption kinetics of PAC obtained a maximum adsorption of 3.542 g.g^-1, while with PCAC, maximum adsorption was 4.583 g.g^-1. Equilibrium studies obtained maximum capacity of 7.3 g.g^-1 and 8.13 g.g^-1, for PAC and PCAC biomass, respectively. Isotherms obtained confirmed that, in both systems, adsorption occurred in multilayers, since the best fit occurred with Freundlich model. However, study with longer contact time proved to be unnecessary, as more relevant results were not obtained when compared to previous studies.