Activated carbon synthetized from Sargassum (sp) for adsorption of caffeine: Understanding the adsorption mechanism using molecular modeling

Abstract

This study aims (i) to use Sargassum (sp) for producing activated carbon applied for the removal of caffeine from water (ii) to understand the associated adsorption mechanism by exploring interactions between the micropollutant and acidic groups of AC surface using molecular modeling. The AC preparation was carried out using H3PO4 as an activating agent and the impregnated precursor was pyrolyzed under N2 atmosphere. The AC characterization was performed using N2 adsorption-desorption isotherms, FTIR spectroscopy, X-ray photoelectron spectroscopy, Boehm titration and pHpzc methods. The best adsorption was observed under the following experimental conditions: solution pH 6.0, optimal residence time of 90 min, adsorbate concentration equal to 5 000 mg/L. Adsorption equilibrium was evaluated from the adsorption isotherms at 25 °C, for a maximum adsorption capacity equal to 221.61 mg/g. The mechanism of caffeine adsorption on AC surface was studied using both experimental and molecular modeling approach. This preliminary work on these algae, opens up interesting prospects to produce AC from Sargassum (sp) for water treatment.