Preparation and characterization of activated carbon from medlar seed by chemical activation with phosphoric acid and its application in uranium adsorption

The aim of this work was to synthesize a high-capacity adsorbent from medlar seeds by chemical activation using phosphoric acid. The confirmation of successful biomass activation was achieved through various characterizations, including SEM-EDS, FTIR, and nitrogen adsorption-desorption. The best parameters were found to be a temperature of 500 degrees C, a time of 60 min, and an impregnation ratio of 2:1. The specific surface area, average pore diameter, and total pore volume were identified as 1845.32 m(2)/g, 2.88 nm, and 0.896 cm(3)/g, respectively. The performance of the selected activated carbon was evaluated by using it for the sorption of uranium (VI) in a batch system. The maximum adsorption of 52.08 mg/g was obtained under optimum conditions: pH = 3.54, adsorbent dose of 2 g/L, adsorbate concentration of 100 mg/L, particle size between 0.125 and 0.20 mm, and contact time of 90 min. Until the fifth cycle of use, the prepared activated carbon showed excellent regeneration capacity (84.23%). The pseudo-second-order kinetic and the Langmuir isotherm were the best fitted, implying the monolayer chemical adsorption process. The adsorption process could be considered as spontaneous (Delta G degrees < 0) and exothermic process (- 84.601 kJ/mol).