Adsorptive removal of humic acid on activated carbon prepared from almond shell: approach for the treatment of industrial phosphoric acid solution

摘要

Almond shell was used as a precursor to prepare activated carbon, using carbon dioxide as a physical activation agent. Its ability to remove the humic acid was evaluated. The surface area of almond shell activated carbon was found to be 1,310 m~2/g. The effects of experimental parameters such as pH, initial humic acid concentration, contact time, adsorbent dosage, and solution temperature on the adsorption were investigated. To describe the equilibrium isotherms the experimental data were analyzed by the Langmuir, Freundlich, and Temkin isotherm models. Pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models were used to find out the kinetic parameters and mechanism of adsorption process. The thermodynamic parameters such as △G°, △H°, and △S° were calculated for predicting the nature of adsorption. For an approach to an industrial application, activated carbon prepared from almond shell seems to be an effective, low-cost, and good adsorbent precursor for the removal of humic acid from commercial phosphoric acid solution.