The usage of orange pulp activated carbon in the adsorption of 2,4-dichlorophenoxy acetic acid from aqueous solutions

Among the numerous agrochemicals in use today, the herbicide 2,4-dichlorophenoxy acetic acid (2,4-D), has been widely applied to control broad-leaved weeds in gardens and farming. 2,4-D is commonly preferred because of its low cost and good selectivity. On the other hand, 2,4-D is a poorly biodegradable pollutant. Therefore, this study has focused on the adsorption of 2,4-D from aqueous solutions by using activated carbon. The activated carbon was produced from the orange (Citrus sinensis L.) pulp by chemical activation with zinc chloride. The morphological and chemical characteristics of the activated carbon were investigated by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N₂-adsorption techniques. Then, the effect of adsorption parameters was researched for 2,4-D adsorption on activated carbon. The experimental data indicated that the adsorption isotherms were well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity was 71.94 mg g^-1 at 298 K. The adsorption kinetic of 2,4-D obeys the pseudo-second-order kinetic model. The thermodynamic parameters indicated a feasible, spontaneous and exothermic adsorption. These results show that the prepared activated carbon has good potential for the removal of 2,4-D from aqueous solutions.