One step acid modification of the residual bark from using HSO and application in the removal of 2,4-dichlorophenoxyacetic from aqueous solution.

The residual bark of the tree species was successfully modified with HSO and applied to remove the toxic herbicide 2.4-dichlorophenoxyacetic (2.4-D) from aqueous solutions. The characterization techniques made it possible to observe that the material maintained its amorphous structure; however, a new FTIR band emerged, indicating the interaction of the lignocellulosic matrix with sulfuric acid. Micrographs showed that the material maintained its irregular shape; however, new spaces and cavities appeared after the acidic modification. Regardless of the herbicide concentration, the system tended to equilibrium after 120 min. Using the best statistical coefficients, the Elovich model was the one that best fitted the kinetic data. The temperature increase in the system negatively influenced the adsorption of 2.4-D, reaching a maximum capacity of 312.81 mg g at 298 K. The equilibrium curves showed a better fit to the Tóth model. Thermodynamic parameters confirmed the exothermic nature of the system (ΔH = -59.86 kJ mol). As a residue obtained from urban pruning, the bark of treated with sulfuric acid is a promising and highly efficient alternative for removing the widely used and toxic 2.4-D herbicide from aqueous solutions.