Removal of Phloridzin by Chitosan-Modified Biochar Prepared from Apple Branches

Phloridzin is a phenolic acid associated with the genus Malus (Mill.) that causes apple replant disease. The removal of phloridzin is of great significance to alleviate this condition, and hence biochar was investigated for this purpose. The goal of this study was to improve the adsorption capacity of biochar for phloridzin by chemical modification. Biochar from apple branches and biochar modified with chitosan to were characterized by elemental analysis, Brunauer Emmett Teller analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Batch adsorption experiments were employed to select the optimal biochar dosage and adsorption time. The results showed that biochar treated for 24 h at 6 g L−1 achieved best adsorption properties and that the chitosan-modified biochar provided a higher adsorption capacity than the unmodified material. The influence of pH upon the adsorption was studied and the results were fitted with isotherm and kinetic equations. The results showed that adsorption process corresponds to a Langmuir isotherm and pseudo-second-order kinetics. The qmax of the biochar was increased from 15.93 to 28.96 mg g−1 by modification with chitosan. The pH was shown to play an important role in the adsorption process. The adsorption of phloridzin to biochar was demonstrated to be a single-layer multiple component adsorption process based on chemisorption. This study provides a theoretical basis to alleviate apple replant disease.