High-efficiency removal of Cr(VI) by modified biochar derived from glue residue

A series of cost-effective, high-efficiency and sustainable adsorbent for Cr(VI) were prepared from waste glue residue. Considering that chemical modification has great influence on the properties of biochar, several modifiers (HCl, KOH, and ZnCl2) were used to improve the adsorption capacity of biochar. Besides that, the effect of prepare conditions (i.e., pyrolysis temperature and impregnation ratio of modifier and glue residue) were also investigated. Emission scanning electron microscopy, transmission electron microscopy, X-ray diffractometer, X-ray photoelectron spectroscopy and Autosorb1-MP Quantachrome were used to characterize the physicochemical properties of waste glue residue biochar. Reaction time, solution pH, adsorbent dosage, and initial adsorbate concentration on contaminant removal were also examined. The maximum sorption capacity of ZnCl2 modified glue residue biochar reached 325.54 mg/g, which is higher than previous reported adsorbents. The recycling experiment demonstrated that the removal efficiency of the optimal biochar was 90% after six cycles. Hence, waste glue residue exhibits a great potential in Cr(VI) contaminated water’s management.