RESUMEN
Chitosan-modified biochar ï¼CBCï¼ was prepared as a low-cost and highly efficient adsorbent for Cd2+ in aqueous solutions. Batch adsorption experiments were conducted to evaluate the adsorption performance. Characterization experiments with SEM-EDSï¼ FTIRï¼ and XPS were used to analyze the surface microstructure and chemical composition of the adsorbent. The results showed that the adsorption performance of CBC was remarkably improved by the introduction of surface functional groups ï¼-OHï¼ -C=Oï¼ and -NH2ï¼. The pseudo-second-order kinetic model and Langmuir model were better for describing the kinetics and isotherms for Cd2+ adsorption onto CBCï¼ indicating that the adsorption rate was determined by the active sites and controlled by monolayer chemisorption. The adsorption process was endothermic spontaneousï¼ and the key mechanisms involved complexationï¼ precipitationï¼ cation exchangeï¼ and cation-π bonds. After five instances of adsorption-desorption cyclesï¼ the adsorption capacity of CBC for Cd2+ still remained above 80% of the initial adsorption capacityï¼ indicating that CBC had a favorable recyclability. The current work embodies the concept of green chemistryï¼ and the prepared chitosan-modified biochar was a promising adsorbent for the removal of Cd2+ in wastewater and soil.