Adsorption Characteristics of Cadmium Ions from Aqueous Solution onto Pine Sawdust Biomass and Biochar

The adsorption capacity of cadmium ions by pine sawdust biomass and biochar was evaluated in batch experiments. Pine sawdust biochars were pyrolyzed at 500 degrees C and 700 degrees C and obtained in the absence of oxygen. The adsorption capacity of biochar was higher than the raw biomass (3.47 mg/g). Biochars produced at 700 degrees C showed better adsorption efficiency (6.09 mg/g) than that produced at 500 degrees C (4.78 mg/g). Also, the adsorption kinetics and adsorption isotherms were studied. The adsorption behavior of cadmium by pine sawdust biomass and biochar fitted Langmuir isotherms and pseudo-second order kinetics. In addition, the desorption experiment by different solutions (neutral, acidic, and alkaline) were conducted. The desorption of cadmium ions in neutral and alkaline environments was not obvious, while the desorption in an acidic environment was. Pine sawdust biochar, pyrolyzed at 700 degrees C, is a potential adsorbent for cadmium removal in neutral and alkaline environments.