Sorption of cd (II) ions by chitosan modified peanut shell biochar from aqueous solution

Abstract

In this paper, biochar was prepared from peanut shells, and then the pristine biochar (PBc) was modified by chitosan (CBc). The characteristics of the absorbents were investigated using infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer, Emmett and Teller analysis (BET). The effects of the biochars dosage, pH, initial cadmium concentration, and contact time on cadmium removal were evaluated. Adsorption isotherms and kinetic models were used to explain the adsorption process. The results indicated that CBc could be used as a biosorbent for the removal of heavy metals from the aqueous solution. The adsorption data conformed best to the Langmuir isotherm. Optimum conditions for the highest removal of Cd (II) were obtained at the biochar dosage of 0.6 g/L, 30 mg/L initial concentration of Cd (II) solution, pH value of 6, and within 30 minutes. The maximum adsorption capacities of pristine and modified biochar were found to be 40 mg/g and 58.823 mg/g, respectively. The kinetic data displayed that pseudo-second-order kinetic model can well fit the process of cadmium biosorption. The coatings of biochar with chitosan can greatly improve the absorbent efficiency in the removal of heavy metals and the chitosan-modified biochar can be used as a, low-cost, effective and environmental-friendly adsorbent.