Biosorption of cadmium ions from aqueous solution by modified Auricularia Auricular matrix waste

Abstract In order to reduce the harm of cadmium(II) to environment and health, the NaOH modified Auricularia Auricular matrix waste (AAMW) was used to adsorb cadmium(II) in aqueous solution. The cadmium(II) adsorption onto modified AAMW was pH and concentration-dependent, high pH and cadmium(II) initial concentration favored the adsorption. This biosorption underwent a rapidly physical process followed by a slowly chemical process and equilibrated at 60 min with a adsorption capacity of 35.51 mg/g. The experimental data fitted well with Freundlich isothermal model and Elovich equation model. The amino, hydroxy, carboxy and phosphonate groups were responsible for cadmium(II) adsorption onto modified AAMW. Sodium hydroxide could remove the impurities on the adsorbent and provide more space for cadmium(II) binding as well as increase polarity of the adsorbent. The ion exchange also took place during the adsorption process. The adsorption capacity remained 14.02 mg/g after three reuse cycles.