Adsorption of RE3+ from aqueous solutions by bayberry tannin immobilized on chitosan

Abstract

ABSTRACTBayberry tannin immobilized on chitosan (CS-BT) was successfully prepared, and its adsorption performance was studied for aqueous solutions of rare earth ions. The as-prepared absorbents were characterized by Fourier transform infrared spectrometry and scanning electron microscopy. The equilibrium adsorption capacity was achieved in approximately 30 min. The adsorption process of CS-BT for Nd3+ was well fitted with a Freundlich model and the kinetics followed the pseudo-second-order rate equation. The maximum adsorption capacity for Nd3+ was 133.72 mg/g and dynamic adsorption characteristics of single ion (La3+, Ce3+, Nd3+) were investigated. The solution concentration was less than 30 mg/L when effluent volume was approximately 800 mL. Subsequently, the adsorbent column was desorbed by HNO3 solution. There was no significant loss of adsorption capacity after three cycles of regeneration, showing a satisfactory recyclability. Furthermore, CS-BT exhibited excellent dynamic adsorption performance of two mixed ions (La3+/Ce3+, La3+/Nd3+, Ce3+/Nd3+) and three mixed ions (La3+/Ce3+/Nd3+). The competitive adsorption capacity was La3+ < Ce3+ < Nd3+. The results indicate that the adsorption selectivity of column adsorption could provide a theoretical basis for the adsorption and separation of light rare earth ions. Therefore, this efficient adsorbent shows promising potential for the treatment of industrial wastewater.