Composite of chitosan and bentonite cladding Fe-Al bimetal: Effective removal of nitrate and by-products from wastewater.

Abstract Chitosan was used as crosslinking agent to load bimetal particles onto bentonite. The Fe–Al bimetal chitosan bentonite (Fe–Al bimetal @ bent) complex was prepared for the efficient removal of nitrate from wastewater and its by-products at low temperature. The samples were characterized by Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Zeta potential, X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area and Energy Dispersive X-ray Detector (EDX). SEM and EDX showed that Fe0 was deposited on the surface of aluminum, the Fe–Al bimetal were surrounded by chitosan and bentonite. XRD showed that Al can effectively protect the reactivity of Fe. The experimental results of nitrate removal showed that pH was the main factor affecting on nitrate removal rate and performance. The removal efficiency of nitrate wastewater with a concentration of 50 mg/L was approximately 90% in 60min. Fe–Al bimetal @ bent has better nitrate removal performance and faster reduction rate at low temperature(2–7 °C) than normal temperature (25 °C). The reason was that chitosan, bentonite and bimetal have excellent synergistic effect. It can effectively improve the reaction rate, pH buffering capacity, reduce secondary pollution and total nitrogen (TN). Fe–Al bimetal @ bent has better N2 selectivity than Fe–Al bimetal.