Adsorption of Arsenate from Water by Iron-Chitosan Modified Fly Ash

Abstract

Abstract Group F fly ash which was obtained from Pha Lai Thermal Power Plant (Hai Duong, Vietnam) is used as a raw material for zeolite preparation. CTS-ZFA-Fe3O4 adsorbent is a zeolite composite material combined with chitosan modified with iron salts to remove As(V) from water. The granules have advantages such as biodegradability, economy and ease of separation. SEM, FTIR and XRF methods are utilized to characterize the material. The experimental data showed that the material was successfully modified by adding iron oxide and amine group from chitosan. These functional groups contributed significantly to the improvement of As(V) adsorption in solution. Furthermore, the bond of C=N is obtained from the cross-linking reaction between glutaraldehyde and chitosan improve structure of adsorbent. From batch experiments, it was found that the material could adsorb As(V) at pH 3 optimally, reaching an adsorption capacity of 160 μg/g. As(V) was completely adsorbed by CTS-ZFA-Fe3O4 material at the dosage of 10g/L and reached equilibrium after 180 min. Since then, the As(V) adsorption mechanism is related to electrostatic interactions between As(V) anions with OH2 + and NH3 + (positively charged groups) existing on the adsorbent’s surface at low pH conditions. Moreover, the formation of arsenic complexes (As-N, As(V)-Fe) is also believed to be the adsorption mechanism of post-modified zeolite materials.