POLYMER-BENTONITE NANOCOMPOSITES AND MAGNETIC LDH FOR REMOVAL OF ARSENIC FROM AQUEOUS SOLUTION

Abstract

This work aimed to incorporate the designed functional parts into both cationic and anionic clays so that they became efficient in arsenate adsorption. Both pAPTMA/bentonite and pAETMA/bentonite nanocomposites were synthesized via solution intercalation and in-situ intercalative polymerization method. The characterization revealed that both polymers intercalated in between the interlayers of bentonite. Comparing between two methods, the composites prepared via solution intercalation method provided higher As(V) adsorption amount. The maximum As(V) adsorption amounts were 47.7 mg/g polymer (for pAPTMA/bentonite) and 46.2 mg/g polymer (pAETMA/bentonite). The adsorption kinetics indicated the chemisorption process. The adsorption isotherm is fitted to the Freundlich model for both pAPTMA/bentonite and pAETMA/bentonite nanocomposites describing the adsorption behavior of As(V) onto the heterogeneous surface of nanocomposites. The magnetic layered double hydroxide composite was synthesized by coprecipitation of layered double hydroxide (LDH) precursors in the presence of Fe3O4 particles. The characterization revealed that the composite was comprised of Fe3O4 particles covered by a LDH. The As(V) adsorption capacity (188 mg/g) was achieved at pH 3. The kinetics studies and adsorption isotherms suggested a two-stepped adsorption mechanism of the monolayer adsorption inside the interlayers of LDH. The adsorption mechanism involved the reconstruction process of LDH phase and the ion-exchange between the interlayers of reconstructed LDH.