Preparation of regenerable modified montmorillonite with amino acids for arsenic removal from water

Modified montmorillonites (Mts) with arginine (Arg) and lysine (Lys) amino acids were synthesized by cation exchange method and used to remove arsenate, As(V), from water. The modified Mts were characterized by X-ray diffraction (XRD)and zeta potential. XRD results showed that both Arg and Lys can be intercalated into the Mt and increase the interlayer space. The adsorption of As(V) onto modified samples as a function of initial As(V) concentration and solution pH was investigated. The removal efficiency was increased with increasing the As(V) concentration, however it decreased with increasing solution pH. The maximum As(V) adsorption capacities of Mt-Arg and Mt-Lys were 11.5 and 11 mg/g, respectively, which were 5 times larger than unmodified Mt. The regeneration studies were carried out up to 10 cycles for both modified Mts. The removal efficiency of Mt-Arg decreased from 98% to 89.5% while it decreased from 96% to 83.7% for Mt-Lys. Modified adsorbents could also be effectively used for As(V) removal from surface water for multiple adsorption-desorption cycles.

Keywords:

: Montmorillonite , Amino acid , Arsenic , Regenerable