Synthesis and characterization of novel adsorbent for groundwater remediation purpose

Abstract

Arsenic pollution has become a worldwide environmental concern. Dangerous arsenic concentrations in natural waters threaten the health of millions of people, and this has received significant attention. Among the various technologies that have been developed for arsenic removal from water, the use of adsorption technology is considered to be a prevailing method, because the adsorption approach usually has high removal efficiency and the advantage of convenience of handling. In recent years, layered double hydroxides (LDHs) have become prime candidates for arsenic removal, due to their hydrophilic nature and cationic layered structures. Ion exchange is the most prominent and effective mechanism for removal of metal ions from water by LDH. In this study, Ni doped Mg- Fe LDH with four different Mg/Ni/Fe (2:2:1, 2:1:1, 1:2:1, 1:1:1) have been synthesized via co-precipitation method. A series of batch experiments were performed under various conditions, such as M2+/M3+ ratio, initial anions concentrations, contact time, solution pH and competitive adsorption, for the adsorption of arsenic (V) and lead (II) on Ni doped Mg/Fe LDH. It is found Ni doped Mg/Fe with Mg/Ni/Fe ratio 2:2:1 at pH 6 shows maximum removal of 91% for arsenic(V) and 81.5 % for Lead (II). The equilibrium and kinetic adsorption data were best fitted into the Freundlich isotherm for higher concentration of arsenate and adsorption data were best fitted into Langmuir isotherm for higher concentration of lead (II). The adsorbents were characterized by TGA, SEM, XRD, FT-IR and XPS, and the analysis results demonstrated that the adsorption mechanism involved surface adsorption, ion exchange interaction and concomitant intercalation of lead and arsenate ions into the interlayer region.