Insight into the adsorption mechanisms of aqueous hexavalent chromium by EDTA intercalated layered double hydroxides: XRD, FTIR, XPS, and zeta potential studies. (25th September 2019) - Li, Jing
Abstract : To understand the possible mechanisms of Cr(vi ) adsorption on the surface of modified LDHs, we synthesized EDTA intercalated MgAl-LDH and its magnetic product, and evaluated their adsorption performance for Cr(vi ) by batch experiments. Abstract : To understand the possible mechanisms of hexavalent chromium (Cr(vi )) adsorption on the surface of modified layered double hydroxides (LDHs), we synthesized ethylenediaminetetraacetic acid intercalated MgAl-LDH (LDH-EDTA) and its magnetic product (Mag-LDH-EDTA), and evaluated their adsorption performance for Cr(vi ) by batch equilibrium experiments. The characterization analysis proved that the EDTA was intercalated into MgAl-LDH and the adsorbents had an ordered structure and abundant functional groups. The adsorption mechanisms of Cr(vi ) by LDH-EDTA and Mag-LDH-EDTA could be attributed as electrostatic attraction, surface complexation, anion exchange, and reduction reaction speculating from the detailed X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and zeta potential analysis. The removal ratio remained above 96% and 79% for 50 mg L −1 Cr(vi ) using 0.03 g LDH-EDTA and Mag-LDH-EDTA, respectively. The adsorption process was less influenced by the pH value of the aqueous solution. The pseudo-second-order model and the Langmuir equation well fitted to the adsorption kinetic and isotherm data. Thus, the EDTA intercalated LDH materials had potential applications for Cr(vi ) removal in real wastewater treatment.