Cu(II) and Cd(II) removal from aqueous solution with LDH@GO-NH2 and LDH@GO-SH: kinetics and probable mechanism

• DOI: 10.1007/s11356-021-15558-y
• Publication Date: 2021-07-28T20:02:31Z
• Authors: Wei Liao; Di Bao; Hui-qiang Li; Ping Yang
• Keywords: Kinetics; Metals, Heavy; Adsorption; 01 natural sciences; Water Pollutants, Chemical; Cadmium; 0105 earth and related environmental sciences

Abstract Two novel adsorbents of thiol- and amino-functionalized GO grafted onto LDH (LDH@GO-NH2 and LDH@GO-SH) were synthesized and contrasted for adsorption properties for Cu(II) and Cd(II). Characterization experiments illustrated that thiol group (-SH) and amino group (-NH2) were existed onto LDH@GO-NH2 and LDH@GO-SH. Adsorption isotherm results showed that the adsorption processes were satisfactorily fitted by both Langmuir and Freundlich models. The maximum adsorption capacity of Cd(II) on LDH@GO-SH at 308 K was 102.77 mg/g, which was about triple that of LDH@GO-NH2. The enhancement in adsorption capacity was due to the cooperative effect of LDH and GO-SH. The kinetic experimental data for LDH@GO-NH2 and LDH@GO-SH were found to be in good agreement with pseudo-second-order model. The thermodynamic parameters calculated from the temperature dependent adsorption isotherms indicated that the adsorption was a spontaneous and endothermic process. The possible adsorption mechanisms comprising formation of precipitation, isomorphic substitution of Mg(II), and formation of complexation with amino-groups and thiol-groups were proposed. Desorption experiments put into evidence that the LDH@GO-NH2 and LDH@GO-SH may be promising suitable candidates for the remediation of metal ions from aqueous solutions in real work in the near future.