A diatomite-template self-sacrificing route for Mg-chlorite and its adsorption behavior towards Pb(II)/Cd(II)

Heavy metal pollution has caused worldwide attention due to its toxicity to people's health. It's necessary to design and synthesize adsorbents with excellent adsorption performance in low cost. In this work, diatomite is adopted as a self-sacrificing template for the synthesis of adsorbent Mg-chlorite. The three-dimensional (3D) hierarchical porous Mg-chlorite perfectly inherits structure characters from diatomite and exhibits a high specific surface area of 337 m(2)/g. The maximum adsorption capacities of Mg-chlorite towards Pb(II) and Cd(II) reach 961 mg/g and 506 mg/g, respectively, higher than that of the referenced adsorbents. The Pb(II), Cd(II) adsorption onto Mg-chlorite is a monolayer exothermic process. Chemisorption mainly controls the adsorption rate, in which mass transfer exerts greater influence than intra-particle-diffusion. Electrostatic attraction, chemisorption and co-precipitation are involved in the adsorption process, and co-precipitation mainly contributes to the excellent adsorption performance according to XRD, FT-IR and XPS analysis. This study provides a novel diatomite-template self-sacrificing method in the synthesis of 3D hierarchical porous magnesium silicate. The excellent adsorption performance for Pb(II) and Cd(II) species makes the low cost Mg-chlorite a great potential in the application of practical environment remediation.