Effective removal and expedient recovery of As(V) and Cr(VI) from soil by layered double hydroxides coated waste textile

Mg-Al layered double hydroxides coated waste textile (MgAl-LDH@WT) was prepared by an in-suit method for the separation of toxic metal ions such as As(V) and Cr(VI) from soil samples. Kinetics studies of As(V)/Cr(VI) removal by MgAl-LDH@WT with different Mg/Al ratio were well described by intraparticle diffusion and pseudo-second-order model. Adsorption isotherm data of As(V)/Cr(VI) yielded a better accordance of Langmuir model, manifesting that accessible adsorption site was the main influence factor and the removal of As(V)/Cr(VI) was a charge-limited process. The adsorption capacity was 69.8 mg/g, 49.8 mg/g, 45.6 mg/g and 38.2 mg/g by Mg2M-LDH@WT, Mg3M-LDH@WT, Mg4Al-LDH@WT and LDHs, and for Cr(VI) were 27.5 mg/g, 24.9 mg/g, 19 mg/g and 6.8 mg/g, respectively. Adsorption behavior of As(V) and Cr(VI) co-existing in soil indicated that As(V) possess a preferential adsorption rather than Cr(VI) by Mg2Al-LDH@WT, and molecular simulation was selected to explain the results of competitive relationship by bonding energy and variation of bond length. The effect of co-existing ions, column leaching experiment and recycle experiment for practical performance assessment were also examined, and these results revealed a high stability and a good partition capability. The performance of excellent removal and convenient recovery suggested a promising strategy in anionic heavy metals contaminated soil.