Synthesis and characterization of ZnNiCr-layered double hydroxides with high adsorption activities for Cr(VI)

ZnNiCr-layered double hydroxides (ZnNiCr-LDHs) applied for Cr(VI) removal were designed and synthesized through the microwave hydrothermal method. When molar ratio of Zn2+/Ni2+ is 7:1 and (Zn2+, Ni2+)/Cr3+ is 3:1, the morphology of the as-prepared ZnNiCr-LDHs was irregular blocky structure, which comprised a flake structure. The specific surface area could reach 354.36 m(2)/g, providing rich adsorption sites for Cr(VI) adsorption. Adsorption experimental results suggested that ZnNiCr-LDHs possess a maximum adsorption capacity of 28.2 mg/g at pH = 2, which is larger than that of ZnCr-LDHs and NiCr-LDHs. The adsorption experiment conforms to the Langmuir monolayer adsorption model and the kinetic adsorption data are well fitted by the pseudo-second-order adsorption kinetic equation. The as-prepared ZnNiCr-LDHs have potential application prospects in the removal of Cr(VI) in wastewater.

Automated summary

ZnNiCr-layered double hydroxides (LDHs) were synthesized using the microwave hydrothermal method for Cr(VI) removal, exhibiting a high adsorption capacity at pH=2 compared to ZnCr-LDHs and NiCr-LDHs. The materials have potential application prospects for the removal of Cr(VI) in wastewater.