Superstable Mineralization Coupled with Photocatalysis toward Cr(VI) Remediation Using Layered Double Hydroxide Material

The extensive utilization of chromium in electroplating, leather tanning, dyeing, and other industries has resulted in significant environmental pollution. Therefore, there is a pressing need for highly efficient materials to tackle the pollution caused by Cr(VI). Throughout the study, a variety of layered double hydroxides (LDHs) were synthesized, and the NiCr-LDH showed remarkable removal properties for the heavy metal chromium. The NiCr-LDH exhibits rapid equilibrium within 60 min and possesses a maximum capacity of 218 mg/g. Notably, when exposed to visible light, the ability of NiCr-LDH to remove toxic Cr(VI) anions is significantly improved, and it is capable of treating actual electroplating wastewater to remove the Cr concentration to well below 0.5 mg/L. In-depth analysis revealed compelling evidence that the highly toxic Cr(VI) anions transformed into harmless Cr(III) anions, resulting in an improved removal efficiency.