Stabilizing Cr(III) deriving from tannery sludge with kaolin and organic matter

Stabilizing Cr(III) in tannery sludge (TS) via harmless method has always been the goal of environmental pollution treatment. In this study, a simple method to stabilize Cr(III) in TS is proposed via adding kaolin, based on the fact a large amount of organic matter contained in TS. Comprehensive characterizations confirm that kaolin can stabilize Cr(III) via its abundant -OH and lamellar structure. Moreover, there are hydrogen bond interactions and ligand exchange-surface complexation between organic matter and kaolin, which is more conducive to form a stable ternary complex with Cr(III), in a state of organic matter-Cr(III)-kaolin. Simultaneously, the BCR sequential extraction experiment shows that the unstable water and acid soluble state of Cr(III) are reduced (from 0.61% to 0.35%), which further indicates that the stabilization of Cr(III) is successful.

Automated summary

A simple method of stabilizing Cr(III) in tannery sludge (TS) is proposed by adding kaolin, which is based on the abundant organic matter contained in TS. Comprehensive characterizations confirm that kaolin can stabilize Cr(III) through its abundant -OH and lamellar structure. Hydrogen bond interactions and ligand exchange-surface complexation between organic matter and kaolin are also found, which facilitate the formation of a stable ternary complex with Cr(III) in the form of organic matter-Cr(III)-kaolin. The BCR sequential extraction experiment demonstrates that the unstable water and acid soluble state of Cr(III) are reduced (from 0.61% to 0.35%), indicating the success of Cr(III) stabilization.