Immobilization of high concentration hexavalent chromium via core-shell structured lightweight aggregate: A promising soil remediation strategy

Abstract

Among industrially polluted soils, chromium contaminated sites, especially hexavalent chromium contaminated (Cr 6+ ) sites, are particularly difficult to manage. The Cr 6+ in such soils is usually at a high concentration. Several studies show that sintering and solidification are effective ways to treat Cr 6+ in soil. In this study, a coreshell lightweight aggregate (CS-LWA) was prepared using Cr 6+ contaminated soil as the core and clean bulk materials as a shell to seal the Cr 6+ pollutant in the core, and the shell prevents it from leaching out. A reductant, pulverized coal, was added to assist the solidification and reduce chromium toxicity. The results show that this method can effectively reduce the leaching of chromium in polluted soil with varying chromium content, and that chromium leaching can be further reduced by increasing the amount of coating material. The chromium in leachate from coated CS-LWA mixed with 8% pulverized coal was only 0.02 mg/L, much lower than 1042.8 mg/L in leachate from untreated chromium-contaminated soil. Moreover, the strength, density, and water absorption characteristics of CS-LWA met the Chinese national standards, enabling its use as a lightweight aggregate for construction.

Insight into chromium adsorption from contaminated soil using Mg/Al LDH-zeolite

“…The leaching of Cr(VI) from stainless steel manufacturing processes significantly plays a part in the contamination of Cr(VI) in water and soils, as noted by Radhan et al (2017) [ 4 ]. The mobility of Cr(VI) in the soil, allowing it to disperse easily through water, leads to extensive pollution over large areas, as highlighted by Li et al (2020) [ 5 ].…”

Influence of Wave-Absorbing Materials on the Heating Efficiency in Microwave Heating Treatment of Contaminated Soil

“…Their study showed that the performance of the products obtained would meet the requirements for lightweight aggregates for construction if the contaminated soil with a Cr 6+ content of 20,000 mg/kg was heated into core-shell-structured ceramic granules. Once this process was completed, the Cr leaching of the ceramic grains could be as low as 0.02 mg/L, and such ceramic grains would still maintain a high curing stability under extreme conditions like strong acidity, strong alkalinity, freezing, and thawing [9].…”