Sustainable and integrated approaches for carbon capture and rapid remediation of Cr- and Zn-contaminated soils

Abstract

Soil contamination is a growing concern for sustainable development worldwide. Conventional remediation approaches, such as using ordinary Portland cement (OPC) or lime are limited due to high CO2 emissions, energy consumption, and natural resource consumption. This paper proposes a sustainable method using CO2 and a waste from steel production (ladle slag, LS) for rapid remediation of Cr and Zn-contaminated soils. Contaminated soils spiked by Cr and Zn with various initial concentrations were treated with 10% LS and subjected to conventional and CO2 curing for different periods. The results demonstrated that LS with conventional curing could reduce leaching concentrations of Cr and Zn in contaminated soils. However, it necessitated 28 days to meet the criteria of inert waste and drinking water standards. In contrast, LS with CO2 curing required significantly less time (32 h for Cr and 8 h for Zn) to achieve lower leaching concentrations of Cr and Zn than those with 28-day conventional curing. After CO2 curing for 152 h for Cr- and 80–120 h for Zn-contaminated soils, leaching concentrations of Cr and Zn were 1.5–4 times and 6–72 times lower than those with 28-day conventional curing, respectively. Simultaneously, carbon capture was increased from 10.6% to 17.5% and 19.9%, respectively, with the initial Cr and Zn concentrations increased from 0 to 8000 mg/kg. The strength of Cr- and Zn-contaminated soils with CO2 curing also effectively enhanced up to around 3.3–3.6 times and 1.3–3.3 times higher than those with 28-day conventional curing, respectively.