Fangjie Pang

Southeast University, China

Title: TBA

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Biography

Abstract

Calcium sulfoaluminate cement (CSA) produced through the collaborative utilization of solid wastes is an effective way to realize the resource utilization of solid waste. In this research, different states of Cr(VI), as a heavy metal with great environmental toxicity, are introduced into sulfoaluminate cement. As a result, the introduction of 3% sodium chromate and potassium dichromate increased the setting time of CSA to 47.2% and 117.9%. After hydration for 7 days, chromium ion leaching experiments were performed in different solutions. The leaching concentration of chromium ions gradually increases with the oscillation time and remains basically unchanged after 12 hours. In NaCl solution, the immobilization of Cr(VI) in CSA cement is the highest (20.3 mg/g) but the lowest that in NaCO3 solution (14.2 mg/g). The research results confirmed that the chloride ions in the NaCl solution promote the crystal growth of ettringite, thus facilitating the immobilization of Cr(VI) ions in their lattice, while in NaCO3 solution, Cr(VI) ions are easily released due to CO32- ions binding calcium ions in ettringite crystals but still maintain a high curing amount. Therefore, this work provides a theoretical criterion for toxicity leaching and safety application in different environments for calcium sulfoaluminate cement from solid waste.