Efficient adsorption of heavy metals using Friedel's salt synthesized from municipal solid waste incineration fly ash leachate
Yushan Guan, Yan Xia, Liang Chen, Binling Guo, Lei Wang
Abstract
Municipal solid waste incineration fly ash (MSWIFA) is a hazardous waste with high content of complex pollutants and soluble chlorides, generally requiring water-washing dechlorination for resource utilization. However, the abundant leachate with environmental risks requires energy-intensive purification treatment. Herein, we employed a novel and scalable coprecipitation strategy for in-situ synthesis of Friedel's salt directly from chlorine-rich MSWIFA washing leachate, transforming waste into a valuable adsorbent. Experimental results showed that the products reached 95 % purity with high crystallinity under optimal synthesis conditions of pH 12.5, Ca/Al ratio 1:1 and 40 °C. Friedel's salt possessed satisfactory adsorption of Cr(VI) and Cd(II) with maximum capacities achieving 132.5 mg/g and 680.1 mg/g, outperforming many hydrotalcite-based materials. The main adsorption mechanisms of isomorphic substitution and interlayer exchange were revealed by various techniques such as X-ray photoelectron spectrometer. This work explores the potential value of MSWIFA washing leachate as an adsorbent, offering new perspectives for promoting the sustainable development of solid waste.