Converting Building Waste Soil into GIS Zeolite to Remediate Cd-Polluted Soil

Abstract

The massive output of building waste soil poses a significant challenge to urban sustainable development. However, high-efficiency building waste soil recycling solutions are extremely scarce. Meanwhile, as a significant environmental hazard, Cd-contaminated soil has posed severe threats to public health. This work demonstrates a sustainable strategy to transform multiple building waste soils into low-cost and nontoxic GIS-type zeolite for Cd-contaminated soil remediation. Leveraging the high adaptability and flexibility of GIS-zeolite’s crystallization properties, this "soil-to-GIS-zeolite" conversion process is simple, reliable, and highly universal, exerting high atom conversion rates of 87.28% for Al and 78.75% for Si, efficiently decreasing the raw materials cost and energy consumption. Notably, the GIS-zeolite exhibits remarkable Cd stabilization ability for soil remediation, effectively reducing the exchangeable Cd species in soil from 41.4% down to 21.3% with only a 0.3% GIS-zeolite addition. Mechanistic studies reveal that GIS-zeolite could fast capture Cd²⁺ via surface chemisorption and gradually lock Cd²⁺ into its framework via Na⁺ release. Overall, this study proposes a sustainable approach to advancing construction waste soil recycling, GIS-zeolite synthesis, and Cd pollution control. Furthermore, it demonstrates the huge potential of soil resources for zeolite synthesis and environmental protection, which has been heavily ignored before.