Solid waste derived material-based compound fertilizer for simultaneous remediation of Pb/Zn contaminated soil

The remediation of heavy metals (HMs) contaminated soils is crucial for safeguarding environmental health and ensuring agricultural safety. This study presents a novel strategy for the co-remediation of HMs contaminated soils and the simultaneous enhancement of soil fertility through the use of a tailing-derived composite material. A silica-supported hydrotalcite material (SHM) was synthesized from solid waste through a coprecipitation method followed by atmospheric hydrothermal treatment. SHM was functionalized as a carrier for nitrogen (N), phosphorus (P), and potassium (K) nutrients to fabricate a slow-release fertilizer (SRF). SHM exhibited a typical hydrotalcite-like layered structure, a high specific surface area (199.03 m 2 /g), and a mesoporous architecture that facilitates nutrient retention and HMs uptake. Pot experiments demonstrated that 1 % and 2 % SRF significantly enhance plant growth while effectively reducing the uptake of Pb by 71.51 %-85.29 % and that of Zn by 14.54 %-53.36 %. Moreover, SRF application markedly reduced the bioavailability and leaching potential of Pb and Zn, promoting their transition from soluble and exchangeable fractions to more stable iron-manganese oxide-bound and residual forms. The formation of phosphate precipitation serving as the primary adsorption mechanism after SRF application. SHM derives from tailings exhibit significant potential as efficient dual-functional amendments for sustainable soil remediation and nutrient management.