Valorization of phosphogypsum into carbon-neutral lime for soil lead immobilization

초록

Conventional hydrated lime (Ca(OH)(2)) is widely applied to immobilize heavy metals in soils but is associated with substantial CO2 emissions during limestone calcination. This study presents a carbon-neutral waste valorization technology that converts phosphogypsum waste into hydrated lime (HLPG) via alkaline conversion without CO2 release. The synthesized HLPG was fully transformed into Ca(OH)(2) and exhibited physicochemical properties comparable to commercial hydrated lime (CHL). In aqueous systems, HLPG achieved > 95% Pb2 + removal at pH >= 3, matching CHL performance. In Pb-contaminated soil, HLPG increased soil pH from 5.6 to 9.4, reduced phytoavailable Pb by up to 99.6%, enhanced microbial activity by 40%, decreased Pb uptake by lettuce by 82%, and increased plant biomass by 17% at optimal application rates. By integrating waste valorization, carbon-neutral lime production, and effective soil remediation<bold>,</bold> this technology offers a scalable and sustainable solution for managing Pb-contaminated soils while mitigating greenhouse gas emissions.

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