인산석고 유래 석회의 중금속 복합 오염토양 안정화 효과 평가

초록

Phosphogypsum (PG) is a by-product from the phosphate fertilizer industry and it consists mainly of CaSO4⋅2H2O with some impurities. The presence of these impurities in PG significantly limits its utilization and it can be stockpiled in large quantities. Therefore, it is imperative to seek a new pathway to utilize the PG. This study aimed to evaluate the chemical conversion process of hydrated lime derived from PG (HLP) and examine its effect on Cd and Pb immobilization and subsequent uptake by lettuce. The HLP was incorporated into a Cd and Pb-contaminated soil at four application rates (0, 0.5, 1 and 2% (w/w)) and soil HLP mixtures were examined using pot trials for cultivation of lettuce. The reaction for the chemical conversion process of PG was carried out in aqueous NaOH solution, resulting in HLP with its properties (Ca content, XRD pattern) similar to conventional hydrated lime. Furthermore, lettuce growth studies showed that HLP incorporation induced significant declines in the soil phytoavailable Cd and Pb pool as assessed via 1M NH4NO3 extraction, possibly due increases in soil pH. Consequently, the uptake of Cd and Pb by lettuce was significantly reduced as HLP application rate increased. Results demonstrated that HLP can be used as an eco-friendly alternative to conventional hydrated lime.

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