원위치 철산화물 반복합성법을 이용한 토양 내카드뮴 안정화 효율 향상 및 현장 실증

초록

In situ iron (Fe) oxide synthesis is an effective chemical precipitation technique for heavy metal stabilization incontaminated soils. However, surface-adsorbed metals remain vulnerable to remobilization under changing environmentalconditions. Aqueous Cd stabilization experiments demonstrated that repetitive synthesis progressively reduced the surfaceadsorbed Cd fraction from 68.7 ± 1.0% (1st synthesis) to 53.9 ± 2.6% (2nd synthesis) and 23.5 ± 0.8% (3rd synthesis),while single synthesis with equivalent Fe showed no such reduction. Aberration-corrected scanning transmission electronmicroscopy (Cs-TEM) with energy dispersive spectroscopy (EDS) line scanning revealed that surface-adsorbed Cdmigrated from edge sites to bulk sites during repetitive synthesis, confirming physical encapsulation by newlyformed Fe oxide layers. Fast Fourier Transform (FFT) analysis indicated lattice distortion in Fe oxide structures,suggesting simultaneous incorporation mechanisms. Stabilization of Cd in soil experiments revealed that stabilization efficiencystrongly depended on the Fe/Cd molar ratio in soil solution, with ratios >400 achieving 99% reduction in Cdleachability through single synthesis via discrete Fe oxide formation, while lower ratios (Fe/Cd = 63) requiredrepetitive synthesis to achieve enhanced stabilization through progressive encapsulation mechanisms. Field demonstrationvalidated the practical applicability, achieving complete suppression of Cd leaching in most soil depths after twosynthesis cycles. This study establishes repetitive in situ Fe oxide synthesis as a viable remediation strategy for Cdcontaminated soils.

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