저분자 유기산에 의한 중금속 오염토양의 복원

For the remediation of the contaminated soil with heavy metals, Cd, Cr, Cu, and Pb, the reaction parameters were optimized. Tartaric acid (TA) and oxalic acid(OA) as a washing agent were evaluated as a function of concentration, reaction time, mixing ratio of washing agent and recovery of metals. The optimum washing conditions of TA and OA were in the ratio of 1 : 20 between soil and acid solution during 2 hr reaction under unbuffered pH solutions. At the optimized reaction conditions, the removal efficiencies were compared with that of 0.1 M HC1 and ethylenediamine tetraacetic acid(EDTA). TA showed higher efficiency on the removal of Pb than that of EDTA, which established for the remediation of contaminated soil with Pb and Cd metals. The recovery of metal ions from washing solution was achieved by adding calcium hydroxide and sodium sulfide by forming the precipitation of metal hydroxide and metal sulfide. Optimum amounts of sodium sulfide and calcium hydroxide were Cd = 25g/l, Cu = 5∼10g/l and Pb = 5∼10g/l for the washing solution of OA and 2∼5g/l for the washing solution of TA, respectively. The amounts of Na_2S and Ca(OH)_2 for the tartaric acid was less than that of oxalic acid.