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通过半动态淋滤试验,研究淋滤液pH分别为2,4,7时水泥固化铅污染土的溶出特性,以定量评价水泥固化铅污染土的环境安全特性。结果表明,当淋滤液初始pH为2时,试样中累积铅溶出质量约为pH为4和7时的47~106倍;而pH为4和7时累积铅溶出质量差别不明显。试样水泥掺量由12%提高到18%时,试样累积铅溶出质量降低了28%~68%,表明增大水泥掺量有利于铅的固定。通过对试验结果的理论分析,求算得出了铅扩散系数De;淋滤液初始pH=4,7时De很接近;而淋滤液初始pH=2时,De比pH=4或7时的De高约3,4个数量级;当水泥掺量由12%提高到18%时,试样De降低了约17%~99%。上述研究结果表明,强酸性淋滤液和水泥掺量明显影响固化污染土中铅溶出量和扩散系数。
The semi-dynamic leaching test was used to study the leaching characteristics of cement-contaminated lead contaminated soil with leachate pH of 2, 4 and 7 respectively to quantitatively evaluate the environmental safety characteristics of cement-contaminated lead contaminated soil. The results showed that when the initial pH of the leachate was 2, the mass of accumulated lead in the sample was about 47 ~ 106 times higher than that at pH 4 and 7. However, there was no significant difference in the mass of leached Pb between 4 and 7 at pH 4. When the sample cement content increased from 12% to 18%, the mass of lead accumulated in the sample decreased by 28% ~ 68%, indicating that increasing the cement content is conducive to the fixing of lead. Through the theoretical analysis of the test results, the lead diffusion coefficient De was calculated. When the initial pH value of the leachate was 4,7, the De was very close. When the leachate initial pH value was 2, De was higher than De = About 3 and 4 orders of magnitude. When the cement content increased from 12% to 18%, the sample De decreased about 17% ~ 99%. The above results show that strong acid leachate and cement content significantly affect the solidified contaminated soil lead elution and diffusion coefficient.