铬污染土壤还原固化稳定化药剂的筛选

龚亚龙 范敏 高晓梅 宋安康 胡思扬

摘 要：固化/穩定化技术是铬污染土壤处置的有效手段，不同性质的药剂对铬的还原、吸附、固化效果不同，优选出低价、高效的药剂对治理铬污染土壤具有重大的意义。采用常见的7种还原剂、10种吸附剂和6种固化剂分别对铬污染土壤进行修复，筛选出较好的还原剂、吸附剂和固化剂，并研究不同添加量对药剂修复效果的影响。研究结果表明：多硫化钙、硫化钠、氯化亚铁和硫酸亚铁优选为铬污染土壤还原剂，其中多硫化钙的效果最好，当投加摩尔比为0.8时，六价铬的稳定效率达90%以上;钙镁磷肥、弱碱性阴离子交换树脂、氧化镁和三水铝石为优选铬污染土壤吸附剂，综合考虑，钙镁磷肥的效果最好，当投加质量比为20%时，六价铬的稳定效率达90%以上，总铬的稳定效率达80%以上;粒化高炉矿渣粉（分别购自重庆、河南）和水玻璃为优选铬污染土壤固化剂，其中粒化高炉矿渣粉（重庆）效果最好，当投加质量比为16%时，六价铬的固化效率达98%以上，总铬的固化效率达70%以上。所用材料在修复铬污染土壤方面发挥了重要作用，在实验室能达到较高的六价铬稳定性效率，作为铬固化/稳定化药剂的潜在价值及其修复效果值得在大规模的现场试验中进一步研究。

关键词：铬污染土壤;土壤修复;还原;固化稳定化;药剂

Abstract： Solidification/stabilization was an effective mean for the remediation of chromium （Cr）-contaminated soil. Different agents differ in their abilities of Cr-reduction， adsorption and stabilization. Screening agents that are low-cost and high-efficiency is vital to remediate Cr-contaminated soil. In the present study， in order to screen out the better reductants， adsorbents and stabilizers and study on the effect of different dosage on remediation，seven reductants， ten adsorbents and six stabilizers in different doses were used as amendments to remediate Cr-contaminated soil， respectively.The main findings were as follows： （1） Calcium polysulfide （CPS）， sodium sulfide （Na2S）， ferrous chloride （FeCl2） and ferrous sulfate （FeSO4） can be used as reducing materials of Cr-contaminated soil. CPS had the best Cr （VI）-stability efficiency exceeding 90% when it was added at the mole ratio of 0.8.（2） Calcium magnesium phosphate （CMP）， weak-base anion-exchange resin （WAR）， magnesium oxide （MgO） and diaspore （Al2O3·3nH2O） can be used as absorbing materials of Cr-contaminated soil. CMP demonstrated the best adsorptivity with Cr （Ⅵ）-stability efficiency being above 90% and total Cr 80% when it was added at the mass ratio of 20%.（3） Furnace slag powder （FSP， bought from Chongqing and Henan） and sodium silicate （Na2SiO3·9H2O） can be used as immobilizing materials of Cr-contaminated soil. FSP from Chongqing was the best in immobilizing Cr （Ⅵ） with stability efficiency reaching 98% and total Cr higher 70% when it was added at the mass ratio of 16%. In conclusion， the materials used in this study played important role in remediation of Cr-contaminated soil and achieved the high Cr （Ⅵ）-stability efficiency under laboratory conditions.Their potential value as Cr-solidification/stabilizing agents and their remediation efficacy deserve further studies in large-scale field trials.

Keywords： chromium-contaminated soil;soil remediation;reduction;solidification/stabilization; agents

铬（Cr）是自然环境中常见的一种金属污染物，也是美国超级基金优先控制的前20种有毒物质之一[1]，主要以六价铬和三价铬形态存在，六价铬比三价铬毒性高100倍[2]，可通过消化、呼吸道、皮肤及粘膜被人体吸收并在体内蓄积[3]。……