Leaching characteristics and mechanism of heavy metal in solidified/ stabilized contaminated soil under acid solution soaking
LI Jiang-shan, WANG Ping, ZHANG Ting-ting, HUANG Qian, XUE Qiang
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
Abstract:KH2PO4—cement is used to soildify/stabilize the Pb contaminated soil. Leaching tests are conducted to study the leaching characteristics and mechanism of Pb in solidified bodies under acid rain soaking, and the effects of KH2PO4 addition, leaching time and leachate pH are took into account. The results show that KH2PO4 is effective to stabilize the Pb-contaminated soil. The Pb leaching is related to pH of leachant directly, and the leaching amount of Pb increases with acidity. What’s more, Pb leaching is also related to pH of leachate, and strong alkaline of leachate is conducive to the Pb mobility. For the acid solutions with pH of 2 and 5, the cumulative leaching ratio of Pb changes with time linearly, but the two-stage linear variation is founded for the acid solutions with pH of 3. pH of the leachate is in relation to the leaching amount of alkaline materials in S/S bodies. The controlling leaching mechanism of Pb changes with leachant pH, and it is presented that the leaching mechanism changes from dissolution to diffusion with the increasing leachant pH.
李江山,王平,张亭亭,黄茜,薛强. 酸溶液淋溶作用下重金属污染土固化体浸出特性及机理[J]. 岩土工程学报, 2017, 39(s1): 135-139.
LI Jiang-shan, WANG Ping, ZHANG Ting-ting, HUANG Qian, XUE Qiang. Leaching characteristics and mechanism of heavy metal in solidified/ stabilized contaminated soil under acid solution soaking. Chinese J. Geot. Eng., 2017, 39(s1): 135-139.
[1] WEI B, YANG L. A review of heavy metal contaminations in urban soils, urban road dusts and agricultural soils from China[J]. Microchemical Journal, 2010, 94: 99-107. [2] BOZKURT S, MORENO L, NERETNIEKS I. Long term processes in waste deposits[J]. The Science of Total Environment, 2000, 250: 101-121. [3] US. EPA, 2004. Treatment technologies for site cleanup: annual status report[R]. 11 th ed. Washington D C: Office of Solid Waste and Emergency Response. [4] 杜延军, 金 飞, 刘松玉, 等. 重金属工业污染场地固化/稳定处理研究进展[J]. 岩土力学, 2011, 32(1): 116-124. (DU Yan-jun, JIN Fei, LIU Song-yu, et al. Review of stabilization/solidification technique for remediation of heavy metals contaminated lands[J]. Rock and Soil Mechanics, 2011, 32(1): 116-124. (in Chinese)) [5] YANG Y, XUE J, HUANG Q. Studies on the solidification mechanisms of Ni and Cd in cement clinker during cement kiln co-processing of hazardous wastes[J]. Construction and Building Materials, 2014, 57: 138-143. [6] JOHN U E, JEFFERSON I, BOARDMAN D I, et al. Leaching evaluation of cement stabilisation/solidification treated kaolin clay[J]. Engineering Geology, 2011, 123(4): 315-323. [7] FLERI M A, WHETSTONE G T. In situ stabilisation/ solidification: project lifecycle[J]. Journal of Hazardous Materials, 2007, 141(2): 441-456. [8] LI X D, POON C S, SUN H, et al. Heavy metal speciation and leaching behaviour in cement based solidified/stabilized waste materials[J]. Journal of Hazardous Materials, 2001, 82(3): 215-230. [9] MOON D H, DEMATAS D. An evaluation of lead leachability from stabilized/solidified soils under modified semi-dynamic leaching conditions[J]. Engineering geology, 2006, 85(1): 67-74. [10] DU Y J, JIANG N J, SHEN S L, et al. Experimental investigation of influence of acid rain on leaching and hydraulic characteristics of cement-based solidified/stabilized lead contaminated clay[J]. Journal of hazardous materials, 2012, 225: 195-201. [11] XUE Q, LI J, LIU L. Effect of Compaction Degree on Solidification Characteristics of Pb-contaminated soil treated by cement [J]. CLEAN-Soil, Air, Water, 2014, 42(8): 1126-1132. [12] CUISINIER O, BORGNE T L, DENEELE D, et al. Quantification of the effects of nitrates, phosphates and chlorides on soil stabilization with lime and cement, Engineering Geology[J]. 2011, 117(3): 229-235. [13] ANS 161, 1986 American national standard for the measurement of the leachability of solidified low-level radioactive wastes by a short-term tests procedure[S]. New York: American National Standards Institute.