Microstructural Evaluation of Progress of Lime Pozzolanic Reactions in Stabilization and Solidification of Zn Contaminant

Subject Areas : Heavy metal

Vahidreza Ouhadi ¹ , Mohammad Amiri ² , Mohammadhassan Bagher ³

1 - Prof., Bu-Ali Sina University, Faculty of Engineering
2 - Assistant Professor, Hormozgan University, Faculty of Engineering
3 - Master Student, Bu-Ali Sina University, Faculty of Engineering

Received: 2014-05-07 Accepted : 2014-11-12 Published : 2016-03-20

Keywords: Stabilization and Solidificati, Zn contaminant, Lime, C-S-H Nanostructure, XRD,

Abstract :

Introduction and objective: The present research aims to investigate the mechanism of clay particles - heavy metal contaminant - lime interaction process over time from a microstructural point of view. Material and method: To achieve this objective, different percentage of lime was added to a laboratory contaminated natural soil. Then, the mechanism of contaminant retention was analyzed through studying pH changes and evaluating microstructure study (XRD). Result and discussion: The results of this research show that the addition of 10% lime to the contaminated natural clay not only stabilizes the soil, but also for a sample contaminated with 250 cmol/kg-soil concentration of zinc as a heavy metal, more than 37% increase in retention observes. The XRD evaluation shows that the presence of heavy metal contaminant reduces the extent of lime-clay interaction; consequently a reduction in the formation of C-S-H and C-A-H nanostructures happens. Based on the results of XRD experiment and soil contaminant retention measurement of the treated sample with less than 6% lime, the presence of heavy metal contaminant was probably the main cause for  peak intensity reduction of clay minerals. The results of this research show that the formation of C-S-H nanostructure improves absorption characteristics due to its high specific surface area.  In addition, its formation reduces contaminant mobility through encapsulation of heavy metal ions (solidification). Moreover, the presence of heavy metal contaminant of zinc reduces C-S-H nanostructure formation, in a way that the presence of 25 cmol/kg-soil of heavy metal contaminant of zinc reduces peak intensity of C-S-H nanostructure about 90 CpS.

References:

1. Krishna B. G. and Gupta, S. S., (2008). "Adsorption of a few heavy metals on natural and modified kaolinite and montmorillonite: A review", Advances in Colloid and Interface Science 140, pp. 114–131.


2. Ouhadi, V.R., and Amiri, M., (2011). "Geo-environmental Behaviour of Nanoclays in Interaction with Heavy Metals Contaminant", Amirkabir J, Civil, 42, 3, pp. 29-36.


3. Ouhadi,V.R., Amiri, M., and Goodarzi, A.R., "The Special Potential of Nano-Clays for Heavy Metal Contaminant Retention in Geo-Environmental Projects", Journal of Civil and Surveying Engineering, Vol. 45 (2012), pp. 631-642


4. Guozhong. C. and Glen. E. F. (2007). "Environmental Applications of Nanomaterials Synthesis, Sorbents and Sensors". Imperial College Press, pp. 507.


5. Sevim, İ. and Seniha, F. G., (2005), "Investigation of rheological and colloidal properties of bentonitic clay dispersion in the presence of a cationic surfactant", Progress in Organic Coatings.  54 (1), pp. 28-33.


6. Taylor, H.F.W. (1993). "Nanostructure of C–S–H: current status". Advanced Cement Based Materials 1, pp. 38–46.


7. Chen, Q.Y., Tyrer, M., Hills, C.D and Yang, X.M. (2009), "Immobilization of heavy metal in cement-based solidification/stabilization: a review", Waste Manage., 29, pp. 390–403


8. Desogus, P., Manca, P.P., Orrù, G and Zucca, A. (2013)."Solidification/stabilization of landfill leachate concentrate using different aggregate materials", Minerals Engineering, 45, pp. 47-54.


9. Murat, M.L. and Yüksel, Y., (2001). "Potential use of fly ash bentonite mixture as liner or cover as waste disposal areas" Environ. Geol., 40, pp. 1316–1324


10. Bonen, D. and Shondeep, L.S., (1995), "The effects of simulated environmental attack on immobilization of heavy metals doped in cement-based materials" J. Hazard. Mater., 40, pp. 321–335.


11. Hong, S.Y. and Glasser, F.P. (2002)."Alkali sorption by C–S–H and C–A–S–H gels – part II. Role of alumina". Cement and Concrete Research 32 (7), pp. 1101–1111.


12. Malviya, R. and Chaudhary, R. (2006). "Factors affecting hazardous waste solidification/stabilization: a review". Journal of Hazardous Materials 137, pp. 267–276.


13. American Society for Testing and Materials, (1992). "ASTM, 1992 American Society for Testing and Materials, ASTM, Annual Book of ASTM Standards", P.A., Philadelphia V.4, 08.


14. EPA, (1983), “Process design manual, land application of municipal sludge, Municipal Environmental Research Laboratory”, EPA-625/1-83-016, U.S. Government Printing Offices, New York.


15. Hesse, P. R., (1971), “A textbook of soil chemical analysis”, William Clowes and Sons, 519p.


16. Eltantawy and Arnold, I.N., (1973), “Reappraisal of ethylene glycol mono-ethyl ether (EGME) method for surface area estimation of clays”, Soil Sci. 24, pp. 232–238.


17. Handershot, W. H and Duquette, M., (1986), “A simple barium chloride method for determining cation exchange capacity and exchangeable cations”, Soil Sci. Soc. Am. J. 50, pp. 605–608.


18. Ouhadi. V.R and Yong. R.N., (2003),“Experimental and theoretical evaluation of impact of clay microstructure on the quantitative mineral evaluation by XRD analysis,”Appl. Clay Sci, 23. Pp. 141-148.


19. Yong, R. N. and Phadangchewit, Y., (1993), “pH Influence on selectivity and retention of heavy metals in some clay soils”, Can. Geotech. J., 30, pp. 821-833


20. Yong, R. N. and Warkentin, B. P. and Phadangchewit, Y. and Galvez, R., (1990) "Buffer capacity and lead retention in some clay minerals",  Water, Air, Soil, Pollution, J., 53, pp. 53-67.