Effects of Cr³⁺, Cu²⁺, and Pb²⁺ on Fly Ash based Geopolymer

Abstract

The effects of Cr³⁺, Cu²⁺, and Pb²⁺ on compressive strength, reaction products, and pore structures of fly ash based geopolymer were studied. In addition, the immobilization and bonding interaction between heavy metal and fly ash based geopolymers were investigated by X-ray photoelectron spectroscopic (XPS) and environmental scanning electron microscope (ESEM) techniques. The experimental results showed that the incorporation of Cr³⁺, Cu²⁺, and Pb²⁺ had a great effect on the later compressive strength and resulted in producing reinhardbraunsite in the solidified body. Moreover, the Pb²⁺ reduced the total pore volume of the solidified body, while Cr³⁺ and Cu²⁺ increased it. The XPS results indicated that O(1s), Si(2p), and Al(2p) bind energy increased due to Cr³⁺ and Cu²⁺ addition, but it did not change significantly due to Pb²⁺ addition. The microstructure of calcium silicate hydrate (C-S-H) gel and sodium silicoaluminate hydrate (N-A-S-H) gel changed in different degree according to the ESEM results. The immobilization of Cr³⁺, Cu²⁺, and Pb²⁺ using fly ash based geopolymer is attributed not only to the physical encapsulation, but also to the chemical bonding interaction.

Keywords

geopolymer / heavy metal / chemical bonding interaction / physical encapsulation

References

[1] Jaarsveld JGSV, Deventer JSJ, Lorenzen L. Factors Affecting the Immobilization of Metals in Geopolymerized Fly Ash[J]. Metallurgical and Materials Transactions B, 1998, 29(1): 283-291.

[2] Zhang JG, Provis JL, Feng DW, et al. Geopolymers for Immobilization of Cr⁶⁺, Cd²⁺, and Pb²⁺[J]. Journal of Hazardous Materials, 2008, 157(2-3): 587-598.

[3] Xu JZ, Zhou YL, Chang Q, et al. Study on the Factors of Affecting the Immobilization of Heavy Metals in Fly Ash-Based Geopolymers[J]. Materials Letters, 2006, 60(6): 820-822.

[4] Jin MT. Immobilization of Heavy Metals in Municipal Solid Waste Incineration(MSWI) Fly Ash with Geopolymer [D], 2011 Nanjing: Nanjing University of Science and Technology.

[5] Cheng TW, Lee ML, Ko MS, et al. The Heavy Metal Adsorption Characteristics on Metakaolin-Based Geopolymer[J]. Applied Clay Science, 2012, 56(2): 90-96.

[6] Al-Zboon K A-, Harahsheh MS, Hani FB. Fly Ash-Based Geopolymer for Pb Removal from Aqueous Solution[J]. Journal of Hazardous Materials, 2011, 188(1): 414-421.

[7] Wang SB, LI L, Zhu ZH. Solid-State Conversion of Fly Ash to Effective Adsorbents for Cu Removal from Wastewater[J]. Journal of Hazardous Materials, 2007, 139(2): 254-259.

[8] Davidovits J. Geopolymer Chemistry and Applications[M], 2008

[9] Li S. Inorganic Polymer-Statusin Geopolymer Material[J]. Journal of Functional Materials, 2007, 38(9): 3

[10] Guo XL, Shi HS. Experiment Analysis High-Calcium Fly Ash Geopolymers Solidification/Stabilization of Heavy Metal[J]. Journal of Civil, Architectural and Environment Engineering, 2013, 35(2): 124-128.

[11] Bulletin of The Chinese Ceramic Society, 2007, 26(3

[12] Phair J, Deventer JV, Smith J. Effect of Al Source and Alkali Activation on Pb and Cu Immobilisation in Fly-Ash Based “Geopolymers”[J]. Applied Geochemistry, 2004, 19(3): 423-434.

[13] Zhu Q, Lu DY. Preparation and Compatibility of Geopolymer Matrix for Stabilization/Solidification of Heavy Metal Ions[J]. Journal of Nanjing University of Technology(Natural Science Edition), 2010, 32(3): 61-66.

[14] Guo B, Pan D, Liu B, et al. Immobilization Mechanism of Pb in Fly Ash-Based Geopolymer[J]. Construction and Building Materials, 2017, 134(3): 123-130.

[15] Everett D. Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry[J]. Pure and Applied Chemistry, 1972, 31(4): 577-638.

[16] Zheng L, Wang W, Shi Y. The Effects of Alkaline Dosage and Si/ Al Ratio on The Immobilization of Heavy Metals in Municipal Solid Waste Incineration Fly Ash-Based Geopolymer[J]. Chemosphere, 2010, 79(6): 665-671.

[17] Black L, Stumm A, Garbev K, et al. X-Ray Photoelectron Spectroscopy of Aluminium - Substituted Tobermorite[J]. Cement and Concrete Research, 2005, 35(1): 51-55.

[18] Sophia AC, Swaminathan K. Assessment of the Mechanical Stability and Chemical Leachability of Immobilized Electroplating Waste[J]. Chemosphere, 2005, 58(1): 75-82.

[19] Wang X, Yan BL, Wang L, et al. The Research on Capturing Several Heavy Metal Irons and Its Stability of C-S-H with Different Ca/Si[J]. Bulletin of The Chinese Ceramic Society, 2012, 31(6): 1

[20] Guo XL, Shi HS. Research on Solidfication/Stabilization of Heavy Metal Ions by Class C Fly Ash Geopolymer[J]. Journal of Building Materials, 2013, 15(6): 751-754.