Co-hydrothermal processing for stabilize of different waste incinerator fly ash and its mechanism
RUAN Yu1, ZONG Da2, CHEN Zhi-liang1, ZHANG Han-wei2, HUANG Qun-xing1, LU Sheng-yong1, CHI Yong1, YAN Jian-hua1
1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China;
2. Everbright Green Environmental Protection Institute, Nanjing 211100, China
MSWI fly ash is rich in heavy metals which is easily leached to pollute the environment. By studying the physical and chemical characteristics of fly ash in fluidized bed and grate furnace, it was found that hibschite and tobermorite could be co-hydrothermally synthesized by the fluidized-bed fly ash and grate-furnace fly ash without any additives. The fluidized-bed fly ash is used as a source of silicon and aluminum while the grate-furnace fly ash is used as an alkali activator. Heavy metals were stabilized in the crystal. The mechanism of hydrothermal synthesis was analyzed based on the hydrothermal products and the surface morphology of fly ash. The mechanism of adsorption of heavy metals was explained by the crystal structure of tobermorite. There was almost no heavy metal in the liquid phase after the hydrothermal reaction. The leaching toxicity of heavy metals was quantitatively evaluated with heavy metal leaching rate. Heavy metal leaching rate of fly ash after hydrothermal reaction was significantly lower than that of fluidized bed fly ash. When the mass ratio of fluidized bed fly ash to grate furnace fly ash added by the hydrothermal reaction was 7:3, the leaching rates of Cd, Cr, Cu, Pb, and Zn after hydrothermal heating were the lowest. The leaching rates were 0.073%, 0.006%, 0.107%, 0.006%, 0.326%, respectively.
阮煜, 宗达, 陈志良, 张汉威, 黄群星, 陆胜勇, 池涌, 严建华. 水热法协同处置不同垃圾焚烧炉飞灰及其机理[J]. 中国环境科学, 2018, 38(7): 2602-2608.
RUAN Yu, ZONG Da, CHEN Zhi-liang, ZHANG Han-wei, HUANG Qun-xing, LU Sheng-yong, CHI Yong, YAN Jian-hua. Co-hydrothermal processing for stabilize of different waste incinerator fly ash and its mechanism. CHINA ENVIRONMENTAL SCIENCECE, 2018, 38(7): 2602-2608.
Zhang H Y, Zhao Y C, Qi J Y. Characterization of heavy metals in fly ash from municipal solid waste incinerators in Shanghai[J]. Process Safety and Environmental Protection, 2010,88(2):114-124.
[5]
Nollet H, Roels M, Lutgen P, et al. Removal of PCBs from wastewater using fly ash[J]. Chemosphere, 2003,53(6):655-665.
Hollmana G G, Steenbruggena G, Janssen-Jurkovicova M. A two-step process for the synthesis of zeolites from coal fly ash[J]. Fuel, 1999,78(10):1225-1230.
[12]
Musyoka N M, Ren J W, Langmi H W, et al. A comparison of hydrogen storage capacity of commercial and fly ash-derived zeolite X together with their respective templated carbon derivatives[J]. International Journal of Hydrogen Energy, 2015,40(37):12705-12712.
[13]
Karamanis D, Vardoulakis E. Application of zeolitic materials prepared from fly ash to water vapor adsorption for solar cooling[J]. Applied Energy, 2012,97(9):334-339.
[14]
Shigemoto N, Hayashi H, Miyaura K. Selective formation of Na-X zeolite from coal fly ash by fusion with sodium hydroxide prior to hydrothermal reaction[J]. Journal of Materials Science, 1993,28(17):4781-4786.
[15]
Hui K S, Chao C Y, Kot S C. Removal of mixed heavy metal ions in wastewater by zeolite 4A and residual products from recycled coal fly ash[J]. Journal of Hazardous Materials, 2005,127(1-3):89-101.
Yang G C C, Yang T Y. Synthesis of zeolites from municipal incinerator fly ash[J]. Journal of Hazardous Materials, 1998,62(1):75-89.
[18]
Fan Y, Zhang F S, Zhu J X, et al. Effective utilization of waste ash from MSW and coal co-combustion power plant-Zeolite synthesis[J]. Journal of Hazardous Materials, 2008,153(1/2):382-388.
Luo F, Wei C D, Xue B, et al. Dynamic hydrothermal synthesis of Al-substituted 11Å tobermorite from solid waste fly ash residue-extracted Al2O3[J]. Research on Chemical Intermediates, 2012,39(2):693-705.
Show S, Clark S M, Henderson C M B. Hydrothermal Formation of the Calcium Silicate Hydrates, Tobermorite (Ca5Si6O16(OH)2×4H2O) and Xonotlite (Ca6Si6O(OH)2):An in situ Synchrotron Study[J]. Chemical Geology, 2000,167(1/2):129-140.
[25]
Richardson I G. The calcium silicate hydrates[J]. Cement & Concrete Research, 2008,38(2):137-158.
[26]
Jing Z Z, Fan X W, Zhou L. Hydrothermal solidification behavior of municipal solid waste incineration bottom ash without any additives[J]. Waste Management, 2013,33(5):1182-1189.
[27]
Coleman N J, Brassington D S, Raza A, et al. Sorption of Co2+ and Sr2+ by waste-derived 11A? tobermorite[J]. Waste Management, 2006,26(3):260-267.
[28]
Merlino S, Bonaccorsi E, Armbruster T. Tobermorites:Their real structure and order-disorder (OD) character[J]. American Mineralogist, 1999,84(10):1613-1621.
[29]
Hamid S A. The crystal structure of the 11Å natural tobermorite Ca2.25[Si3O7.5(OH)1.5]·1H2O[J]. Zeitschrift für Kristallographie, 1981, 154(1-4):189-198.
[30]
Merlino S, Bonaccorsi E, Armbruster T. The real structure of tobermorite 11Å:normal and anomalous forms, OD character and polytypic modifications[J]. European Journal of Mineralogy, 2001, 13(3):65-80.
[31]
LI X Y, Chen Q Y, Zhou Y S. Stabilization of heavy metals in MSWI fly ash using silica fume[J]. Waste Management, 2014,34(12):2494-2504.
[32]
Larosa-Thompson J L, Grutzeck M W. C-S-H, tobermorite, and coexisting phases in the system CaO-Al2O3-SiO2-H2O[J]. World Cement, 1996,27(1):69-74.
[33]
Miyake M, Niiya S, Matsuda M. Microwave-assisted Al-substituted tobermorite synthesis[J]. Journal of Materials Research, 2000,15(4):850-853.
[34]
Murayama N, Yamamoto H, Shibata J. Mechanism of zeolite synthesis from coal fly ash by alkali hydrothermal reaction[J]. International Journal of Mineral Processing, 2002,64(1):1-17.
[35]
Houston J R, Maxwell R S, Carroll S A. Transformation of meta-stable calcium silicate hydrates to tobermorite:reaction kinetics and molecular structure from XRD and NMR spectroscopy[EB/OL]. http://www.geochemicaltransactions.com/content/10/1/1,2009-01-10.
[36]
Matsui K, Kikuma J, Tsunashima M, et al. In situ time-resolved X-ray diffraction of tobermorite formation in autoclaved aerated concrete:Influence of silica source reactivity and Al addition[J]. Cement and Concrete Research, 2011,41(5):510-519.
