飛灰與底渣是都市垃圾焚化（MSWI）後之固體副產物，其去化及資源化都是當前環保重要課題。其中飛灰中的反應灰(R-FA)因其含有氯鹽、硫酸鹽及重金屬，為一有害事業廢棄物，會對鋼筋混凝土產品造成鋼筋腐蝕及混凝土耐久性之問題，影響其資源化之途徑，目前多經固化/穩定化後送往掩埋場處置。文獻指出層狀雙氫氧化物(LDHs)是一種以二價與三價金屬離子中間夾帶陰離子及結晶水的礦物，而弗氏鹽為LDHs其中一種，是自然界中少數穩定的含氯礦物，若能掌握LDHs生成條件及其對氯鹽之穩定化作用，不僅能促進反應灰之資源循環利用，更可紓緩掩埋場漸趨飽和的問題。
本研究以焚化飛灰中的反應灰（R-FA）為對象，首先利用試藥級的NaAlO2及Ca(OH)2以高水灰比的條件探討R-FA生成LDHs的最佳條件，並觀察其液相及固相中氯鹽及重金屬之分布，判斷其穩定效果。而為達成產製過程零廢水的目標，降低產製LDHs的用水量，探討最佳水消耗量，並檢討添加R-FA生成的LDHs於水泥砂漿時之影響，評估做為綠色工程材料之可行性。
研究結果顯示，R-FA中含有高達43%的水溶性氯鹽及9.4%的水溶性鈣，為產製LDHs潛力之材料。本研究藉由添加NaAlO2、Ca(OH)2與水製作LDHs粉體。在純添加NaAlO2之情形下，當NaAlO2添加劑量比為1.2時，其Cl穩定化效果為7%，對於Pb、Zn亦具穩定效果。因反應灰中Ca不足，故僅添加NaAlO2對Cl的穩定效果有限。
根據NaAlO2劑量調整Ca(OH)2劑量做為額外鈣源之後，可以發現在NaAlO2劑量為0.9，Ca(OH)2劑量為1.2時，Cl總穩定效果最佳達49%，且相較僅添加NaAlO2時，其Pb、Zn之溶出大幅減少。另外當實際所添加之鋁、鈣藥劑量超過理論生成LDHs所需的藥劑量時，可觀察到Katoite晶相，是一種單純由Ca、Al金屬離子所構成的LDH，雖具吸附重金屬之潛力，但對於Cl鹽的穩定化沒有貢獻。晶相中的Ca(OH)2的殘留可以視為是Cl穩定化反應達濃度平衡之指標。再溶出試驗結果顯示，無論產製LDHs的過程中添加多少藥劑，其所生成的LDHs之Cl再溶出穩定度皆可達90 %，顯示產出之LDHs對Cl離子的穩定性佳。
後續以最佳Cl總穩定度之LDH所添加之藥劑量：NaAlO2劑量0.9及Ca(OH)2劑量1.2，探討降低用水量的實驗得知，水灰比為5時R-FA的Cl穩定效果較佳，可達45%。pH值的高低影響LDHs對Cl的穩定效果，LDHs在初始pH值4以下時，Cl的溶出會大幅上升，而在中性及鹼性環境下，LDHs對於Cl的穩定度較佳。此外，將LDHs應用於水泥砂漿時，其添加對於水泥會有些許緩凝效果，並大幅降低溶出之Cl鹽，可知其有作為綠色工程材料之潛力。
綜合而言，本研究以R-FA產製LDHs，得知添加NaAlO2及Ca(OH)2可成功穩定R-FA中的Cl鹽及重金屬。在水灰比為5、NaAlO2劑量為0.9及Ca(OH)2劑量為1.2的條件下產製LDHs時，Cl總穩定效果達45%，重金屬Pb、Zn之溶出大幅降低，屬於無廢水、低耗能之綠色製程，且具有工程應用價值及優良環境效益。

Fly ash is the solid by-products of MSWI, and their depletion and recycling are important issues of environmental protection at present. Among them, the reactive fly ash (R-FA) is a hazardous industrial waste because it contains chlorides, sulfates and heavy metals. It will cause corrosion in reinforced concrete products and affect its resource utilization. At present, most of them are sent to the landfill for disposal after being solidified/stabilized. The literature pointed out that layered double hydroxides (LDHs) are minerals with anions and crystal water between divalent and trivalent metal ions. Friedel's salt is one of the LDHs and is one of the few stable chloride-containing minerals in nature. If we can clarify the formation conditions of LDHs and its stabilizing effect on chloride salts, it can not only promote the recycling of R-FA, but also alleviate the problem of gradual saturation of landfills. In this study, LDHs are produced by magnet mixing R-FA, NaAlO2, Ca(OH)2 and water. Observe the Cl and heavy metal in solid and liquid phase respectively. Use XRD to confirm LDHs crystal phase.
Research results show that R-FA contains up to 43% soluble Cl and 9.4% soluble Ca, which is a potential material for producing LDHs. In the case of pure addition of NaAlO2, its Cl stability is 7%, when the dosage ratio of NaAlO2 is 1.2. It also has a stabilizing effect on Pb and Zn. After adjusting the dosage of Ca(OH)2 according to the dosage of NaAlO2, it can be found that when the dosage of NaAlO2 is 0.9 and the dosage of Ca(OH)2 is 1.2, the total stabilization effect of Cl is the best 49%. It is found that the Cl stability can reach 45%, when the water-cement ratio is 5. LDHs is unstable when pH value is smaller than 4. In addition, when LDHs are applied to cement mortar, the addition of LDHs will have a little retarding effect on the cement and greatly reduce the dissolved Cl, which shows that it has the potential as a green engineering material.

參考文獻
Abate, C., & Scheetz, B. E. Aqueous Phase Equilibria in the System CaO-Al2O3-CaCl2-H2O: The Significance and Stability of Friedel's Salt. Journal of the American Ceramic Society, 78(4), 939-944, 1995.
Atwood, J. L. Comprehensive supramolecular chemistry II: Elsevier, 2017.
Auerbach, S. M., Carrado, K. A., & Dutta, P. K. Handbook of layered materials: CRC press, 2004.
Balonis, M., Lothenbach, B., Le Saout, G., & Glasser, F. P. Impact of chloride on the mineralogy of hydrated Portland cement systems. Cement and Concrete Research, 40(7), 1009-1022, 2010.
Becchio, C., Corgnati, S. P., Kindinis, A., & Pagliolico, S. Improving environmental sustainability of concrete products: Investigation on MWC thermal and mechanical properties. Energy and Buildings, 41(11), 1127-1134, 2009.
Chang, C.-Y., Wang, C.-F., Mui, D. T., Cheng, M.-T., & Chiang, H.-L. Characteristics of elements in waste ashes from a solid waste incinerator in Taiwan. Journal of Hazardous Materials, 165(1), 766-773, 2009.
Charbaji, M., Baalbaki, O., Elkordi, A., & Khatib, J. Processing of incinerated municipal solid waste fly ash for use in concrete. International Journal of Civil Engineering and Technology, 9, 1853-1864, 2018.
Chen, P., Ma, B., Tan, H., Liu, X., Zhang, T., Qi, H., . . . Wang, J. Effects of amorphous aluminum hydroxide on chloride immobilization in cement-based materials. Construction and Building Materials, 231, 117171, 2020.
Choi, Y.-S., Kim, J.-G., & Lee, K.-M. Corrosion behavior of steel bar embedded in fly ash concrete. Corrosion Science, 48(7), 1733-1745, 2006.
Dai, Y., Qian, G., Cao, Y., Chi, Y., Xu, Y., Zhou, J., . . . Qiao, S. Effective removal and fixation of Cr(VI) from aqueous solution with Friedel's salt. Journal of Hazardous Materials, 170(2), 1086-1092, 2009.
Deng, D., Qiao, J., Liu, M., Kołodyńska, D., Zhang, M., Dionysiou, D. D., . . . Chang, M.-b. Detoxification of municipal solid waste incinerator (MSWI) fly ash by single-mode microwave (MW) irradiation: Addition of urea on the degradation of Dioxin and mechanism. Journal of Hazardous Materials, 369, 279-289, 2019.
Drochytka, R., & Černý, V. Influence of fluidized bed combustion fly ash admixture on hydrothermal synthesis of tobermorite in the mixture with quartz sand, high temperature fly ash and lime. Construction and Building Materials, 230, 117033, 2020.
Fahami, A., Duraia, E.-S. M., Beall, G. W., & Fahami, M. Facile synthesis and structural insight of chloride intercalated Ca/Al layered double hydroxide nanopowders. Journal of Alloys and Compounds, 727, 970-977, 2017.
Goh, K.-H., Lim, T.-T., & Dong, Z. Application of layered double hydroxides for removal of oxyanions: A review. Water Research, 42(6), 1343-1368, 2008.
Gruber, K. A., Ramlochan, T., Boddy, A., Hooton, R. D., & Thomas, M. D. A. Increasing concrete durability with high-reactivity metakaolin. Cement and Concrete Composites, 23(6), 479-484, 2001
Hjelmar, O. Waste management in Denmark. Waste Management, 16(5), 389-394, 1996
Hoornweg, D., & Bhada-Tata, P. What a waste: a global review of solid waste management, 2012.
Hu, Y., Zhang, P., Chen, D., Zhou, B., Li, J., & Li, X.-w. Hydrothermal treatment of municipal solid waste incineration fly ash for dioxin decomposition. Journal of Hazardous Materials, 207-208, 79-85, 2012.
Jiang, J.-g., Du, X.-j., Chen, M.-z., & Zhang, C. Continuous CO2 capture and MSWI fly ash stabilization, utilizing novel dynamic equipment. Environmental Pollution, 157(11), 2933-2938, 2009.
Jones, M. R., Macphee, D. E., Chudek, J. A., Hunter, G., Lannegrand, R., Talero, R., & Scrimgeour, S. N. Studies using 27Al MAS NMR of AFm and AFt phases and the formation of Friedel's salt. Cement and Concrete Research, 33(2), 177-182, 2003.
Kim, T. The effects of polyaluminum chloride on the mechanical and microstructural properties of alkali-activated slag cement paste. Cement and Concrete Composites, 96, 46-54, 2019.
Kulkarni, P. S., Crespo, J. G., & Afonso, C. A. M. Dioxins sources and current remediation technologies — A review. Environment International, 34(1), 139-153, 2008.
Kurashima, K., Matsuda, K., Kumagai, S., Kameda, T., Saito, Y., & Yoshioka, T. A combined kinetic and thermodynamic approach for interpreting the complex interactions during chloride volatilization of heavy metals in municipal solid waste fly ash. Waste Management, 87, 204-217, 2019.
Liang, M.-T., Huang, R., & Jheng, H.-Y. Revisited to the relationship between the free and total chloride diffusivity in concrete. Journal of Marine Science and Technology, 18, 442-448, 2010.
Lu, J.-W., Zhang, S., Hai, J., & Lei, M. Status and perspectives of municipal solid waste incineration in China: A comparison with developed regions. Waste Management, 69, 170-186, 2017.
Ma, J., Li, Z., Zhang, Y., & Demopoulos, G. P. Desilication of sodium aluminate solution by Friedel's salt (FS: 3CaO·A12O3·CaCl2·10H2O). Hydrometallurgy, 99(3), 225-230, 2009.
Park, Y. J., & Heo, J. Vitrification of fly ash from municipal solid waste incinerator. Journal of Hazardous Materials, 91(1), 83-93, 2002.
Pereira, J. A. M., Schwaab, M., Dell'Oro, E., Pinto, J. C., Monteiro, J. L. F., & Henriques, C. A. The kinetics of gibbsite dissolution in NaOH. Hydrometallurgy, 96(1), 6-13, 2009.
Rives, V. Layered double hydroxides: present and future: Nova Publishers, 2001.
Shi, C., Hu, X., Wang, X., Wu, Z., & Schutter, G. d. Effects of Chloride Ion Binding on Microstructure of Cement Pastes. Journal of Materials in Civil Engineering, 29(1), 04016183, 2017.
Sun, X., Li, J., Zhao, X., Zhu, B., & Zhang, G. A Review on the Management of Municipal Solid Waste Fly Ash in American. Procedia Environmental Sciences, 31, 535-540, 2016.
Suryavanshi, A. K., Scantlebury, J. D., & Lyon, S. B. Mechanism of Friedel's salt formation in cements rich in tri-calcium aluminate. Cement and Concrete Research, 26(5), 717-727, 1996.
Um, N. Effect of Cl Removal in MSWI Bottom Ash via Carbonation with CO2 and Decomposition Kinetics of Friedel’s Salt. MATERIALS TRANSACTIONS, 60(5), 837-844, 2019.
Yamaguchi, H., Shibuya, E., Kanamaru, Y., Uyama, K., Nishioka, M., & Yamasaki, N. Hydrothermal decomposition of PCDDs/PCDFs in MSWI fly ash. Chemosphere, 32(1), 203-208, 1996.
Zhang, D., Jia, Y., Ma, J., & Li, Z. Removal of arsenic from water by Friedel's salt (FS: 3CaO·Al2O3·CaCl2·10H2O). Journal of Hazardous Materials, 195, 398-404, 2011.
行政院環境保護署，環境白皮書，245–277頁，2018。
李祐承，焚化飛灰與脫硫石膏產置高溫蒸氣養護氣泡混凝土之研究，國 立成功大學環境工程學系，碩士論文，2013。
黃兆龍，混凝土性質與行為（初版），詹氏出版社，台灣，2007。
陳豪吉，焚化廠反應灰及飛灰再生為輕質粒料之研究內政部建築研究 所委託研究報告，2008。
謝錦松，黃正義，固體廢棄物處理，淑馨出版社，台北市，1997。
曾亦宏，飛灰中戴奧辛類化合物之分佈特性研究，屏東科技大學，環境 工程與科學系，碩士論文，2003。
曾迪華，廢棄物與資源再生，環境工程會刊，1–16頁，2012。
張建智，電化學除鹽對含氯混凝土中鋼筋腐蝕行為及握裹性質影響之 研究，國立海洋大學，河海工程學系，碩士論文，2000。
胡靜，呂亮，鎂鋁水滑石去除氯鹽性能研究，工業水處理，28卷，59– 60頁，2008。
曾淑滿，高氯含量廢水去除氯離子之研究，國立台北科技大學，資源工程學系，碩士論文，2011。
劉厚伯，垃圾焚化飛灰產製鈣矽水合材料及氯鹽穩定化之探討，國立成功大學環境工程學系，碩士論文，2019。
鄭智龍，焚化飛灰特性及氯含量分析方法之研究，東海大學環境科學與工程學系，碩士論文，2013