為了解決牡蠣殼廢棄物對於環境所造成的影響，本實驗將廢棄的牡蠣殼再利用去除水中氟離子，並探討不同顆粒大小、酸鹼值以及起始濃度對於氟的去除效果，為了避免牡蠣殼在酸性下溶解以及增加其吸附效果，本實驗在其表面改質包覆一層氫氧化鋁來增加穩定性。實驗結果發現，雖然氫氧化鋁並沒有完全包覆而是部分沉積在表面，但大幅提高比表面積以及減少鈣的溶出而有利於吸附反應。吸附反應皆在二至四小時內達到平衡並可以用擬二階動力學模型來描述。在酸鹼值影響方面，在低濃度(10 mg/L)時，改質後牡蠣殼達到最好的效果，但當濃度提高(100 mg/L)時，使用未改質的牡蠣，氟的去除效果到接近100% 且吻合PHREEQC模擬軟體所預測的結果，但不利於改質後牡蠣殼，氟的去除效果皆隨酸鹼值增加而減少。在等溫吸附的結果中顯示，初始氟濃度的不同會影響其反應機制；在低濃度時，實驗結果符合Langmuir 和Freundlich等溫吸附模型，並利用Langmuir 公式推算，改質後牡蠣殼得到單層最大吸附量為5.84 mg/g，推測以吸附反應為主；在高濃度時，吸附量隨氟的平衡濃度線性關係增加，利用X-射線繞射分析和電子能量損失譜結果來推論其主要為沉澱反應。藉由X射線光電子能譜學結果得知，若利用未改質的牡蠣殼，氟主要是藉由和鈣與鎂之間的鍵結而被去除；而改質後的牡蠣則是藉由氟和鋁之間的鍵結或是氟與羥基離子交換所去除。

Waste oyster shell from mariculture is a serious waste problem in the southwest coast of Taiwan. Due to the wide availability and the low cost, it was used as an alternative absorbent for fluoride removal from wastewater. The waste oyster shell is composed of calcium carbonate with some impurities, mainly magnesium. To enhance the stability and adsorption capacity, oyster shell was impregnated with Al(OH)3. There are three kinds of adsorbents used in this study, including original, ground, and impregnated oyster shell. Base on the results of dissolution of Ca2+, it was confirmed that Al(OH)3 was partially impregnated on oyster shell. Kinetic studies showed that the adsorption reached equilibrium in 4 h and could be fitted by pseudo second-order kinetic model. The impregnated oyster shell achieved the highest removal efficiency at pH 7.2 at low initial fluoride concentration (10 mg/L). The removal efficiency of oyster shell without impregnation reached over 90% and was significantly affected by pH at high initial fluoride concentration (100 mg/L). Adsorption isotherms could be fitted by Langmuir and Freundlich isotherm models. Impregnated oyster shell resulted in the highest adsorption capacity of 5.84 mg/g at pH 8. Depending upon initial fluoride concentration, the reaction mechanisms could be adsorption dominant at low initial concentration (< 40 mg/L), and precipitation dominant at high concentration (> 100 mg/L). The proposition was confirmed by XPS, EDS and XRD. The bondings were found between Ca-F and Mg-F in XPS.

Al-Harahsheh, M., Batiha, M., Kraishan, S., and Al-Zoubi, H. (2014). Precipitation treatment of effluent acidic wastewater from phosphate-containing fertilizer industry: Characterization of solid and liquid products. Separation and Purification Technology, 123, 190-199.

Alidoust, D., Kawahigashi, M., Yoshizawa, S., Sumida, H., and Watanabe, M. (2015). Mechanism of cadmium biosorption from aqueous solutions using calcined oyster shells. Journal of Environmental Management, 150, 103-110.

Aoudj, S., Khelifa, A., Drouiche, N., Belkada, R., and Miroud, D. (2015). Simultaneous removal of chromium (VI) and fluoride by electrocoagulation–electroflotation: application of a hybrid Fe-Al anode. Chemical Engineering Journal, 267, 153-162.

Arahman, N., Mulyati, S., Lubis, M. R., Takagi, R., and Matsuyama, H. (2016). The removal of fluoride from water based on applied current and membrane types in electrodialyis. Journal of Fluorine Chemistry, 191, 97-102.

Barathi, M., Kumar, A. S. K., and Rajesh, N. (2013). Efficacy of novel Al–Zr impregnated cellulose adsorbent prepared using microwave irradiation for the facile defluoridation of water. Journal of Environmental Chemical Engineering, 1(4), 1325-1335.

Barathi, M., Kumar, A. S. K., and Rajesh, N. (2015). Aluminium hydroxide impregnated macroreticular aromatic polymeric resin as a sustainable option for defluoridation. Journal of Environmental Chemical Engineering, 3(2), 630-641.

Bejaoui, I., Mnif, A., and Hamrouni, B. (2014). Performance of reverse osmosis and nanofiltration in the removal of fluoride from model water and metal packaging industrial effluent. Separation Science and Technology, 49(8), 1135-1145.

Blum, W. E., de Baerdemaeker, J., Finkl, C. W., Horn, R., Pachepsky, Y., Shein, E. V., and Grundas, S. (2011). Encyclopedia of agrophysics. J. Gliński, J. Horabik, and J. Lipiec (Eds.). Springer Science & Business Media.

Budyanto, S., Kuo, Y. L., and Liu, J. C. (2015). Adsorption and precipitation of fluoride on calcite nanoparticles: A spectroscopic study. Separation and Purification Technology, 150, 325-331.

Cai, H. M., Chen, G. J., Peng, C. Y., Zhang, Z. Z., Dong, Y. Y., Shang, G. Z., Zhu, X. H., Gao, H. J., and Wan, X. C. (2015). Removal of fluoride from drinking water using tea waste loaded with Al/Fe oxides: A novel, safe and efficient biosorbent. Applied Surface Science, 328, 34-44.

Cai, H., Xu, L., Chen, G., Peng, C., Ke, F., Liu, Z., Li, D., Zhang, Z., and Wan, X. (2016). Removal of fluoride from drinking water using modified ultrafine tea powder processed using a ball-mill. Applied Surface Science, 375, 74-84.

Chaudhary, V., and Prasad, S. (2015). Rapid removal of fluoride from aqueous media using activated dolomite. Analytical Methods, 7(19), 8304-8314.

Chen, G. J., Peng, C. Y., Fang, J. Y., Dong, Y. Y., Zhu, X. H., and Cai, H. M. (2016a). Biosorption of fluoride from drinking water using spent mushroom compost biochar coated with aluminum hydroxide. Desalination and Water Treatment, 57(26), 12385-12395.

Chen, T. Y., Huang, H. C., Cao, J. L., Xin, Y. J., Luo, W. F., and Ao, N. J. (2016b). Preparation and characterization of alginate/HACC/oyster shell powder biocomposite scaffolds for potential bone tissue engineering applications. RSC Advances, 6(42), 35577-35588.

Chen, W. T., Lin, C. W., Shih, P. K., and Chang, W. L. (2012). Adsorption of phosphate into waste oyster shell: thermodynamic parameters and reaction kinetics. Desalination and Water Treatment, 47(1-3), 86-95.

Chiou, I. J., Chen, C. H., and Li, Y. H. (2014). Using oyster-shell foamed bricks to neutralize the acidity of recycled rainwater. Construction and Building Materials, 64, 480-487.

Dada, A. O., Olalekan, A. P., Olatunya, A. M., & Dada, O. (2012). Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms studies of equilibrium sorption of Zn2+ unto phosphoric acid modified rice husk. IOSR Journal of Applied Chemistry, 3(1), 38-45.
Dessalegne, M., Zewge, F., and Diaz, I. (2016). Aluminum hydroxide supported on zeolites for fluoride removal from drinking water. Journal of Chemical Technology and Biotechnology.

Dissanayake, C. B. (1991). The fluoride problem in the ground water of Sri Lanka—environmental management and health. International Journal of Environmental Studies, 38(2-3), 137-155.

Dolar, D., Košutić, K., and Vučić, B. (2011). RO/NF treatment of wastewater from fertilizer factory—removal of fluoride and phosphate. Desalination, 265(1), 237-241.

Du, X., Zhao, S., Liu, Y., Li, J., Chen, W., and Cui, Y. (2014). Facile synthesis of monodisperse α-alumina nanoparticles via an isolation-medium-assisted calcination method. Applied Physics A, 116(4), 1963-1969.

Ganvir, V., and Das, K. (2011). Removal of fluoride from drinking water using aluminum hydroxide coated rice husk ash. Journal of Hazardous Materials, 185(2), 1287-1294.

García-Sánchez, J. J., Solache-Ríos, M., Martínez-Gutiérrez, J. M., Arteaga-Larios, N. V., Ojeda-Escamilla, M. C., and Rodríguez-Torres, I. (2016). Modified natural magnetite with Al and La ions for the adsorption of fluoride ions from aqueous solutions. Journal of Fluorine Chemistry, 186, 115-124.

Ghosh, A., Mukherjee, K., Ghosh, S. K., and Saha, B. (2013). Sources and toxicity of fluoride in the environment. Research on Chemical Intermediates, 39(7), 2881-2915.

Ghosh, S. B., Bhaumik, R., and Mondal, N. K. (2016). Optimization study of adsorption parameters for removal of fluoride using aluminium-impregnated potato plant ash by response surface methodology. Clean Technologies and Environmental Policy, 18(4), 1069-1083.

Goldberg, S., Tabatabai, M. A., Sparks, D. L., Al-Amoodi, L., and Dick, W.A. (2005). Equations and models describing adsorption processes in soils. Soil Science Society of America Book Series, 8, 498.

Gong, W. X., Qu, J. H., Liu, R. P., and Lan, H. C. (2012). Effect of aluminum fluoride complexation on fluoride removal by coagulation. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 395, 88-93.

Gunasekaran, S., Anbalagan, G., and Pandi, S. (2006). Raman and infrared spectra of carbonates of calcite structure. Journal of Raman Spectroscopy, 37(9), 892-899.

He, Z., Lan, H., Gong, W., Liu, R., Gao, Y., Liu, H., and Qu, J. (2016). Coagulation behaviors of aluminum salts towards fluoride: Significance of aluminum speciation and transformation. Separation and Purification Technology, 165, 137-144.

Heikens, A., Sumarti, S., Van Bergen, M., Widianarko, B., Fokkert, L., Van Leeuwen, K., and Seinen, W. (2005). The impact of the hyperacid Ijen Crater Lake: risks of excess fluoride to human health. Science of the Total Environment, 346(1), 56-69.

Hsiao, S. T., Chuang, S. C., Chen, K. S., Ho, P. H., Wu, C. L., and Chen, C. A. (2016). DNA barcoding reveals that the common cupped oyster in Taiwan is the Portuguese oyster Crassostrea angulata (Ostreoida; Ostreidae), not C. gigas. Scientific Reports, 6.

Hsu, T. C. (2009). Experimental assessment of adsorption of Cu2+ and Ni2+ from aqueous solution by oyster shell powder. Journal of Hazardous Materials, 171(1), 995-1000.

Huang, C. J., and Liu, J. C. (1999). Precipitate flotation of fluoride-containing wastewater from a semiconductor manufacturer. Water Research, 33(16), 3403-3412.

Huh, J. H., Choi, Y. H., Lee, H. J., Choi, W. J., Ramakrishna, C., Lee, H. W., Lee, S. H., and Ahn, J. W. (2016). The Use of Oyster Shell Powders for Water Quality Improvement of Lakes by Algal Blooms Removal. Journal of the Korean Ceramic Society, 53(1), 1-6.

Jain, S., and Jayaram, R. V. (2009). Removal of fluoride from contaminated drinking water using unmodified and aluminium hydroxide impregnated blue lime stone waste. Separation Science and Technology, 44(6), 1436-1451.
Jung, S., Heo, N. S., Kim, E. J., Oh, S. Y., Lee, H. U., Kim, I. T., Hur, J., Lee, G. W., Lee, Y. C., and Huh, Y. S. (2016). Feasibility test of waste oyster shell powder for water treatment. Process Safety and Environmental Protection, 102, 129-139.

Khichar, M., and Kumbhat, S. (2015). Defluoridation-A review of water from aluminium and alumina based compound. International Journal of Chemical Studies, 2(5), 04-11.

Kwon, H. B., Lee, C. W., Jun, B. S., Weon, S. Y., and Koopman, B. (2004). Recycling waste oyster shells for eutrophication control. Resources, Conservation and Recycling, 41(1), 75-82.

Lee, C. W., Kwon, H. B., Jeon, H. P., and Koopman, B. (2009). A new recycling material for removing phosphorus from water. Journal of Cleaner Production, 17(7), 683-687.

Li, P., Qian, H., Wu, J., Chen, J., Zhang, Y., and Zhang, H. (2014). Occurrence and hydrogeochemistry of fluoride in alluvial aquifer of Weihe River, China. Environmental Earth Sciences, 71(7), 3133-3145.

Lin, C. W., and Chang, W. L. (2011). The study of adsorption isotherm by
using oyster shell powder adsorbs phosphorus. Journal of Taiwan Agricultural Engineering, 57(3), 32-43.

Liu, C. C., and Liu, J. C. (2016). Coupled precipitation-ultrafiltration for treatment of high fluoride-content wastewater. Journal of the Taiwan Institute of Chemical Engineers, 58, 259-263.

Meher, T., Basu, A., and Ghatak, S. (2005). Physicochemical characteristics of alumina gel in hydroxyhydrogel and normal form. Ceramics International, 31(6), 831-838.
Miretzky, P., and Cirelli, A. F. (2011). Fluoride removal from water by chitosan derivatives and composites: a review. Journal of Fluorine Chemistry, 132(4), 231-240.

Mondal, N. K., Bhaumik, R., and Datta, J. K. (2015). Removal of fluoride by aluminum impregnated coconut fiber from synthetic fluoride solution and natural water. Alexandria Engineering Journal, 54(4), 1273-1284.

Moulder, J. F. (1995). Handbook of X-ray photoelectron spectroscopy: a reference book of standard spectra for identification and interpretation of XPS data (pp. 84-85). J. Chastain, and R. C. King (Eds.). Eden Prairie, MN: Physical Electronics.

Mount, A. S., Wheeler, A. P., Paradkar, R. P., and Snider, D. (2004). Hemocyte-mediated shell mineralization in the eastern oyster. Science, 304(5668), 297-300.

Mulugeta, E., Zewge, F., Annette Johnson, C., and Chandravanshi, B. S. (2014). A high-capacity aluminum hydroxide-based adsorbent for water defluoridation. Desalination and Water Treatment, 52(28-30), 5422-5429.

Nath, S. K., and Dutta, R. K. (2010). Fluoride removal from water using crushed limestone. Indian J. Chem. Technol, 17, 120-125.

Park, W., and Polprasert, C. (2008). Roles of oyster shells in an integrated constructed wetland system designed for P removal. Ecological Engineering, 34(1), 50-56.

Parkhurst, D. L., and Appelo, C. A. J. (1999). User's guide to PHREEQC (Version 2): A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations.

Ramdani, A., Taleb, S., Benghalem, A., and Ghaffour, N. (2010). Removal of excess fluoride ions from Saharan brackish water by adsorption on natural materials. Desalination, 250(1), 408-413.

Ren, T., Gao, X. R., Zheng, T., and Wang, P. (2016). Study on Treatment of acidic and highly concentrated fluoride waste water using calcium oxide-calcium chloride. In IOP Conference Series: Earth and Environmental Science (Vol. 39, No. 1, p. 012003). IOP Publishing.

Rowlands, W. N., O'brien, R. W., Hunter, R. J., and Patrick, V. (1997). Surface properties of aluminum hydroxide at high salt concentration. Journal of Colloid and Interface Science, 188(2), 325-335.

Ryu, M., Kim, H., Lim, M., You, K., and Ahn, J. (2010). Comparison of dissolution and surface reactions between calcite and aragonite in L-glutamic and L-aspartic acid solutions. Molecules, 15(1), 258-269.

Sandoval, M. A., Fuentes, R., Nava, J. L., and Rodríguez, I. (2014). Fluoride removal from drinking water by electrocoagulation in a continuous filter press reactor coupled to a flocculator and clarifier. Separation and Purification Technology, 134, 163-170.

Shen, Y., Yang, S., Liu, J., Xu, H., Shi, Z., Lin, Z., Ying, X., Guo, P., Lin, T., and Yan, S. (2014). Engineering scaffolds integrated with calcium sulfate and oyster shell for enhanced bone tissue regeneration. ACS Applied Materials & Interfaces, 6(15), 12177-12188.

Shih, P. K., and Chang, W. L. (2015). The effect of water purification by oyster shell contact bed. Ecological Engineering, 77, 382-390.

Shin, W. S., Kang, K., and Kim, Y. K. (2014). Adsorption characteristics of multi-metal ions by red mud, zeolite, limestone, and oyster shell. Environmental Engineering Research, 19(1), 15-22.

Singh, K., Lataye, D. H., Wasewar, K. L., and Yoo, C. K. (2013). Removal of fluoride from aqueous solution: status and techniques. Desalination and Water Treatment, 51(16-18), 3233-3247.

Speight, J. G. (2005). Lange's handbook of chemistry (Vol. 1): McGraw-Hill New York.
Teutli-Sequeira, A., Solache-Ríos, M., Martínez-Miranda, V., and Linares-Hernández, I. (2014). Comparison of aluminum modified natural materials in the removal of fluoride ions. Journal of Colloid and Interface Science, 418, 254-260.

Trombetta, M., Busca, G., and Willey, R. J. (1997). Characterization of silica-containing aluminum hydroxide and oxide aerogels. Journal of Colloid and Interface Science, 190(2), 416-426.

Tsai, H. C., Lo, S. L., and Kuo, J. (2011). Using pretreated waste oyster and clam shells and microwave hydrothermal treatment to recover boron from concentrated wastewater. Bioresource Technology, 102(17), 7802-7806.

Turner, B. D., Binning, P., and Stipp, S. L. S. (2005). Fluoride removal by calcite: evidence for fluorite precipitation and surface adsorption. Environmental Science & Technology, 39(24), 9561-9568.

Un, U. T., Koparal, A. S., and Ogutveren, U. B. (2013). Fluoride removal from water and wastewater with a bach cylindrical electrode using electrocoagulation. Chemical Engineering Journal, 223, 110-115.

Velazquez-Jimenez, L. H., Vences-Alvarez, E., Flores-Arciniega, J. L., Flores-Zuñiga, H., and Rangel-Mendez, J. R. (2015). Water defluoridation with special emphasis on adsorbents-containing metal oxides and/or hydroxides: A review. Separation and Purification Technology, 150, 292-307.

Wagner, C. D., and Muilenberg, G. E. (1979). Handbook of x-ray photoelectron spectroscopy. G. E. Muilenberg (Ed.). Perkin-Elmer.

Wang, Z., Dong, J., Liu, L., Zhu, G., and Liu, C. (2013). Screening of phosphate-removing substrates for use in constructed wetlands treating swine wastewater. Ecological Engineering, 54, 57-65.

Wongrueng, A., Sookwong, B., Rakruam, P., and Wattanachira, S. (2016). Kinetic Adsorption of Fluoride from an Aqueous Solution onto a Dolomite Sorbent. Engineering Journal, 20(3), 1-9.

World Health Organization. (2004). Guidelines for drinking-water quality (Vol. 1). World Health Organization.

Wu, Q., Chen, J., Clark, M., and Yu, Y. (2014). Adsorption of copper to different biogenic oyster shell structures. Applied Surface Science, 311, 264-272.

Wu, X., Zhang, Y., Dou, X., Zhao, B., and Yang, M. (2013). Fluoride adsorption on an Fe–Al–Ce trimetal hydrous oxide: characterization of adsorption sites and adsorbed fluorine complex species. Chemical Engineering Journal, 223, 364-370.

Xiang, W., Zhang, G., Zhang, Y., Tang, D., and Wang, J. (2014). Synthesis and characterization of cotton-like Ca–Al–La composite as an adsorbent for fluoride removal. Chemical Engineering Journal, 250, 423-430.

Xu, X., Gao, B., Jin, B., and Yue, Q. (2016). Removal of anionic pollutants from liquids by biomass materials: A review. Journal of Molecular Liquids, 215, 565-595.

Yin, H., Kong, M., and Tang, W. (2015). Removal of Fluoride from Contaminated Water Using Natural Calcium-Rich Attapulgite as a Low-Cost Adsorbent. Water, Air, & Soil Pollution, 226(12), 1-11.

Yu, Y., Wang, C., Guo, X., and Chen, J. P. (2015). Modification of carbon derived from Sargassum sp. by lanthanum for enhanced adsorption of fluoride. Journal of Colloid and Interface Science, 441, 113-120.

Yuangsawad, R., and Na-Ranong, D. (2011). Recycling oyster shell as adsorbent for phosphate removal. Paper presented at the The 21st Thai Institute of Chemical Engineering and Applied Chemistry. Hatyai, Songkhla.

Zhang, Y. X., and Jia, Y. (2016). Fluoride adsorption onto amorphous aluminum hydroxide: Roles of the surface acetate anions. Journal of Colloid and Interface Science, 483, 295-306.