電容去離子技術(capacitive deionization, CDI)為新興海水淡化技術，透過施加低電壓，使擁有儲存離子之能力，並移除施加電壓後即可進行脫附，於水再生領域已是未來發展的趨勢之一。廢污水經生物處理後之出流水，尚包含二級程序未能完全處理之有機物質，然而有機物質會堵塞奈米碳材電極裡之孔洞以導致去離子效果不佳。故本研究開發奈米鈦管(titanate nanotube, TNT)修飾活性碳電極(TNTAC electrode)，透過CDI技術降低水中離子濃度，加上奈米鈦管之電催化效果，於CDI去除離子的同時降低有機物的堵塞。研究中分別利用Ti wt.%為3、5與10 wt.%的TNTAC電極進行去離子試驗，其為5 wt.% Ti含量時，複合電極有最佳的去離子效果。此外，比較水熱溫度120、150與180°C所製備之TNTAC，以150°C製備之TNTAC電極具有最佳的處理效果。接著針對黃腐酸與NaCl混合水樣進行重覆去離子試驗，結果顯示本研究所製備之5-TNTAC-150電極，重覆使用可達9次之多，且去離子效能與吸附黃腐酸之能力皆優於活性碳電極，經X射線光電子能譜(X-ray photoelectron spectroscopy, XPS) 測定重複使用後的電極表面C1s化學態之組成變化，得知TNTAC電極不僅能在吸附黃腐酸之同時，卻不造成電極阻塞，有效降低有機物對電極結垢之問題。

Capacitive deionization (CDI) is a rising technology for water desalination. CDI is based on the electrosorption of ions onto the electrical double layer (EDL) of electrode surface which formed by applying low voltage, and the desorption is processed easily by removing voltage. There has been a dearth of research about the CDI performance when there is organic compounds in wastewater for reuse. The biologically treated still contains dissolved organic matter (DOM) which cannot be treated completely by the secondary process, and it will block the pores of carbon nano-material and make poor deionization efficiency.
The titanate nanotube (TNT) modified activated carbon electrode (TNTAC electrode) has been developed in this study to reduce the adverse effect which is from organic compounds in aqueous solution. In this study, TNTAC electrodes with 5 wt.% of Ti and hydrothermal temperature of 150°C has the best deionization efficiency. The adsorption-desorption has been carried out for the mixture of fulvic acid and NaCl. The results show that the TNTAC electrode prepared in this study can be reused up to 9 times, and both the deionization efficiency and the ability of fulvic acid adsorption are superior to the activated carbon electrode. The composition of the chemical state for the surface of electrode after reuse is determined by X-ray photoelectron spectroscopy (XPS). It is found that the TNTAC electrode may decompose fulvic acid and limit the fouling of electrode at the same time, and effectively extend the working time of electrodes.

Abdullah, M., Kamarudin, S., and Shyuan, L.,"TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell", Nanoscale research letters, 11, 553 (2016).
Abdullah, M., and Kamarudin, S.K.,"Titanium dioxide nanotubes (TNT) in energy and environmental applications: An overview", Renewable and Sustainable Energy Reviews, 76, 212-225 (2017).
Abida, B., Chirchi, L., Baranton, S., Napporn, T.W., Morais, C., Léger, J.-M., and Ghorbel, A.,"Hydrogenotitanates nanotubes supported platinum anode for direct methanol fuel cell", Journal of Power Sources, 241, 429-439 (2013).
Aslan, M., Zeiger, M., Jäckel, N., Grobelsek, I., Weingarth, D., and Presser, V.,"Improved capacitive deionization performance of mixed hydrophobic/hydrophilic activated carbon electrodes", Journal of Physics: Condensed Matter, 28, 114003 (2016).
Azizian, S.,"Kinetic models of sorption: a theoretical analysis", Journal of Colloid and Interface Science, 276, 47-52 (2004).
Bavykin, D.V., Parmon, V.N., Lapkin, A.A., and Walsh, F.C.,"The effect of hydrothermal conditions on the mesoporous structure of TiO2 nanotubes", Journal of Materials Chemistry, 14, 3370-3377 (2004).
Cai, Z., Sun, Y., Liu, W., Pan, F., Sun, P., and Fu, J.,"An overview of nanomaterials applied for removing dyes from wastewater", Environmental Science and Pollution Research, 24, 15882-15904 (2017).
Camposeco, R., Castillo, S., Mejía-Centeno, I., Navarrete, J., Nava, N., and Rodríguez-González, V.,"Synthesis of protonated titanate nanotubes tailored by the washing step: Effect upon acid properties and photocatalytic activity", Journal of Photochemistry and Photobiology A: Chemistry, 341, 87-96 (2017).
Chang, L.M., Duan, X.Y., and Liu, W.,"Preparation and electrosorption desalination performance of activated carbon electrode with titania", Desalination, 270, 285-290 (2011).
Chang, T.-h.,"利用不同黏土-幾丁聚醣吸附劑去除水中二價銅離子之研究", 嘉南藥理科技大學環境工程與科學系, 碩士論文, 台南 (2012).
Chen, B., Wang, Y., Yu, F., Zhu, Y., Zhang, L., and Wu, Y.,"Enhanced Capacitive Desalination Performance of Porous Carbon Spheres@ MnO2 Composite", Chinese Journal of Chemistry, 35, 55-60 (2017).
Cheng, W.-Y.,"無機鹽類在碳氣凝膠電容去離子系統中之競爭吸附; A study of competitive adsorption of inorganic salts by carbon aerogel-based capacitive deionization system", 國立中央大學環境工程研究所, 碩士論文, 中壢 (2016).
Chueng, H.-J.,"利用水熱法合成鈦酸鹽奈米管及其性質研究", 國立高雄應用科技大學化學工程與材料工程系, 碩士論文, 高雄 (2008).
Corchado-García, J., and Cabrera, C.R.,"Ethylene Glycol Oxidation at Pt/TiO2/Carbon Hybrid Catalysts Modified Glassy Carbon Electrodes in Alkaline Media", Electrocatalysis, 5, 402-407 (2014).
Dehkhoda, A.M., Ellis, N., and Gyenge, E.,"Effect of activated biochar porous structure on the capacitive deionization of NaCl and ZnCl2 solutions", Microporous and Mesoporous Materials, 224, 217-228 (2016).
Dong, Q., Wang, G., Wu, T., Peng, S., and Qiu, J.,"Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes", Journal of Colloid and Interface Science, 446, 373-378 (2015).
El-Deen, A.G., Choi, J.-H., Khalil, K.A., Almajid, A.A., and Barakat, N.A.,"A TiO2 nanofiber/activated carbon composite as a novel effective electrode material for capacitive deionization of brackish water", RSC Advances, 4, 64634-64642 (2014).
El-Deen, A.G., Choi, J.-H., Kim, C.S., Khalil, K.A., Almajid, A.A., and Barakat, N.A.M.,"TiO2 nanorod-intercalated reduced graphene oxide as high performance electrode material for membrane capacitive deionization", Desalination, 361, 53-64 (2015).
Fan, C.-S., Liou, S.Y.H., and Hou, C.-H.,"Capacitive deionization of arsenic-contaminated groundwater in a single-pass mode", Chemosphere, 184, 924-931 (2017).
Frackowiak, E., and Béguin, F.,"Carbon materials for the electrochemical storage of energy in capacitors", Carbon, 39, 937-950 (2001).
Gardy, J., Hassanpour, A., Lai, X., Ahmed, M.H., and Rehan, M.,"Biodiesel production from used cooking oil using a novel surface functionalised TiO2 nano-catalyst", Applied Catalysis B: Environmental, 207, 297-310 (2017).
Gui, H.J., Li, F.S., Wei, Y.F., and Yamada, T.,"Adsorption characteristics of natural organic matter on activated carbons with different pore size distribution", International Journal of Environmental Science and Technology, (2017).
Herrmann, J.-M.,"Heterogeneous photocatalysis: state of the art and present applications In honor of Pr. R.L. Burwell Jr. (1912–2003), Former Head of Ipatieff Laboratories, Northwestern University, Evanston (Ill)", Topics in Catalysis, 34, 49-65 (2005).
Ho, Y.S., and McKay, G.,"Pseudo-second order model for sorption processes", Process Biochemistry, 34, 451-465 (1999).
Hosseini, M., Momeni, M.M., and Faraji, M.,"An innovative approach to electro-oxidation of dopamine on titanium dioxide nanotubes electrode modified by gold particles", Journal of Applied Electrochemistry, 40, 1421-1427 (2010).
Hou, C.-H., and Huang, C.-Y.,"A comparative study of electrosorption selectivity of ions by activated carbon electrodes in capacitive deionization", Desalination, 314, 124-129 (2013).
Hou, C.-H., Huang, J.-F., Lin, H.-R., and Wang, B.-Y.,"Preparation of activated carbon sheet electrode assisted electrosorption process", Journal of the Taiwan Institute of Chemical Engineers, 43, 473-479 (2012).
Hou, C.-H., Liu, N.-L., and Hsi, H.-C.,"Highly porous activated carbons from resource-recovered Leucaena leucocephala wood as capacitive deionization electrodes", Chemosphere, 141, 71-79 (2015).
Hou, C., Huang, C., and Hu, C.,"Application of capacitive deionization technology to the removal of sodium chloride from aqueous solutions", International Journal of Environmental Science and Technology, 10, 753-760 (2013).
Hoyer, P.,"Formation of a Titanium Dioxide Nanotube Array", Langmuir, 12, 1411-1413 (1996).
Hsu, S.-Y.,"鄰苯二甲酸氫鉀對於電容去離子系統脫鹽之影響", 國立中央大學環境工程研究所, 碩士論文, 中壢 (2016).
Huang, S.-Y., Fan, C.-S., and Hou, C.-H.,"Electro-enhanced removal of copper ions from aqueous solutions by capacitive deionization", Journal of hazardous materials, 278, 8-15 (2014).
Huang, W., Zhang, Y., Bao, S., and Song, S.,"Desalination by capacitive deionization with carbon-based materials as electrode: a review", Surface Review and Letters, 20, 1330003 (2013).
Huang, Z.-H., Yang, Z., Kang, F., and Inagaki, M.,"Carbon electrodes for capacitive deionization", Journal of Materials Chemistry A, 5, 470-496 (2017).
Huang, Z., Lu, L., Cai, Z., and Ren, Z.J.,"Individual and competitive removal of heavy metals using capacitive deionization", Journal of Hazardous Materials, 302, 323-331 (2016).
Imai, A., Fukushima, T., Matsushige, K., Kim, Y.-H., and Choi, K.,"Characterization of dissolved organic matter in effluents from wastewater treatment plants", Water Research, 36, 859-870 (2002).
JI, M.,"Fulvic acid degradation using nanoparticle TiO2 in a submerged membrane photocatalysis reactor", Journal of Environmental Sciences, 17, 942-945 (2005).
Kasuga, T., Hiramatsu, M., Hoson, A., Sekino, T., and Niihara, K.,"Formation of Titanium Oxide Nanotube", Langmuir, 14, 3160-3163 (1998).
Kasuga, T., Hiramatsu, M., Hoson, A., Sekino, T., and Niihara, K.,"Titania nanotubes prepared by chemical processing", Advanced Materials, 11, 1307-1311 (1999).
Kim, C., Lee, J., Kim, S., and Yoon, J.,"TiO2 sol–gel spray method for carbon electrode fabrication to enhance desalination efficiency of capacitive deionization", Desalination, 342, 70-74 (2013).
Kim, J.H., Zhang, X.H., Kim, J.D., Park, H.M., Lee, S.B., Yi, J.W., and Jung, S.I.,"Synthesis and characterization of anatase TiO2 nanotubes with controllable crystal size by a simple MWCNT template method", Journal of Solid State Chemistry, 196, 435-440 (2012).
Kowanga, K.D., Gatebe, E., Mauti, G.O., and Mauti, E.M.,"Kinetic, sorption isotherms, pseudo-first-order model and pseudo-second-order model studies of Cu (II) and Pb (II) using defatted Moringa oleifera seed powder", The Journal of Phytopharmacology, 5, 71-78 (2016).
Lai, Y.-R.,"氧化鈦奈米管之製備, 鑑定及催化應用", 國立中央大學化學研究所, 碩士論文, 中壢 (2005).
Lee, C.H., Kim, K.H., Jang, K.U., Park, S.J., and Choi, H.W.,"Synthesis of TiO2 nanotube by hydrothermal method and application for dye-sensitized solar cell", Molecular Crystals and Liquid Crystals, 539, 125/[465]-132/[472] (2011).
Lee, C.H., Rhee, S.W., and Choi, H.W.,"Preparation of TiO2 nanotube/nanoparticle composite particles and their applications in dye-sensitized solar cells", Nanoscale research letters, 7, 48 (2012).
Lee, K., Mazare, A., and Schmuki, P.,"One-Dimensional Titanium Dioxide Nanomaterials: Nanotubes", Chemical Reviews, 114, 9385-9454 (2014).
Leong, Z.Y., and Yang, H.Y.,"Porous carbon hollow spheres synthesized via a modified Stöber method for capacitive deionization", RSC Advances, 6, 53542-53549 (2016).
Li, H.-h., Yang, J., Zhang, C., Li, H.-y., and Pei, P.-p.,"The influence of the acidic scouring treatment on the wastewater treatment of TiO2 loaded activated carbon electrode", Journal of Porous Materials, 22, 887-895 (2015).
Li, H., Ma, Y., and Niu, R.,"Improved capacitive deionization performance by coupling TiO2 nanoparticles with carbon nanotubes", Separation and Purification Technology, 171, 93-100 (2016).
Li, Y., Jiang, Y., Wang, T.-J., Zhang, C., and Wang, H.,"Performance of fluoride electrosorption using micropore-dominant activated carbon as an electrode", Separation and Purification Technology, 172, 415-421 (2017).
Lin, H.,"製備活性碳電極於電容去離子技術之應用", 東海大學環境科學與工程學系, 碩士論文, 台中 (2012).
Lin, L.-C.,"利用活性碳電極對磷酸鹽類進行電容去離子之研究", 國立中央大學, 碩士論文, 中壢 (2017).
Liu, P.-I., Chung, L.-C., Ho, C.-H., Shao, H., Liang, T.-M., Horng, R.-Y., Chang, M.-C., and Ma, C.-C.M.,"Effects of activated carbon characteristics on the electrosorption capacity of titanium dioxide/activated carbon composite electrode materials prepared by a microwave-assisted ionothermal synthesis method", Journal of Colloid and Interface Science, 446, 352-358 (2015).
Liu, P., Wang, H., Yan, T., Zhang, J., Shi, L., and Zhang, D.,"Grafting sulfonic and amine functional groups on 3D graphene for improved capacitive deionization", Journal of Materials Chemistry A, 4, 5303-5313 (2016a).
Liu, Y.-C.,"氧化鈦奈米管擔體金屬觸媒之製備及特性分析
Preparation and Characterization of Titanium Oxide Nanotube Supported Metal Catalysts", 臺灣大學化學研究所, 博士論文, 台北 (2004).
Liu, Y.-H., Hsi, H.-C., Li, K.-C., and Hou, C.-H.,"Electrodeposited manganese dioxide/activated carbon composite as a high-performance electrode material for capacitive deionization", ACS Sustainable Chemistry & Engineering, 4, 4762-4770 (2016b).
Liu, Z., Jian, Z., Fang, J., Xu, X., Zhu, X., and Wu, S.,"Low-temperature reverse microemulsion synthesis, characterization, and photocatalytic performance of nanocrystalline titanium dioxide", International Journal of Photoenergy, 2012, (2012).
LUO, H.-J.,"利用二氧化鈦/活性碳電極進行電容去離子處理鄰苯二甲酸氫鉀之研究", 碩士論文, 國立中央大學環境工程研究所, 碩士論文, 中壢 (2017).
Ma, X., and Ouyang, F.,"Adsorption properties of biomass-based activated carbon prepared with spent coffee grounds and pomelo skin by phosphoric acid activation", Applied Surface Science, 268, 566-570 (2013).
MCKNIGHT, D.M.W., R. L. ."Humic Substances in the Suwannee River, Georgia: Interactions, Properties, and Proposed Structures", United States Geological Survey Water-Supply Paper, 87-557, (1989).
Mombeshora, E.T., Simoyi, R., Nyamori, V.O., and Ndungu, P.G.,"Multiwalled carbon nanotube-titania nanocomposites: Understanding nano-structural parameters and functionality in dye-sensitized solar cells", South African Journal of Chemistry, 68, 153-164 (2015).
Mor, G., Varghese, O.K., Paulose, M., Mukherjee, N., and Grimes, C.A.,"Fabrication of tapered, conical-shaped titania nanotubes", Journal of Materials Research, 18, 2588-2593 (2003).
Mossad, M., and Zou, L.,"Evaluation of the salt removal efficiency of capacitive deionisation: Kinetics, isotherms and thermodynamics", Chemical Engineering Journal, 223, 704-713 (2013a).
Mossad, M., and Zou, L.,"Study of fouling and scaling in capacitive deionisation by using dissolved organic and inorganic salts", Journal of Hazardous Materials, 244-245, 387-393 (2013b).
Namane, A., Mekarzia, A., Benrachedi, K., Belhaneche-Bensemra, N., and Hellal, A.,"Determination of the adsorption capacity of activated carbon made from coffee grounds by chemical activation with ZnCl 2 and H 3 PO 4", Journal of hazardous materials, 119, 189-194 (2005).
Oriekhova, O., and Stoll, S.,"Effects of pH and fulvic acids concentration on the stability of fulvic acids – cerium (IV) oxide nanoparticle complexes", Chemosphere, 144, 131-137 (2016).
Polovina, M., Babić, B., Kaluderović, B., and Dekanski, A.,"Surface characterization of oxidized activated carbon cloth", Carbon, 35, 1047-1052 (1997).
Porada, S., Zhao, R., van der Wal, A., Presser, V., and Biesheuvel, P.M.,"Review on the science and technology of water desalination by capacitive deionization", Progress in Materials Science, 58, 1388-1442 (2013).
Ramadan, M., Hassan, H.M.A., Shahat, A., Elshaarawy, R.F.M., and Allam, N.K.,"Ultrahigh performance of novel energy-efficient capacitive deionization electrodes based on 3D nanotubular composites", New Journal of Chemistry, 42, 3560-3567 (2018).
Regonini, D., Bowen, C.R., Jaroenworaluck, A., and Stevens, R.,"A review of growth mechanism, structure and crystallinity of anodized TiO2 nanotubes", Materials Science and Engineering: R: Reports, 74, 377-406 (2013).
Schellekens, J., Buurman, P., Kalbitz, K., Zomeren, A.v., Vidal-Torrado, P., Cerli, C., and Comans, R.N.J.,"Molecular Features of Humic Acids and Fulvic Acids from Contrasting Environments", Environmental Science & Technology, 51, 1330-1339 (2017).
Sharma, K., Kim, Y.-H., Gabitto, J., Mayes, R., Yiacoumi, S., Bilheux, H., Walker, L., Dai, S., and Tsouris, C.,"Transport of ions in mesoporous carbon electrodes during capacitive deionization of high-salinity solutions", Langmuir, 31, 1038-1047 (2014).
Shon, H., Vigneswaran, S., and Snyder, S.,"Effluent organic matter (EfOM) in wastewater: constituents, effects, and treatment", Critical reviews in environmental science and technology, 36, 327-374 (2006).
Sillanpää, M.,"Natural Organic Matter in Water: Characterization and Treatment Methods", (2014).
Soares, G.B., Vaz, C.M.P., Ribeiro, C., and Hermans, I.,"Insight into the Photocatalytical Activity of TiO2 Nanoparticles Through the Electrochemical Characterization of Carbon Paste Electrodes", Electrocatalysis, 6, 92-101 (2015).
Srimuk, P., Ries, L., Zeiger, M., Fleischmann, S., Jäckel, N., Tolosa, A., Krüner, B., Aslan, M., and Presser, V.,"High performance stability of titania decorated carbon for desalination with capacitive deionization in oxygenated water", RSC Advances, 6, 106081-106089 (2016).
Srimuk, P., Zeiger, M., Jäckel, N., Tolosa, A., Krüner, B., Fleischmann, S., Grobelsek, I., Aslan, M., Shvartsev, B., Suss, M.E., and Presser, V.,"Enhanced performance stability of carbon/titania hybrid electrodes during capacitive deionization of oxygen saturated saline water", Electrochimica Acta, 224, 314-328 (2017).
Suss, M., Porada, S., Sun, X., Biesheuvel, P., Yoon, J., and Presser, V.,"Water desalination via capacitive deionization: what is it and what can we expect from it?", Energy & Environmental Science, 8, 2296-2319 (2015).
Tang, W., Kovalsky, P., Cao, B., and Waite, T.D.,"Investigation of fluoride removal from low-salinity groundwater by single-pass constant-voltage capacitive deionization", Water Research, 99, 112-121 (2016).
Thamaphat, K., Limsuwan, P., and Ngotawornchai, B.,"Phase characterization of TiO2 powder by XRD and TEM", Kasetsart J.(Nat. Sci.), 42, 357-361 (2008).
Tsai, C.-C.,"由水熱處理二氧化鈦所合成奈米管之結構分析", 成功大學化學工程學系, 博士論文, 台南 (2005).
Wang, C., Song, H., Zhang, Q., Wang, B., and Li, A.,"Parameter optimization based on capacitive deionization for highly efficient desalination of domestic wastewater biotreated effluent and the fouled electrode regeneration", Desalination, 365, 407-415 (2015).
Wang, G., Qian, B., Dong, Q., Yang, J., Zhao, Z., and Qiu, J.,"Highly mesoporous activated carbon electrode for capacitive deionization", Separation and Purification Technology, 103, 216-221 (2013).
Wang, S.G., Liu, X.W., Gong, W.X., Nie, W., Gao, B.Y., and Yue, Q.Y.,"Adsorption of fulvic acids from aqueous solutions by carbon nanotubes", Journal of Chemical Technology & Biotechnology: International Research in Process, Environmental & Clean Technology, 82, 698-704 (2007).
Wei, K., Zhang, Y., Han, W., Li, J., Sun, X., Shen, J., and Wang, L.,"A novel capacitive electrode based on TiO2-NTs array with carbon embedded for water deionization: Fabrication, characterization and application study", Desalination, 420, 70-78 (2017).
Wu, P., Xia, L., Dai, M., Lin, L., and Song, S.,"Electrosorption of fluoride on TiO2-loaded activated carbon in water", Colloids and Surfaces A: Physicochemical and Engineering Aspects, 502, 66-73 (2016).
Xu, P., Drewes, J.E., Heil, D., and Wang, G.,"Treatment of brackish produced water using carbon aerogel-based capacitive deionization technology", Water research, 42, 2605-2617 (2008).
Yan, C., Zou, L., and Short, R.,"Polyaniline-modified activated carbon electrodes for capacitive deionisation", Desalination, 333, 101-106 (2014).
Yang, K., and Xing, B.,"Adsorption of fulvic acid by carbon nanotubes from water", Environmental Pollution, 157, 1095-1100 (2009).
Yeh, C.-L., Hsi, H.-C., Li, K.-C., and Hou, C.-H.,"Improved performance in capacitive deionization of activated carbon electrodes with a tunable mesopore and micropore ratio", Desalination, 367, 60-68 (2015).
Yuan, Z.-Y., and Su, B.-L.,"Titanium oxide nanotubes, nanofibers and nanowires", Colloids and Surfaces A: Physicochemical and Engineering Aspects, 241, 173-183 (2004).
Yuh-Shan, H.,"Citation review of Lagergren kinetic rate equation on adsorption reactions", Scientometrics, 59, 171-177 (2004).
Zhang, L.L., and Zhao, X.,"Carbon-based materials as supercapacitor electrodes", Chemical Society Reviews, 38, 2520-2531 (2009).
Zhang, P., Fritz, P.A., Schroën, K., Duan, H., Boom, R.M., and Chan-Park, M.B.,"Zwitterionic Polymer Modified Porous Carbon for High-Performance and Antifouling Capacitive Desalination", ACS Applied Materials & Interfaces, 10, 33564-33573 (2018).
Zhang, W., and Jia, B.,"Toward anti-fouling capacitive deionization by using visible-light reduced TiO 2/graphene nanocomposites", MRS Communications, 5, 613-617 (2015).
Zhang, W., Mossad, M., Yazdi, J.S., and Zou, L.,"A statistical experimental investigation on arsenic removal using capacitive deionization", Desalination and Water Treatment, 57, 3254-3260 (2016).
Zhao, S., Yan, T., Wang, Z., Zhang, J., Shi, L., and Zhang, D.,"Removal of NaCl from saltwater solutions using micro/mesoporous carbon sheets derived from watermelon peel via deionization capacitors", RSC Advances, 7, 4297-4305 (2017).