以太陽能驅動之氧化還原液流式電池系統達成近零能耗脫鹽之研析

Abstract

隨著氣候變遷、人口成長和經濟發展，水資源以及能源的需求都在逐年上升，如何將高效率的淨水技術結合再生能源應用已成為現今全球重要的研究議題。氧化還原液流式電池脫鹽技術(redox-flow battery desalination, RFB)為一項新興的電化學技術，透過低電壓驅動電解液材料對進行氧化還原，利用電子遷移的機制去除水中離子，可連續操作並應用於較大的脫鹽濃度範圍，而染料敏化電池(dye-sensitized solar cell, DSSC)作為一發展成熟的光伏技術，製備流程和成本的門檻相對傳統矽太陽能電池低，且兩者系統皆是靠電解液的氧化還原去運行，因此結合 DSSC 以光驅動 RFB 的技術被進一步提出，也就是太陽能驅動氧化還原液流式電池脫鹽系統(solar-driven redox-flow battery desalination, SRFB)。 本研究目的為建立一SRFB裝置以達成近零能耗脫鹽之應用，並探討系統中不同變因與反應機制的結果表現。在本研究中，比較了DSSC不同製備流程、墊片厚度、電解液濃度和對電極的表現，並決定一組最佳操作條件進行SRFB實驗。SRFB模組具有五個腔室，包括光電池室、濃室、淡室、陽極室和陰極室，將碘電解液(iodide/triiodide)密封於系統中的光電池室避免洩漏，使用鐵氰化物(ferricyanide/ferrocyanide)作為氧化還原液流電池材料在陽極室和陰極室中以流速5 mL/min循環，並於濃室和淡室通入濃度35 g/L的氯化鈉進行批次式脫鹽實驗，探討其脫鹽效能和離子遷移的現象。結果顯示在48小時的脫鹽實驗中，淡室的導電度從46.52 mS/cm降到42.94 mS/cm，儘管效果因系統中腔室濃度差過大而有所限制，但仍足以可見其脫鹽成效。結論而言，SRFB系統於電化學脫鹽技術中具有高發展潛力，期望此研究有助於SRFB系統與淨零能耗脫鹽技術的應用與發展。

As climate change intensifies with population growth and economic development, the demand for water and energy resources continues to rise annually. In response, high-efficiency water desalination technologies powered by renewable energy have become a crucial research topic worldwide. Redox-flow battery desalination (RFB) is an innovative electrochemical technology that uses low-voltage-driven redox reactions of electrolyte materials to remove ions from water via electron migration. This technology enables continuous operation and is effective across a wide range of desalination concentrations. Meanwhile, dye-sensitized solar cells (DSSCs), a well-established photovoltaic technology, offer simplified preparation process and lower cost in their preparation process compared to traditional solar cells. Both RFB and DSSC systems operate based on the redox reactions of electrolytes, leading to the further proposal of integrating DSSC to drive the RFB technology. This concept is known as a solar-driven redox-flow battery desalination system (SRFB). The objective of this research is to develop a SRFB module to achieve zero-energy desalination and investigate the mechanisms and parameters within the system. Various factors including DSSC preparation methods, gasket thicknesses, electrolyte concentrations, and counter electrodes were compared, in order to identify the optimal conditions for the SRFB experiment. The SRFB module consists of five chambers: a solar cell chamber, a concentrate chamber, a dilute chamber, an anode chamber, and a cathode chamber. The iodide/triiodide electrolyte is sealed within the solar cell chamber. In the anode and cathode chambers, ferricyanide/ferrocyanide serves as the redox flow battery electrolyte, circulating at a flow rate of 5 mL/min. Sodium chloride solution of 35 g/L is introduced to the concentrate and dilute chambers for batch mode desalination experiments. Results from a 48-hour desalination experiment showed that the conductivity in the dilute chamber decreased from 46.52 mS/cm to 42.94 mS/cm. In conclusion, the SRFB system exhibits significant potential in the field of electrochemical desalination technologies. These findings are expected to contribute to the advancement and application of SRFB systems and zero-energy desalination technologies.