全球氣候變遷與石油燃煤對環境汙染影響日益嚴重，使得全球替代能源需求提升，而生質柴油為可再生利用、不含硫、對環境污染低等優點之優質替代能源。此能源可透過合適且對應的方法，從動物脂肪、廢油品、植物和藻類中進行提煉。利用電化學法 (其可在低電壓、安全溫度範圍以低廉成本設備生產等條件下操作生產)。可稱為生產生質柴油的絕佳方案。本研究使用電解方法、多種綠色環保溶劑生產生質柴油，即: (1) 離子液體(（Bmim]Cl、[Bmim]OH、[Emim]Cl 和[Emim]OH）(2)深共熔溶劑(氯仿、乙二醇、甘油、對甲苯磺酸組成) (3)可切換溶劑(來自2級胺的DPA和EBA)、(3級胺2-DABE、DMCHA)、(醯胺基中DBU)。在所有優化要求下，使用表面偶合法和響應曲面法進行27次實驗。
在首項研究中，使用多樣離子液體(IL)為生質柴油中的電解質。在相似實驗中對離子液體對生質柴油產率進行篩選。所有被使用的咪唑離子液體須具備將三酸甘油酯轉化為生質柴油(> 88%)良好轉化率，在製備生質柴油環境中有著絕佳適用性和良好反應條件試劑。為了使RSM與BBD耦合實驗結果更佳，遂選擇[Emim]Cl(在電解過程中具最高轉化率、導電率)。透過使用氣象分析儀(GC)，在最佳反應條件下，我們得到了97.76%的生質柴油轉化率:電解電壓(19.42V)，[Emim]Cl(4.43% w/w)，含水量(1.62% w/w)，甲醇和油脂莫耳比(26.38:1)，反應過程所需時間為1小時。此實驗主要反應參數對生質柴油轉化率的影響因素。在此，我們還發現了具更高關聯性的數值模型值，其中可以發現預估生產量與實驗生產量有緊密的一致性。另外，[Emim]能有效率的重複利用四個循環，包含最初和證明後的生質柴油產率依舊超過94.81%，由此可知是能有效控制成本的生質柴油製程方法。採用傅立葉紅外線光譜對原油及電解法生產的生質柴油進行分析，FT-IR分析結果中證實，在電解系統下合成出高純度柴油，且此產品性能符合ASTMD和EN規範標準。
其次，探討各類低共熔溶劑(DES)生成生質柴油。以不同莫耳比形成ChCl與EG、Gly和PTSA等四類DES。含有PTSA的DES之ChCl在液態狀態下達到穩態時間所需甚短。此外，生產生質柴油的最低潛能<59%。ChCl/EG莫爾比為1:2提供了最佳的生質柴油產率和導電率，再者，透過BBD對DES-2的電化學方法進行了實驗改善，通過GC分析出94.71%的最優產率，改善後反應條件:電壓22.06V、DES-2 (7.91% w/w)、含水率1.44%、M:O莫耳比 25.09:1、反應時間2小時、溫度:25℃從數值上看出生質柴油產量的變化量來自反應條件(電壓、含水率、DES-2和M:O莫耳比)。R2=0.99，調整後R2=0.98的模型，證實了預測產量和實際產量為良好的正相關。包括最初研究顯示DES-2在五次循環內重複使用生質柴油產率>80%。FT-IR定性分析結果也證明電解過程中可以產出高純度的生質柴油。且符合ASTMD和EN規範。
最後，發現有一種可在電解法下使用各類可切換溶劑生產生質柴油的方法。在使用催化劑中，僅DBU在製程中有著優異表現，後在DBU電化學方法由BBD優化，並在下述條件中有著 97.52%產率。反應條件:電解電壓25.24V，含水率1.47%w/w，反應時間:1.5小時，M:O莫耳比17.0:1，DBU/oil 10.95% w/w，25℃。上述研究中優化反應條件顯示，電解對生質柴油製備有著莫大影響。此研究使用模型確保預估產量與實驗產量有著強烈關聯性。更重要的是，DBU(含原始)可以在8次循環內依然保有產率>92%的數值。並且符合ASTMD和EN規範。研究成果可顯示，[Emim]Cl、DES-2和DBU為高產能、低成本且環保有前景的綠色材料。

Global fossil fuels scarcity and environmental harm have driven the demand for alternative energy. One alternative source of energy with excellent characteristics of being renewable, sulfur free, biodegradable, and environmental-friendly is biodiesel, which can alleviate the aforementioned issues. It can be derived from animals’ fat, oily waste products, plant oils, and algal oils via appropriate biodiesel synthesis approach. Electrochemical approach can be an excellent alternative technology for producing biodiesel due to its ecofriendly operation requirements such as low energy voltage, safer temperature, and inexpensive equipment usage.
This study investigated electrolysis approach of biodiesel synthesis using various green solvents, namely: (i) ionic liquids (Bmim]Cl, [Bmim]OH, [Emim]Cl, and [Emim]OH), (ii) deep eutectic solvents (synthesized from Choline chloride (ChCl) with ethylene glycol (EG), glycerol (Gly), and para-Tolunesulfonic acid (PTSA)), and (iii) switchable solvents (DPA and EBA from secondary amines; 2-DBAE and DMCHA from tertiary amines; and DBU from amidine group). In all the optimization requirements, response surface method coupled with Box-Behnken design (RSM-BBD) was applied using 27 experimental runs.
In the first study, the biodiesel production using various ionic liquids (ILs) as supporting electrolytes was investigated. The screening of ILs potential for biodiesel preparations were conducted at similar experimental operations. All the chosen imidazolium-ILs have demonstrated very good potential of converting triglyceride into biodiesel (> 88%), which seem their suitability and promising candidates for biodiesel preparation context in the electrolysis process. For the sake of further optimization on the main experimental variables via RSM coupled to BBD, [Emim]Cl was chosen owing to its exhibited highest biodiesel yield and electrical conductivity in the electrolysis process. Using gas chromatography (GC), a maximum biodiesel yield of 97.76% was achieved at optimum conditions of: electrolysis voltage, 19.42 V; [Emim]Cl amount, 4.43% (w/w); water content, 1.62% (w/w); methanol to oil molar ratio, 26.38:1; and reaction time, 1 h. These tested main reaction parameters were statistically significant influential factors to the response (biodiesel yield). Herein, higher model values of correlation coefficients were also found, in which the developed model demonstrated an existence of strong agreement on predicted and experimental yields. Furthermore, [Emim]Cl was efficiently reused for four cycles including the original and demonstrated biodiesel yield of more than 94.81%, suggesting its suitability in cost effective way of preparing biodiesel. The feedstock oil and its prepared biodiesel via electrolysis process were also characterized by Fourier transform infrared spectroscopy. The FT-IR analysis finding revealed that biodiesel was successfully synthesized with high purity in the electrolysis system. Moreover, the synthesized biodiesel fuel properties complied ASTMD and EN specification.
Secondly, biodiesel synthesis using various deep eutectic solvents (DESs) in electrolysis method was explored. Four kinds of DESs such as ChCl with EG, Gly, and PTSA were synthesized at different molar ratios. Among these, ChCl with PTSA kind of DESs had very short period of stability in liquid sate after their synthesis. Also, they showed the least potential of producing biodiesel (<59%). Herein, ChCl/EG (DES-2) with 1:2 molar offered the highest biodiesel yield as well as electrical conductivity in the electrolysis process. Then, the DES-2-based electrochemical approach of main experimental variables were optimized through BBD, leading to 94.71% of maximum yield via GC analysis. The optimized reaction conditions were: voltage of 22.06 V, DES-2 amount of 7.91% (w/w), water content of 1.44% (w/w), M:O ratio of 25.09:1, reaction time of 2 h and ~25 ℃. Statistically, the biodiesel yield was significantly dependent on the examined variables (voltage, water content, DES-2 amount, and M:O ratio). The high model values of R2 = 0.99 and adjusted R2 = 0.98 verified a good correlation with the predicted and actual yields. Furthermore, the five cycles including the original reusability study of DES-2 showed >80% yield of biodiesel. Adding more, the FT-IR analysis result also qualitatively confirmed that the electrolysis process could be a successfully synthesized biodiesel consisting of high purity. Moreover, the synthesized biodiesel fuel properties fitted ASTMD and EN specification.
Thirdly, an electrolysis method-based biodiesel production using various switchable solvents (SSs) was proposed. Among the tested catalysts, only DBU demonstrated an excellent potential for the electrochemical approach of biodiesel production. Subsequently, the DBU-based electrochemical approach applied in further optimizing the main reaction variables via BBD and achieved 97.52% of maximum yield at: electrolysis voltage of 25.24 V, water content of 1.47% (w/w), reaction time of 1.5 h, M:O ratio of 17.0:1, DBU/oil ratio of 10.95% (w/w), and ~25 ℃. These studied optimization factors statistically showed significant influence on the electrolysis-assisted biodiesel preparation. The developed model of this study also ensured an existence of strong correlation for the predicted and experimental yields. Importantly, the eight cycles reusability of DBU including the original demonstrated >92% yield of biodiesel. Moreover, the synthesized biodiesel fuel properties fitted ASTMD and EN specification.
Therefore, the findings of the study suggested that [Emim]Cl, DES-2, and DBU were the promising green candidates in the inexpensive and environmentally friendly electrolysis process for efficient biodiesel production.

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