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Title: | 全固態式陰離子網印選擇電極製備與養液元素感測應用之研究 On the Preparation of All-Solid-State Screen-printed Anion Selective Electrodes for Nutrient Element Sensing |
Authors: | Chia-Hao Chang 張家豪 |
Advisor: | 陳林祈(Lin-Chi Chen) |
Keyword: | 全固態式,網印陰離子選擇電極,石墨烯,植物工廠, all-solid-state,screen-printed anion selective electrodes,graphene,plant factory, |
Publication Year : | 2015 |
Degree: | 碩士 |
Abstract: | 本研究製備平面型全固態式網印陰離子選擇電極,為進行檢測水耕養液中硝酸根 (NO3-) 、硫酸根 (SO42-)、磷酸氫根 (HPO42-)、氯離子 (Cl-) 等重要陰離子元素。主要探討修飾離子電子傳導層材料於感測時的電位穩定性以及搭配合適之各類陰離子選擇載體,以發展具有良好感測性能之陰離子選擇電極。離子選擇電極結構上區分成三部分-導電層、離子電子傳導層及離子選擇膜。導電層部分,本研究係將銀墨及碳墨以網版印刷技術先後網印至聚對苯二甲酸乙二酯 (polyethylene terephthalate, PET) 的基材。離子電子傳導層部份,導電高分子如polypyrrole與poly-o-aminophenol係以電鍍方式聚合於導電層表面;無機材料如石墨烯、還原態石墨烯氧化物與膠態高分子PEDOT:PSS則係以液滴塗佈法修飾於導電層,並且利用電化學方法探討離子電子傳導層之電位訊號穩定度。因石墨烯具低電阻率及可提高電容等特性,其修飾電極電荷轉移阻抗降低24%,低頻率下之電容值提升25.5倍,表面接觸角度提高1.09倍,達到減少電荷轉移阻抗,增進交換電流;電容值越大則電位穩定度高;且其疏水性能夠避免微小水層產生。離子選擇膜部份,本研究將含有硝酸根、硫酸根、磷酸氫根以及氯離子選擇載體滴覆於離子電子傳導層上形成離子選擇膜,完成各式全固態式網印陰離子選擇電極。實驗結果顯示,硝酸根離子選擇電極靈敏度為59.3 mV/decade (R2=0.9998),偵測極限為63.1 μM;硫酸根離子選擇電極靈敏度為29.3 mV/decade (R2=0.9900),偵測極限為29.3 μM;氯離子選擇電極為53.0 mV/decade (R2=0.9848),偵測極限為120.2 μM;磷酸氫離子選擇電極靈敏度為32.9 mV/decade (R2=0.9702),偵測極限為12.6 μM。透過檢驗電極感測靈敏度之測試,確認此離子選擇電極使用壽命為六個月。另外,進行陰離子選擇電極與高效液相層析法之比較,以單一離子水溶液驗證,硝酸根離子選擇電極測得相近的離子濃度,兩者量測方法之相對誤差為2%。以植物工廠水養液驗證硝酸根以及硫酸根離子選擇電極與高效液相層析法所得到離子濃度之相關係數R2分別為0.8795和0.8892,皆呈現高度相關性。最後,建構硝酸根離子感測模組應用於植物工廠結球萵苣水養液進行兩週量測,與高效液相層析法相對誤差平均為12.36±7.2 %。本研究陰離子選擇電極搭配實驗室前人所開發之陽離子選擇電極,發展出可應用於養液元素之感測包含硝態氮離子、硫酸根離子、磷酸氫根離子、氯離子、銨態氮離子、鉀離子、鈣離子及鎂離子等。 In order to monitor the concentration of individual anions in hydroponic system, we developed all-solid-state planar anion selective electrodes for nitrate, sulfate, hydrogen phosphate, chloride. There were three layers in the ion selective electrode, including a conducting layer, an ion-to-electron transducer, and an ion selective membrane. Firstly, the screen printed technology was used to construct the conducting layer. We sequentially coated the silver paste and carbon paste on the substrate of polyethylene terephthalate. Secondly, we utilized graphene to be as a transducer and investigated its stability of the voltage signal by electrochemistry. Compared to unmodified electrodes, graphene as an ion-to-electron transducer could reduce 24% of charge transfer resistance, and enhanced 25.5 times of a capacitance under the low frequency, and increased the contact angle by 1.09 times. Generally speaking, the less the charge transfer resistance was, the more the exchange current was. Besides, the higher capacitance was equaled to the higher stability of voltage signal. Moreover, the hydrophobicity could avoid the water layer happened. Thirdly, ion selective electrodes were accomplished by drop coating the ion selective membrane on the top of the transducer. In the part of ion selective electrodes, the sensitivities for nitrate, sulfate, chloride, and hydrogen phosphate ion were 59.3 mV/decade (R2=0.9998), 29.3 mV/decade (R2=0.9900), 53.0 mV/decade (R2=0.9848), and 32.9 mV/decade (R2=0.9702), respectively, by measuring their open circuit potential. Furthermore, the detection limits of those electrodes were 63.1 μM, 29.3 μM, 120.2 μM and 12.6 μM, respectively. The lifetime of the all-solid-state nitrate selective electrode was about 6 months. Furthermore, we used those ion selective electrodes to detect the single target ion solution and the results were verified by HPLC that shows a 2% of relative error. The trend of nutrient element sensing from the plant factory was consistent between the anion selective electrodes and the results from HPLC. At the final part of this thesis, the nitrate ion sensing module was fabricated to monitor the concentration change in the nutrient of iceberg lettuce for 2 weeks. With the cation selective electrodes developed by previous members, we have ion selective electrodes including nitrate, sulfate, hydrogen phosphate, chloride, potassium, calcium, ammonium and magnesium. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/52941 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 生物機電工程學系 |
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