| 摘要: | 光電-芬頓程序是一套以長波長紫外光與電促進傳統芬頓反應效率的程序，設計概念源自於傳統芬頓程序中的亞鐵在反應進行之初會快速與過氧化氫反應，一方面產生氫氧自由基氧化有機物，另一方面產生大量的氫氧化鐵污泥。當系統中的鐵離子自二價氧化成三價後，可提供給過氧化氫的催化能力隨即大幅下降，且芳香族類的化合物在經過傳統的芬頓程序氧化後，通常礦化效果不佳，污染物多半轉而以小分子型態的有機酸存在於系統中。過去之研究發現此類有機酸多半為草酸及其他少量甲酸及醋酸，三價鐵容易與這類副產物產生化合，而這些化合物對近紫外光或可見光區波長的吸收度很高，可接受光能量還原成亞鐵離子再次參與芬頓反應，故研究設計以電流及長波長紫外光源促進系統中的鐵還原反應。唯其詳細的機制尚未做深入的瞭解，並且有許多反應現像與操作參數有待釐清。因此，有必要從學理上來探討其反應行為，瞭解其真正的反應機制，目標以節省能源為方向設計一系列可見光反應程序。有鑑於過去與電解相關的電解槽裝置一般均為單一陰極與陽極相對，可提供的反應面積受限於陰陽極板相對之處。因此，將透過實驗室自行設計的一系列電-芬頓與光電-芬頓電解氧化裝置，外以圓形不鏽鋼板為電解槽，內設不鏽鋼圓管，以此兩者為陰極，中間放置一網狀不溶解性陽極，藉提高極板有效工作面積，增加鐵還原量。計畫第一年，預期以單、雙層陰極電解槽效能評估與極板間距影響效應，尋求最佳電解槽設計參數，並透過反應時間、pH、 Fe2+/H2O2 莫爾比、電流與過氧化氫進藥模式影響效應，瞭解最適芬頓、電-芬頓程序操作參數，最後以草酸鐵螯合比例試驗與pH 影響效應對光電-芬頓程序之操作參數進行評估。第二年計畫中將使用實驗室批式反應器，利用氣相層析儀、液相層析儀及COD 分析污染物降解濃度，以積分法、初速率法與過量法決定污染物在不同氧化程序之反應階數及反應速率常數，藉此動力參數設計一pilot 反應槽。第三年計畫再利用氣相層析儀、液相層析儀及離子層析儀進行中間產物鑑定，推導污染物的氧化機制，並透過第一年的最佳化參數研究成果與第二年設計的pilot 反應槽，進行高濃度廢液處理，整合芬頓、電-芬頓及光電-芬頓程序，對pilot 反應槽效能與操作經費做相關評估。
A new approach of photoelectro assisted Fenton process has been developed in our laboratory. By using long wave of UV light and current as electro donate can efficiently initiate Fenton reaction because Fe(Ⅲ) may complex with certain target compounds or other byproducts, especially those acting as ligands. The new design for our system came from the concept of promoting the ferric reduction rate, which can increase the amount of hydroxyl radicals. Literatures reported that oxalic, formic and acetic acids are the major products of aromatic compound degradation, which can complex with ferric ions. These complexes typically have higher molar absorption coefficients in the near-UV and visible regions to generate ferrous ions. Meanwhile, the ferrous ion is regenerated via the reduction of ferric ion on the cathode. However, the reaction mechanism is still unclear. Therefore, we will design a functional reactor to clarify the mechanism of ferric reduction between near-UV visible and electricity and also try to design a new photo reactor with the aim of saving energy. According to our past experience, single working electrode is not enough for electrolysis. For this reason, we will develop a new device to increase the working area and promote the current efficiency. In the first year, we will focus on the operation parameters, such as single and double electrode effect, electrode distance, initial pH, Fe2+/H2O2 molar ratio, applied current, H2O2 feeding mode to investigate the optimum parameters of Fenton and electro-Fenton processes. Afterwards, using the test of Fe(Ⅲ)-oxalate ratio and pH to explore the effect of photoelectro assisted Fenton process. In the second year, we will use the integral, initial rate and excess methods to determine the kinetics of reaction. Based on the data obtained from the experiments, a pilot reactor will be designed and setup. In the third year, we will identify the intermediates of reaction to find the mechanisms and evaluate the cost of photoelectro assisted Fenton process with the pilot reactor. |
