以TiO2和Fe/TiO2覆膜光纖處理人工底泥中環丙沙星之研究

本研究以光纖光催化系統處理人工合成底泥中環丙沙星，並探討在不同實驗條件下對於環丙沙星去除效率之影響。本研究選用發光二極體(Light-emitting diode, LED)作為光催化之光源，製備之鐵改質二氧化鈦(Fe/TiO2)及商業化Degussa TiO2光觸媒以SEM/EDS觀察表面特性，結果顯示Ti、O、Fe元素出現在Fe/TiO2光觸媒中並呈現均勻分佈。反射率分析儀分析其能隙變化發現，TiO2經Fe改質後明顯將波長延伸至可見光波段下，能隙由3.0 eV降低至2.6 eV。本研究光催化實驗採用之不同條件包括：光觸媒劑量、初始濃度、波長之光源、觸媒種類等，評估不同條件下光催化去除環丙沙星之影響。由實驗結果發現，在不同光觸媒劑量覆鍍光纖光催化時，以Fe/TiO2觸媒、劑量5 mg覆鍍為最佳條件，其底泥中環丙沙星去除率為37.4 %相較於未摻雜TiO2底泥去除率只有28.8%，提升了8.6%。在不同初始濃度條件下，以環丙沙星初始濃度1 mg/L降低至0.5 mg/L時，Fe/TiO2底泥去除率由32.5提升至37.4%，未摻雜TiO2去除率由25.8%提升28.8%，污染物初始濃度越低時，去除率則提高。在不同波長光源條件下，光催化去除底泥中環丙沙星仍以Fe/TiO2觸媒於紫外光去除效果最佳，但在可見光光源條件下，Fe/TiO2(35.5%)去除效果也比TiO2 (22.1%)提升13.4%。當以不同觸媒種類進行光催化時，不論在何種初始濃度、光源種類、觸媒劑量下，皆以Fe/TiO2觸媒有最好的去除效果。本實驗反應動力學主要以擬一階為主，在紫外光下k值為7.6×10-3 min-1，可見光下k值為6.9×10-3 min-1。本研究同時探討了環丙沙星在人工合成底泥的分佈情形，但Kd計算因水相濃度低於偵測極限，因此推測本研究Kd值非常大，由此結果可得知，CIP在人工合成底泥中非常容易吸附在底泥中。

關鍵字

光催化；環丙沙星；人工底泥； LED

並列摘要

In this study, a fiber-optic photocatalytic system was used to treat ciprofloxacin in artificial sediments. The effects on the removal efficiency of ciprofloxacin under different experimental conditions were discussed. The system uses the light-emitting diode (LED) as the light source. The SEM and EDS were used to observe the surface characteristics of the prepared iron-modified titanium dioxide (Fe/TiO2) and commercial Degussa TiO2 (TiO2). It can be seen that Ti, O, and Fe are present in Fe/TiO2, and these three elements are evenly distributed in the catalyst. It proves that Fe is successfully doped in TiO2. The analysis of the energy gap shows that the modified Fe/TiO2 is easier to be excited in the visible light band than TiO2, and its energy gap decreases from 3.0 eV to 2.6 eV. The system varied photocatalyst dose, initial concentration, the wavelength of the light source, and catalyst type to evaluate the effect of photocatalysis on the removal of ciprofloxacin. From the experimental results, it was found that using Fe/TiO2 catalyst with 5 mg coated on optical fiber achieved the optimal removal rate of 37.4% of ciprofloxacin in the sediment. When the initial concentration of ciprofloxacin was reduced from 1 to 0.5 mg/L, the removal rate by Fe/TiO2 increased from 32.5 to 37.4%, compared to the removal rate of undoped TiO2 only increased from 25.8 to 28.8%. The lower the initial concentration of ciprofloxacin, the higher the removal rate. Using ultraviolet light as the light source obtained a better removal rate of ciprofloxacin in sediments than using visible light. However, the Fe/TiO2 (35.5%) still got better removal efficiency than TiO2 (22.1%). When performing photocatalysis with different photocatalysts, regardless of the initial concentration, type of light source, and catalyst dosage, Fe/TiO2 photocatalyst shows the best removal effect. The reaction kinetics of the photocatalytic system is mainly based on the pseudo-first-order. The k value under ultraviolet light and visible light are 7.6×10-3 min-1 and 6.9×10-3 min-1, respectively. This study also discussed the distribution of ciprofloxacin in artificially synthesized sediments. However, the ciprofloxacin level in the water phase is below the detection limit. It infers that the Kd value is very large and the ciprofloxacin is easy to adsorb in the sediments.