二氧化鈦結合四氧化三鐵顆粒光催化降解乙醯胺酚與觸媒回收之研究

由於近年來新興污染物(Emerging Contaminants, ECs)備受關注，本研究主要探討藥物與個人保健用品(Pharmaceuticals and Personal Care Products, PPCPs)對環境之影響。因為PPCPs在生物體內代謝率低，多數藥物皆直接被排放於環境中，其中以乙醯胺基酚(Acetaminophen, APAP)濃度最高。高級氧化處理程序(Advanced Oxidation Processes, AOPs)中，以光催化處理被認為具有無毒性、化學穩定性且具有效降解、操作簡單、價格便宜，為一理想處理PPCPs之方法。但近期發現奈米材料有影響環境，進而回到人體危害健康之疑慮。本研究藉由四氧化三鐵(Fe3O4)作為二氧化鈦(TiO2)之載體，在紫外光波長為365 nm的條件下，在500 mL的燒杯中置入20 mg/L APAP，利用光催化測試其反應參數如添加劑量和pH值，以及回收率和再利用率，最後探討反應動力學。結果發現TiO2和Fe3O4的多寡，皆會影響光催化降解和回收效率。在相同反應時間下，10-F/T(20)相較於其他觸媒種類有較好之降解率75%和回收率103%。降解率隨著添加劑量的增加而提升，但過量可能產生遮蔽效應，使降解率下降，故最佳添加量為100 mg/500 mL。在不同pH值批次實驗中，添加緩衝溶液調配pH值之降解率為中性(54%)>鹼性(32%)>酸性(20%)，但皆劣於未添加緩衝溶液。在未添加緩衝溶液於相同反應時間降解率達100%，故後續之回收再利用實驗皆無添加緩衝溶液控制pH值。在進行10-F/T(20)之回收再利用實驗時，發現第1次回收率只有原先測試(100 mg)的60% (60 mg)，推測原因可能是反應槽容積過大、Fe3O4本身磁性不足、磁棒之尺寸與磁性太小，或者是沉澱時間不足而影響觸媒回收率，進而影響其再利用率。若排除第1次回收率之影響，進一步計算將第1次回收量和降解率同時乘上1.6倍，回收量(96 mg)較接近原本添加之劑量100 mg，降解率(81.6%)亦與原先的降解率(94%)相近，調整後得到第1~4次回收量約87.7~96 mg與第1~4次降解率約81.6~96%。由此可得知即便是觸媒經光催化反應後回收再利用四次仍有良好之降解效果。本研究發現TiO2/Fe3O4 (10-F/T(20))降解APAP為擬一階反應。

關鍵字

二氧化鈦；四氧化三鐵；乙醯胺酚；回收；光催化程序

並列摘要

Due to the recent attention of Emerging Contaminants (ECs), this study focuses on the environmental impact of Pharmaceuticals and Personal Care Products (PPCPs). Because of the low metabolic rate of PPCPs in living organisms, most of the drugs are directly discharged into the environment, with the highest concentration of Acetaminophen (APAP). Photocatalytic treatment, one of Advanced Oxidation Processes (AOPs), is considered to be a non-toxic, chemically stable and effective in degradation, simple in operation, and inexpensive, that is an ideal method for treating PPCPs. However, it has recently been discovered that nanomaterials have an impact on the environment and return to the human body for health concerns. In this study, ferric oxide (Fe3O4) was used as the carrier of titanium dioxide (TiO2). 20 mg/L APAP was placed in a 500 mL beaker, and the reaction parameters such as addition dose and pH value, recovery and reuse level were measured by photocatalytic reaction at an ultraviolet wavelength of 365 nm. Finally, the reaction kinetics was investigated. The results showed that the dose of TiO2 and Fe3O4 affects the photocatalytic degradation and recovery efficiency. At the same reaction time, 10-F/T(20) has a better degradation rate of 75% and recovery rate of 103% compared to other catalysts. The degradation rate increases with the addition dose, but the excess dose may cause shadowing effect, which reduces the degradation rate. Therefore the optimum addition dose is 100 mg/500 mL. In the batch experiments with various pH values, the degradation rates of the pH values adjusted by the buffer solution were neutral (54%) > alkaline (32%) > acidic (20%), but all were inferior to that of pH without addition of buffer solution. In the case where no buffer solution was added, the degradation rate reached 100% in the same reaction time, so the subsequent recovery and reuse tests did not control the pH value with any buffer solution. When the 10-F/T (20) recovery and reuse experiment was carried out, it was found that the first recovery rate was only 60% (60 mg) of the original test (100 mg). The presumed reasons may be that the reactor volume is too large, Fe3O4 itself possesses insufficiently magnetism, and the size of magnetic rod and its magnetism are too small, or the precipitation time is insufficient to affect the recovery rate of the catalysts, which in turn affects the reuse rate. If the effect of the first recovery rate is excluded, further calculation will multiply the first recovery amount and degradation rate by 1.6 times. The recovery amount (96 mg) is closer to the originally added dose of 100 mg, and the degradation rate (81.6%) is similar to the original one (91%). After adjustment, the recovery amount is about 87.7-96 mg and degradation rate is around 81.6-96%. It can be seen that even if the catalysts are recovered after the photocatalytic reaction and reused four times, they still possess a good degradation effect. This study found that APAP degraded by TiO2/Fe3O4 particles (10-F/T(20)) is a pseudo first-order reaction.