光催化降解異丙醇水溶液並同步水分解分離生成的氫氣

Abstract

本研究旨在探討光催化降解異丙醇水溶液並同步水分解分離生成的氫氣。異丙醇做為晶圓清洗液，廣泛存在於半導體與光電業的有機廢水之一，光催化降解可去除廢水中的異丙醇，並且達到水資源能循環再利用；氫氣為乾淨的綠色能源之一，燃燒後僅會產生水蒸氣，不會產生任何汙染廢棄物，以光催化進行水分解產生氫氣是最乾淨且低耗能的技術。 本研究透過雙胞反應器行光催化降解異丙醇廢水並且同時進行水分解產生氫氣，與單一反應器相比其優點為避免觸媒之間的遮蔽效應與水分解逆反應的發生，以商用WO3作為降解異丙醇觸媒，而以高溫固態熔融法搭配光沉積法負載釕金屬製備Ru/SrTiO3:Rh 做為產氫觸媒，於酸性的條件下，搭配Fe2+和 Fe3+作為電子傳遞介質，透過Nafion薄膜進行離子交互擴散，所使用的燈源為300 W Xe燈加上AM1.5濾片來模擬太陽光源，行光催化雙胞反應器之雙功全反應，五個小時的光反應時間中，異丙醇降解率達到38% (起始濃度20 ppm) 比單一反應器行雙功全反應多降解了約125%的異丙醇總量，氫氣產量高達143.08 µmol/g同樣比單一反應器雙功全反應多了約37%的氫氣產量，同時由於降解端與產氫端反應分開進行，可以達到95%的氫氣產物分離。並且，隨著異丙醇的初始濃度增加(0 ~ 20 ppm)，水分解產生氫氣的量也比使用純水的產生量提高15%，與相同條件的水分解相比，證實於雙功反應器添加異丙醇廢水能確實有效的幫助產生氫氣。

This research focuses on the photodegradation of aqueous isopropanol and simultaneous separation of produced hydrogen. First, isopropanol widely exists in wafer cleaning processes so it is one of the most extensive organic wastewater in semiconductor and photoelectric industries. In order to remediate isopropanol wastewater problem, photodegradation is one of the promising technology and meet the goal of water reuse. Secondly, hydrogen is green energy so it would not produce any pollutant but water after combustion. Moreover, hydrogen evolution by photocatalysis is a clean and low-energy consuming technique. This research takes advantage of a twin reactor to photodegrade aqueous isopropanol and separate produced hydrogen simultaneously. Compared to a single reactor, the twin reactor can prevent sking effect of photocatalyst and inhibit reverse reaction of water splitting. In experiment, WO3 is selected for isopropanol photodegradation catalyst, and Ru/SrTiO3:Rh is selected for hydrogen evolution catalyst which is synthesized by solid-state fusion at high temperature, and Ru is loaded by photodeposition. A Nafion membrane allows counter diffusion of Fe2+ and Fe3+ as electron mediators under the acid condition in the twin reactor. In order to simulate sunlight, the irradiation used a 300 W Xe lamp with AM1.5 filter as light source. Dual function reaction is conducted in the twin reactor. The result shows that 38% of isopropanol is degraded during 5-hrs reaction (initial concentration 20 ppm). Compared with a single reactor, the twin reactor can increase more isopropanol degradation up to 125%. Also, the amount of 143.08 µmol/g H2 is generated by the twin reactor, which is 37% more in hydrogen evolution compared to a single reactor. Furthermore, due to the separation of the hydrogen evolution side and the degradation side, 95% of pure hydrogen is achieved in hydrogen evolution side, thus decrease cost of afterward purification. Compared to pure water splitting, hydrogen evolution increases up to 15% by additional isopropanol (initial concentrations ranged 0 ~ 20 ppm). In summary, this study demonstrates that adding isopropanol wastewater can indeed increase H¬2 production in the twin reactor.