研發奈米級過氧化鈣與微/奈米氣泡於柴油生物降解之應用

Abstract

環境中汙染屢見不鮮，如柴油意外洩漏汙染土壤與地下水。各個復育方法中，生物復育為低成本且環境友善之整治技術，然而生物反應受到許多因子影響其效率，氧氣為參與好氧降解柴油反應的重要反應物，近年來研究也發現許多金屬過氧化物具有挾帶氧氣之能力。本次研究目的為透過化學沉澱法與物理法合成奈米釋氧顆粒，了解其基本特性及對微生物柴油降解的影響，並透過幫浦生成含有氧氣之微/奈米氣泡來進行生物降解的比較。化學沉澱法及物理研磨法合成的過氧化鈣顆粒，以動態光散射儀量測溴化十六烷基三甲銨 (hexadecyl trimethyl ammonium bromide)、Triton X-100、羧甲基纖維素 (carboxymethyl cellulose, CMC)合成與添加分散劑下研磨之過氧化鈣顆粒大小，前兩者大於6 μm，透過田口式實驗設計可以得到最佳CMC之過氧化鈣 (CMC-CaO2)則為190 nm，溼式研磨 (wet-ground CaO2)平均粒徑則可達到110 nm。合成之顆粒X-ray diffraction均顯示具有過氧化鈣之特徵峰。穿透式電子顯微鏡觀測wet-ground CaO2與CMC-CaO2的顆粒皆小於100 nm。傅里葉轉換紅外光譜顯示wet-ground CaO2具有分散劑之官能基，拉曼光譜顯示出具有O-O之過氧化鈣官能基的存在。以微生物進行柴油降解，氧氣幫浦CMC+AlCl3與basic medium可以產生顆粒大小約400 nm微/奈米氣泡，pH接近中性下，初始溶氧提升至30 mg/L，然而溶氧在第一天後迅速下降。添加wet-ground CaO2 與CMC-CaO2在basic medium中，初始溶氧提升至10 mg/L以上，並可在21天後仍然維持在4 mg/L；CMC+AlCl3與basic medium分別可幫助微生物將柴油於21天由200 ppm降解78 ppm與91 ppm， wet-ground CaO2 與CMC-CaO2則可將柴油降解至118 ppm與101 ppm，結果顯示本次合成之奈米過氧化鈣與微/奈米氣泡均具有提升微生物柴油降解的能力。

Environmental pollution such as diesel spill or accidental leakage into soil and groundwater occurs frequently. In the remediation methods, biological remediation can save costs and be an environmentally friendly remediation technique. However, biological reactions are affected by many factors. For example, oxygen is an important reactant involved in aerobic degradation of diesel. In recent years, many metal peroxide compounds with the ability to carry oxygen have used in remediation. The purpose of this study is to prepare and to characterize nano-scale oxygen-releasing calcium peroxide particles by chemical precipitation and physical grinding methods. Furthermore, synthesized micro/nano bubbles pumping with oxygen and the calcium peroxide nanoparticles were sutdied on their effects of microbial diesel degradation. The calcium peroxide particles synthesized by the chemical precipitation method using hexadecyl trimethyl ammonium bromide, Triton X-100, and carboxymethyl cellulose (CMC) were measured by dynamic light scattering. The size of the first two particles was more than 6 μm; however, the size of the calcium nanoparticles synthesized by CMC using Takuchi method (CMC-CaO2) was around 190 nm. The size of calcium peroxide nanoparticles synthesized by physical wet grinding method (wet-ground CaO2) with the addition of dispersant was 110 nm. All particles showed the characteristic peaks with calcium peroxide by X-ray diffraction. The particle sizes of the CMC-CaO2 and wet-ground CaO2 were less than 100 nm by means of a transmission electron microscope. Fourier transform infrared spectroscopy showed that the surface of the wet-ground CaO2 had a functional group of dispersants. The results of Raman spectroscopy also showed characteristic peaks of O-O function group. By pumping CMC+AlCl3 and basic medium with oxygen, micro/nano bubbles were generated. The particle sizes were around 400 nm and the dissolved oxygen (DO) can rise to 30 mg/L at around neutral pH. However, the DO both went down to 0 mg/L after a day. The DO could rise to 10 mg/L by adding wet-ground CaO2 and CMC-CaO2 into basic medium and can maintain up to 4 mg/L until 2 days. The pH values for these two treatments were 10.82 and 9.36, respectively. Micro/nano bubbles synthesized by CMC+AlCl3 and basic medium could help microorganisms to degrade diesel from 200 ppm to 98 and 125 ppm, respectively. Wet-ground CaO2 and CMC-CaO2 could help microorganisms to degrade diesel from 200 ppm to 118 and 101 ppm, respectively. The results showed wet-ground CaO2, CMC-CaO2 nanoparticles, and micro/nano bubbles had an ability to promote diesel degradation by microbes.