因應工業發展，生質能源等具永續經營之議題的開發儼然成為當今重要的研究方向。纖維素奈米纖維(Cellulose Nanofiber, CNF)，作為地球上產量最豐富的再生資源，同時兼具可生物降解、低密度、高長寬比、較大的比表面積以及高強度等優點，在複合材料、生物工程等領域表現出了良好的前景。
氣凝膠具有低密度、高比表面積、高孔隙率等特性，目前被廣泛研究在各領域，纖維素奈米纖維氣凝膠(CNF aerogel)，除了保有傳統氣凝膠高孔隙率、高比表面積的優點外，更結合纖維素本身優異性能，在吸附、儲能、隔熱和生物醫學等方面皆有不少應用。
本研究開發一更具環保且低成本的新製程來製備CNF，並以此CNF作為基材，接著透過冷凍乾燥法來製備聚多巴胺(PDA)-聚乙烯醇(PVA)-奈米纖維素(CNF)混和有機氣凝膠，並將此氣凝膠混摻WO2.72@Fe3O4粉體製成具有光催化降解/還原特性之複合材料。
本研究應用端分為兩個部分，第一部分將製備出的複合氣凝膠作為吸附材，用於去除空氣中的游離甲醛，其吸附效率可達85 %，單位面積甲醛吸附量2033 ppm/m2∙24h，而在照射UV光(波長254 nm) 後，甲醛透過WO2.72@Fe3O4光催化粉體被降解，其降解效率為78.2 %。第二部分則是將複合氣凝膠作為過濾材，用來去除汙水中的六價鉻金屬離子(Hexavalent chromium, Cr (VI))，且在太陽光照射210分鐘後，鉻酸鉀溶液中六價鉻的還原效率為97.4 %，並經由三次重複光催化實驗後，還原效率仍有97.3 %。
經由研究結果顯示，WO2.72@Fe3O4/PDA-CNF複合氣凝膠同時具有吸附汙染物並將其去除之功效，且在氣相以及水相皆可以應用，再加上材料本身製成環保且具有可生物降解，在吸附及過濾領域中具有相當好的前景。

In response to industrial development, the development of sustainable management issues such as biomass energy has become an important research direction today. Cellulose Nanofiber (CNF), as the most abundant renewable resource on earth, has the advantages of biodegradation, low density, high aspect ratio, large specific surface area and high strength. It has shown good prospects in the fields of composite materials and bioengineering.
Aerogel has the characteristics of low density, high specific surface area, high porosity, etc., and is currently widely studied in various fields. Cellulose nanofiber aerogel (CNF aerogel) not only retains the advantages of high porosity and high specific surface area of traditional aerogels, but also combines the excellent properties of cellulose itself. It has many applications in adsorption, energy storage, thermal insulation and biomedicine.
In this study, a new, more environmentally friendly and low-cost process was developed to prepare CNF. Using this CNF as a substrate, polydopamine (PDA)-polyvinyl alcohol (PVA)-nanocellulose (CNF) composite aerogel were prepared by freeze-drying method. The aerogel was mixed with WO2.72@Fe3O4 powder to make a composite material with photocatalytic degradation/ reduction characteristics.
The application side of this study is divided into two parts. The first part is the composite aerogel used as an adsorbent to remove formaldehyde in the air. Its adsorption capacity is 2033 ppm/ m2∙24h of formaldehyde adsorption per unit area. After being irradiated with UV light (wavelength =254nm), formaldehyde was degraded through the WO2.72@Fe3O4 photocatalytic powder, and the degradation efficiency was 85 %.
The second part uses the composite aerogel as a filter material to remove hexavalent chromium metal ions (Cr(VI)) in sewage. It was confirmed by experiments that the reduction efficiency of hexavalent chromium in potassium chromate solution was 97.4%. After 210 minutes of sunlight exposure. And after three repeated photocatalytic experiments, the reduction efficiency is still 97.3 %.
The research results show that the WO2.72@Fe3O4/PDA-CNF composite aerogel has the effect of adsorbing pollutants and removing them at the same time, and can be applied in both the gas phase and the water phase. In addition, the material itself is environmentally friendly and biodegradable, and has a very good prospect in the field of adsorption and filtration.

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