Details

Autor(en) / Beteiligte

• da Costa, Cláudia Mendes

Titel

Development of a Coaxial Fiber Membrane Reactor With Immobilized Horseradish Peroxidase

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2016

Link zum Volltext

• ProQuest

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Fiber membranes obtained by electrospinning are a powerful tool in different areas. One of the ways to broaden the potential of these membranes is to functionalize them through the immobilization of biological species. Encapsulation within fiher membranes offers a protective microenvironment for enzymes, with a high surface area for the exchange of compounds involved in catalytic processes, and may promote enzyme activity even in less favorable environments. The objective of this work was to make coaxial fibers with an inert silicu shell and a core that was suited for the immobilization of an oxido-reductase. The shell was prepared using the sol-gel process. This process is complex. Studies were made varying the silica/water/acid molar ratio, the silica precursor (tetramethoxysilane, TMOS, or tetraethoxysilane, TEOS), the amount of polyvinyl alcohol, which lends flexib ility and porosity to the fibers, and also other compounds such as acetic acid, citric acid, methanol and ethanol, in addition to experimental parameters such as time and temper ature, time of heating before adding species. Regular fibers with a narrow diameter distri bution were obtained by using a 1:2:1,1:8E 3.5ETMOS/water/methanol/HC/PVA molar ratio. For the fiber cores, the choice was the "Ion jelly", an ionic gelatin formed through cross- linking of gelatin and ionic liquid (IL) molecules. The gelatin was used in low concentration in order to keep the solution fluid for longer times, and the temperature of the electrospin- ning chamber was kept lower to slow down the solidification of the sol-gel solution. The most used IL in these assays was choline dihydrogenphosphate. This gelatin/IL. combina tion was tested to make films within which the enzyme horseradish peroxidase (HRP) was immobilized. It was found that the enzyme exhibited good activity in films prepared with 10% gelatin and 10% IL (w/w). The fibers obtained were characterized using several techniques, such as scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infra-red spectroscopy, electrical conductivity measurements. In addition to studying experimental conditions that were adequate for preparing each solution, it was also necessary to study the best conditions to combine the two solutions in coaxial electrospinning assays. It was possible to make coaxial fibers that were shown to have a shell rich in silicon and a core rich in phosphorous and sodium. Coaxial fibers with Immobilized enzyme were also made, but they revealed no evidence of enzymatic activity. One possible reason for this fact is the low amount of membrane produced, which results in too low an amount of enzyme. It was difficult to control the temperature and humidity in the electrospinning chamber, but by controlling these variables better, it is believed that the formulations developed will allow the fulfilment of the goal to make a coaxial fiber membrane with immobilized HRP for bioremediation.