Adsorption Kinetics of VOCs adsorbed on Activated Carbon Fibers

Autor: Tai-Chun Chen, 陳泰君
Rok vydání: 2007
Druh dokumentu: 學位論文 ; thesis
Popis: 95
In this study, we use several treatments including nitric acid impregnation, potassium hydroxide (KOH) impregnation, electrochemical oxidation and heat treatment on PAN-based activated carbon fibers (ACFs). In order to find out what have been done in these treatments, there’s some analysis been taken. Surface morphology of ACFs were observed by field emission scanning electric microscope (FESEM) image. Textural characterization was performed using nitrogen adsorption at 77K. Thermal stability of ACFs were analyzed by using thermal gravity analysis (TGA). Quantities of surface oxygen groups and graphitic crystallite size were analyzed by using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Breakthrough curves of methyl-ethyl-ketone (MEK) and isopropyl alcohol (IPA) were carried out understanding the adsorption kinetics of ACFs. In the results of FESEM, we could find that surface morphology of ACFs were changed with different kinds of modification. There’s corrosion occurred on ACFs when using nitric acid or KOH for treatment. Electrochemical oxidation enabled ACFs to be stripped from its surface. Thermal stability of ACFs reduced after treatment were observed by TGA analysis. Surface chemistry of ACFs also changed after treatment. We could find that graphitic carbon decreased and phenolic groups increased after treatment. Carbonyl groups only decreased in the samples treated by nitric acid and heat treatment after electrochemical oxidation. The results of X-ray diffraction (XRD) analysis indicate that there are graphitic carbon peaks located at 2θ are 26 and 44 o, which can be indexed to C (0 0 3) and C (1 0 1), respectively. Each sample is micro-porous material analyzed by using nitrogen adsorption at 77K. In the breakthrough experiments, we could find that breakthrough time and VOCs amount adsorbed on ACFs decreased when temperature rised. Adsorption kinetic constant of Wheeler equation were fitted. Results of curve fitting tell us there remains some other parameters would affect the breakthrough time of adsorption of VOCs.
Databáze: Networked Digital Library of Theses & Dissertations
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