Regeneration of Carbon Materials Saturated with Organic Pollutants by Fenton Oxidation Based Technologies

Date
2018-06-11
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Abstract
Organic pollutants, which may be carcinogenic and endocrine disrupting, are frequently detected in different water bodies. Carbon adsorption is an effective and efficient approach to remove organic pollutants from water even for the toxic and bio-refractory ones. After adsorption, it is economically and environmentally beneficial to regenerate the carbon materials. Fenton and electro-Fenton oxidation are promising technologies for regeneration because they can regenerate the adsorbents and degrade the adsorbed organic pollutants simultaneously under ambient conditions. In this thesis, the Fenton and electro-Fenton oxidation were studied for the regeneration of carbon saturated with methyl orange (MO) with a focus on the impact of adsorbent properties and operational parameters. First, the impact of pore structure on Fenton regeneration was investigated using γ-Fe2O3 loaded carbon with different microporosity. The fresh and regenerated carbon materials were characterized by adsorption isotherm and kinetics measurements. The regeneration efficiency decreased with increasing microporosity; essentially complete regeneration was achieved with the mesoporous carbon. The results were consistent with the MO adsorbed in micropores being strongly bond and difficult to remove using the Fenton regeneration method. As an attempt to regenerate the adsorption sites in micropores, carbon materials were regenerated using electro-Fenton oxidation. The regeneration efficiency was improved with higher cathodic potential, better contact with cathode, and lower microporosity. Compared with Fenton oxidation, electro-Fenton oxidation could regenerate the adsorption sites in the micropores < 1 nm. The results indicated that electro-Fenton regeneration was controlled by the electro-desorption process. Because better contact with the cathode was necessary for electro-Fenton regeneration, activated carbon - polytetrafluoroethylene electrodes were proposed to act as both the adsorbent for adsorption and the cathode for electro-Fenton regeneration. MO adsorption capacity of 176 mg/g and regeneration efficiency of 81% were obtained using one of these electrodes. A higher MO adsorption rate and regeneration efficiency were obtained with a higher electrode hydrophilicity. Overall, this thesis provides mechanistic insights on the regeneration of carbon materials by the Fenton and electro-Fenton oxidation, which can guide further research and practical application of these methods in carbon regeneration.
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Keywords
Water treatment, Carbon adsorption, Fenton oxidation, Electro-Fenton oxidation, Methyl orange, Organic pollutants
Citation
Xiao, Y. (2018). Regeneration of Carbon Materials Saturated with Organic Pollutants by Fenton Oxidation Based Technologies (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31999