Nitrogen-doped char as a catalyst for wet oxidation of phenol-contaminated water
| Autor: | Aidan Garcia, Iva Tews, Manuel Garcia-Perez, Jean-Sabin McEwen, Michael Ayiania, Sohrab Haghighi Mood, Kalidas Mainali |
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| Rok vydání: | 2021 |
| Předmět: |
Aqueous solution
Renewable Energy Sustainability and the Environment Chemistry 020209 energy Radical chemistry.chemical_element 02 engineering and technology Activation energy 010501 environmental sciences 01 natural sciences Oxygen Catalysis chemistry.chemical_compound 0202 electrical engineering electronic engineering information engineering Phenol Wet oxidation Char 0105 earth and related environmental sciences Nuclear chemistry |
| Zdroj: | Biomass Conversion and Biorefinery. |
| ISSN: | 2190-6823 2190-6815 |
| DOI: | 10.1007/s13399-020-01184-0 |
| Popis: | Catalytic wet oxidation (CWO) of aqueous effluents rich in organic compounds is a very promising technology for the treatment of liquid wastes from biomass conversion processes. CWO reactions occur through the formation of free radical species, produced in the presence of an oxidant, which act on organic contaminates in the effluent. Although the reaction is well known, there exists a lack of affordable catalysts to conduct this process at the lower temperatures and pressures in novel bioenergy processes. This study assessed the catalytic effect of nitrogen-doped chars as such an option. Phenol in aqueous solution was used as a model waste effluent. Treatment was conducted at moderate temperatures (190 to 260 °C), oxygen partial pressure of 1 MPa, and reaction times of 15, 30, and 45 min in stainless steel and glass-lined tube reactors. High pressure liquid chromatography (HPLC) analyses of the products quantified phenol and by-product concentrations used in the calculation of reaction activation energy. The char catalyst was studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) in order to gain insight into its structure and surface composition. The results indicate that nitrogen-doped char catalysts accelerate the oxidation of phenol by decreasing its reaction activation energy from 82.2 kJ/mol (non-catalyzed) to 40.4 kJ/mol (catalyzed). An analysis from first principles using density functional theory (DFT) was conducted to ascertain which N functional group has the most significant impact on free radical formation in the presence of oxygen. Among all the N functional groups studied, the dipyridinic functional groups showed the most promising characteristics to facilitate the formation of hydroxyl free radicals. |
| Databáze: | OpenAIRE |
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