Topic
Wet oxidation
About: Wet oxidation is a research topic. Over the lifetime, 3094 publications have been published within this topic receiving 61536 citations.
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TL;DR: In this article, the authors used activated carbons (ACs) as catalysts for the removal of 2,4,6-trinitrophenol (TNP) from aqueous solutions by catalytic wet air oxidation (CWAO).
Abstract: Activated carbons (ACs), with different activation degrees, were obtained by chemical activation of olive stones and tested for the removal of 2,4,6-trinitrophenol (TNP) from aqueous solutions by catalytic wet air oxidation (CWAO). These materials were characterized using different techniques (e.g., N 2 and CO 2 adsorption, temperature programmed desorption, immersion calorimetry and scanning electron microscopy). The non-catalytic oxidation of TNP in water, at 473 K and 0.7 MPa of oxygen partial pressure, is negligible, while the use of ACs as catalysts leads to complete removal of this organic compound. Competition between adsorption and catalytic oxidation reaction pathways, occurring simultaneously in the CWAO process, depends on the carbon porous texture. The extent of oxidation is given by the amount of nitrates formed during reaction. When a highly microporous carbon with large surface area ( S BET = 1530 m 2 /g) is used, all dissolved TNP is adsorbed and oxidation takes place in wide micropores. However, when using a carbon material with low surface area ( S BET = 121 m 2 /g) and low microporosity, TNP degradation will also occur on the external surface area, since there is enough TNP available in the bulk liquid media; in this case fast degradation takes place on the carbon macro–mesopores. Following that, the degradation mechanism is always heterogeneous but takes place in different ranges of porosity and depends on the amount of dissolved TNP. In addition, the surface chemistry of the carbon materials is modified during the CWAO process due to the presence of oxygen at the conditions employed.
29 citations
TL;DR: In this article, a series of detailed isothermal unsteady-state two-dimensional models are developed and solved in the context of sub-critical catalytic wet oxidation with a non-deactivating catalyst of organic-containing contaminated wastewaters.
Abstract: Compared with other mature industrial fields where multiphase reactors are prevalent, the design of three-phase catalytic reactors for wet air oxidation processes is still in emergence. A series of detailed isothermal unsteady-state two-dimensional models is therefore developed and solved in the context of sub-critical catalytic wet oxidation with a non-deactivating catalyst of organic-containing contaminated wastewaters. A comparative analysis is made for trickle-bed reactors, packed-bubble columns, three-phase fluidized beds and slurry bubble columns. This paper discusses from a multiphase reactor engineering perspective, the design of such contactors by setting an exhaustive modeling framework of catalytic wet oxidation in which the molecular, particle and reactor scales are integrated. The simulation results indicate that when wet oxidation is liquid-reactant limited, packed bubble columns outperform trickle beds regardless of the pressure level, whereas three-phase fluidized beds exhibit a critical particle size maximizing the pollutant conversion. At equal effluent residence times, slurry bubble columns are found less efficient than three-phase fluidized bed reactors.
29 citations
Patent•
04 Feb 1992
TL;DR: In this paper, a process is provided for treating a sulfide-containing alkaline aqueous effluent to improve its environmental acceptability, which comprises: (a) intimately mixing a water-immiscible solvent, such as a pyrolysis gasoline, therewith for a sufficient time to extract polymerizable hydrocarbon compounds and/or other compounds which may cause fouling of downstream plant, (b) allowing the solvent phase and the annealing phase to separate, removing the solventphase, and subjecting the separated aquous phase to an oxidation treatment which oxid
Abstract: A process is provided for treating a sulfide-containing alkaline aqueous effluent to improve its environmental acceptability, which comprises: (a) intimately mixing a water-immiscible solvent, such as a pyrolysis gasoline, therewith for a sufficient time to extract polymerizable hydrocarbon compounds and/or other compounds which may cause fouling of downstream plant, (b) allowing the solvent phase and the aqueous phase to separate, (c) removing the solvent phase, and (d) subjecting the separated aqueous phase to an oxidation treatment which oxidizes sulfide ions to environmentally acceptable sulfur acid ions, particularly sulfate ions, e.g. a wet air oxidation process. The invention has been particularly developed for treating spent caustic which has been used to scrub gases produced by cracking for ethylene production. Such effluents have been found to cause fouling of the oxidation plant and the Applicants have found that this is due to polymerizable hydrocarbons. Furthermore they have found that prolonged contact times between a readily available solvent and the effluent can ensure that the fouling problem is cured.
29 citations
TL;DR: In this article, stillage from cane molasses based alcohol distillery was thermally treated at 160 to 250°C at high pressure and in the absence of air, and a solid charred residue was precipitated that was easily separated by gravity filtration from a liquid suitable for anaerobic digestion or wet oxidation.
Abstract: Stillage from cane molasses based alcohol distillery was thermally treated at 160 to 250°C at high pressure and in the absence of air. A solid charred residue was precipitated that was easily separated by gravity filtration from a liquid suitable for anaerobic digestion or wet oxidation. The charred residue was comparable with typical lignite coal in terms of carbon content and calorific value. Effects of temperature and pH on COD reduction, biodegradability, and filterability were studied.
29 citations
TL;DR: In this paper, an optimal design methodology is applied to the catalytic mixture Fe:Cu:Mn in order to determine the optimal proportions of each metal in the mixture, which results in the determination of an important synergistic effect between the metals and an optimal zone.
Abstract: The wet peroxide oxidation process (WPO®) which was developed at the laboratory uses the Fenton's reagent at high temperature. But the reaction efficiency is limited by the accumulation of volatile fatty acids such as oxalic, malonic, succinic and acetic acids (hereafter OMSA). In order to improve the efficiency of the original process, different transition metal ions are tested as catalyst. The experimental results indicate that the system using homogeneous Fe, Cu, and Mn is a promising one. The oxidation of carboxylic acids is quite completed under mild working conditions (T < 100°C, pH = 3, p = 1 atm, reaction time = 1 h, stoichiometric quantity of H2O2 = 1.5). Optimal design methodology is applied to the catalytic mixture Fe:Cu:Mn in order to determine the optimal proportions of each metal. This results in the determination of an important synergistic effect between the metals and an optimal zone. Cu(II), Mn(II) or Fe(II) alone have a slight catalytic effect while the association is very effective on ...
29 citations