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Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient- wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3 wt.
One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3 wt. Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution.
The dechlorination reaction auh promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play ex major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption – Catalytic wet air oxidation on activated carbons.
The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater.
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The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation CWAO of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process.
Three activated carbons ACs from different source materials were used as catalysts: During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent.
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This different ageing was examined through AC physico-chemical properties. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption — Catalytic cohlra air oxidation on activated carbons.
Conora catalysts for continuous catalytic wet air oxidation of phenol. Catalytic wet oxidation has proved to be effective at eliminating hazardous organic compounds, such as phenol, from waste waters. However, the lack of active long-life oxidation catalysts which can perform in aqueous phase is its main drawback. This study explores the ability of bimetallic supported catalysts to oxidize aqueous phenol solutions using air as oxidant.
The oxidation was carried out in a packed bed reactor operating in trickle flow regime at degrees C and kPa of oxygen partial pressure. Lifetime tests were conducted et 8 days. The pH of the feed solution was also varied. The results show that all the catalysts tested undergo severe deactivation during the first 2 days of operation.
Later, the catalysts present steady activity until the end of the test. The catalyst deactivation is related to the dissolution of the metal oxides from the catalyst surface due to the acidic reaction conditions. Generally, the performance of the catalysts was better when the pH of the feed solution was increased. Catalytic and non- catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Wet air oxidation WAO and catalytic wet air oxidation CWAO were investigated as suitable precursors for couora biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate DBS.
Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial ckhora P O2 and atand degrees C. Based on the main identified intermediates acetic acid and sulfobenzoic acid a reaction pathway for DBS and a kinetic model in Cohra were proposed.
In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in ex trickle flow regime, using a commercial activated carbon AC as catalyst.
The temperature and P O2 were degrees C and bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity in terms of substrate removal were established.
Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture. Kinetics and biodegradability enhancement.
Cohoar Catalans 26, Tarragona, Catalonia Spain ]. C and bar, respectively. Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure P O 2 and atand deg. The temperature and P O 2 were deg. The results showed that in mild operation conditions at cohkra of degrees C, pressure of 3 MPa, liquid feed rate of 1.
The curve of phenol conversion is similar to “S” like autocatalytic reaction, and is accordance with chain reaction of free radical. The kinetic model of pseudo homogenous reactor fits the catalytic wet air oxidation reaction of phenol. The effects of initial concentration of exf, liquid feed rate and temperature for reaction also were investigated.
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Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts. Quite cohoar straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed.
Catalytic wet air oxidation of aniline with nanocasted Mn-Ce-oxide catalyst. A range of liquid hourly space velocities h -1 and temperatures degrees C atu 10 bar of oxygen were tested. The experiments cohra conducted to provide the intrinsic performance of the catalysts. Given the high cost of space launch, the repurposing of biological and plastic wastes to reduce the need for logistical support during long distance and long duration space missions has long been recognized as a high priority.
Described in this paper are the preliminary efforts to develop a wet air oxidation system in order to produce fuels from waste polymers. Preliminary results of partial oxidation in near supercritical water conditions are presented. Inherent corrosion and salt precipitation are discussed as system design issues for a thorough assessment of a second generation wet air oxidation system. Directory of Open Access Journals Sweden. Full Text Available The catalytic wet air oxidation CWAO technology is used for the treatment of the simulated printing and dyeing wastewater and also for investigating the catalyst performance indicators such as catalyst activity and stability.
The catalyst activity is mainly reflected from the water decolorization and CODCr removal rates, and the stability of the catalyst is mainly reflected by the quantity of metal dissolution. Catalytic wet air oxidation of coke-plant wastewater on ruthenium-based eggshell catalysts in a bubbling bed reactor. Catalytic wet air of coke-plant wastewater was studied in a bubbling bed reactor.
Two types of supported Ru-based catalysts, eggshell and uniform catalysts, were employed. Compared to the corresponding uniform catalysts with the same Ru loading 0. The high activity of eggshell catalyst for treatment of coke-plant wastewater can be attributed to the higher density of active Ru sites in the shell layer than that of the corresponding uniform catalyst with the same Ru loading.
It has been also evidenced that the active Ru sites in the internal core of uniform catalyst have very little or no contribution to CODcr and NH3-N removal in the total oxidation of coke-plant wastewater.
Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production. Full Text Available In the present work a process of cohofa wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found.
For the purpose of producing aromatic aldehydes in continuous regime, a three-phase atu reactor was built, and it was operated using atmospheric air as the oxidizer. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model PHADM applied to the liquid phase.
HPLC analysis and yeast estrogen screen assay were used to evaluate the ccohora of E2 and estrogenicity of treated samples. After the reaction, a 1. The performance of TOC and dye removal does not decrease after two regeneration cycles. In total, a 57 h effective reaction has been carried out with no loss of catalytic activity.
Total etx and air flow were 25 bar and mL min -1respectively. Catalytic wet air oxidation of bisphenol A solution in a batch-recycle trickle-bed reactor over titanate nanotube-based catalysts.
Catalytic wet air oxidation CWAO is classified as an advanced oxidation process, which proved to be highly efficient for the removal of emerging organic pollutant bisphenol A BPA from water.
In this study, BPA was successfully removed in a batch-recycle trickle-bed reactor over bare titanate nanotube-based catalysts at very short space time of 0. The catalyst was chemically stable in the given range of operating conditions for h on stream. Critical roles of cerium incorporation. In catalytic wet-air oxidation CWAO process for the printing and dyeing wastewater PDWthe effects of Ce addition on performance, mechanism and kinetics of the catalyst were investigated.
The Ce addition increases the Brunauer-Emmett-Teller BET surface area and pore volume of the catalyst and makes the active components uniformly distributed on the catalyst surface.
Therefore, the catalytic activity and stability of the Ce-modified catalyst are considerably improved. The scavengers experiments identify the active species existed in the CWAO reaction system, with the order of reactivity: This work presents the experimental results obtained at a pilot plant which works with a slow, wet and catalytic pyrolysis process of dry fowl manure.
This kind of process mainly consists in the cracking of the organic matrix and in the following reaction of carbon with water, which is either already contained in the organic feed or added, to produce carbon monoxide and hydrogen.
Removal of ammonia solutions used in catalytic wet oxidation processes.
Ammonia NH 3 is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological cohlra is unfeasible. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h -1 in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water.
The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around Development of a catalytic system for gasification of wet biomass.
A gasification system is under development at Pacific Northwest Laboratory that can be used with high-moisture biomass feedstocks. Since a pressurized system is used, the wet biomass can be fed as a slurry to the reactor without drying.