The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
A Ritter - One of the best experts on this subject based on the ideXlab platform.
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iron powder graphite and activated carbon as catalysts for the oxidation of 4 Chlorophenol with hydrogen peroxide in aqueous solution
Water Research, 1998Co-Authors: F Lucking, H Koser, M Jank, A RitterAbstract:Abstract Solid materials as iron powder, graphite and activated carbon were tested for their catalytic properties for the oxidation of 4-Chlorophenol in aqueous solution with hydrogen peroxide. Batch tests were performed at 30°C, and continuous tests with granular activated carbon under ambient conditions (20°C). Iron powder was shown to act as a catalyst for the activation of hydrogen peroxide and owing to this for the oxidation of 4-Chlorophenol. The catalytic activity is based on iron ions leached from the iron powder which act as homogeneous catalysts. Thus, the process can be described as a Fenton reaction enabled by a dissolution of iron powder. The same phenomenon was observed when iron impregnated activated carbon was applied as a catalyst. In contrast to iron powder, graphite and activated carbon were found to act as heterogeneous catalysts for the activation of hydrogen peroxide and the oxidation of 4-Chlorophenol. During the oxidation of 4-Chlorophenol with activated carbon as a catalyst the decomposition of H 2 O 2 is significantly slower than in the absence of 4-Chlorophenol. This can be explained by the adsorption of 4-Chlorophenol, due to which the surface area of the activated carbon available for the decomposition of H 2 O 2 , is reduced. At the same concentration of catalytic material in batch tests, the oxidation of 4-Chlorophenol proceeds much faster when iron powder instead of graphite or activated carbon is used. On the other hand, graphite and activated carbon are stable catalysts not affected by dissolution processes. Activated carbon can be utilized for a continuous process in a fixed bed reactor. For this purpose the efficiency of 4-Chlorophenol oxidation in granular activated carbon filled columns was investigated and a 25% conversion of the 4-Chlorophenol (1 g l −1 ) was achieved at a retention time of 26 min.
Juan Lv - One of the best experts on this subject based on the ideXlab platform.
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removal of chlorpheniramine in a nanoscale zero valent iron induced heterogeneous fenton system influencing factors and degradation intermediates
Chemical Engineering Journal, 2016Co-Authors: Lin Wang, Juan Lv, Yongmei Li, Juan YangAbstract:Abstract Removal of chlorpheniramine in a nanoscale zero-valent iron (nZVI) induced heterogeneous Fenton system was investigated. The removal efficiency of chlorpheniramine depended on its initial concentration, initial pH, H 2 O 2 concentration and nZVI dose. Chlorpheniramine (⩽15 mg/L) was completely removed after 60 min oxidation under the following optimal conditions: initial pH = 3.0, H 2 O 2 concentration = 0.1 mM and nZVI dose = 22.4 mg/L. The degradation of chlorpheniramine fitted well with the pseudo first-order kinetics model, and the rate constants ( k obs ) were obtained ( R 2 > 0.9). Several degradation intermediates of chlorpheniramine were detected and confirmed, including 4-hydroxy-4-methyl-2-pentanone, 2-methylaminopyridine, 4-Chlorophenol, 2-propionylpyridine, 2-acetylpyridine, 4-chlorophenyl-2-pyridyl ketone, dimethylamine (DMA) and N-nitrosodimethylamine (NDMA). Based on the identified intermediates, a tentative degradation pathway of chlorpheniramine in the nZVI/H 2 O 2 system was proposed. After nZVI/H 2 O 2 reaction, 52.2% of NDMA formation potential (FP) from chlorpheniramine was reduced. Therefore, nZVI as the catalyst used in the heterogeneous Fenton system is not only an alternative to remove chlorpheniramine, but also effective in reducing NDMA FP.
F Lucking - One of the best experts on this subject based on the ideXlab platform.
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iron powder graphite and activated carbon as catalysts for the oxidation of 4 Chlorophenol with hydrogen peroxide in aqueous solution
Water Research, 1998Co-Authors: F Lucking, H Koser, M Jank, A RitterAbstract:Abstract Solid materials as iron powder, graphite and activated carbon were tested for their catalytic properties for the oxidation of 4-Chlorophenol in aqueous solution with hydrogen peroxide. Batch tests were performed at 30°C, and continuous tests with granular activated carbon under ambient conditions (20°C). Iron powder was shown to act as a catalyst for the activation of hydrogen peroxide and owing to this for the oxidation of 4-Chlorophenol. The catalytic activity is based on iron ions leached from the iron powder which act as homogeneous catalysts. Thus, the process can be described as a Fenton reaction enabled by a dissolution of iron powder. The same phenomenon was observed when iron impregnated activated carbon was applied as a catalyst. In contrast to iron powder, graphite and activated carbon were found to act as heterogeneous catalysts for the activation of hydrogen peroxide and the oxidation of 4-Chlorophenol. During the oxidation of 4-Chlorophenol with activated carbon as a catalyst the decomposition of H 2 O 2 is significantly slower than in the absence of 4-Chlorophenol. This can be explained by the adsorption of 4-Chlorophenol, due to which the surface area of the activated carbon available for the decomposition of H 2 O 2 , is reduced. At the same concentration of catalytic material in batch tests, the oxidation of 4-Chlorophenol proceeds much faster when iron powder instead of graphite or activated carbon is used. On the other hand, graphite and activated carbon are stable catalysts not affected by dissolution processes. Activated carbon can be utilized for a continuous process in a fixed bed reactor. For this purpose the efficiency of 4-Chlorophenol oxidation in granular activated carbon filled columns was investigated and a 25% conversion of the 4-Chlorophenol (1 g l −1 ) was achieved at a retention time of 26 min.
Ferhan Cecen - One of the best experts on this subject based on the ideXlab platform.
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adsorption desorption and bioregeneration in the treatment of 2 Chlorophenol with activated carbon
Journal of Hazardous Materials, 2007Co-Authors: Ozgur Aktas, Ferhan CecenAbstract:This study aims to clarify the effect of activated carbon type on the extent of adsorbability, desorbability, and bioregenerability in the treatment of 2-Chlorophenol. Four different activated carbon types; thermally activated and chemically activated powdered carbons (PAC), and their granular countertypes (GAC) with similar physical characteristics were used. Thermally activated carbons adsorbed 2-Chlorophenol much better than chemically activated ones. However, adsorption was more reversible in the case of chemically activated ones. The use of powdered and granular activated carbon countertypes resulted in comparable adsorption and desorption characteristics. For each activated carbon type, 2-Chlorophenol exhibited higher adsorbability and lower desorbability than phenol. Biodegradation of 2-Chlorophenol took place very slowly when it was used as the sole carbon source in acclimated and non-acclimated activated sludges. Bioregeneration occurred only via desorption due to an initial concentration gradient and no further desorption took place due to low biodegradability. Bioregeneration of activated carbon loaded with 2-Chlorophenol was not a suitable option when 2-Chlorophenol was the only carbon source. It is suggested to remove 2-Chlorophenol via adsorption onto activated carbon rather than applying biological treatment. Also in such cases, the use of thermally activated carbons with higher adsorption and lower desorption capacities is recommended rather than chemically activated carbons.
Christian Petrier - One of the best experts on this subject based on the ideXlab platform.
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effects of ultrasound on adsorption desorption of p Chlorophenol on granular activated carbon
Ultrasonics Sonochemistry, 2003Co-Authors: Oualid Hamdaoui, Emmanuel Naffrechoux, L Tifouti, Christian PetrierAbstract:Abstract The aim of this work is the evaluation of the effects of ultrasound on p-Chlorophenol adsorption–desorption on granular activated carbon. Adsorption equilibrium experiments and batch kinetics studies were carried out in the presence and the absence of ultrasound at 21 kHz. Results indicate that the adsorption of p-Chlorophenol determined in the presence of ultrasound is lower than the adsorption observed in the absence of ultrasound. Desorption of p-Chlorophenol from activated carbon with and without the application of ultrasound was studied. The desorption rates were favoured by increased ultrasound intensity. This rise is more noticeable as temperature increases. The addition of ethanol or NaOH to the system causes an enhancement of the amount of p-Chlorophenol desorbed, especially in the presence of ultrasound. A synergetic enhancement of the desorption rate was observed when ultrasonic irradiation was coupled with ethanol chemical regeneration.