Artykuły w czasopismach: „4-Chlorophenol (4-CP)”

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Artemyanov, Andrey P., i Larisa A. Zemskova. "СHLOROPHENOLS REMOVAL FROM SOLUTION USING ADSORPTION AND OXIDATION IN PRESENCE OF ACTIVATED CARBON FIBER". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, nr 6 (9.07.2019): 138–44. http://dx.doi.org/10.6060/ivkkt.20196206.5821.

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Adsorption and catalytic decomposition of 3- and 4-chlorophenols in the presence of hydrogen peroxide were studied for estimation of efficiency of the adsorption and catalytic methods for purification of solutions from chlorophenols related to special group of the priority toxic water pollutants. Activated carbon fiber and fiber modified with iron/iron oxide having highly developed surface and porous structure were used as the adsorbents. It was shown that adsorption of chlorophenols on the initial carbon fiber was higher as compared to the modified one and equaled to 309 mg/g for 3-chlorophenol and 301 mg/g for 4-chlorophenol. The sorption isotherm of 4-chlorophenol on the initial fiber is described by Langmuir equation with constant equals to 0.065 L/mg, while for composite sorbent constant equals to 0.037 L/mg. It was discovered that removal of chlorophenols from aqueous solutions in the processes of catalytic oxidation in the presence of a heterogeneous catalyst was more efficient than that in the adsorption process. Experimental data have been obtained on the dependence of the concentration of 3-and 4-chlorophenols on the time of destruction at specified pH values and the ratios of the pollutant and hydrogen peroxide. With an increase in the 4-chlorophenol: H2O2 ratio from 1:1 to 1:6, the degree of chlorophenol destruction increases from 75% to 88% (pH 3); when the pH changes from 1 to 9, the greatest degree of destruction is 70% (3-CP) and 87% (4-CP) was achieved at pH 3 (chlorophenol: H2O2 1:4). It was shown that in the system chlorophenol / H2O2 / catalyst there are optimal parameters (pH is 3 and chlorophenol : H2O2 ratio is 1:6), which provide the most complete removal of chlorophenol from solution. The results of chromatography-mass spectrometry analysis show that during contact with the modified fiber, the content of 4-CP decreases dramatically and degradation products are formed (for example, maleic acid), which is consistent with the known schemes for the oxidative destruction of chlorophenols.

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Chen, Xiurong, Yuan Wang, Qiuyue Li, Yingying Yang, Xiao Wei, Shanshan Wang, Quanlin Lu i Xiaoli Sun. "Contrast of sludge toxicity variation during treatment of wastewater containing mixed chlorophenols and single chlorophenol". Environmental Engineering Research 26, nr 5 (15.09.2020): 200335–0. http://dx.doi.org/10.4491/eer.2020.335.

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To address problems associated with the potential toxicity of sludge when it is applied in land utilization, this study investigated the variations by which activated sludge becomes toxic when fed with wastewater containing mixed chlorophenols, and compared variations in sludge toxicity due to inputs of mixed chlorophenols and single chlorophenol groups. In this study, 4-chlorophenol (4-CP), 2,4,6-trichlorophenol (2,4,6-TCP) and mixed chlorophenols which consist of both 4-CP and 2,4,6-TCP were studied in sequencing batch reactors (SBR). The results indicate that in 0-30 d, the toxicity of sludge fed with mixed chlorophenols is higher than that of sludge fed with single chlorophenol groups. During 50-100 d, the toxicity of sludge fed with mixed chlorophenols ranged between two single chlorophenol groups. EPS and protein in EPS had a significant relationship with sludge toxicity, but there was no significant relationship between polysaccharide in EPS and sludge toxicity.

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Wang, Fen, Yong Wei Ye, Chun An Ma i Mei Chao Li. "Studies on Electrooxidation Reaction of 4-Chlorophenol on Carbon Electrode by In Situ FTIR". Advanced Materials Research 549 (lipiec 2012): 370–73. http://dx.doi.org/10.4028/www.scientific.net/amr.549.370.

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Electrooxidation of 4-chlorophenol in acidic solution was studied by cyclic voltammetry and in situ FTIR spectroscopy. Compared with platinum (Pt) and glassy carbon (GC) electrodes, carbon electrode exhibited a high electrocatalytic activity during the electrooxidation reaction of 4-chlorophenol. The possible mechanism of 4-chlorophenol on carbon electrode was studies by in situ FTIR. At first, 4-chlorophenol was electrooxidized to 4-chlorophenolic radical, and then to phenoxylic radical. Then, the radical was electrooxidized to hydroquinone, benzoquinone or unsaturated carboxylic acids with potential increasing. In addition, with the reaction of phenoxyl radicals, the insoluble aromatic ether oligomer generated on the carbon electrode surface and prevented the further oxidation reaction of 4-CP in some degree.

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Ma, Dehua, Jianjian Wei, Hongbo Zhang, Yukun Zhou, Jinyou Shen, Lianjun Wang i Peng Zhang. "Acute toxicity evolution during ozonation of mono-chlorophenols and initial identification of highly toxic intermediates". Environmental Science: Processes & Impacts 21, nr 9 (2019): 1509–18. http://dx.doi.org/10.1039/c9em00225a.

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Kuo, W. S., i I. T. Lin. "Biodegradability of chlorophenol wastewater enhanced by solar photo-Fenton process". Water Science and Technology 59, nr 5 (1.03.2009): 973–78. http://dx.doi.org/10.2166/wst.2009.052.

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The combination of solar irradiation and Fenton reagent have been used to enhance the biodegradability (BOD5/COD) of chlorophenol wastewater, including 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), and 2,4-dichlorophenol (2,4-DCP). Results showed that the solar photo-Fenton process improved significantly the biodegradability of chlorophenol wastewater. Basically, increasing initial H2O2 dosage was much more beneficial for increasing biodegradability of wastewater than increasing initial Fe2 + dosage. Among the conditions studied, the optimum condition of increasing biodegradability of chlorophenol wastewater was found with a [H2O2]0/[Fe2 + ]0/[chlorophenol]0 ratio of 10.0/0.2/1.0, 10.0/0.3/1.0, and 10.0/0.2/1.0 for 2-CP, 4-CP, and 2,4-DCP, respectively. As a result, the value of BOD5/COD was increased from 0 for untreated solution up to 0.231, 0.248, and 0.193 for 2-CP, 4-CP, and 2,4-DCP, respectively with a 15-min treatment. Under the operation of optimum conditions, the oxidative state of chlorophenol wastewater could be easily controlled into a higher biodegradability stage. The COD and TOC degradation efficiency could be in excess of 90% on the whole as the preoxidized chlorophenol solution was treated by a following batch-type biological unit. In the meanwhile, the microtoxicity of wastewater reduced more than 95%.

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Wu, Shangze, Ka Tang, Jingqi Zhang, Xi Chen, Hanjun Hu, Qing Hu i Xiao Jin Yang. "Removal of 4-chlorophenol from polluted water by aluminum–iron alloys". Water Science and Technology 80, nr 6 (15.09.2019): 1099–106. http://dx.doi.org/10.2166/wst.2019.349.

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Abstract Chlorophenols are extremely toxic to the environment and recalcitrant to biological degradation. Herein chemical degradation of 4-chlorophenol (4-CP) from aqueous solutions by zero-valent aluminum (Al), zero-valent iron (Fe), Al and Fe mixtures (Al/Fe mass ratio 90/10, labeled as Al/Fe10) and Al-Fe alloy (Al/Fe mass ratio 90/10, labeled as Al-Fe10) were investigated. No removal was found for 50 mg·L−1 4-CP under anoxic conditions at initial pH 2.5 during a period of 10 hrs while 56%, 83%, 78% and 99% of 4-CP were removed by Fe, Al, Al/Fe10 and Al-Fe10, respectively under aeration conditions. The removal of 4-CP by Al/Fe10 mixtures was primarily in the Fe mode in the beginning 4 h and then transitioned to the Al mode. The removal of 4-CP by Al-Fe10 alloy was accomplished via two intermediate products, hydroquinone (HQ) and 4-chlorocatechol (4-CC), and it was speculated that reactive oxygen species and hydroxyl radicals (·OH) play an important role in the degradation of 4-CP and that Al-Fe intermetallic compounds might catalyze the reactions. This study demonstrates that alloying Al with Fe offers a promising strategy for developing new materials for water and wastewater remediation.

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Katayama-Hirayama, Keiko, Shusaku Tobita i Kimiaki Hirayama. "Biodegradation of phenol and monochlorophenols by yeast Rhodotorula glutinis". Water Science and Technology 30, nr 9 (1.11.1994): 59–66. http://dx.doi.org/10.2166/wst.1994.0444.

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Biodegradation of phenol and monochlorophenols (CPs) by a yeast strain of Rhodotorula glutinis was examined. The strain completely degraded 5 mM of phenol and utilized phenol as a sole carbon source. The strain may degrade phenol by the “ortho” type of ring fission because muconolactone was observed in the cultured broth. 3-Chlorophenol (3-CP) and 4-chlorophenol (4-CP) were well degraded and stoichiometric release of chloride ion was observed, but degradation of 2-chlorophenol was low with a small quantity of chloride ions. Biodegradability of 3-CP and 4-CP was increased by the addition of phenol or CPs to the medium at the cell cultivation. Since 4-chlorocatechol and maleylacetic acid were determined as metabolites of 3-CP and 4-CP by GC/MS analysis, dechlorination may take place between the formation of 4-chlorocatechol and maleylacetic acid.

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Duan, X. Y., F. Ma i L. M. Chang. "Electrochemical degradation of 4-chlorophenol in aqueous solution using modified PbO2 anode". Water Science and Technology 66, nr 11 (1.12.2012): 2468–74. http://dx.doi.org/10.2166/wst.2012.440.

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The electrochemical oxidation of 4-chlorophenol (4-CP) in aqueous solution was studied by electrochemical oxidation using modified PbO2 electrode as anode. The influence of several operating parameters, such as initial 4-CP concentration, applied current density, and supporting electrolyte (Na2SO4) concentration was investigated. Ultraviolet spectroscopy and total organic carbon (TOC) measurements were conducted to study the kinetics of 4-CP electrochemical reaction and the mineralization efficiency of 4-CP. The experimental results showed that the 4-CP degradation always followed a pseudo-first-order kinetics. The higher mineralization of 4-CP and the lower current efficiency (CE) were obtained by the lower initial 4-CP concentration. The applied current density showed a positive influence on the degradation of 4-CP and the removal of TOC, but a higher applied current density led to a lower CE. Although Na2SO4 concentration of 0.05 M resulted in a higher 4-CP and TOC removal, the result of one-way analysis of variance (ANOVA) indicates that Na2SO4 concentration is not the significant parameter for 4-CP removal in electrochemical oxidation.

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Yang, Chu-Fang, i Chi-Mei Lee. "Enrichment, isolation, and characterization of 4-chlorophenol-degrading bacterium Rhizobium sp. 4-CP-20". Biodegradation 19, nr 3 (18.07.2007): 329–36. http://dx.doi.org/10.1007/s10532-007-9139-1.

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Kannan, Padmanathan Karthick, Rogerio V. Gelamo, Hywel Morgan, Palaniswamy Suresh i Chandra Sekhar Rout. "The electrochemical 4-chlorophenol sensing properties of a plasma-treated multilayer graphene modified photolithography patterned platinum electrode". RSC Advances 6, nr 107 (2016): 105920–29. http://dx.doi.org/10.1039/c6ra24136k.

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Chen, Jong-Nan, Yi-Chin Chan i Ming-Chun Lu. "Photocatalytic oxidation of chlorophenols in the presence of manganese ions". Water Science and Technology 39, nr 10-11 (1.05.1999): 225–30. http://dx.doi.org/10.2166/wst.1999.0661.

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The decomposition of chlorophenols in aqueous solution with UV-illuminated TiO2 suspensions in the presence of manganese ions was studied. It was found that the removal rate of chlorophenols would be the highest at pH 3 in the presence of 1.18×10−4 M manganese ion. The effect of ionic strength on the 2-CP decomposition can be ignored in the range from 0.1 to 0.005 M for NaClO4. This study is also to explore the relationship between the adsorption rate and reaction rate. Results showed that the more the adsorption rate the more the decomposition rate for the three chlorophenols. Manganese ions can increase the photocatalytic oxidation of 2-chlorophenol in terms of DOC. The relationship between temperature and reaction rate for 2-CP is k = 0.0043T - 1.2146.

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Li, Ji Wu, Xiao Hong Zhu i Jun Ya Pan. "The Characteristics and Kinetic Equation of 4-CP Biodegradation by Fusarium sp. HJ01". Advanced Materials Research 554-556 (lipiec 2012): 1925–28. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.1925.

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The stain of Fusarium sp. HJ01 used in 4-chlorophenol (4-CP) degradation was isolated in our laboratory. The effects of pH, temperature, 4-CP concentration, carbon source on 4-CP degradation rate were studied. It was concluded that Fusarium sp. HJ01 could grow with 4-CP as the sole carbon and energy source. 4-CP concentration of 100mg/L in the pH range of 4~10 and temperature range of 25°C~35°C could be degraded completely. The capacity of 4-CP degradation was effectively enhanced by the addiction of sucrose. The kinetics of 4-CP degradation could well accord with the Haldane model for 4-CP as the sole carbon source and with first order equation for added other sucrose.

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Wang, Xiao Xiao, Xiao Qin Yu, Jun Ya Pan i Ji Wu Li. "The Characteristics and Kinetics of 4-CP with Pb²⁺ Biodegradation by Fusarium sp." Advanced Materials Research 726-731 (sierpień 2013): 2506–9. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.2506.

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The effects of Pb2+concentration, pH and additional carbon source on biodegradation of 4-chlorophenol (4-CP) byFusariumsp. were investigated, and the characteristic and kinetic of 4-CP biodegradation were analyzed. It was concluded that 4-CP biodegradation rate byFusariumsp. decreased a little at concentration of Pb2+0.20 mg/L and 4-CP 50 mg/L. The suitable biodegradation pH was range from 6 to 7. Additional carbon source (phenol) might increase the rate of 4-CP biodegradation. The kinetic equations of 4-CP biodegradation were well accord with the zero order reaction equation at different concentration of Pb2+.

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Xing-long, Jin, Zhao Xiao-qing, Wang Xiao-yan i Wang Zhi-rong. "Degradation and toxicity change of 4-chlorophenol in aqueous solution during CGDE treatment". Water Science and Technology 67, nr 10 (1.05.2013): 2190–94. http://dx.doi.org/10.2166/wst.2013.115.

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This study focused on the degradation and toxicity change of 4-chlorophenol (4-CP) in aqueous solution by contact glow discharge electrolysis (CGDE) with and without Fe2+. It was found that the addition of Fe2+ increased the degradation rate of 4-CP and decreased the toxicity of the solution. After 90 min CGDE treatment, only 28.0% 4-CP was removed and EC50 increased from 33.8 to 63.1 mg/L. With 25.0 mg/L Fe2+ in solution, the degradation rate of 4-CP reached 93.3% and EC50 changed from 35.9 to 93.9 mg/L after 90 min CGDE treatment.

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Dey, Apurba, Priyanka Sarkar i Ananya Das. "Studies on Biodegradation of 4-Chlorophenol and 4-Nitrophenol by Isolated Pure Cultures". European Journal of Sustainable Development 8, nr 4 (1.10.2019): 281. http://dx.doi.org/10.14207/ejsd.2019.v8n4p281.

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Metabolically versatile pure cultures were isolated from textile dye effluent and petrochemical industry which were able to utilize 150 mg/l of 4-Chlorophenol and 85 mg/l of 4-Nitrophenol as the sole carbon and energy source respectively. Phylogenetic analysis based on 16 S rRNA gene sequence reveals that the strains were found to be phylogenetically close to Bacillus cereus HWB1 and Pseudomonas taiwanensis ECAe22 respectively. Optimization of physicochemical parameters was performed with Change of one variable at a time (COVT) approach. Optimized physical parameters for degradation by Bacillus cereus HWB1 was found to be 30 0C, pH 7 and 150 rpm whereas for Pseudomonas taiwanensis ECAe22 it was found to be 30 0C, pH 8.5 and 150 rpm. Supplementation of an additional substrate such as yeast extract was found to increase the rate of 4-Chlorophenol and 4-Nitrophenol degradation owing to the increase in biomass production resulting in enhanced biodegradation. Biodegraded samples of these phenolic compounds showed negligible phytotoxicity as compared to the untreated samples thereby proving that employing these pure cultures can help in mitigating environmental contamination by phenolic compounds in the near future.Keywords: Biodegradation, 4-Chlorophenol,4-Nitrophenol, pure cultures,16S rRNA, phylogenetic analysisAbbreviation: 4-CP: 4-Chlorophenol; 4-NP: 4-Nitrophenol; AU: Absorbance Unit; MSM: MinimalSalt Media

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Mukhopadhyay, Mausumi, i Dhiraj P. Daswat. "Photochemical degradation of 4-chlorophenol in the aqueous phase using peroxyacetic acid (PAA)". Water Science and Technology 67, nr 2 (1.01.2013): 440–45. http://dx.doi.org/10.2166/wst.2012.591.

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The photochemical degradation of 4-chlorophenol (4-CP) using ultraviolet irradiation (UV) of 6, 12 and 18 W with peroxyacetic acid (PAA) was studied in a batch reactor. The objective of this work was to investigate degradation and mineralization of 4-CP by PAA. The degradation efficiency increased with increasing UV input. The degradation process was also pH and initial PAA concentration dependent. The optimum conditions for the photochemical degradation of 4-CP as UV input, pH and PAA concentration was found to be 18 W, 9.5 and 3,040 ppm. The reaction efficiency decreased with increasing initial 4-CP concentrations. More than 95% mineralization of 4-CP was achieved with the UV/PAA process. The chloride ion concentration and chemical oxygen demand (COD) was evaluated. The chloride ion concentration and COD were decreased gradually with increasing UV input. Samples were analyzed by high pressure liquid chromatography (HPLC), UV spectrophotometry and gas chromatography–mass spectrometry (GC-MS) for residual concentration and identification of final degraded products.

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Madriz, Lorean, José Tatá i Ronald Vargas. "The Photocatalytic Oxidation of 4-Chlorophenol Using Bi2WO6 under Solar Light Irradiation". International Journal of Photochemistry 2014 (5.08.2014): 1–6. http://dx.doi.org/10.1155/2014/387536.

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This report discusses the effects of the initial concentration of 4-chlorophenol (4-CP) on its solar light photoinduced oxidation/mineralization kinetics on Bi2WO6 catalyst. Photocatalytic degradation followed the Langmuir-Hinshelwood (L-H) mechanism. From the kinetic data the Langmuir adsorption equilibrium constant of 4-CP on the Bi2WO6 surface and the L-H maximum reaction rate for 4-CP oxidation have been evaluated. Chromatographic and spectroscopy studies show the presence of p-benzoquinone and maleic acid as the main reaction products; these compounds first increase and then decay until they disappear. Chemical oxygen demand (COD) and produced CO2 measurement show that photocatalytic mineralization of the phenolic compound was readily possible in a wide concentration range.

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Wei, Xuefeng, Laiyuan Zeng, Weiwei Lu, Juan Miao, Ruichang Zhang, Ming Zhou i Jun Zhang. "A Polypyrrole-Modified Pd-Ag Bimetallic Electrode for the Electrocatalytic Reduction of 4-Chlorophenol". Catalysts 9, nr 11 (7.11.2019): 931. http://dx.doi.org/10.3390/catal9110931.

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A polypyrrole-modified bimetallic electrode composed of Pd-Ag on a Ti substrate (Pd-Ag/PPY/Ti) was successfully prepared via a chemical deposition method, and was applied to the electrocatalytic hydrodechlorination of 4-chlorophenol (4-CP) in aqueous solution. The electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Various influences on the dechlorination efficiency of 4-chlorophenol, including applied current, initial pH value, and temperature, were studied. The dechlorination efficiency of 4-CP reached 94% within 120 min under the optimum conditions, i.e., a dechlorination current of 6 mA, an initial pH of 2.30, and a temperature of 303 K. The apparent activation energy of the dechlorination of 4-CP by the Pd-Ag/PPY/Ti electrode was calculated to be 49.6 kJ/mol. The equivalent conversion rate constant kPd was 0.63 L.gPd−1·min−1, which was higher than the findings presented in comparable literature. Thus, a highly effective bimetallic electrode with promising application prospects and low Pd loading was fabricated.

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Liu, Wanpeng, Lili Xu, Xingfa Li, Chensi Shen, Sadia Rashid, Yuezhong Wen, Weiping Liu i Xiaohua Wu. "High-dispersive FeS2 on graphene oxide for effective degradation of 4-chlorophenol". RSC Advances 5, nr 4 (2015): 2449–56. http://dx.doi.org/10.1039/c4ra11354c.

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High-dispersive FeS₂ particles on graphene oxide (FeS₂@GO) was prepared by a one-pot hydrothermal method for efficient removal and mineralization of aqueous 4-chlorophenol (4-CP) under slightly acidic or alkaline conditions.

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Sharma, Swati, Mausumi Mukhopadhyay i Zagabathuni Venkata Panchakshari Murthy. "Investigation of UV-assisted chlorophenol congeners’ degradation by organic oxidant p-nitrobenzoic acid in basic media". Water Science and Technology 67, nr 11 (1.06.2013): 2418–27. http://dx.doi.org/10.2166/wst.2013.131.

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This research specifically addressed the photodegradation of selected model chlorophenol (CP) congeners, 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), by an organic oxidant, p-nitrobenzoic acid (PNBA), in basic media. The reactions were followed by high-pressure liquid chromatography and gas chromatography–mass spectroscopy analysis for residual concentration and the identification of photodegraded products respectively. Initial degradation was confirmed by the formation of ring cleavage compounds, and subsequent mineralization was evidently marked by an increase in release of chloride ions in the time course profile. The presence of fewer/no chlorine atoms in the degraded compounds corroborated the mineralization by UV/PNBA action. The chemical oxygen demand (COD) was also observed to fall appreciably to the extent of 73% during all CP congeners’ degradation. The maximum COD decrease was observed in PNBA-assisted 4-CP degradation. The overall degradation kinetics conforming to second-order reaction is observed to follow the order 4-CP > 2,4,6-TCP ∼ PCP ∼ 2,4-DCP. The findings of this investigation elucidated the fact that PNBA was capable of successfully degrading/mineralizing the selected CP congeners.

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Fang, Xu, i Deren Fang. "Performance of palladium–tin bimetallic catalysts supported on activated carbon for the hydrodechlorination of 4-chlorophenol". RSC Advances 7, nr 64 (2017): 40437–43. http://dx.doi.org/10.1039/c7ra07754h.

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Wang, Xiao Xiao, Shi Bo Wang, Jun Ya Pan, Xiao Ping Shi i Ji Wu Li. "The Characteristics of p-Chlorophenol with Cu²⁺ Biodegradation by Fusarium Sp. ". Advanced Materials Research 781-784 (wrzesień 2013): 127–30. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.127.

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The stain ofFusariumsp. used in 4-chlorophenol (4-CP) degradation was isolated in our laboratory. The effects of pH, Cu2+concentration, carbon source on 4-CP degradation rate byFusariumsp. were investigated. The kinetic equation of 4-CP biodegradation was discussed. It was concluded thatFusariumsp. could grow with 4-CP as the sole carbon and energy source. 4-CP concentration of 50mg/L in the Cu2+concentration of 3mg/L could be degraded completely. The capacity of 4-CP degradation was effectively enhanced by the addiction of phenol. Phenol concentration of 200 mg/L in the pH 7 and the Cu2+concentration of 3 mg/L could be degraded completely. Cu2+at high concentration might reduce the biodegradation rate of 4-CP. The kinetic equation of 4-CP biodegradation could well accord with the zero order equation for 4-CP as the sole carbon source with Cu2+coexistence byFusariumsp..

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Makgato, Stanford S., i Evans M. Nkhalambayausi-Chirwa. "Performance Evaluation of AOP/Biological Hybrid System for Treatment of Recalcitrant Organic Compounds". International Journal of Chemical Engineering 2010 (2010): 1–10. http://dx.doi.org/10.1155/2010/590169.

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Process water from nuclear fuel recovery unit operations contains a variety of toxic organic compounds. The use of decontamination reagents such asCCl4together with phenolic tar results in wastewater with a high content of chlorophenols. In this study, the extent of dehalogenation of toxic aromatic compounds was evaluated using a photolytic advanced oxidation process (AOP) followed by biodegradation in the second stage. A hard-to-degrade toxic pollutant, 4-chlorophenol (4-CP), was used to represent a variety of recalcitrant aromatic pollutants in effluent from the nuclear industry. A UV-assisted AOP/bioreactor system demonstrated a great potential in treatment of nuclear process wastewater and this was indicated by high removal efficiency (>98%) under various 4-CP concentrations. Adding hydrogen peroxide (H2O2) as a liquid catalyst further improved biodegradation rate but the effect was limited by the scavenging ofOH•radicals under high concentrations ofH2O2.

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Skrzypczyńska, Katarzyna, Krzysztof Kuśmierek, Andrzej Świątkowski, Lidia Dąbek i Ilona Piros. "Nutshells as modifiers of carbon paste electrodes used in detecting chloroorganic water pollutants". BioResources 15, nr 1 (25.11.2019): 368–81. http://dx.doi.org/10.15376/biores.15.1.368-381.

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Electrochemical properties of a carbon paste electrode (graphite) modified with hazelnut and walnut shells were investigated. The adsorption of 4-chlorophenol (4-CP) on the studied materials was determined, and the hazelnut shells were found to provide a higher adsorption capacity. The hazelnut and walnut shells were used to modify the carbon paste electrode to detect 4-CP by cyclic voltammetry. Compared to an unmodified electrode, all of the new paste electrodes showed much higher sensitivity in the 4-CP detection.

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Suresh, S., V. C. Srivastava i I. M. Mishra. "Studies of adsorption kinetics and regeneration of aniline, phenol, 4-chlorophenol and 4-nitrophenol by activated carbon". Chemical Industry and Chemical Engineering Quarterly 19, nr 2 (2013): 195–212. http://dx.doi.org/10.2298/ciceq111225054s.

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The present paper reports kinetic studies of the adsorption of aniline (AN), phenol (P), 4-chlorophenol (CP) and 4-nitrophenol (NP) from aqueous solution onto granular activated carbon (GAC). In FTIR spectral analysis, the transmittance of the peaks gets increased after the loading of AN, P, CP and NP signifying the participation of these functional groups in the adsorption and it seems that the adsorption of AN, P, CP and NP is chemisorptive in nature. The rates of adsorption were found to obey a pseudo-second order model and that the dynamics of AN, P, CP and NP adsorption are controlled by a combination of surface and pore diffusion. The diffusion coefficient were of the order of 10-10 m2 s-1. Thermal desorption at 623 K was found to be more effective than solvent desorption. GAC performed well for at least five adsorption-desorption cycle, with continuous decrease in adsorption efficiency after each thermal desorption. Owing to its relative high heating value, the spent GAC can be used as co-fuel for the production of heat in a boiler or a furnace.

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Zeng, Jia, Guilin Zhou, Yongmei Ai, Ning Li i Guizhi Zhang. "Catalytic Wet Peroxide Oxidation of Chlorophenol Over a Ce0.86Cu0.14–x O2 Catalyst". International Journal of Chemical Reactor Engineering 11, nr 1 (30.11.2013): 577–85. http://dx.doi.org/10.1515/ijcre-2013-0079.

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Abstract A Ce0.86Cu0.14–x O2 catalyst was prepared by the citric acid complex method and characterized by X-ray diffraction, scanning electron microscopy, and temperature-programmed reduction, and its activity in the catalytic wet peroxide oxidation of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) was investigated. The results showed that the Cu2+ ions dissolved into the CeO2 lattice to form a Ce0.86Cu0.14–x O2 solid solution with a coarse, interconnected, porous, and cotton-like morphology. The metal–oxygen bonds were weakened by solid-solution formation in the Ce0.86Cu0.14–x O2 catalyst. This weakening facilitated H2O2 activation and decomposition to form highly oxidative HO∙ species that can lead to significant chlorophenol mineralization. A total organic carbon removal rate greater than 80% was achieved after 2 h reaction at 50°C and at an initial 4-CP and 2,4-DCP concentration of 50 mg/L. The effects of H2O2 dosage, catalyst dosage, and initial chlorophenol concentration on catalytic efficiency were also determined.

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Fu, Jie, Guo Chen, Ying Yang, Zhi-Ming Zhang, Qing-Fu Zeng, Shu-Qing An i Hai-Liang Zhu. "Ultraviolet irradiation combined with manganese ore catalyzed ozonation of 4-chlorophenol in aqueous solution". Water Supply 10, nr 1 (1.03.2010): 97–104. http://dx.doi.org/10.2166/ws.2010.048.

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We have investigated ultraviolet (UV) irradiation combined with manganese ore (MO) catalyzed ozonation of 4-cholorophenol (4-CP) in aqueous solution. The preliminary results showed UV irradiation and MO had a strong synergetic catalytic effect on ozonation. We also studied the effect of UV lamp power, MO dosage, O3 dosage, initial 4-CP concentration, pH value and temperature. The results showed that high pressure mercury lamp (HPML) was more favorable for the degradation of 4-CP than low pressure mercury lamp (LPML). The optimal MO and O3 dosages were 2 g/L and 2 g/h respectively. When the 4-CP concentration was over 15 mg/L, the decrease of degradation efficiency accelerated. The acid condition was favorable for the degradation of 4-CP by UV/MO/O3. The reaction temperature could not be over 50°C. Through the mechanism discussion, we found that Mn2 + was the most important species to catalyze the ozonation. In addition, UV irradiation could also accelerate the degradation by promoting the production of ∙OH.

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Zhang, Shuo-Shuo, Ning Yang, Shou-Qing Ni, Vinothkumar Natarajan, Hafiz Adeel Ahmad, Shiping Xu, Xu Fang i Jinhua Zhan. "One-pot synthesis of highly active Ni/Fe nano-bimetal by simultaneous ball milling and in situ chemical deposition". RSC Advances 8, nr 47 (2018): 26469–75. http://dx.doi.org/10.1039/c8ra04426k.

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In this study, nanoscale bimetallic particles (Ni/Fe) were prepared by a simultaneous ball milling and in situ chemical deposition process (B&C) with high dechlorination activity for 4-chlorophenol (4-CP).

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29

Abida, O., C. Emilio, N. Quici, R. Gettar, M. Litter, G. Mailhot i M. Bolte. "Degradation of 4-chlorophenol mediated by Fe(III)-NTA in homogeneous and heterogeneous systems". Water Science and Technology 49, nr 4 (1.02.2004): 123–28. http://dx.doi.org/10.2166/wst.2004.0239.

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In this work, the comparison of 4-chlorophenol (4-CP) degradation by two different AOT processes has been performed: a) a homogeneous system with Fe(III)-NTA (1:1 complex), b) a TiO2/Fe(III)-NTA heterogeneous system. In both cases, NTA appears to play a positive role in the photochemical reaction. In the homogeneous system, the iron salt is the only absorbing species and is proved to be able to photoinduce 4-CP degradation ([4-CP] = 0.1-0.2 mM, [FeNTA] = 0.3-0.9 mM, pH 4, λ = 365 nm). The progress of the reaction was positively affected by the FeNTA concentration, and the reaction kept going even after the total disappearance of FeNTA. However, 4-CP complete degradation requires the presence of oxygen, otherwise the reaction stops. In the heterogeneous system ([4-CP] = 2.0 mM, [FeNTA] = 1.0-2.0 mM, [TiO2] = 0.1 and 1.0 g L-1, pH 3, λ = 300-400 nm), an important effect of the complex on the degradation extent and on the initial reaction rate can be seen, which overcomes the effect of non-complexed Fe(III). This behaviour is more important at the highest TiO2 concentration.

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Abu-Rizaiza, A., M. W. Kadi i M. S. El-Shahawi. "Activated Carbon from Fly Ash of Heavy Fuel Oil: Characterization and its Utilization for Removal and Determination of Chlorophenonls in Water". Biosciences, Biotechnology Research Asia 14, nr 3 (25.09.2017): 1103–16. http://dx.doi.org/10.13005/bbra/2548.

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ABSTRACT: Activated carbons (AC) prepared from volatile fly ash (FA) of heavy fuel oil via gasification with combined steam - CO2 was characterized and used as a low- cost adsorbent for removal of chlorophenols (CPs) e.g. 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), and 2,4,6- tetra chlorphenol (TCP) in water. At pH< 2.0, maximum CPs uptake was achieved and the average half-life time (t1/2) of the equilibrium adsorption of CPs was in the range 0.80 ± 0.01- 1.1 ± 0.04 h. Data suggested use of AC in packed column for separation and determination of various concentrations (0.5-100 µgL-1) of CPs in water (0.5-1.0 L). Complete extraction and recovery (97.4 + 2.9 %, n=5) of CPs were achieved at 2 mL min-1 flow rate. Analysis of CPs spiked onto tap- and seawater were also analyzed by AC packed column and the results were compared with the standard HPLC method at 95% confidence (P-0.05, n=5). The experimental student t test (texp 1.81-1.93) and F (Fexp 1.21-5.76) values were lower than the tabulated t (tcrit. = 2.78) and F (6.38), respectively. AC packed column provides remarkable selectivity, reproducibility, and cost-effectiveness towards removal and/ or determination of CPs. AC adsorbent may serve positively in point-of-care use.

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31

Li, Fuchong, Yansheng Liu, Tianqiong Ma, Dianhong Xu, Xu Li i Guangbi Gong. "Catalysis of the hydrodechlorination of 4-chlorophenol and the reduction of 4-nitrophenol by Pd/Fe3O4@C". New Journal of Chemistry 41, nr 10 (2017): 4014–21. http://dx.doi.org/10.1039/c6nj04045d.

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Aguilera-Ruiz, E., M. de la Garza-Galván, P. Zambrano-Robledo, J. C. Ballesteros-Pacheco, J. Vazquez-Arenas, J. Peral i U. M. García-Pérez. "Facile synthesis of visible-light-driven Cu2O/BiVO4 composites for the photomineralization of recalcitrant pesticides". RSC Adv. 7, nr 73 (2017): 45885–95. http://dx.doi.org/10.1039/c7ra08513c.

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In the present study, a facile synthesis of visible-light-driven Cu₂O/BiVO₄ composites, with different Cu₂O co-catalysts, towards to the mineralization of 4-chlorophenol (4-CP) in aqueous media is reported.

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33

Bakardjieva, Snejana, Jakub Mares, Radek Fajgar, Victor Y. Zenou, Michaela Maleckova, Efthalia Chatzisymeon, Hana Bibova i Jaromir Jirkovsky. "The relationship between microstructure and photocatalytic behavior in lanthanum-modified 2D TiO2 nanosheets upon annealing of a freeze-cast precursor". RSC Advances 9, nr 40 (2019): 22988–3003. http://dx.doi.org/10.1039/c9ra03940f.

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Titanium dioxide modified with 3 wt% La was prepared via a green freeze-casting method, and its photocatalytic activity was tested in terms of its ability to degrade 4-chlorophenol (4-CP) and remove total organic carbon (TOC).

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34

Pérez-Alfaro, J. E., G. González-Blanco, E. Sierra-Palacios, J. Marcial-Quino i R. Beristain-Cardoso. "Acclimation of nitrifying biomass and its effect on 2-chlorophenol removal". Water Science and Technology 71, nr 2 (11.12.2014): 277–82. http://dx.doi.org/10.2166/wst.2014.508.

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The metabolic and kinetic behavior of a nitrifying sludge exposed to 2-chlorophenol (2-CP) was evaluated in batch cultures. Two kinds of nitrifying culture were used; one acclimated to 4-methylphenol (4-mp), and the other unacclimated to 4-mp. The unacclimated culture was affected adversely by the 2-CP's presence, since neither nitrification nor 2-CP oxidation was observed. Nonetheless, the acclimated culture showed metabolic capacity to nitrify and mineralize 2-CP. Ammonium removal was 100%, with a nitrifying yield of 0.92 ± 0.04 mg NO3−-N/mg NH4+-N consumed. The consumption efficiency for 2-CP was 100% and the halogenated compound was mineralized to CO2. Denaturing gradient gel electrophoresis (DGGE) patterns showed the shift in microbial community structure, indicating that microbial diversity was due to the acclimation process. This is the first evidence where nitrifying culture acclimated to 4-mp completely removed ammonium and 2-CP.

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Gao, Hong-Jie, Chun-Li Kang, Yong-Hui Song, Ping Guo, Xing-Hua Lang i Fei Peng. "Comparison of the photoconversion of para-chlorophenol under simulated sunlight and UV irradiation in ice". Water Science and Technology 64, nr 4 (1.08.2011): 841–47. http://dx.doi.org/10.2166/wst.2011.620.

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The photochemistry of para-chlorophenol (4-CP) was studied under simulated sunlight (λ > 300 nm) and UV irradiation by using a 125 W high-pressure mercury lamp with or without a hard glass as light source in an ice matrix. The experiments were carried out in a photochemical cold chamber reactor at −14 to −12 °C. The photoconversion rate, photoproducts and photoconversion mechanism of 4-CP were all inspected and compared. The results show that the 4-CP photoconversion obeys the first order kinetic model and its photoconversion rate is highly affected by the initial concentration of 4-CP, light intensity and water quality. It is found that the conversion rate of 4-CP under UV irradiation is higher than that under simulated sunlight irradiation. The intermediate products of 4-CP were characterized by GC-MS, HPLC-ESI-MS and HPLC techniques and the possible photoconversion mechanism was proposed accordingly. It is concluded that the mechanism and photoproducts of 4-CP photolysis in ice are different from those in water, and the photoproducts and photoconversion pathways of 4-CP in ice varied with different light sources.

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36

Zhao, Jinbo, Wanjun Li i Deren Fang. "Effect of indium-modified palladium catalysts on the hydrodechlorination of 4-chlorophenol". RSC Advances 5, nr 53 (2015): 42861–68. http://dx.doi.org/10.1039/c5ra05957g.

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Kuśmierek, Krzysztof, Katarzyna Zarębska i Andrzej Świątkowski. "Hard coal as a potential low-cost adsorbent for removal of 4-chlorophenol from water". Water Science and Technology 73, nr 8 (27.01.2016): 2025–30. http://dx.doi.org/10.2166/wst.2016.046.

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The potential use of raw hard coals as low-cost adsorbents for the removal of 4-chlorophenol (4-CP) from aqueous solutions was examined. The effect of experimental parameters such as the pH and salt presence was evaluated. The kinetic studies showed the equilibrium time was found to be 2 h for all of the adsorbents and that the adsorption process followed the pseudo-second order kinetic model. The adsorption isotherms of the 4-CP on the hard coals were fitted to the Langmuir, Freundlich, Langmuir–Freundlich, Sips and Redlich–Peterson equations. Based on the results obtained, hard coals appear to be a promising adsorbent for the removal of some hazardous water pollutants, like 4-CP and related compounds.

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38

Wang, Manlin, Guodong Fang, Peng Liu, Dongmei Zhou, Chen Ma, Dongju Zhang i Jinhua Zhan. "Fe 3 O 4 @β-CD nanocomposite as heterogeneous Fenton-like catalyst for enhanced degradation of 4-chlorophenol (4-CP)". Applied Catalysis B: Environmental 188 (lipiec 2016): 113–22. http://dx.doi.org/10.1016/j.apcatb.2016.01.071.

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39

Cheng, Rong, Xingyan Xue, Lei Shi, Tao Zhang, Yaping Liu, Mi Kang i Xiang Zheng. "Degradation of 4-chlorophenol by mixed Fe0/Fe3O4 nanoparticles: from the perspective of mechanisms". Water Science and Technology 75, nr 2 (4.11.2016): 263–70. http://dx.doi.org/10.2166/wst.2016.505.

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Fe0 nanoparticles have been widely studied for pollution abatement in recent years; however, regarding the mechanism for pollutant degradation, studies have mainly focused on the reductive dechlorination by Fe0, and the dynamic process has not been clarified completely. As reported, some organics could be degraded during the oxidation of Fe0 by O2, and hydrogen peroxide was supposed to be produced. In this study, Fe3O4, an oxidation product of Fe0, was used to treat the pollutant combining with Fe0 nanoparticles, and 4-chlorophenol (4-CP) was used as the model pollutant. The results showed that the addition of Fe3O4 nanoparticles hindered the removal of 4-CP by Fe0 nanoparticles under anoxic conditions. However, the dechlorination efficiency was improved in the initial 6 h. Under aerobic conditions, the reused Fe3O4 nanoparticles would improve the removal and dechlorination of 4-CP. Especially, the dechlorination efficiency was obviously increased. It is proposed that the removal of 4-CP was due to the effects of both nanosized Fe0 and Fe3O4 – reducing action of Fe0 and catalytic oxidation action of Fe3O4. The reducing action of Fe0 was the major factor under anoxic conditions. And the catalytic oxidation action of Fe3O4 became an important reason under aerobic conditions.

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40

Luňák, Stanislav, Jiřina Brodilová i Jacques Muzart. "Photoinitiated Degradation of 4-Chlorophenoxyacetic Acid by Hydrogen Peroxide; Photocatalytic Effects of Fe(III) Compounds". Collection of Czechoslovak Chemical Communications 62, nr 12 (1997): 1843–52. http://dx.doi.org/10.1135/cccc19971843.

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Photolysis of 4-chlorophenoxyacetic acid (4-CPA) and the effect of Fe(III) compounds on photochemical oxidative degradation of 4-CPA by hydrogen peroxide were studied. Whereas degradation initiated by 254 nm radiation is affected only moderately by the presence of Fe(III) compounds the reaction initiated by VIS radiation (high-pressure sodium lamp) is photocatalyzed and photosensitized by Fe(III) compounds very markedly. 4-Chlorophenol (4-CP) and phenol were detected as the main degradation intermediates. Formation of phenol prevails in the absence of oxidation agent, 4-CP is the main product in the presence of hydrogen peroxide.

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41

Lin, Yen-Hui. "Kinetics of Cometabolic Transformation of 4-chlorophenol and Phenol Degradation by Pseudomonas putida Cells in Batch and Biofilm Reactors". Processes 9, nr 9 (15.09.2021): 1663. http://dx.doi.org/10.3390/pr9091663.

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The biodegradation kinetics of 4-chlorophenol (4-CP) and phenol and microbial growth of Pseudomonas putida (P. putida) cells were estimated in batch and biofilm reactors. The kinetic parameters of cells on phenol were determined using the Haldane formula. The maximum specific growth rate of P. putida on phenol, the half-saturation constant of phenol and the self-inhibition constant of phenol were 0.512 h−1, 78.38 mg/L and 228.5 mg/L, respectively. The yield growth of cells on phenol (YP) was 0.618 mg phenol/mg cell. The batch experimental results for the specific transformation rate of 4-CP by resting P. putida cells were fitted with Haldane kinetics to evaluate the maximum specific utilization rate of 4-CP, half-saturation constant of 4-CP, and self-inhibition constant of 4-CP, which were 0.246 h−1, 1.048 mg/L and 53.40 mg/L, respectively. The negative specific growth rates of cells on 4-CP obtained were fitted using a kinetic equation to investigate the true transformation capacity and first-order endogenous decay coefficient, which were 4.34 mg 4-CP/mg cell and 5.99 × 10−3 h−1, respectively. The competitive inhibition coefficients of phenol to 4-CP transformation and 4-CP to phenol degradation were 6.75 and 9.27 mg/L, respectively; therefore, phenol had a higher competitive inhibition of 4-CP transformation than the converse. The predicted model examining cometabolic transformation of 4-CP and phenol degradation showed good agreement with the experimental observations. The removal efficiencies for phenol and 4-CP were 94.56–98.45% and 96.09–98.85%, respectively, for steady-state performance.

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42

Enriquez, R., B. Beaugiraud i P. Pichat. "Mechanistic implications of the effect of TiO2 accessibility in TiO2–SiO2 coatings upon chlorinated organics photocatalytic removal in water". Water Science and Technology 49, nr 4 (1.02.2004): 147–52. http://dx.doi.org/10.2166/wst.2004.0246.

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The photocatalytic removal rates r of dichloroacetic acid (DCAA), 4-chlorobenzoic acid (4-CBA) and 4-chlorophenol (4-CP) in water were compared for TiO2 samples used either as a powder or as a coating on a fiber glass tissue, SiO2 being the binder. From SEM-EDX measurements it was deduced that SiO2 prevails over TiO2 in the coating top layers and 18O2-Ti16O2 isotopic exchange showed that the accessibility of O2 to TiO2 was markedly reduced when TiO2 was thus coated. The unfavorable effect of the restricted TiO2 accessibility on r was drastic for DCAA, much less pronounced for 4-CBA, and still smaller for 4-CP. It is inferred that DCAA can be attacked only when it directly interacts with TiO2, whereas 4-CP can also react within the near-TiO2 surface water layers. The 4-CBA intermediate behavior is in line with the structural similarities of 4-CBA with DCAA and 4-CP.

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43

Abeish, Abdulbasit M., H. Ming Ang i Hussein Znad. "Role of ferric and ferrous ions in the enhancement of the heterogeneous solar photocatalytic degradation of combined mixture of chlorophenols". Water Science and Technology 72, nr 9 (17.07.2015): 1561–68. http://dx.doi.org/10.2166/wst.2015.374.

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The solar photocatalytic degradation of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) was investigated individually and combined in the presence of Fe2+ and Fe3+ ions. The results revealed that both Fe2+ and Fe3+ ions enhanced the heterogeneous photocatalytic degradation. Fe3+ ions rapidly converted to Fe2+ ions as soon as the irradiation started. The intermediates formed during the degradation of 4-CP/2,4-DCP were also monitored and identified. Three main intermediates were observed, hydroquinone, phenol, and 4-chlorocatechol with traces of benzoquinone. The results support a new trend of research by utilising other cheap iron ion sources in the photocatalytic degradation.

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44

Wilson, Gregory J., Amid P. Khodadoust, Makram T. Suidan, Richard C. Brenner i Carolyn M. Acheson. "Anaerobic/aerobic biodegradation of pentachlorophenol using GAC fluidized bed reactors: optimization of the empty bed contact time". Water Science and Technology 38, nr 7 (1.10.1998): 9–17. http://dx.doi.org/10.2166/wst.1998.0271.

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An integrated reactor system has been developed to remediate pentachlorophenol (PCP) containing wastes using sequential anaerobic and aerobic biodegradation. Anaerobically, PCP was degraded to approximately equimolar concentrations (>99%) of chlorophenol (CP) in a granular activated carbon (GAC) fluidized bed reactor (FBR) at empty bed contact times (EBCTs) ranging from 18.6 to 2.3 hr. However, at lower EBCTs, chlorophenol concentrations decreased to less than 10% of the influent PCP concentration. The optimal EBCT was determined to be 2.3 hr based on PCP conversion to CPs and stable reactor operation. Decreasing the EBCT fourfold did not inhibit degradation of PCP and its intermediates, and thus, removal of PCP is possible at lower detention times providing a significant cost advantage. Analytical grade PCP was fed via syringe pumps into a GAC FBR at an influent concentration of 200 mg/L. Acting as the primary substrate, ethanol was also fed at a concentration of 1388 mg/L. Effluent PCP and chlorinated phenolic compounds were analyzed weekly to evaluate reactor performance. Biodegradation pathways were also identified. 3-chlorophenol (3-CP) was the predominant CP. Concentrations of 3-CP follow the same trends as 3,5-dichlorophenol (DCP) concentrations. In a similar manner, 4-chlorophenol concentrations correlate with 3,4-DCP concentrations. A second stage aerobic GAC FBR was added after the anaerobic bioreactor which removed the remaining CP and phenols. No phenol or CP has been observed in the effluent or on the GAC. Overall, the influent chemical oxygen demand (COD) loading was reduced from 34 g/L*d to less than 1.36 g/L*d.

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45

Cheng, Rong, Guan-qing Li, Can Cheng, Lei Shi, Xiang Zheng i Zhong Ma. "Catalytic oxidation of 4-chlorophenol with magnetic Fe3O4 nanoparticles: mechanisms and particle transformation". RSC Advances 5, nr 82 (2015): 66927–33. http://dx.doi.org/10.1039/c5ra10433e.

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Nanosized Fe3O4 showed high catalytic activity even after being used several times, and reactive sites on surface increased resulted in the higher activity of particles. ˙OH produced during reaction was the main cause for degradation of 4-CP.

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46

Zhou, Shiwei, Xin Jin, Feifei Sun, Hao Zhou, Cuiyun Yang i Chuanhai Xia. "Combination of hydrodechlorination and biodegradation for the abatement of chlorophenols". Water Science and Technology 65, nr 4 (1.02.2012): 780–86. http://dx.doi.org/10.2166/wst.2012.909.

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A method for abatement for chlorophenols (CPs) in contaminated water based on successive steps of catalytic hydrodechlorination (HDC) over Pd/C at ambient temperature and pressure, followed by aerobic biodegradation using yeast Candida tropicalis (C. tropicalis) was studied. The results showed that 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) could be easily and completely dechlorinated under mild conditions, ultimately yielding phenol as product. Subsequently, phenol (0–900 mg L−1) could be completely degraded by C. tropicalis within 30 h. Moreover, during the biodegradation of phenol, definite mass of ethanol (≤0.5%) caused a modest increase in the duration of the lag phase, but led to a great increase in the maximum degradation rates. This means that CPs with higher concentration could be efficiently detoxified under mild conditions by a combination of HDC and biodegradation in water or water–ethanol systems.

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47

Sandhibigraha, Sudhansu, Soumya Sasmal, Tarun Kanti Bandyopadhyay i Biswanath Bhunia. "Computational fluid dynamics analysis of flow through immobilized catalyzed packed bed reactor for removal of 4-chlorophenol from wastewater". Environmental Engineering Research 25, nr 6 (29.11.2019): 878–89. http://dx.doi.org/10.4491/eer.2019.184.

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The computational fluid dynamics (CFD) simulation of the packed bed reactor (PBR) was carried out using ANSYS Fluent software. The various process parameters, such as inlet concentration of 4-chlorophenol (4-CP), flow rate, bed height, and porosity, were optimized to predict maximum biodegradation of 4-CP in immobilized catalyzed PBR. The geometrical mesh of the PBR was constructed using Gambit software, and a mesh size of 236995 was selected from the grid-independent study. A laminar flow model was used to understand the hydrodynamics as well as concentration profile of 4-CP inside the PBR using Fluent software. Through CFD, the effect of the flow rate, inlet concentration, and the bed height and porosity of the immobilized catalyst bed on the static pressure, mass imbalance, velocity, and stress-strain field inside the PBR was visualized. CFD simulation study predicted that maximum biodegradation of 4-CP was found in the presence of 500 mg/L of inlet concentration of 4-CP, 4 mL/min of flow rate, 18 cm of bed height and 0.375 of porosity. An experimental study was conducted for wastewater flow through the <i>B. subtilis MF447840.1</i> immobilized catalyzed PBR to remove the 4-CP in the laminar flow region. It was evident that CFD simulated results agreed well with experimental values.

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48

Tangsatjatham, Sitthichai, Pramoch Rangsunvigit i Sumaeth Chavadej. "TiO₂ and Metal-Doped TiO₂ Performance for the 4-Chlorophenol Degradation in Batch and Continuous Reactors". Advanced Materials Research 702 (maj 2013): 100–104. http://dx.doi.org/10.4028/www.scientific.net/amr.702.100.

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Photocatalytic degradation of 4-chlorophenol (4-CP) was investigated with a series of TiO2 and TiO2 doped with Ag and Au. Experiments were carried out in both batch and continuous reactors under an 11 W low pressure mercury lamp. Total organic carbon (TOC) was used as an indicator in addition to the concentration of 4-CP for the effectiveness of the degradation. In the batch reactor, a catalyst was suspended in aqueous 4-CP solution. Interestingly, 4-CP degradation did not depend on the catalyst used compared to photolysis. On the contrary, the presence of any of the catalyst significantly affected the intermediates, hydroquinone and hydroxyhydroquinone, degradation. Degussa P25 showed higher catalytic activity than the synthesized TiO2 and in some cases TiO2 doped with a precious metal in terms of TOC degradation. The addition of the precious metal to TiO2 did not improve the 4-CP degradation but it did on the degradation of the intermediate products. Degussa P25 was dip-coated on stainless steel mesh and used in the continuous reactor. With the continuous reactor, experimental conditions could be set so that complete degradation could be achieved.

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Rusek, Jakub, Šárka Paušová, Petr Praus i Josef Krýsa. "Immobilization of Exfoliated g-C3N4 for Photocatalytical Removal of Organic Pollutants from Water". Catalysts 11, nr 2 (3.02.2021): 203. http://dx.doi.org/10.3390/catal11020203.

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Graphitic carbon nitride (g-C3N4) was synthesized from melamine and exfoliated by thermal treatment. Exfoliated g-C3N4 particles were immobilized by electrophoretic deposition from an ultrasonically treated ethanolic suspension aged up to 12 weeks. During the aging of the suspension, the separation of particles bigger than 10 μm was observed. The separated stable part of the suspension contained particles with a relatively uniform size distribution, enabling the fabrication of g-C3N4 films that were stable in a stirred aqueous solution. Such stable immobilized particles of exfoliated g-C3N4 are reported for the first time. The photocatalytic activity of such layers was evaluated using aqueous solutions of Acid Orange 7 (AO7) and 4-chlorophenol (4-CP). The photocatalytic decomposition of AO7 was faster in comparison with the decomposition of 4-CP. Mineralization was observed in the case of AO7, but not in the case of 4-CP, where the decrease of 4-CP concentration is due to 4-CP polymerization and the formation of a dimer, C12H8Cl2O2. This indicates that the use of g-C3N4 as a photocatalyst for oxidative degradation of organic compounds in water is limited.

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50

Molina, C. B., A. H. Pizarro, J. A. Casas i J. J. Rodriguez. "Enhanced Pd pillared clays by Rh inclusion for the catalytic hydrodechlorination of chlorophenols in water". Water Science and Technology 65, nr 4 (1.02.2012): 653–60. http://dx.doi.org/10.2166/wst.2012.916.

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Bimetallic Pd–Rh catalysts supported on pillared clays have been prepared and tested for aqueous-phase hydrodechlorination (HDC) using 4-chlorophenol (4-CP) as target compound. These bimetallic catalysts combine the higher activity of Rh with the better stability of Pd found in previous works with monometallic catalysts. Different combinations of Pd and Rh amounting to 1 wt% total metal load were tested and the catalyst with 0.75 wt% Pd and 0.25 wt% Rh yielded the best results. Ecotoxicity and biodegradability (measured as BOD5/COD ratio) of the effluents were checked. A significant decrease of ecotoxicity was observed while biodegradability was dramatically improved from 0.02 for the initial 4-CP solution up to values higher than 0.6.

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