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Phenols
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Global Resources and Universal Processes, 2020
Leszek Wachowski, Robert Pietrzak
In contrast to neutral alcohols, water solutions of phenol show weak acidic properties; hence, phenol has been referred to as carbolic acid. Phenol dissociates with the formation of phenolate (C6H5O-), also called phenoxide ion, and proton (H3O)+:C6H5OH(aq)+H2O(1)↔C6H5O−(aq)+H3O+(aq)
Treatment of Coal Industry Effluents
Published in Mihir Kumar Purkait, Piyal Mondal, Chang-Tang Chang, Treatment of Industrial Effluents, 2019
Mihir Kumar Purkait, Piyal Mondal, Chang-Tang Chang
All the pollutants of the spent ammoniacal liquor affect the ecology of the waste-receiving water. During the process, phenol is considered to be the most hazardous pollutant. The other objectionable substances include thiocyanate, thiosulfate, cyanide, etc. In some plants, spent ammoniacal liquor is utilized for quenching of hot coke, this practice destroys the toxic matters like phenols in the liquor, but as this causes heavy corrosion in the quenching cars and in other quenching equipment, the method is not generally favored. Being a valuable chemical by-product, phenol may be recovered instead of destroying it. For the recovery of phenol by liquid extraction methods, several techniques have been developed. Most of these processes use benzene as a solvent to extract phenol from the crude ammoniacal liquor, before entering for ammonia stripping. Other solvents used include light oil, petroleum oil, etc. The extracted phenols from all absorption process can be recovered by washing with sodium hydroxide solution. Phenol reacts with a caustic solution to produce sodium phenolate. The crude phenol is then liberated from it using gases containing carbon dioxide. The phenols, thiocyanates, thiosulfates, and ammonia can be biologically oxidized using certain microorganisms such as bacteria and yeast. When optimum pH and temperature are maintained, sufficient nutrients are added, and the reactor is suitably seeded, the proper loading of this phenolic substrate to the reactor may result in a desirable reduction of the pollution load of the waste. Phenol concentrations of ~800 mg/L may be treated biologically. In all practical cases, the phenol concentration in the waste ammoniacal liquor is too high to be treated directly by biological means.
Qualitative Chemical Analysis
Published in Steven L. Hoenig, Basic Chemical Concepts and Tables, 2019
Because all phenols do not produce colored complexes under the test conditions, a negative test must be considered as an ambiguous result. Pyridine is a base which deprotonates the phenol to form phenolate ions. The color is produced by a coordination complex formed between iron(III) and three phenolate ions.
Degradation Pathway of Ozone Oxidation of Phenols and Chlorophenols as Followed by LC-MS-TOF
Published in Ozone: Science & Engineering, 2020
Ogheneochuko Utieyin Oputu, Olalekan Siyabonga Fatoki, Beatrice Olutoyin Opeolu, Michael Ovbare Akharame
At higher pH 10, the degradation proceeds via the formation of other major intermediates. Important amongst these intermediates is an isomer of catechol (C6H6O2, RT = 20.812), the dimerized isomers C12H10O2 (RT = 21.134 and 23.047), the trimer C18H14O3 (RT = 27.573) and an isomer of phenol (C6H6O, RT = 22.888) produced when the solution pH was either initially pH 10, or held constant at pH 10. The mass spectrums (MFE) of these compounds, showing the isotope abundance and spacing used for identification, were acquired from their individual extracted ion chromatograms (EIC) and are presented in SF 5 – SF 8. The trimer C18H14O3 (RT = 27.573) was observed within 20 min when the reaction was kept constant at pH 10. The compound C6H6O at RT = 22.888 identified only in the alkaline experiment, is clearly different from the starting phenol (RT = 17.987) which does not ionize appreciably enough to be detected by the method applied in this study (see SF 1). The pKa for phenol (9.9) allows for the majority of the phenol molecules to exist as phenolate ions at pH 10. The reactions of the phenolate ion with ozone may well account for the presence of the higher dimers, trimer, isomeric phenol and two differing hydroxylated phenols observed at high pH. There is little or no information regarding the ozonation of phenol to generate the dimers and trimer. Structures presented here were arrived at based on searches conducted on the Royal Society of Chemistry’s database ChemSpider, taking into account the molecular features of phenol. In other cases, literature guidance was used.
Application of phenol-cresol-formaldehyde resin as an adhesion promoter for bitumen and asphalt concrete
Published in Road Materials and Pavement Design, 2021
Volodymyr Gunka, Yuriy Demchuk, Iurii Sidun, Denis Miroshnichenko, Bemgba B. Nyakuma, Serhiy Pyshyev
The extraction of phenols from the wide phenolic fraction (WPhF) was performed using 20% NaOH solution. The alkali removal of phenols was based on the ability of phenol and its derivatives to form water-soluble phenolates. Typically, the latter is separated from the hydrocarbon fraction after extraction before conversion to phenols by 38% hydrochloric acid (concentrated HCl). The composition of «raw» phenols in WPhF is typically about 32.3 wt. %.