|Ultima descărcare din IBN:|
| SM ISO690:2012|
COVALIOVA, Olga; COVALIOV, Victor. Electrochemical neutralization of the distillery by-products. In: Achievements and perspectives of modern chemistry. 9-11 octombrie 2019, Chişinău. Chisinau, Republic of Moldova: Tipografia Academiei de Ştiinţe a Moldovei, 2019, p. 168. ISBN 978-9975-62-428-2.
|Achievements and perspectives of modern chemistry 2019|
Conferința "International Conference "Achievements and perspectives of modern chemistry"" |
Chişinău, Moldova, 9-11 octombrie 2019
The brandy alcohol usually contains a series of admixtures, among then upto 57 mg/L aldehydes – undesirable component which regulated contents in the final product should not exceed 2-4 mg/L . One of the most commonly used methods of the distillery products neutralization is the absorption on active carbons . However, the active carbon, in addition to absorption, catalyses also the redox reactions, among then ethanol oxidation to acetaldehyde and then to the acetic acid, following the scheme of reaction: C2H5OH + O2– CH3CHO + H2O – СР3СOOH. The reaction rate at the first stage (ethanol oxidation to acetaldehyde) is higher than acetaldehyde oxidation to acid, so this process is linked with the formation of increased amounts of acetaldehyde which, unlike the acetic acid, is not absorbed by the carbon and makes part of the final product. To remove the aldehydes and other admixtures of alcohol digestion products from the distillate, a new technology was proposed, including the undesired products reduction with the electrochemically generated active hydrogen . The proposed processis carried out in the flowthrough conditions with the linear flow rate of 0.1-0.3 m/s. The treated liquid is passed through the three-dimensional Ni cathode covered with catalytic layer, within the cathodic compartment of diaphragm electrolyzer, under the cathode current density of 0.15-0.5 A/dm2. A new type of the voluminous porous material made of foamy metal with high active surface, modified with the coating containing small percentage of Re, MoorW, was used. A total active surface of the cathode was by 2-3 orders higher than the visible surface. Hydrogen reduction on the cathode is connected with water molecules dissociation H2O – H+ + OH– and hydrogen ions discharge, including a series of competing reactions with primary emission of protonated hydrogen (•Hads): H+ + e – •Hads, which ensures the high efficiency of aldehydes reduction. Further on, a part of atomic hydrogen, which is not involved in aldehydes reduction, will be molized, following the recombination reaction: •Hads. + •Hads. – H2, or as a result of electrochemical desorption (Geyrovsky reaction): H3O+ + •Hads. + e – H2 + H2O. Another significant advantage of three-dimensional cathodes application with modified catalytically active surface is low overvoltage of hydrogen emission, making 0.03-0.05 V, which is substantially lower than for Ni electrodes. Due to this fact, the overall energy consumption to electrolytic process is much lower as compared to the application of plate Ni electrodes