INFLUENCE OF CATHODIC PROTECTION ON PH AND CHANGE OF SOIL ELECTROLYTE COMPOSITION

1 MSALLAMOVÁ Šárka
Co-authors:
1 NOVÁK Pavel 1 KOUŘIL Milan
Institution:
1 University of Chemistry and Technology Prague, Prague, Czech Republic, EU, msallams@vscht.cz, novakp@vscht.cz, kourilm@vscht.cz
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1052-1057
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
71 views / 32 downloads
Abstract

Cathodic protection is applied especially to protection of coating fault on a buried pipe line in a soil. According to some authors, the mechanism of cathodic protection of carbon steel is a shift of open circuit potential into the immunity region or reducing of anodic reaction rate in the active state. The importance of change of pH and soil electrolyte composition during applying cathodic protection is sometime ignored.The study deals with influence of cathodic protection on pH change and anions migration in soil electrolyte close to protected carbon steel surface. Concentration of chlorides, sulphates and hydrogen carbonates decreased about two orders of magnitude during applying cathodic protection. The migration rate of hydroxides during cathodic polarization is lower than their production by cathodic reduction of oxygen. As a result of cathodic reduction of oxygen, the pH of soil electrolyte close to protected surface gradually increases up to 12.The final pH of soil electrolyte close to protected surface depends on the migration rate of anions, the diffusion rate of oxygen into soil electrolyte and neutralizing capacity of soil.

Keywords: Cathodic protection, soil electrolyte, migration

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