Study of the effect of biocide additives on the protective effect of metal corrosion inhibitors

• S.M. Gaidar, A.S. Barchukova and S.M. Vetrova

Russian State Agrarian University – Moscow Timiryazev Agricultural Academy, 49 Timiryazevskaya St., Moscow, 127434, Russia

Abstract: In order to improve biostability while maintaining the protective efficiency of St3 steel in a 3.5% NaCl solution, the efficiency of zinc undecylenate as a biocidal additive to a preservative oil (PO) containing a non-ionic surfactant was studied. The resistance of the oils to mold fungi was evaluated according to GOST 9.052-88 (method 3) using a mixed suspension of spores of five fungal species: Aspergillus niger, Scopulariopsis brevicaulis, Penicillium chrysogenum, Penicillium cyclopium, and Paecilomyces varioti, under conditions simulating mineral contamination. The corrosion behavior was evaluated by gravimetric mass-loss measurements (GOST 9.054-75) and potentiodynamic polarization in a 3.5% NaCl solution. The initial preservative oil without the biocidal additive was shown to promote the growth of mold fungi, whereas the addition of zinc undecylenate at the concentrations of 1.0–3.0% to the preservative oil suppressed visible mycelial growth without reducing the protective properties. All the formulations under study retained a high level of protective efficiency (Z ≥ 98.4%), while the maximum protective effect reached 99.6–99.7% according to the gravimetric tests and up to 99.4% according to the electrochemical measurements at 3.0% content of zinc undecylenate. Analysis of the polarization curves showed that the protective mechanism corresponded to anodic-type inhibition. The addition of zinc undecylenate did not alter the inhibition mechanism but improved the biostability of the preservative oil, while maintaining a high level of protection of St3 steel against electrochemical corrosion.

Keywords: biocorrosion, corrosion inhibitors, preservative oil, surfactants, zinc undecylenate, biocidal additives, mold fungi, polarization curves, corrosion rate, protective effect

Int. J. Corros. Scale Inhib., 2026, 15, no. 2, 331-345
doi: 10.17675/2305-6894-2026-15-2-19

Download PDF (Total downloads: 1)

Back to this issue content: 2026, Vol. 15, Issue 2 (pp. 1-... (in progress))