Study on the bactericidal activity of dodecyl dipropylene triamine and anionic mixed surfactant systems

Abstract

In this study, we anticipated that cocamidopropyl betaine (CAPB) and isomeric alcohol ethoxylates (TO) could protect the antibacterial properties of dodecyl dipropylene triamine (BDA) under the influence of anionic surfactants. Different concentrations of anionic surfactants such as sodium lauryl polyoxyethylene ether sulfate (AES) and sodium dodecyl sulfate (SDS) were added to a mixture of the cationic surfactants BDA and benzalkonium chloride (BZK) with two protective agents: a branched nonionic surfactant TO and a zwitterionic surfactant CAPB. Opticaldensity (OD) and Cell Counting Kit-8 (CCK-8) methods were used to evaluate the antibacterial activity of these systems against sulfate-reducing bacteria (SRB) such as Escherichia coli, Staphylococcus aureus, and Desulfovibrio sp. The protective mechanisms of the different protective agents were studied by measuring their respective viscosities. The protective agents (TO and CAPB) had a negative effect on the biocidal performance of the BZK (C12-C14) but had an excellent protective effect in the presence of anionic surfactants. In the BDA systems (AES and SDS concentrations of 100 mM), the BDA-CAPB-AES, BDA-CAPB-SDS, BDA-TO-AES, and BDA-TO-SDS systemseliminated almost all E.coli and S.aureus bacteria within 2 min of exposure, among which the BDA-CAPB-AES and BDA-TO-AES systems showed the strongest bactericidal activity against sulfate reducingbacteria (SRB). Therefore, these multicomponent surfactant antibacterial systems can potentially be used to replace traditional cationic surfactant systems in the chemical industry, thereby reducing the microbial corrosion caused by SRB.