Abstract
Microbial corrosion is a universal phenomenon in salt water media such as seawater and wastewater environments. As a kind of efficient protective metal coating for steel, the damage of the Zn–Ni alloy coating was found to be accelerated under microbial corrosive conditions. To solve this problem, chitosan, which is considered a natural product with high antibacterial efficiency, was added to Zn–Ni electrolytes as a functional ingredient of electrodeposited Zn–Ni–chitosan coatings. It was found that the addition of chitosan significantly and negatively shifted the electrodeposition potentials and influenced the Ni contents, the phase composition, and the surface morphologies. By exposing the coatings in a sulfate-reducing bacteria medium, the microbial corrosion resistance was investigated. The results showed that compared to the Zn–Ni alloy coating, Zn–Ni–chitosan coatings showed obvious inhibiting effects on sulfate-reducing bacteria (SRB) and the corrosion rates of these coatings were mitigated to some degree. Further research on the coatings immersed in an Escherichia coli-suspended phosphate buffer saline medium showed that the bacteria attachment on the coating surface was effectively reduced, which indicated enhanced antibacterial properties. As a result, the Zn–Ni–chitosan coatings showed remarkably enhanced anticorrosive and antibacterial properties.
Highlights
Zn-based coating electrodeposited on steel is considered one of the most effective and economical methods for providing efficient and reliable corrosion protection [1]
For ACS3, the attached bacteria decreased to 93% compared to A0, revealing the best antibacterial property. These results revealed that the existence of chitosan in the coatings could effectively inhibit the adhesion of bacteria to the coating surface
It was found that chitosan turned the electrodepositing potential strongly negative by adsorbing onto the depositing surfaces, which led to the decrease of the cathodic current efficiency
Summary
Zn-based coating electrodeposited on steel is considered one of the most effective and economical methods for providing efficient and reliable corrosion protection [1]. In an aquatic environment, the Zn–Ni coatings possess relatively high corrosion resistance and good mechanical properties, which offers an important eco-friendly alternative to toxic Cd coatings [4]. The most serious problems are considered to be microbiological-induced corrosion (MIC) and biofouling [5,6,7]. In a natural aquatic environment, microorganisms are spontaneously attached to material surfaces, resulting in microbial corrosion and biofouling [8,9,10]. As a kind of anaerobe, sulfate-reducing bacteria (SRB) is considered one of the most significant bacteria responsible for MIC. As a result, making the Zn-Ni coating a biocide that is inhibitive to bacteria is considered to be the main task for MIC and biofouling problems in marine environments
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