High-performance corrosion resistance of chemically-reinforced chitosan as ecofriendly inhibitor for mild steel

•Chitosan-5-HMF as efficient corrosion and antibacterial inhibitor for mild steel.•Chitosan-5-HMF acts as a mixed type inhibitor with cathodic predominance.•Surface analysis provide insight into the mechanism of corrosion inhibition.•MD simulations revealed the interaction of chitosan-5-HMF with mild steel surface. Finding new cost-effective and environmentally friendly anti-corrosion materials is a never-ending task. The present study is to prepare a new formulation based on chitosan derivatives with different degrees of substitution (chitosan-5-HMF) as an efficient green corrosion inhibitor to protect mild steel against corrosion in 1 M HCl. The inhibition performance of chitosan-5-HMF was determined by electrochemical tests coupled with theoretical study like as molecular dynamics (MD) simulations to assess the reactivity and adsorption mechanisms between chitosan-5-HMF and Fe. The obtained results revealed that chitosan-5-HMF3 performs excellently inhibition performance where its inhibition efficiency reached 97.01% at 200 mg/L, and it acted as an anode-based mixed inhibitor. SEM and contact angle analysis showed the formation of compact chitosan-5-HMF film on the steel surface. Molecular dynamic simulations also manifested that chitosan-5-HMF was absorbed more strongly on the metal surface in a parallel mode.