Study of thioureas derivatives synthesized from a green route as corrosion inhibitors for mild steel in HCl solution

•1,3-Dibenzylthiourea/DBTU and 1-benzyl-3-diisopropylthiourea/DPTU were studied.•DPTU and DBTU act as good corrosion inhibitors for C-steel in acid solution.•The inhibition efficiency of DPTU and DBTU increased with concentration.•DBU did not act as an effective corrosion inhibitor for C-steel in acid solution.•The sulphur atom may play an important role in the inhibition process.

The behaviour of 1,3-dibenzylthiourea (DBTU) and 1-benzyl-3-diisopropylthiourea (DPTU) have been investigated as carbon steel corrosion inhibitors in HCl solution by weight loss measurements, potentiodynamic polarization curves, electrochemical impedance and scanning electron microscopy analysis. Quantum chemical calculation was applied to correlate electronic structure parameters of thiourea derivatives with their inhibition performances. DPTU results were slightly superior to those obtained in the presence of DBTU, showing that the replacement of one benzyl group for two isopropyl groups enhances the inhibitory properties. The 1,3-dibenzylurea derivative has also been studied in order to assess the importance of the sulphur atom to the inhibitory effect.

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