Exploration of procyanidin C1 from Uncaria laevigata as a green corrosion inhibitor in industry: Electrochemical assessment, theoretical simulation, and environmental safety

Traditional corrosion inhibitors have made great contributions to equipment cleaning, metal industry and oil well pipelines, but also cause serious environmental pollution. Therefore, green corrosion inhibitors are gradually explored. Unfortunately, their environmental toxicities have not been experimentally proved, and few of them can be applied in industry. Herein, procyanidin C1 (PCC1), isolated from the abandoned crop Uncaria laevigata, is expected to become a potential green corrosion inhibitor. The corrosion inhibition performance of PCC1 in HCl medium is investigated by electrochemical tests and theoretical calculation. Then the effects of PCC1 on the acute toxicity, antioxidant defense system and apoptosis gene expression of zebrafish are comprehensively explored and analyzed. The electrochemical test confirms that 160 mg/L PCC1 shows a high corrosion inhibition efficiency of 97.70% for Q235 steel exposed to 1 M HCl for 120 h, performing a sustainable and excellent corrosion inhibition performance. The morphology analysis, molecular dynamics and quantum chemistry proves that the protective film is firmly adsorbed on the steel surface like octopuses, together with many active adsorption centers. The acute toxicity tests reveal that PCC1 is a non-toxic corrosion inhibitor. The antioxidant enzyme activity experiment also shows that PCC1 have no obvious damage and neurotoxicity to zebrafish antioxidant system. Apoptosis experiments further demonstrates that PCC1 exhibits no significant effect on the level of apoptosis-related genes under high concentration and long-term exposure. As a proven green corrosion inhibitor, PCC1 may display great potential in industry.