Study On Anti-corrosion Mechanism Of Cauliflower Extract And Losartan Potassium For Copper And Q235 Steel In Acidic Solution

The corrosion of metals such as copper and steel in nature is inevitable.Adding corrosion inhibitors to media where metals are located can effectively inhibit their corrosion and play a role in reducing economic losses and saving resources.However,many corrosion inhibitors are highly toxic,which is not conducive to constructing an eco-friendly society.Therefore,the development of eco-friendly,new,and efficient corrosion inhibitors is both the focus of research in the chemical engineering field,and the best response and implementation of the development concept of"lucid waters and lush mountains are invaluable assets".Based on this,this paper proposes to employ green cauliflower extract and eco-friendly chemical drug(losartan potassium)as corrosion inhibitors,and then through systematic experiments to investigate the protective ability of them for metals in acid media.Combined with theoretical calculations,the structure-function relationship of inhibitor molecule and the physicochemical mechanism between corrosion inhibitor and metal surface are further revealed.The main works are as follows:(1)A cauliflower extract(CFE)corrosion inhibitor was prepared by a one-step extraction method,and its protective ability for copper was systematically studied.Traditional electrochemical measurement and scanning vibrating electrode technology had proved that CFE could effectively inhibit the corrosion of copper in 0.5 M sulfuric acid.Moreover,the anti-corrosion effect of CFE for copper was still strong with the extension of time,and the highest inhibition efficiency was 99%after immersed in acid for 48 h.According to the surface composition analysis,CFE formed a protective film on the copper substrate,thereby significantly shielding copper active sites'corrosion.Besides,the parallel adsorption and high E_binding value of CFE molecules in theoretical simulations indicated a strong interaction between the CFE and copper,which was an important reason to explain the excellent anti-corrosion of CFE for copper at molecular levels.(2)The corrosion inhibition ability of Brassica oleracea L extract(BOLE)for Q235steel in 0.5 M sulfuric acid and 1 M hydrochloric acid was investigated.The experimental results showed that BOLE was a mixed corrosion inhibitor and exhibited excellent anti-corrosion ability due to form a dense protective film on the Q235 steel surface.The inhibition efficiency was 92.3%in H₂SO₄ and 93.8%in HCl when the added dose of BOLE was merely 300 mg/L.At the same time,the N-Fe bond in XPS proved the chemical adsorption reaction between the BOLE and the steel surface.In theoretical calculations,low energy gap(?E)and high dipole moment(?)values,as well as high E_binding under neutralization and protonation conditions were all related to the strong interaction between the BOLE and steel,clarifying the internal reason why BOLE possessed excellent corrosion resistance to Q235 steel.(3)Based on electrochemical methods and theoretical calculations,the corrosion inhibition performance of losartan potassium(LP)for copper in 0.5 M sulfuric acid was studied.The results showed that LP was a mixed inhibitor,which inhibited cathodic and anodic reactions of copper by forming a protective film.The corrosion inhibition efficiency was the maximum when the added dose of LP was 40 mg/L.The protection ability enhanced with the increase of temperature and finally reached 92.8%at 298 K;93.6%at 303 K;and 94.9%at 308 K.The entire adsorption process followed the Langmuir adsorption model while chemical adsorption was the dominator.XPS analysis confirmed that coordination complexes were formed by the interaction between N atoms(derived from LP)and copper surface.Theoretical calculations further revealed the interaction mechanism between LP and copper surface at atomic and molecular levels.