Dimocarpus longan Lour Leaf Extract as Green Corrosion Inhibitor for Copper in Sulfuric Acid Solution

Abstract

In this work, the Dimocarpus longan Lour Leaf Extract (DLLE) was obtained by soaking in sulfuric acid solution. Dimocarpus longan Lour Leaf Extract contains 3,4,5-Trihydroxybenzoic acid ethyl ester (TBE), 3,4,5,7-Tetrahydroxyflavone (TDF) and 3,3',4', 5,7-Pentahydroxyflavone2-(3,4-Dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one (PDH). The experimental and theoretical calculation results show that the DLLE can exhibit excellent corrosion inhibition performance. As the concentration of DLLE increases, the corrosion inhibition performance increases significantly. When the concentration of DLLE reaches 400 mg/L, its corrosion inhibition efficiency can reach about 98% at 318 K. Quantum chemical calculation results show that TBE, TDF and PDH in DLLE have large dipole moments and small energy gap values. All these indicate that the DLLE can exhibit high corrosion inhibition performance. Molecular dynamics simulations show that TBE, TDF and PDH can be adsorbed on the Cu (111) surface in parallel with high adsorption energy. Therefore, both experimental and theoretical calculation results demonstrate that the DLLE can exhibit high corrosion inhibition performance.