Chunting Guo,Yang Li,Caixia Qi,Huilai Sun,Dejian Zhang,Yong Wan
This study evaluated the effect of solvent acids on the structure and corrosion resistance performance of chitosan (CS) film on MAO-treated AZ31B magnesium (Mg) alloy. Initially, CS solutions were prepared in four solvent acids: acetic acid (HAc), lactic acid (LA), hydrochloric acid (HCl), and citric acid (CA). The CS films were subsequently deposited on MAO-treated AZ31B Mg alloy via a dip-coating technique. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FT-IR), contact angle measurement, and atomic force microscopy (AFM) were employed to characterize the surface and cross-sectional morphology as well as chemical composition. Furthermore, the samples were subjected to potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests to assess their resistance against corrosion in simulated body fluid (SBF). These results indicated that the CS film prepared with LA exhibited the lowest surface roughness (R a = 31.2 nm), the largest contact angle (CA = 98.50°), and the thickest coating (36 μm). Additionally, it demonstrated superior corrosion protection performance, with the lowest corrosion current density ( I corr = 3.343 × 10 −7 A/cm 2 ), highest corrosion potential ( E corr = −1.49 V ), and highest polarization resistance ( R p = 5.914 × 10 4 Ω·cm 2 ) in SBF. These results indicated that solvent acid types significantly influenced their interactions with CS. Thus, the structure and corrosion protection performance of CS films can be optimized by selecting an appropriate solvent acid.
Shengfu Liao,Jianguo Liu,Long Yan,Qiying Liu,Guanghui Chen,Longlong Ma
Anthraquinones are recognized as high efficiency photocatalysts which can perform various redox reactions in aqueous or organic phases. We have experimentally proven that 2-BrAQ can undergo hydrogen transfer with an alpha-aromatic alcohol under light conditions, thereby efficiently oxidizing the aromatic alcohol to the corresponding product. The yield of 1-phenethanol to acetophenone can reach more than 96%. In subsequent catalyst screening experiments, it was found that the electronegativity of the substituent at the 2 position of the anthraquinone ring and the acidity of the solvent affect the photocatalytic activity of anthraquinones. After using various aromatic alcohol substrates, 2-BrAQ showed good conversion and selectivity for most aromatic alcohols, but showed C–C bond cleavage and low selectivity with non-α-position aromatic alcohols. In order to explore the mechanism of the redox reaction of 2-BrAQ in acetonitrile solution, the corresponding free radical reaction pathway was proposed and verified by density functional theory (DFT). Focusing on calculations for 2-BrAQ during the reaction and the first-step hydrogen transfer reaction between the 2-BrAQ triplet molecule and the 1-phenylethanol molecule, we recognized the changes that occurred during the reaction and thus have a deeper understanding of the redox reaction of anthraquinone compounds in organic systems.
危险品化学品经营许可证（带存储）