二硫代酰胺类化合物在盐酸中对碳钢的缓蚀性能(英文)

采用失重实验,动电位极化,交流阻抗,量子化学计算和拉曼光谱等方法研究了N,N′-二异丙氧基丙基二硫代二丙酰胺(DPDA)在1 mol.L-1盐酸溶液中对碳钢的缓蚀性能.失重实验结果表明,DPDA在盐酸溶液中能够有效地抑制碳钢的腐蚀,当缓蚀剂DPDA的浓度为1×10-3 mol.L-1时,其缓蚀效率达到90.2%.极化曲线表明DPDA为混合型缓蚀剂,单一的容抗弧变化表明碳钢电极表面的腐蚀过程主要由电荷转移步骤控制.由失重实验,动电位极化和电化学交流阻抗方法得到的DPDA缓蚀效率具有较好的相关性,均表现为缓蚀效率随着DPDA浓度的增大而增加.另外,DPDA在碳钢表面的吸附符合Langmuir吸附等温式.吸附过程的吉布斯自由能(ΔG0a0d0s)为-38.65 kJ.mol-1,这说明DPDA分子在碳钢表面形成共价键而发生了自发的化学吸附.拉曼光谱表明DPDA分子有效地吸附在碳钢表面,量子化学计算结果证明DPDA分子在碳钢表面的化学吸附活性中心集中在S原子上.

Dithioamide Derivative as an Efficient Inhibitor for Mild Steel in Hydrochloric Acid

Dithio-N,N'-dimethoxypropyldipropionamide (DPDA) was investigated as a corrosion inhibitor for mild steel in 1 mol·L~(-1) hydroehloric acid using weight loss test,potenfiodynamic polarization,electrochemical impedance spectroscopy (EIS),quantum chemical study,and Raman spectroscopy.The weight loss test results showed that DPDA was an excellent inhibitor for mild steel in acid media with an inhibition efficiency of 90.2% at the DPDA concentration of 1×10~(-3) mol·L~(-1).The polarization curves indicared that DPDA behaved as a mixed-type inhibitor while the single capacitive loop in the Nyquist plots revealed that the corrosion was a charge transfer controlled process.Inhibition efficiencies incmased with the increase of DPDA concentrations,and the values of the inhibition efficiencies.obtained from the weight loss test.potentiodynamic polarization,and EIS,were in reasonable agreement.The absorption of DPDA was found to obey the Langmuir adsorption isotherm.The free energy of adsorption (△G_(ads)~0)was found to be -38.65 kJ·mol~(-1) and this value indicated that the adsorption was mainly chemisorpfion.This results from the sharing or/and transfer of electrons from the DPDA molecules to the metal surface to form coordinate bonds.The negative △G_(ads)~0 value revealed that the adsorption of DPDA was a spontaneous process.Raman spectra suggest that DPDA adsorbed well onto the mild steel surface, and the quantum chemical study showed that the sulphur atoms in the DPDA molecule were the main active sites that resulted in absorption on the surface of the mild steel.