核桃青皮提取物和十二烷基硫酸钠对冷轧钢在H3PO4溶液中的缓蚀协同效应

Synergistic Inhibition Effect of Walnut Green Husk Extract and Sodium Dodecyl Sulfate on Cold Rolled Steel in H3PO4 Solution

目的研究核桃青皮提取物(WGHE)和阴离子表面活性剂十二烷基硫酸钠(SDS)混合复配后,对冷轧钢(CRS)在H3PO4中的缓蚀协同效应,揭示缓蚀协同性能影响规律,并探究缓蚀协同机理。方法采用回流提取法从农林废弃物核桃青皮中提取制备出WGHE。利用失重法、电化学法、紫外光谱(UV)、扫描电子显微镜(SEM)、原子力显微镜(AFM)研究WGHE和SDS的复配缓蚀协同性能、电化学作用机理、紫外吸收曲线以及钢表面的微观形貌。结果高浓度的WGHE对冷轧钢在1.0 mol/L H3PO4中具有较好的缓蚀作用,但低浓度时的缓蚀效果较差。单独SDS使用时,最大缓蚀率不超过60%;将WGHE与SDS复配后,缓蚀性能可进一步提升,尤其在WGHE用量为10~40 mg/L时,复配协同作用显著。缓蚀率随着缓蚀剂浓度的增加而升高,但随着温度的上升有所降低,WGHE、SDS复配前后在钢的表面吸附均符合Langmuir吸附等温式。动电位极化曲线表明,WGHE、SDS为阴极抑制型缓蚀剂,但WGHE/SDS为混合抑制性缓蚀剂。Nyquist图在高频区呈单一弥散容抗弧,而在低频区出现小段感抗弧,WGHE与SDS复配后电荷转移电阻显著增大。协同体系中WGHE和SDS会发生相互作用。SEM和AFM所呈现的微观形貌更加清晰地表明WGHE/SDS具有良好的缓蚀协同性能。结论WGHE和SDS对冷轧钢在1.0 mol/L H3PO4中具有明显的缓蚀协同效应,复配后缓蚀性能进一步提升,同时有效抑制了钢的阴极和阳极腐蚀反应。

The work aims to study the synergistic inhibition effect of walnut green husk extract(WGHE)and sodium dodecyl sulfate(SDS)of anionic surfactant on the corrosion of cold rolled steel(CRS)in H3 PO4 solution,so as to reveal the synergistic inhibitive action rule and discuss the synergistic inhibitive mechanism.WGHE was extracted and prepared by reflux extraction method from the agricultural waste of walnut green husk.The synergistic inhibitive action of WGHE and SDS,electrochemical mechanism,ultra-violet(UV)absorption curve and micro-graphs of steel surface were studied by weight loss,electrochemical technique,ultra-violet spectrum(UV),scanning electron microscope(SEM)and atomic force microscope(AFM).WGHE exhibited better inhibitive performance at higher concentration for CRS in 1.0 mol/L H3 PO4 solution,but poor inhibition at lower concentration.The maximum inhibition efficiency of individual SDS was below 60%.Incorporation of WGHE with SDS could further improve the inhibitive performance,and there was a strong synergistic inhibition effect for the WGHE concentration range of 10~40 mg/L.Inhibition efficiency increased with the increase of additive inhibitor dosage,while decreased with increase of temperature.The adsorption of WGHE,SDS or WGHE/SDS on CRS surface followed Langmuir adsorption isotherm.Potentiodynamic curves indicated that both WGHE and SDS could be arranged as the cathodic inhibitors,while the mixture of WGHE/SDS acted as a mixed-type inhibitor.Nyquist spectra showed a depressed capacitive loop at high frequencies,while a small inductive section at low frequencies.The charge transfer resistance value increased prominently after the mixture of WGHE/SDS was added.An interaction occurred between WGHE and SDS in synergetic system.SEM and AFM microphotographs clearly showed that there was a true synergism between WGHE and SDS.There is a strong synergistic inhibition effect of WGHE and SDS on the corrosion of CRS in 1.0 mol/L H3PO4 solution,and the inhibitive action of the mixture of WGHE and SDS drastically strengthens,which retards both cathodic and anodic corrosive reactions simultaneously.