Abstract

The fungal biomass of cocoa bean shell (FBCS) obtained by solid-state fermentation (SSF) with Penicillium roqueforti was used as a natural corrosion inhibitor of carbon steel in an acidic solution with 0.5 mol.L⁻¹ HCl. The evaluation of the corrosive process was carried out using gravimetric, electrochemical, and surface analysis techniques. The gravimetric test data were used to calculate the corrosion rate, current density, and efficiency. Electrochemical measurements provided the polarization curves and the electrochemical impedance spectroscopy (EIS). Finally, the surface analysis was performed using an optical microscope. From Tafel's extrapolation, the largest deviation was noticed at 69.9 mV, confirming that FBCS acted as a partially cathodic inhibitor. Inhibitor molecules were physically adsorbed on the carbon steel surface and the adsorption mechanism followed the Langmuir isotherm model. The results of the EIS confirmed the gravimetric results. FBCS inhibited the acid corrosion of carbon steel AISI 1008 at a concentration range from 0.44 g.L⁻¹ to 1.77 g.L⁻¹, and the higher the concentration, the higher the inhibition rate. The maximum corrosion inhibition efficiency was 93%. The EIS by time results showed that the FBCS should not be applied for very long periods of immersion in the electrolyte. The maximum inhibition efficiency was verified within 12 hours of immersion (95.96%). Therefore, this study encourages the use of FBCS as inhibitor due to good inhibit efficiency and to be environmental friendly, as well as the use of others news materials, such as biomass resulting from the fermentation of other residues, proposed in an unprecedented way in this work.

摘要

可可豆壳 (FBCS) 的真菌生物质通过固态发酵 (SSF) 与罗氏青霉 ( Penicillium roqueforti)获得，在 0.5 mol.L ⁻¹的酸性溶液中用作碳钢的天然缓蚀剂盐酸。使用重量分析、电化学和表面分析技术对腐蚀过程进行了评估。重量测试数据用于计算腐蚀速率、电流密度和效率。电化学测量提供了极化曲线和电化学阻抗谱 (EIS)。最后，使用光学显微镜进行表面分析。根据 Tafel 的推断，最大偏差出现在 69.9 mV，证实 FBCS 充当部分阴极抑制剂。缓蚀剂分子物理吸附在碳钢表面，吸附机理遵循朗缪尔等温模型。EIS 的结果证实了重量分析结果。FBCS 在 0.44 gL 浓度范围内抑制碳钢 AISI 1008 的酸腐蚀^-1至1.77 gL ^-1，浓度越高，抑制率越高。最大缓蚀效率为93%。按时间计算的 EIS 结果表明，FBCS 不应在电解液中浸泡很长时间。最大抑制效率在浸泡 12 小时内得到验证 (95.96%)。因此，本研究鼓励使用FBCS作为抑制剂，因为它具有良好的抑制效率和环境友好性，以及使用其他新材料，例如其他残留物发酵产生的生物质，在本研究中以前所未有的方式提出。工作。