Experimental and theoretical studies on the corrosion inhibition performance of molecules containing tert-butyl benzyl group on mild steel in acid media

The inhibition by (4-tert-butyl-phenyl)-acetic acid hydrazide (TPAH), 5-(4-tert-butyl-benzyl)-[1,3,4] oxadiazole-2-thiol (TBOT) and 5-(4-tert-butyl-benzyl)-4H-[1,2,4] triazole-3-thiol (TBTT) of mild steel corrosion in 0.5 M HCl was investigated using gravimetric and electrochemical techniques. These inhibitors acted more effectively at higher concentration and at lower temperature; among these TBTT being the most efficient inhibitor, which showed highest efficiency of 92.6% at 303 K and 4.8 mM concentration. Adsorption of TPAH followed Freundlich isotherm, whereas TBOT and TBTT followed Langmuir isotherm. Energy of activation for corrosion increased after the addition of inhibitors. Free energy of adsorption showed that all the three inhibitors get adsorbed to the mild steel surface by both physical and chemical processes. EIS studies confirmed that all the inhibitors offered higher charge transfer resistance to the corrosion current and this led to decreased double-layer capacitance. Polarization studies showed that all inhibitors emerged as mixed type. Surface studies confirmed that the pits caused by corrosion were decreased by protective film of inhibitors. Corelation of experimental data with quantum chemical parameters like ELUMO, energy gap, dipole moment, hardness and softness confirmed the superior performance of TBTT as compared to TPAH and TBOT

Tribological study of OH- and N-containing imidazoline derivatives as additives in water–glycol

Tribological properties of two hydroxyl- and only active nitrogen-containing water-soluble imidazoline derivatives, benzotriazole-containing imidazoline (BML) and caprylic acid-containing imidazoline (CML), as lubrication additive in water–glycol hydraulic fluid were evaluated with a four-ball tester. And the antirust and anticorrosion behaviors were also investigated. Results show that BML and CML were able to remarkably improve the antirust properties of water–glycol fluid when added at a low adding concentration, and also these performances of BML was better than CML. All additives exhibited good extreme pressure and antiwear properties, and BML showed better tribological properties than CML. Besides, the difference in the tribological and anticorrosion properties of these derivatives was closely related to their different molecular structures. There exists a synergistic tribological effect between benzotriazole and imidazoline group in the tribological and antiwear performances. Furthermore, significant improvement in the tribological performances of BML was detected and attributed to organic nitrogen compounds, iron oxide, and so on in tribofilm on the worn surfaces