Thermal behaviour and adsorption properties of some benzothiazole derivatives

• Published in: Journal of thermal analysis and calorimetry 2014-11, Vol.118 (2), p.651-659
• Main Authors: Samide, Adriana, Rotaru, Petre, Ionescu, Cătălina, Tutunaru, Bogdan, Moanţă, Anca, Barragan-Montero, Véronique
• Format: Article
• Language: English
• Subjects: Adsorption; Analysis; Analytical Chemistry; Carbon steel; Carbon steels; Chemical properties; Chemisorption; Chemistry; Chemistry and Materials Science; Corrosion; Corrosion inhibitors; Inhibition; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Steel; Surface chemistry; Thermal analysis; Thermal stability
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-014-3644-3

The thermal stability and the adsorption properties have been investigated for three benzothiazole compounds: 2-mercaptobenzothiazole (MBT), N -cyclohexyl-2-benzothiazole sulfenamide (NCBSA), and 2,2′-dibenzothiazole disulphide (BTD), reported in our early studies as corrosion inhibitors for carbon steel in different media. The electrochemical results were used to calculate the degree of surface coverage ( θ ). The adsorption mechanism of the three inhibitors was discussed according to the free energy of adsorption ( Δ G ads ∘ ) value obtained from Temkin adsorption isotherm, this being the best way to quantitatively express the adsorption process of their molecules on carbon steel surface. Thus, a mixed type mechanism involving the synergism between physisorption and chemisorption was proposed. The thermal analysis curves showed that, for the occurred events up to 470 °C, mass losses take place with endothermic effects followed by the total oxidation of the residue with an exothermic effect around 520 °C. Consequently, their effectiveness follows the order: BTD > NCBSA ≥ MBT, while the thermal stability ranges as follows: NCBSA