Anticorrosive properties of theophylline on aluminium corrosion in 1M HCl: Experimental, Computational assessment and synergistic effect iodide ions

The aim of this study is to show the anticorrosive properties of 1,3-dimethyl-7H-purine-2,6-dione on aluminium corrosion in 1M hydrochloric acid and to study the synergy effect between iodide ions and this molecule. Research of eco-friendly, low toxic and biodegradable corrosion inhibitors capable of protecting metals in order to support industrialists who spend large sums of money to replace their corroded equipment. The main objective is to study the anticorrosive properties of theophylline on aluminium corrosion in 1M HCl. The anticorrosive properties study of theophylline on aluminium corrosion in 1M HCl was evaluated using mass loss, Density Functional Theory at B3LYP/6-31G (d) and Quantitative Structure-Property Relationship methods. The results obtained show that theophylline inhibition efficiency increases with concentration but decreases with increasing temperature with a maximum value of 88% for 5.10-3M at T = 298 K. The result from absorption isotherms reveals that theophylline adsorbs to the aluminium surface according to the modified Langmuir isotherm. Adejo Ekwenshi's isotherm has shown that the molecule adsorption on aluminium is essentially of a physical nature. Thermodynamic adsorption and activation parameters were calculated and analyzed. A synergistic effect between the molecule studied and the iodide ions was found. Furthermore, global and local reactivity were analyzed through density functional theory calculations. Quantitative structure-property relationship methods model has been permitted to correlate experimental and theoretical inhibition efficiencies. Theophylline is an excellent aluminum inhibitor corrosion in the studied solution. Theoretical results were in agreement with experimental data. Finally to find the best set of parameters for modeling the inhibition efficiency.