Inhibition of acidic corrosion of pure aluminum by some organic compounds

Inhibition of the corrosion of aluminum (Al) in hydrochloric acid (HCl) by sulfonic acid (SA), sodium cumene sulfonate (SCS), and sodium alkyl sulfate (SAS) has been studied using weight-loss and potentiostatic polarization methods. The results drawn from the two techniques are comparable and exhibit small discrepancy. The inhibition action depends on the chemical structure and the concentration of the inhibitors, the concentration of the corrosive medium, and the temperature. The efficiency of inhibitors increases in the order: SAS < SCS < SA in the studied concentration range. Results for weight loss indicated inhibitor efficiency (I%) increased with increasing inhibitor concentration, reaching a maximum inhibiting power of 85.6% at its highest values. The inhibitor efficiency (I%) decreased as the concentration of HCl increases. For the tested additives, the increase in temperature resulted in decreasing of the inhibitor efficiency (I%) and decreasing in the degree of surface coverage (θ). These results were indicative of increased aluminum dissolution with increasing temperature. The degree of surface coverage (θ) increased linearly with the logarithm of the inhibitor concentration fitting a Temkin isotherm.