Inhibition of dissolution of aluminium in hydrocWoric acid solutions by 1,3,4-thiodiazole derivatives

M Moussa, Abu Ei-Nader, A Shalby&, E Fakhry~
1995 Indian Journal of Chemical Technology   unpublished
The dissolution of aluminium in 2N hydrochloric acid solution is retarded by the addition of some 1,3,4-thiodiazole derivatives to the medium. Three different techniques, viz., weight loss, gasometric and thermometric are applied. Temperature effect has been investigated in the range 25·40°C and the activation energies have been calculated. The inhibition efficiency decreases with the rise in temperature while the activation energy increases in the presence of the additives. The inhibitive
more » ... The inhibitive character of the additives depends on the concentration as well as the composition of the inhibitor. The inhibition efficiency was calculated as follows: From weight loss measurements where wfree and Winh are the losses in weight of the piece of aluminium in absence and presence of the inhibitor, respectively. From thermometric measurements Ti= initial temperature, Tm = maximum temperature and (= the time from start of the experiment upto maximum temperature. From gasometric method ... (3) ... (2) ... (1) R-R % Inhibition = free inh X 100 Rfree where Rf and R h are the rates of dissolu-fee m tion of aluminium (nite of hydrogen evolution) in mL min-1 cm-1 in free and in presence of the given inhibitor, respectively. The inhibitors used in the present study are where % Inhibition-R Nfree-R Ninh X 100 RNfree W-Wh % Inhibition = free III X 100