Corrosion inhibition of aluminium by some picrate salts

Corrosion of aluminium in hydrochloric acid solution has been studied by hydrogen evolution, weight loss as well as galvanostatic measurements without and with some picrate salts as inhibitors. The inhibitors used are: Sodium, Potasium and Ammonium picrate, mono, di, tri and tetramethylammonium picrate. The compounds have a marked inhibitive effect on the corrosion of aluminium. The dependence of corrosion rate on inhibitor concentration is highly marked. The effect of substitution of hydrogen atoms in ammonium by methyl groups in alkylannnonium picrate salts on corrosion rate is investigated.