Quaternary aryl phosphonium salts as corrosion inhibitors for iron in HCl

Cathodic and anodic Tafel extrapolation data for the corrosion inhibition of iron in deaerated 1 M HCl at 22 °C are obtained for five synthesized phosphonium salts, 4-tolyltriphenyl-phosphonium chloride (TTPPC), 4-phenoltriphenylphosphonium chloride (PTPPC), 4-anilinetriphenylphosphonium bromide (ATPPB), 4-benzyl alcoholtriphenylphosphonium chloride (BATPPC), 4-hlorophenyltriphenylphosphonium bromide (CPTPPB), and two commercially available phosphonium salts, tetraphenylphosphonium bromide (TPPB) and methyltriphenylphosphonium bromide (MTPPB). The inhibitor concentrations ranged from 1 × 10−7 to 1 × 10−3 M. The inhibition of iron corrosion in 1 M HCl at 22 °C was found to be in the order TPPB > BATPPC > CPTPPB > PTPPC > MTPPB > TTPPC > ATPPB.