Benzyltrimethylammonium iodide as a corrosion inhibitor for steel in phosphoric acid produced by dihydrate wet method process

The inhibition effect of benzyltrimethylammonium iodide (BTAI) on the corrosion of cold rolled steel (CRS) in phosphoric acid produced by dihydrate wet method process (7.0 M H3PO4) solution was investigated for the first time by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) methods. The results show that BTAI is a good inhibitor, and the adsorption of BTAI obeys Langmuir adsorption isotherm. Polarization curves show that BTAI behaves as a mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. The inhibition action of BTAI is also evidenced by SEM images.

Research highlights
► Benzyltrimethylammonium iodide (BTAI) is found to be a good inhibitor for the corrosion of CRS in phosphoric acid produced by dihydrate wet method process (7.0 M H3PO4) solution.
► The corrosion inhibition is satisfactorily discussed by the thermodynamic parameters.
► The experimental methods include weight loss, potentiodynamic polarization curves, EIS and SEM.
► The inhibitive mechanism is proposed.