Synergistic corrosion inhibition of low carbon steel in HCl and H2SO4 media by 5‐methyl‐3‐ phenylisoxazole‐4‐carboxylic acid and iodide ions.
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Taylor and Francis Online
Abstract
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The inhibition performance of 5‐methyl‐3‐phenylisoxazole‐4‐carboxylic acid (MPC) alone and in
combination with potassium iodide (KI) for low carbon steel in 1.0 M HCl and H2SO4 solutions is studied
using weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS),
linear polarization resistance (LPR), ultraviolet–visible (UV–vis) spectrophotometry, and surface
observation methods. The influence of solution temperature on the performance of MPC and MPC + KI
is also investigated. Results obtained indicate that the optimum concentration of MPC in 1.0 M HCl and
H2SO4 solutions is 500 and 50 mg/L, respectively. The maximum inhibition at the optimum
concentrations of MPC in HCl and H2SO4 solutions at 25 °C is 46 and 23%, respectively. Addition of
3 mM KI to 500 mg/L MPC in HCl solution and to 50 mg/L MPC in H2SO4 solution at 25 °C raised the
inhibition efficiency to 86 and 89%, respectively. Inhibition efficiency of MPC and MPC + KI increases
with rise in solution temperature with MPC + KI inhibition reaching 88 and 91%, respectively in HCl and
H2SO4 solutions at 60 °C. Both MPC and MPC + KI acted as a mixed‐type corrosion inhibitor according to
the PDP results. Surface examination results confirm the effectiveness of MPC + KI mixture in retarding
low carbon steel corrosion in 1.0 M HCl and H2SO4 solutions. It could be profitable utilizing MPC + KI
mixture in the formulation of corrosion inhibitor cocktail for acid cleaning operations.
Keywords
TJ Mechanical engineering and machinery, TP Chemical technology