Synergistic corrosion inhibition of carbon steel in cooling tower systems using sodium benzoate, zinc sulfate, and EDTA

The corrosion protection of cooling tower system is important due to the different types of salts and their concentrations increase continuously. The effectiveness of selected corrosion inhibitors—100 ppm sodium benzoate (C₆H₅COONa), 60 ppm zinc sulfate (ZnSO₄), and ethylenediaminetetraacetic acid (EDTA) at 10 and 20 ppm was investigated for carbon steel (CS) in saline environments with varying salt concentrations (1000, 3000, and 5000 ppm) and temperatures (28, 33, and 38 °C). Potentiodynamic polarization techniques were employed to assess corrosion potential (Ecorr), corrosion current density (Icorr), and Tafel slopes (βa and βc). The results demonstrated a significant reduction in corrosion rates with the addition of inhibitors. The highest inhibition efficiency, exceeding 96%, was achieved with 20 ppm EDTA at 33 °C in all salt concentrations. The synergistic effect of used inhibitors in mitigating corrosion was indicated. A notable synergistic effect among the inhibitors was also observed, further enhancing corrosion resistance.