Preparation, characterization of sodium diphenylcarbodithioate as a corrosion inhibitor and for use in CPE method to trace metals determination

• R.J. Tuama and M.T. Khathi

Department of Chemistry, College of Science, University of Thi-Qar, Thi-Qar 64001, Iraq

Abstract: This study involved the synthesis of sodium diphenylcarbodithioate (SDPCDT) that is a dithiocarbamate derivative because of its great propensity to form complexes with most toxic metals, and its characterization using Fourier transform infrared spectroscopy and 1H-NMR spectrometry. The synthetic compound’s (SDPCDT) corrosion inhibitory effect on St3sp steel in 0.5 M H₂SO₄ solution was evaluated by polarization and weight loss tests. The weight loss measurements findings indicate that inhibiting corrosion efficacy of SDPCDT enhances with increasing its concentrations, which were used in this study (3×10^⁠–⁠3, 5×10^–3, 7×10^–3 and 1×10^–2 M) respectively. The corrosion inhibition attains 93.01% when St3sp steel is submerged in a 0.5 M H₂SO₄ solution containing the corrosion inhibitor (SDPCDT) for duration of 5 hours at 25°C. The results of the polarization measurement indicate that the synthesized compound (SDPCDT) functions as a mixed-type corrosion inhibitor. Surface analysis techniques reveal that the forming of a protective layer on the St3sp steel surface is the source of the inhibitor SDPCDT’s corrosion inhibition effectiveness. This protective layer reduces the corrosion rate by the adsorption on the surface of SDPCDT molecules, the rate of which is concentration dependent. Several quantum chemical parameters were computed by density functional theory of inhibitor SDPCDT, which affect the interactions of the molecule with the metal surface and the surrounding environment. These results were in agreement with the experimental results. The prepared compound (SDPCDT) was used as a reagent (complicating agent) in the separation of lead Pb(II) ions from their aqueous solutions in the cloud point extraction (CPE) method using Triton X-400 as an appropriate surfactant. This study investigated the optimal extraction conditions, including the concentration of the reagent SDPCDT, the concentration of the surfactant Triton X-400, the pH of the aqueous solution, incubation time, and temperature, to achieve the highest extraction efficiency at a concentration of 1×10^–2 M SDPCDT, 1% (v/v) Triton X-400, pH 5, an incubation time of 20 minutes, and a temperature of 50°C.

Keywords: dithiocarbamate derivative, St3sp steel, corrosion inhibitor, cloud point extraction, Pb(II) ions, Triton X-400

Int. J. Corros. Scale Inhib., 2025, 14, no. 1, 206-226
doi: 10.17675/2305-6894-2025-14-1-13

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