Corrosion inhibition of low-carbon steel in the medium of ammonium sulfate, a liquid mineral fertilizer

• G.E. Gornostaeva, G.V. Redkina and Yu.I. Kuznetsov

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation

Abstract: An effective corrosion inhibitor of St3 mild steel in a liquid mineral fertilizer (LMF), namely in (NH₄)₂SO₄ solutions, based on a mixture of amino alcohols and organic acids was developed (brand name GSMCh). The results of electrochemical tests showed that GSMCh is a mixed type corrosion inhibitor with predominant suppression of the anodic process. Optimal concentrations of the mixed inhibitor in 10 and 40% (NH₄)₂SO₄ solutions were selected to provide effective protection of mild steel in three zones: in the liquid bulk, along the waterline, and in the vapor-gas phase both at room temperature (20°C) and at an elevated temperature (50°C). It was shown that the efficiency of GSMCh in the (NH₄)₂SO₄ solutions studied can be increased and/or its protective concentration can be decreased by alkalization with potassium hydroxide. The formulation consisting of 0.25% GSMCh and 0.5% KOH completely suppresses the corrosion of St3 steel for a long time in all the three zones studied, both at room temperature and at the elevated temperature (50°C).

Keywords: mild steel, corrosion, liquid mineral fertilizers, ammonium sulfate, corrosion inhibitors

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1964-1978
doi: 10.17675/2305-6894-2023-12-4-28

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