Corrosion of low-carbon steel in sodium chloride solution containing a water-soluble fraction of humic acid

Abstract

Humic acids are a heterogeneous mixture of organic compounds that are naturally found in water and soil. In recent years, there has been a growing interest in the application of green fertilizers containing humic acids in agricultural activities. Water-soluble fraction of humic acid (WSHA) can be released from these fertilizers and subsequently interact with metallic materials (e.g. steel) located in soils and waters. WSHA were leached from an aqueous suspension of humic acids isolated from South Moravian lignite. Corrosion tests were performed on a low-carbon steel using a potentiodynamic polarization test and electrochemical impedance spectrometry. Results suggest that corrosion was initially promoted due to the formation of complex compounds of watersoluble humic acids with released iron ions. After a long time, a positive effect of WSHA was observed as the corrosion resistance of low-carbon steel increased.

Influence of humic acid on corrosion of low carbon steel in neutral aqueous solution containing chlorides

“…The shape of the potentiodynamic curves in the anodic region indicates that HA7 influences the anodic reaction of the low carbon steel. This is consistent with the notion of the role of HA7 during corrosion as pointed out in the literature [5][6][7][8]. The deterioration of low carbon steel corrosion by HA7 can be related to the complexing reaction between the released iron ions and oxygen groups such as carboxylic groups.…”

“…Humic acid precipitation on the surface of galvanized steel formed a thick layer of deposits acting as a physical barrier between the steel component and corrosive environment. Doskočil et al performed corrosion tests of low carbon steel in 3.5% NaCl in the presence of a water-soluble fraction obtained from humic acid [8]. The authors found that there was a deterioration of corrosion process during short-term measurements, but longer-term tests suggested that there may be an improvement in corrosion resistance.…”

CORROSION BEHAVIOUR OF AZ31 ALLOY IN AN ALKALINE ENVIRONMENT OF 0.1 m nacl in the presence of lignitic humic acid

“…The study also suggested that the presence of humic acid could promote the formation of magnesium hydroxide nanoparticles on the surface of AZ31 alloy [10]. There are also studies on the effect of humic acids on the corrosion behavior of other metallic materials such as low carbon steel [11].…”