Synthesis of biodegradable polyelectrolytes for the inhibition of both CaSO₄ scales and the corrosion of carbon steel

This study presents the synthesis and characterization of two polyelectrolytes derived from itaconic acid and vinyl sulfonic acid sodium salt. These polyelectrolytes were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The biodegradability of the synthesized polyelectrolytes was assessed according to the ISO-10707 method. It was found that the biodegradation was higher than 30% for both polyelectrolytes, indicating that these compounds are moderately biodegradable. The aim of this work is to study the effect of the synthesized polyelectrolytes on the formation of CaSO₄-scales and the corrosion of AISI─1810 carbon steel. Static precipitation experiments were carried out to investigate the effect of the polyelectrolytes on the precipitation of CaSO₄-scale. The results showed that both polyelectrolytes are effective scale inhibitors under static conditions, with high efficiencies (> 80%) at low concentrations. The polyelectrolyte influence on the corrosion of AISI carbon steel was examined by open circuit potential (OCP), linear polarization resistance (LRP) and potentiodynamic polarization studies. The results showed that the polyelectrolytes provided corrosion inhibition efficiencies ranging from 60 to 90%. Compatibility experiments were carried out to investigate the stability of the synthesized polyelectrolytes in the corrosive media and to observe the influence of these compounds on the inhibition of CaSO₄-scale. The polyelectrolytes were shown to be compatible with the corrosive solution. Furthermore, the results demonstrated that an increase in polyelectrolyte concentration led to enhanced scale inhibition.