Preparation and scale inhibition mechanism of phosphorus-free carboxy-rich polymer scale inhibitors

Abstract

In this paper, itaconic acid, aconitic acid, and 4-acryloylmorpholine were selected as monomers for free radical polymerization to generate a phosphorus-free carboxy-rich polymeric scale inhibitor p(IA-ANA-ACMO). The use of FTIR, ¹H NMR and ¹³C NMR were used to characterize the structure of the synthesized polymer. The synthesis conditions were optimized using the static scale inhibition method. Phosphorus-free polycarboxylate polymer scale inhibitors with excellent scale inhibition properties against CaCO₃ and CaSO₄ were finally synthesized. In addition, the correlation between the molecular mass of the polymers and their scale inhibition performance under different initiator dosages was investigated by the GPC method. The results showed that when the monomer ratio n(IA): n(ANA): n(ACMO) = 1:1:0.5, the initiator dosage of ammonium persulfate was 7.5 %, the reaction temperature was 80 °C, and the reaction time was 2 h, the scale inhibition effect on CaCO₃ was 97.7 % and that on CaSO₄ was 98.1 % at the measured dose of 30 mg l^-1. At the same time, the dynamic scale inhibition experiment was carried out. The experiment showed that when the dosage of polymer scale inhibitor p(IA-ANA-ACMO) was 30 mg l^-1, the dynamic scale inhibition rate was 96.6 %. TGA, XRD, and SEM analyzed the thermal properties, crystal structures, and microscopic morphologies of the copolymers, and the scale inhibition mechanisms were investigated by conductivity analysis and molecular dynamics simulation.