Synthesis, scale inhibition performance evaluation and mechanism study of 3-amino-1-propane sulfonic acid modified polyaspartic acid copolymer

Abstract

A water-soluble polyaspartic acid derivative scale inhibitor (PASP-Ho) was synthesized from 3-amino-1-propanesulfonic acid (Ho) and polysuccinimide (PSI) as raw materials. The structure of PASP-Ho was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (¹H NMR). The scale inhibition performance of PASP and PASP-Ho was determined by static scale inhibition method. The results show that compared with PASP the scale inhibition performance of PASP-Ho has been greatly improved, especially at low concentrations. The scale inhibition performance of PASP-Ho reaches 100% against CaSO₄, which is 54% higher than that of PASP at the dose of 4 mg·L⁻¹; the scale inhibition performance of PASP-Ho against CaCO₃ is improved by 42% at the dose of 5 mg·L⁻¹. The crystal surface morphology and crystal structure were characterized by field emission scanning electron microscopy (SEM), X-ray diffraction techniques (XRD), and X-ray photoelectron spectroscopy (XPS), indicating that the addition of PASP-Ho enhanced the chelation and dispersion effect, destroying the surface morphology of the crystal. The scale inhibition mechanism was further deduced by conductivity measurement and density functional theory (DFT). The addition of PASP-Ho can increase the surface energy of CaSO₄ and CaCO₃ scales, reduce the nucleation rate of crystals and inhibit the formation of scales. The scale inhibition mechanism of PASP-Ho is a combination of chelation, dispersion, threshold effect and lattice distortion, but only a little lattice distortion is exhibited for CaSO₄ scale.