Synthesis and evaluation of polyaspartic acid/furfurylamine graft copolymer as scale and corrosion inhibitor

Abstract

A novel scale and corrosion inhibitor, polyaspartic acid/furfurylamine graft copolymer (PASP/FA), was synthesized using maleic anhydride, urea, and furfurylamine (FA) as raw materials. The structure of PASP/FA was characterized by ¹H NMR. PASP/FA exhibits excellent scale inhibition performance at low concentration, and its overall performance was significantly improved as compared with polyaspartic acid. The inhibition efficiency of PASP/FA was close to 100% against CaCO₃ with 1 mg L⁻¹ inhibitor at 80 °C and reached up to 100% against CaSO₄ at 70 °C when dosage of the inhibitor was 5 mg L⁻¹. The best inhibition efficiency against Ca₃(PO₄)₂ at 80 °C was about 96% when the concentration of inhibitor was 10 mg L⁻¹. The maximum corrosion inhibition efficiency at 45 °C was as high as 30%, when 16 mg L⁻¹ of inhibitor was adopted. When the temperature was 50 °C and a pH = 9, the best dispersion capacity for Fe₂O₃ (according to 69% of transmittance) was reached when 48 mg L⁻¹ of inhibitor was applied in the tested system. The structure and morphology of CaCO₃ and CaSO₄ were observed by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD).