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

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).