Homopolymers and copolymers with iminodiacetic acid chelating units for scale inhibition

Abstract

Novel homopolymer and copolymer scale inhibitors with iminodiacetic acid chelating units were synthesized for inhibiting calcium carbonate and calcium sulfate precipitation. Static scale inhibition tests of SI-1 demonstrated excellent performance, with inhibition performance of 83 % at a concentration of 30 mg/L for CaCO3 and >99 % at a concentration of 8 mg/L for CaSO4. These novel inhibitors surpassed the performance of a commercially available industrial scale inhibitor, 2-phosphonobutane-1,2,4-tricarboxylic acid. The homopolymer significantly altered CaCO3 and CaSO4 crystal structures and reduced crystal size at low concentrations. The primary mechanism of inhibition appears to be a two-fold effect: strong and specific complexation between the iminodiacetic acid chelating units and free Ca2+ ions, coupled with the adsorption of the polymers on the crystal surfaces. These promising scale inhibitors offer a potential replacement for phosphorus-containing compounds currently used in industrial applications.