Testing the formation of Ca–phosphonate precipitates and evaluating the anionic polymers as Ca–phosphonate precipitates and CaCO3 scale inhibitor in simulated cooling water

The inhibition performance of different phosphonates as CaCO3 scale inhibitors in simulated cooling water was evaluated. Based on experimental data, various phosphonates form weakly soluble Ca–phosphonate precipitates, with the order of the phosphonates in terms of Ca2+ tolerance being BHMTPMP > PAPEMP > HDTMP ≫ PBTCA > DTPMP > EDTMP > ATMP > HEDP. Homo-, co-, and ter-polymers were also investigated for their performance as Ca–phosphonate inhibitors, the order of inhibit Ca–phosphonate precipitation: terpolymer > copolymer > homopolymer. Addition of polymers as inhibitors with phosphonates could reduce Ca–phosphonate precipitation and enhance the inhibition efficiency for CaCO3 scale. Moreover, polymer composition and concentration are critical to the inhibitory performance.

Research highlights
► Investigate the Ca–phosphonate of phosphonate inhibitors in simulated cooling water.
► Ca–phosphonates precipitations decrease the inhibition performance of phosphonate inhibitors.
► Investigate the anionic polymers performance for inhibiting Ca-precipitation and CaCO3 scale.
► Molecular structure and concentration of the polymer are critical to inhibitory performance.