Chinese Journal of Applied Chemistry ›› 2019, Vol. 36 ›› Issue (11): 1308-1316.DOI: 10.11944/j.issn.1000-0518.2019.11.190089

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Inhibition of Scale by Environmentally Friendly Scale Inhibitor and the Interaction Simulation

ZHENG Dandan,ZHANG Ying()   

  1. School of Chemical Engineering and Technology,Hebei University of Technology,Tianjin 300130,China
  • Received:2019-04-02 Accepted:2019-06-25 Online:2019-11-01 Published:2019-11-05
  • Contact: ZHANG Ying

Abstract:

In order to solve the problem that polyaspartic acid (PASP) has poor scale inhibition effect at high Ca2+ concentration and poor effect of dispersing iron oxide, tyrosine (Tyr) was grafted to the side chain of PASP by ring-opening modification of the intermediate polysuccinimide (PSI). An environmentally friendly scale inhibitor of tyrosine-polyaspartic acid copolymer (Tyr-PASP) was synthesized and possessed a plurality of functional groups such as carboxyl group, amino group, amide group and phenolic hydroxyl group. The static scale inhibition experiment proved that Tyr-PASP possessed a better scale inhibition ability than PASP. When the molar ratio of n(Tyr):n(PSI)=1:1, Tyr-PASP showed the best scale inhibition effect against CaCO3, and the inhibition efficiency reached up to 100% with a mass concentration of 4 mg/L. At 5 mg/L, the inhibition efficiency against CaSO4 also achieved 100%. After the addition of Tyr-PASP, the crystal form of scale changed from stable calcite and aragonite to unstable vaterite, and the morphology became loose. Molecular dynamics simulations show that the binding between Tyr/PASP and calcite is exothermic and the binding energy is much higher than that of conventional adsorption energy. Electrostatic forces play a major role in the binding between Tyr-PASP and calcite. In addition, the dispersion effect of Tyr-PASP on iron oxide is also significantly improved.

Key words: tyrosine-polyaspartic acid copolymer, scale inhibition, crystal form, dispersion, molecular dynamics simulation