Synthesis of Modified Polyaspartic Acid Scale Inhibitor and Its Scale Inhibition Performance

Abstract

In order to expand the application range of green scale inhibitor polyaspartic acid (PASP)， a new green modified polyaspartic acid scale inhibitor (MPASP) was prepared using polysuccinimide (PSI) as the raw material and methionine (Met) as the modification reagent.The microstructure of the prepared MPASP was analyzed by infrared spectrum and hydrogen nuclear magnetic spectrum. The thermal stability of the MPASP was analyzed by thermogravimetric analysis. The scale inhibition performance of MPASP on CaCO3 and CaSO4 scale was explored by static scale inhibition method. And the crystal morphology of CaCO3 and CaSO4 scale samples inhibited by MPASP was characterized by scanning electron microscope and infrared spectrum. Results showed that the optimum conditions for the synthesis of MPASP were as follows:the reactant ratio m(PSI): m(Met) ＝ 1.00: 0.10， the pH value of reaction solution was 10， and the reaction temperature and time were respectively 70 ℃and 2 h. When the dosage of MPASP was 8 mg/L，the scale inhibition rates on CaCO3 and CaSO4 were 94.40%and 95.49%respectively. In addition， the scale inhibition effect of MPASP on CaCO3 and CaSO4 scales was better than that of PASP. Generally， the addition of MPASP caused significant change in the crystal structure of CaCO3 and CaSO4 calcium scales in the solution， and the crystallization of calcium scale became loose and fine，which interfered with the formation process of dense calcium scale and achieved good scale inhibition effect.

Keywords

• modified polyaspartic acid|green scale inhibitor|scale inhibition efficiency|scale inhibition mechanism