Evaluation of a polymaleic-based scale inhibitor (HPMA-AEO-9) against calcium carbonate scale

• Published in: Desalination and water treatment 2019-03, Vol.145, p.120-133
• Main Authors: Zhu, Chen-Guo, Zhao, Wei-Dong, Liu, Hong-Bin, Che, Yao, Wang, Liang-Bi, Zhang, Qiao-Ling, Wang, Liang-Chen
• Format: Article
• Language: English
• Subjects: Antiscalant; Calcium carbonate scale; Circulation cooling water; Fatty alcohol polyoxyethylene ether (AEO); Maleic acid
• ISSN: 1944-3986
• DOI: 10.5004/dwt.2019.23674

Hydrolyzed polymaleic anhydride (HPMA) is widely used as a scale inhibitor, but it is easy to form insoluble gel with alkaline earth ions. To overcome this shortcoming, a fatty alcohol ethoxylate (AEO- 9) is introduced into HPMA to obtain a maleic acid-based copolymer HPMA-AEO-9. HPMA-AEO-9 is characterized by FT-IR, 1H NMR and GPC. The effects of HPMA-AEO-9 on CaCO3 scale are studied in several aspects (such as dose, Ca2+ concentration, temperature, inhibition time, pH, and the relative supersaturation of CaCO3 solution) by static experiments. The effect of HPMA-AEO-9 on the scaling process is studied under dynamic conditions. The impact of HPMA-AEO-9 on morphologies of CaCO3 is investigated using SEM and XRD. The results show that the presence of AEO-9 group can significantly improve the resistance of HPMA-AEO-9 to high alkalinity, high hardness and high temperature. Compared with additive of HPMA, the presence of HPMA-AEO-9 can obviously inhibit the nucleation rate at the induction region, accelerate the growth of nuclei at the rapid growth region, and reduce the scaling rate at the stable growth region; HPMA-AEO-9 changes calcium carbonate crystal from stable calcite to unstable aragonite and vaterite. HPMA-AEO-9 is a threshold inhibitor with excellent performance in inhibiting CaCO3 scale.