Cai Yong-Hong, Zhao Jia-Li, Guo Xin-Yu, Zhang Xiao-Juan, Zhang Ran-Ran, Ma Shao-Rong, Cheng Ya-Min, Cao Zhong-Yan, Xu Ying
College of Chemistry and Chemical Engineering, Henan University Kaifeng 475004 China
Engineering Research Center for Water Environment and Health of Henan, Zhengzhou University of Industrial Technology Zhengzhou 451150 China.
RSC Adv. 2022 Aug 30;12(38):24596-24606. doi: 10.1039/d2ra04075a.
Polyaspartic acid (PASP), a well-known green scale inhibitor for industrial water treatment, might be decomposed with prolonged duration, and its anti-scaling performance against CaCO and CaSO is diminished at a low concentration (<10 mg L) and a high temperature. With semi-ethylenediaminetetraacetic acid (EDTA) tetrasodium salt as the mimicking model, novel phosphorus-free PASP-capped 2-aminoethylamino acid (PASP-EDA) containing side chains bearing multi-functional groups is rationally designed and successfully prepared the ring-opening reaction of cheap poly(succinimide) under mild reaction conditions with the assistance of readily available 2-aminoethyl amino acid. The static scale inhibition method is used to evaluate the scale inhibition performance of the as-synthesized PASP derivative. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy are utilized to monitor the crystallization process of calcium carbonate and calcium sulfate scales, and density functional theory calculations are conducted to shed light on the relationship between the molecular structure and scale inhibition mechanism of PASP-EDA. Results show that the as-prepared PASP-EDA shows better scale inhibition performance for CaCO and CaSO than PASP with a low concentration, a high temperature, and an extended duration. Particularly, PASP-EDA with a concentration of 10 mg L exhibits the best scale inhibition performance for CaCO; its scale inhibition capacity is about two times as much as that of PASP. The reason lies in that the coordination atoms in the molecular structure of PASP-EDA can chelate with Ca to inhibit the combination of Ca with anions and prevent the generation of CaCO and CaSO scales. The PASP-EDA derivative can more efficiently retard the formation and growth of CaCO and CaSO crystal nuclei and exerts better inhibition performance against CaCO and CaSO scales than PASP.
聚天冬氨酸（PASP）是工业水处理中一种著名的绿色阻垢剂，长时间可能会分解，且在低浓度（<10 mg/L）和高温下，其对碳酸钙（CaCO₃）和硫酸钙（CaSO₄）的阻垢性能会降低。以半乙二胺四乙酸（EDTA）四钠盐为模拟模型，在廉价的聚琥珀酰亚胺的开环反应中，借助易得的2-氨基乙氨基酸，在温和反应条件下合理设计并成功制备了含多官能团侧链的新型无磷PASP封端的2-氨基乙氨基酸（PASP-EDA）。采用静态阻垢法评估合成的PASP衍生物的阻垢性能。利用扫描电子显微镜、X射线衍射和X射线光电子能谱监测碳酸钙和硫酸钙垢的结晶过程，并进行密度泛函理论计算以阐明PASP-EDA的分子结构与阻垢机理之间的关系。结果表明，所制备的PASP-EDA在低浓度、高温和长时间条件下对碳酸钙和硫酸钙的阻垢性能优于PASP。特别是，浓度为10 mg/L的PASP-EDA对碳酸钙表现出最佳的阻垢性能；其阻垢能力约为PASP的两倍。原因在于PASP-EDA分子结构中的配位原子可以与钙离子螯合，抑制钙离子与阴离子的结合，防止碳酸钙和硫酸钙垢的产生。PASP-EDA衍生物能更有效地延缓碳酸钙和硫酸钙晶核的形成和生长，对碳酸钙和硫酸钙垢的抑制性能优于PASP。
