Evaluation of the structural factors for the flocculation performance of a co-graft cationic starch-based flocculant. (February 2020)

• Record Type: Journal Article
• Authors: Hu, Pan; Xi, Zhonghua; Li, Yan; Li, Aimin; Yang, Hu
• Is Part Of: Chemosphere. Volume 240(2020)
• Publication Date: 2020-02
• Subjects: Graft cationic starch-based flocculant -- Charge density -- Graft-chain length -- Graft-chain distribution -- Modeling of structural factor -- Structure–activity relationship; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.124866
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Three series of co-graft cationic starch (St)-based flocculants with distinct structural characteristics, namely, charge density (CD), graft-chain length (L), and graft-chain distribution (N), were successfully synthesized through graft copolymerization of [(2-methacryloyloxyethyl) trimethyl ammonium chloride] and acrylamide. These St-based flocculants with different molecular structures were used to flocculate various kaolin suspensions with different initial turbidities and a sodium humate (NaHA) aqueous solution. The experimental results indicated that CD contributed to flocculation evidently, whereas average L and its N were insignificant in experimentally measured ranges. On the basis of phenomenological theory, a second-order polynomial equation was used to further quantitatively analyze the effects of the three structural factors on the flocculation performance of these St-based flocculants, which were fully consistent with the experimental results. Besides, the optimal dose and its corresponding removal rate could be predicted exactly, and the flocculation mechanisms were discussed in detail according to the established models. With the combination of floc properties and zeta potentials, the flocculation mechanisms of these St-based flocculants for flocculation of kaolin suspensions and NaHA aqueous solution were mainly ascribed to charge patching and simple charge neutralization, respectively. These results improve the understanding of the structure–activity relationship of these graft St-based flocculants, which is of significant guidance for the utilization and design of novel flocculants. Graphical abstract: Image 1 Highlights: Three series of starch-based flocculants with various molecular structure was prepared. Charge density contributed evidently to flocculation. Average graft-chain length and its distributions contributed insignificantly. The structure–activity relationship was established using a quantitative equation. Flocculation mechanisms were thus discussed deeply based on the established model.