Adsorption of pharmaceuticals on chitosan-based magnetic composite particles with core-brush topology

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2016-11, Vol.304, p.325-334
• Main Authors: Zhang, Shaopeng, Dong, Yayi, Yang, Zhen, Yang, Weiben, Wu, Jiaqing, Dong, Chang
• Format: Article
• Language: English
• Subjects: Adsorption mechanism; Core-brush topology; Diclofenac sodium; Magnetic composite adsorbents; Pharmaceuticals; Tetracycline
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2016.06.087

[Display omitted] •Chitosan-based magnetic composite particles with core-brush topology are synthesized.•These particles have improved surface areas resulting from core-brush topology.•These particles have high adsorption efficiency in the removal of diclofenac sodium.•CD-MCP with polycationic brushes displays the highest adsorption capacities.•Charge attraction was the intrinsic driving force promoting adsorption. A series of magnetic composite adsorbents with core-brush topology were prepared through grafting co-polymerization on the surface of chitosan/Fe3O4 composite particles (CS-MCP), and then applied for the removal of two pharmaceuticals (diclofenac sodium (DCF) and tetracycline hydrochloride) from water. Adsorption performance evaluation, including adsorption capacities from single- and binary-solute solutions at different pHs, influences of coexisting salts, desorption and reusability, demonstrated CD-MCP with polycationic brushes was a cost-effective adsorbent for DCF removal: Compared to CS-MCP, all the modified MCPs exhibited higher removal efficiencies, due to the enhanced surface areas resulting from core-brush topology; Among the modified MCPs with different surface charges, CD-MCP displayed the highest adsorption capacities, attributed to the electrostatic attraction between the positively charged brushes and the anionic contaminant’s species. Adsorption mechanism was investigated from both the macroscopic (thermodynamics and kinetics) and microscopic (changes of solution pH and spectral analyses of the adsorbent after adsorption) viewpoints: Charge attraction was the intrinsic driving force; A monolayer coverage of pharmaceuticals were adsorbed onto the brushes of CD-MCP; OH− exerted competitive adsorption effect; After adsorption, the originally extended polycationic brushes turned collapsed. The current study provided a strategy for the design of adsorbents from both topological and chemical structures.