Preparation of sulfonate chitosan microspheres and study on its adsorption properties for methylene blue

Abstract

Dyes bring a lot of benefits to our lives, however, as common organic pollutants, they have destructive influences on the environment. Firstly, glutaraldehyde crosslinked chitosan microspheres (GCS) are prepared via inverse-phase suspension polymerization. Then, GCS microspheres are acted as the base material, ammonium persulfate (Aps) as the initiator, sodium styrene sulfonate (SSS) as anionic functional monomer, functional microspheres (GCS-g-PSSS) are prepared by surface grafting polymerization. The amount of monomer and Aps, temperature and reaction time is respectively explored. The chemical structures and physicochemical properties of functional microspheres were characterized by FT-IR, zeta potential, scanning electron microscope and X-ray photoelectron spectroscopy. The adsorption kinetic at different temperature and initial concentration is studied and fitted. The adsorption isotherms of GCS-g-PSSS for MB are explored at different pH, temperature and salinity. The adsorption capacity of GCS-g-PSSS for MB is 820.1 mg/g at 318 K. The adsorption isotherms at different temperature are fitted by Langmuir, Freundlich, Dubinin-Radushkevich and Temkin. Thermodynamic parameters imply that adsorption is a spontaneous and endothermic process. And this adsorbent has good reusability. The adsorption ability of GCS-g-PSSS microspheres is also excellent for other cationic dyes. Thus, GCS-g-PSSS microspheres might serve as a promising adsorbent for contaminated water scavenging.

Keywords: Adsorption; Cationic dyes; Chitosan; Sodium styrene sulfonate.