Green synthesis of a magnetic β-cyclodextrin polymer for rapid removal of organic micro-pollutants and heavy metals from dyeing wastewater

Abstract

Adsorption is one of the most preferred techniques in the advanced treatment of dyeing wastewater. Magnetic porous materials with good adsorption performance, excellent reusability, and a green synthesis route are highly desirable adsorbents in commerce. In this study, we synthesized a magnetic β-cyclodextrin polymer (MNP-CM-CDP) containing many macro- and ultramicropores in aqueous phase. CO₂ adsorption-desorption isotherms and a dye adsorption method provided Langmuir specific surface areas for the MNP-CM-CDP of 114.4 m² g^-1 and 153 m² g^-1, respectively. Model pollutants (BPA, MB, BO₂, RhB, Cr(III), Pb(II), Zn(II), and Cu(II)) were rapidly and efficiently removed from the aqueous solution by the MNP-CM-CDP. In addition, the polymer could be easily separated from the solution under an external magnetic field. The adsorption of the contaminants was dependent on pH, while the effects of ionic strength and humic acid were slight in the concentration range studied. The polymer could be easily regenerated at room temperature and retained good adsorption performance. Moreover, the MNP-CM-CDP showed good feasibility for the removal of pollutants from actual dyeing wastewater samples.

Keywords: Advanced treatment; Dyeing wastewater; Porous polymer; Rapid adsorption; Regeneration; β-cyclodextrin.