Lignin immobilized cyclodextrin composite microspheres with multifunctionalized surface chemistry for non-competitive adsorption of co-existing endocrine disruptors in water

The coexistence of multiple endocrine disruptors (EDs) poses new challenges to conventional water treatment technologies . β-Cyclodextrin (β-CD), because of its water-soluble nature, is limited in application as an adsorbent material. In this work, lignin immobilized β-CD composite microspheres (CD-PLMs) were newly fabricated by a reverse-phase suspension method. SEM, FTIR , and XPS analysis showed that CD-PLMs had a good spherical profile and multifunctionalized surface chemistry (O/N-containing functional groups, hydrophobic benzene rings, and internal cavities). Two representative EDs (2,4-D, BPA) were selected as model pollutants to investigate the adsorption performance of CD-PLMs. CD-PLMs showed fast adsorption kinetics for the removal of 2,4-D and BPA, and the adsorption capacity according to the Langmuir model was 497.6 mg/g and 499.2 mg/g, respectively, which is much higher than previously reported activated carbon, graphene oxide, and MOF. Combining the zeta potential , kinetics, thermodynamics, FTIR, and XPS results, the adsorption mechanism was proposed. Due to the multifunctional properties of CD-PLMs, different active sites are available for different pollutants, CD-PLMs exhibited non-competitive adsorption for 2,4-D and BPA in binary systems. Moreover, the CD-PLMs had good reusability during multiple adsorption-desorption cycles. This study provides green materials for the treatment of complex water pollution and new ways to valorize biomass.