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 tech-nologies. beta-Cyclodextrin (beta-CD), because of its water-soluble nature, is limited in application as an adsorbent material. In this work, lignin immobilized beta-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 multi-functionalized 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.

Automated summary

In this study, lignin immobilized beta-CD composite microspheres (CD-PLMs) were successfully fabricated and showed excellent adsorption performance and reusability. CD-PLMs have a good spherical profile and multi-functionalized surface chemistry, providing a green material for the treatment of complex water pollution and a new way to valorize biomass.