Coating layered double hydroxides with carbon dots for highly efficient removal of multiple dyes

Jiahui Ge; Lili Lian; Xiyue Wang; Xueling Cao; Wenxiu Gao; Dawei Lou

doi:10.1016/j.jhazmat.2021.127613

Coating layered double hydroxides with carbon dots for highly efficient removal of multiple dyes

J Hazard Mater. 2022 Feb 15;424(Pt C):127613. doi: 10.1016/j.jhazmat.2021.127613. Epub 2021 Oct 29.

Authors

Jiahui Ge¹, Lili Lian², Xiyue Wang¹, Xueling Cao¹, Wenxiu Gao¹, Dawei Lou³

Affiliations

¹ Department of Analytical Chemistry, Jilin Institute of Chemical Technology, No. 45 Chengde Street, Jilin 132022, PR China.
² Department of Analytical Chemistry, Jilin Institute of Chemical Technology, No. 45 Chengde Street, Jilin 132022, PR China. Electronic address: lililian@jlict.edu.cn.
³ Department of Analytical Chemistry, Jilin Institute of Chemical Technology, No. 45 Chengde Street, Jilin 132022, PR China. Electronic address: dwlou@hotmail.com.

PMID: 34750003
DOI: 10.1016/j.jhazmat.2021.127613

Abstract

Layered double hydroxides (LDHs) and layered double oxides (LDOs) are desirable adsorption materials for printing and wastewater treatment owing to their outstanding anion exchange abilities, abundant active sites, and eco-friendly nature. In this study, a versatile LDO hybrid coated with carbon dots (CDs@MgAl-LDO) was constructed by modifying sodium dodecylbenzene sulfonate on the surface of MgAl-LDH as a carbon precursor, followed by ligand carbonization and hydrotalcite dehydration at 450 °C under N₂ flow. CDs@MgAl-LDO displayed a hexagonal lamellar architecture with a plate lateral size of approximately 500 nm. It had a higher BET specific surface area (28.61 m²/g) than MgAl-LDO (11.48 m²/g). X-ray diffraction analysis revealed that CDs@MgAl-LDO maintained the "memory effect" of LDOs and could retrieve the original structure when dispersed in water. Moreover, the modified carbon dots change the intrinsically hydrophilic nature of LDOs and help to improve the affinity for organic contaminants, including both cationic and anionic dyes. The adsorption of dyes on CDs@MgAl-LDO followed a pseudo-second-order kinetic model with correlation coefficients (R²) ranging from 0.9901 to 0.9911 and exhibited Freundlich-type heterogeneous adsorption. It showed superior adsorption performance for three dyes, with the maximum adsorption capacity of 3628.9-5174.1 mg/g, thereby outperforming previously reported LDH-based adsorbents. This work developed a facile approach for preparing new carbon dots-LDH hybrids for the highly efficient removal of multiple dyes.

Keywords: Adsorption; Carbon dots; Dyes; Hybrids; Layered double hydroxide.