Bioinspired honeycomb-like 3D architectures self-assembled from chitosan as dual-functional membrane for effective adsorption and detection of copper ion

Metal ions released through industrial and human activities are difficult to degrade in the environment, and copper (II) ingestion and accumulation in the body would cause harm to human health and even disease. The environmentally friendly materials for simultaneous detection and removal of toxic ions are urgently required to be developed. Herein, carbon dots (CDs) with excellent optical properties as crosslinking agent introduced into chitosan-based membranes with freeze casting technique. The as-synthesized fluorescent membranes (CS-CDs) could generate fluorescent response to copper (II) with adsorption capacity (12.48-49.97 mg/g). Based on the stable fluorescence signal of CS-CDs and fluorescence quenching with copper (II), a simple fluorescence spec-trometry method for detection of copper (II) was established. The fluorescence intensity of CS-CD-4 decreased linearly with copper (II) concentrations ranging from 0 to 350 mu mol/L. Moreover, the 3D regular honeycomb-like porous structure of CS-CDs facilitated the mass transfer and provided more effective sorption sites. The adsorption isotherm and kinetics were more suitable for the Langmuir model (R = 0.9927) and pseudo-second-order model (R = 0.9989), which indicated the adsorption were monolayer adsorption and chemisorption, respectively. As a result, the CS-CDs with dual-functionalities of detecting and adsorbing copper (II) were suc-cessfully fabricated, demonstrating the potential application prospect in environmental protection.

Automated summary

Metal ions released from industrial and human activities pose a threat to the environment and human health. A novel approach utilizing carbon dots as crosslinking agent in chitosan-based membranes was developed, showing potential for environmental protection with dual functionalities in detecting and adsorbing copper (II).