Efficient photocatalytic removal of Cr6+ by steel slag loaded cellulose nanofiber aerogel

Abstract

Hexavalent chromium (Cr⁶⁺), a notorious toxicant and carcinogen in industrial wastewater, poses severe health hazards. Traditional photocatalytic materials, effective primarily with ultraviolet light, have limited practical application due to their inefficiency under visible light. This study presents an innovative composite, polyethyleneimine-modified nanocellulose aerogel loaded with steel slag (SS/PCNFA), which demonstrates superior Cr⁶⁺ reduction under visible light. Our experiments reveal that SS/PCNFA achieves an impressive Cr⁶⁺ removal efficiency of 96.4 % within a mere 40 min, with the potential for complete removal within 45 min, starting from an initial concentration of 100 mg/L. Kinetic analysis confirms that the adsorption process adheres to a second-order model with an R² value of 0.9985, indicating a high degree of fit. Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses affirm the presence of nitrogen and hydroxyl functional groups that actively participate in the reduction process. Thermodynamic analysis indicates that the adsorption process is endothermic, with excellent fitting to both Langmuir and Freundlich isotherms, suggesting a combination of monolayer and multilayer adsorption mechanisms. Under optimal conditions, SS/PCNFA has proven to be exceptionally effective in reducing Cr⁶⁺ levels, showcasing its promising potential for the remediation of industrial wastewater.