Efficient photocatalytic degradation of ultra-high concentration printing and dyeing wastewater using a SiO2/GCN nanocomposite

Abstract

In this study, we aimed to develop an efficient photocatalyst utilizing a nanocomposite of silicon dioxide (SiO₂) and graphitic carbon nitride (GCN) for the treatment of highly concentrated printing and dyeing wastewater. The nanocomposite of SiO₂ and graphitic carbon nitride (GCN) was synthesized using a simple ultrasonic and solvothermal method. The SiO₂/GCN nanocomposite demonstrated superior photocatalytic performance, efficiently degrading rhodamine B (RhB) at both low (20 mg L⁻¹) and ultra-high concentrations (300 mg L⁻¹). The catalyst exhibited effective charge separation, with SiO₂ acting as an electron trap to suppress electron–hole recombination. Optimized synthesis conditions were achieved by adjusting the hydrothermal temperature and time. The SiO₂/GCN nanocomposite showed good cycling stability, making it suitable for practical applications. To the best of our knowledge, this is the first time that photodegradation of RhB at a concentration of 300 mg L⁻¹ has been achieved without relying on adsorbent materials. Therefore, this work contributes to the design and development of innovative environmentally-friendly photocatalysts for the effective degradation of highly concentrated pollutants.