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

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.