The development of TiO2-biochar composite material for photodegradation of basic blue 41 and erichrome black T azo dyes from water

This study investigates the synthesis and performance of TiO2-biochar composite catalysts for removing Basic Blue 41 and Eriochrome Black T azo dyes, from aqueous solutions. Two types of composites were synthesized using the sol-gel method: one with pure anatase TiO2 and biochar, and the other combining anatase-rutile TiO2 with biochar. Biochar was incorporated at 10%, 20%, and 30% weight percentages. The materials were characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, surface area analysis, and ultraviolet-visible diffuse reflectance spectroscopy. The results showed that biochar significantly enhanced the surface area, increasing it from 38.0 m²/g for pure TiO2 to 78.0 m²/g, 118.8 m²/g, and 147.1 m²/g for composites with 10%, 20%, and 30% biochar, respectively. Biochar also influenced the bandgap energy, reducing it from 3.03 eV to 2.95 eV, 2.69 eV, and 2.82 eV for anatase TiO2 composites. For anatase-rutile composites, the bandgap decreased to 2.69 eV at 10% biochar but increased to 2.81 eV and 2.92 eV at 20% and 30% biochar, respectively. The composites exhibited high photodegradation efficiency, with anatase TiO2-biochar composites achieving 98.4% degradation for Basic Blue 41 and 97.4% for Eriochrome Black T. The degradation followed first-order kinetics, with correlation coefficients of 0.98 and 0.99, respectively. Reusability tests showed the 20% biochar composite retained 95.8% efficiency for Basic Blue 41 after five cycles, while the 10% biochar composite maintained 67.8% efficiency for Eriochrome Black T. These findings demonstrate the potential of TiO2-biochar composites as efficient, non-toxic, and sustainable materials for water treatment, offering an eco-friendly solution for organic pollutant removal. However, further research is needed to evaluate their performance under real-world conditions and long-term stability.