Synthesis of ZnO/TiO2–biochar from durian husk for efficient dye adsorption and degradation

BACKGROUND

The overuse of dyes is causing serious water pollution globally, becoming an urgent environmental problem. Consequently, studying dye wastewater treatment solutions has become a crucial research field. While durian husk biochar (BDH) is recognized for its excellent adsorption of organic molecules, studies on its combination with ZnO and TiO₂ nanoparticles (NPs) and enhancement of methylene blue (MB) degradation remain limited.

RESULTS

In this study, BDH/ZnO/TiO₂ NPs were synthesized via a hydrothermal method using ethanol and ammonia as solvents. BHD was produced through pyrolysis under oxygen-limited conditions and activated with H₃PO₄ to enhance its physicochemical properties. The resulting TiO₂ (anatase phase, 20–35 nm) and ZnO (wurtzite structure, 100–240 nm) were well dispersed on the porous biochar matrix, which exhibited increased porosity (14.761–34.143 Å) and surface area approximately 5.5 times higher than raw biochar. The photocatalytic and adsorption performance of the materials were evaluated under UV irradiation (365 nm, 100 min) using 10 ppm MB. The removal efficiency of BDH achieved 75.77%, significantly outperforming pure TiO₂ (58.52%) and ZnO (40.38%). The novel BDH/ZnO/TiO₂ nanocomposite exhibited superior capabilities, achieving 98.57% removal and maintaining over 95% efficiency after three regeneration cycles. The adsorption of MB by BDH/ZnO/TiO₂ best fits the Freundlich isotherm model, showing a maximum adsorption capacity of 52.21 mg g⁻¹.

CONCLUSION

These results highlight the dual functionality of BDH/ZnO/TiO₂ NPs in dye adsorption and photocatalytic degradation, confirming their potential in wastewater treatment. The study also emphasizes the environmental and economic benefits of valorizing agricultural waste into high-performance, sustainable materials. © 2025 Society of Chemical Industry (SCI).