Sustainable synthesis of ZnO using tectona grandis: Effect of calcination temperature on dye degradation performance

A green synthesis approach was successfully applied to produce zinc oxide (ZnO) nanoparticles using Tectona grandis (teak) leaf extract, with hydroxyl-rich flavonoids and phenolic constituents serving as natural reducing and stabilizing agents. The study investigates the effect of calcination temperature (400°C, 500°C, and 600°C) on the structural and photocatalytic characteristics of ZnO produced from zinc nitrate tetrahydrate, utilizing a fixed extract volume of 30 mL. FTIR spectra validated the involvement of bioactive chemicals in the reduction and stabilization processes throughout production. XRD data demonstrated the emergence of a crystalline hexagonal wurtzite phase, with crystallite diameters escalating from 9.28 to 15.65 nm as the calcination temperature increased. SEM images revealed primarily spherical particles exhibiting mild aggregation. The photocatalytic efficacy was assessed via methylene blue (MB) degradation under UV illumination, revealing that ZnO calcined at 600°C demonstrated the greatest efficiency, attaining 95.0% degradation in 105 minutes. The increased crystallinity and larger particle size at elevated calcination temperatures resulted in enhanced photocatalytic activity. The findings indicate that teak leaf-mediated ZnO nanoparticles serve as efficient and eco-friendly photocatalysts for industrial wastewater treatment, following the fundamental tenets of green chemistry and sustainable approaches in nanomaterial synthesis.