Polysaccharide- and phenolic-rich Pinus patula extract-mediated TiO₂ nanoparticles for photocatalytic degradation of methylene blue and 4-nitrophenol.

Conventional TiO₂ nanoparticle syntheses rely on high temperatures, toxic reagents and multi-step routes that impede scalability and sustainability. Here, we deliver the first green synthesis of TiO₂ nanoparticles (TiO₂ NPs) using polysaccharide- (42 mg GE g) and phenolic-rich (78 mg GAE g) Pinus patula leaf extract. GC-MS and LC-MS fingerprinting identify terpenoids, flavonoids and phenolic glycosides acting as simultaneous reducing, capping and stabilizing agents. X-ray diffraction reveals ultra-small anatase crystallites (2.27 nm), while FTIR, FESEM and HRTEM confirm biomolecule coordination and well-dispersed spherical particles averaging 15 nm. The NPs possess a high BET surface area (149.3 m/g) and a blue-shifted bandgap (3.82 eV), indicative of quantum confinement. Photocatalytic tests show 96.9 % methylene blue removal in 120 min under UV light, following pseudo-first-order kinetics (k = 0.0164 min), and rapid 98.2 % conversion of 4-nitrophenol to 4-aminophenol within 10 min (k = 0.312 min). Post-reaction GC-MS confirms complete mineralization of methylene blue. TGA-DSC indicates a ~ 3 wt% phytochemical sheath that decomposes cleanly at 325 °C, validating surface-bound macromolecules and reconciling bulk-surface composition. These data demonstrate that biomacromolecule-engineered TiO₂ NPs unite record-low crystallite size, robust phytochemical interfaces, and superior photocatalytic activity, positioning them as sustainable nanocatalysts for wastewater remediation.