New waste-derived TiO2 nanoparticles as a potential photocatalytic additive for lime based indoor finishings

Production of sustainable nanomaterials (NMs) through the valorization of heterogeneous wastes is of high importance due to escalating environmental sustainability and depletion of natural resources. Following this motive, in this paper, TiO2 nanoparticles (NPs) were green-synthesized (GS) using metal ions reducing potential of secondary metabolites from organic waste (i.e., autumn leaves). Scanning electron microscopy (SEM) and Xray diffraction (XRD) analysis revealed that GS TiO2-NPs as pure anatase for crystalline fraction, with homogenous granulometry ranging between 12 and 26 nm in size, and crystallite size as small as 3.85 (±0.02) nm are achieved. The effect of carbon-content (modifier) on the structural and surface chemistry of tested TiO2-NPs were deeply investigated through Fourier-transform infrared (FTIR) spectroscopy and thermogravimetry analysis (TG/DTG/DTA). The GS TiO2-NPs have shown photocatalytic (NO)x degradation of around 30% and 18% under UV and visible-light respectively, 10% and 70% higher than that of two commercial TiO2-NPs, P-25 and KRONOS-7404, respectively. Based on the leading performance, GS TiO2-NPs were further tested as an additive to an indoor hydraulic-lime based finishing material to augment its photocatalytic properties. Interestingly, GS TiO2-NPs were able to maintain (NO)x photodegradation (≈11%) performance even at an extremely small concentration of <2 wt%. Hence, waste-mediated production of ecofriendly GS TiO2-NPs introduced in this study will help for next-generation photocatalytic indoor finishing materials.