Utilization of torrefied date stones with synthesized TiO2 nanoparticles for promoting humidity sensing of PVA/PVP nanocomposites for smart food packaging and biomedical applications

Fabricating smart and active packaging films with affordable cost has become the first demand for serving to market needs, particularly after COVID-19 disaster, for ensuring food security. Therefore, the broader goal of this work was to improve intelligent and active packaging films having humidity-sensing and antibacterial properties for biodegradable poly vinyl alcohol (PVA)/Polyvinylidene (PVP) reinforced with torrefied date stones (DS) and lethal amounts of TiO2 nanoparticles by a solvent-casting approach. Various concentrations of TiO2 NPs (i.e. 0.05, 0.15, and 0.30 %) in presence of 10 % torrefied DS (biochar) as a fixed content were used to fabricate PVA/PVP nanocomposite films. FT-IR spectra were utilized to monitor the DS functional groups before and after torrefaction at 270 degrees C. The crystal structure of synthesized TiO2 NPs as well as its impact on the PVA/PVP nanocomposites were verified by X-ray diffraction (XRD). The XRD micrographs and FT-IR spectra-based biofilms showcased that the degree of crystallinity and dispersibility of filler in the blend matrix were promoted, when the nanoparticles added. This was evidenced by SEM images. Mechanical testing also manifested that a great improvement in the tensile properties were noticed, especially at 0.30 % NPs and found the tensile strength reached similar to 33 MPa compared to PVA/PVP blank (similar to 23.70 MPa) or PVA/PVP-BC (similar to 18.20 MPa). The humidity sensing properties were performed over a wide span of relative humidity from (11-97 % RH) and frequency (50 Hz-10 kHz). The data manifested that 100 Hz was the optimum testing frequency. Moreover, the gotten findings from humidity-sensing tests at 100 Hz exhibited that the sensor containing 0.15 % TiO2 NPs had higher sensitivity and could be considered as a nano-sensor for smart food packaging. Furthermore, the impact of TiO2 NPs on antibacterial activity was investigated to probably use these films in active packaging with prolonged shelf-life of food products and other promising applications including biological area.