Ultrasonic irradiation of cellulose at a high frequency induces its selective depolymerization to glucose at room temperature and atmospheric pressure within only a few minutes.

We investigated the impact of ultrasound at 20 kHz on olive leaves to understand how acoustic cavitation could increase polyphenol extraction. Application of ultrasound to whole leaf from 5 to 60 min enabled us to increase extraction from 6.96 to 48.75 µg eq. oleuropein/mL of extract. These results were correlated with Environmental Scanning Electron Microscopy, allowing for leaf surface observation and optical microscopy of treated leaf cross sections to understand histochemical modifications. Our observations suggest that the effectiveness of ultrasound applied to extraction is highly dependent on plant structure and on how this material will react when subjected to acoustic cavitation. Ultrasound seems to impact the leaves by two mechanisms: cuticle erosion, and fragmentation of olive leaf surface protrusions (hairs), which are both polyphenol-rich structures.

The simultaneous coupling of low frequency ultrasound and hydrothermal conditions has proved to be an innovative alternative for zeolite synthesis. Fully crystalline zeolite A was obtained with a 9.6-fold kinetic gain compared to silent conditions.

In this work, we provide new insights into the design of Ti@TiO₂photocatalyst with enhanced photothermal activity in the process of glycerol reforming. Ti@TiO₂nanoparticles have been obtained by sonohydrothermal treatment of titanium metal nanoparticles in pure water. Variation of sonohydrothermal temperature allows controlling nanocrystalline TiO₂shell on Ti⁰surface. At 100 < T < 150°C formation of TiO₂NPs occurs mostly by crystallization of Ti(IV) amorphous species and oxidation of titanium suboxide Ti₃O presented at the surface of Ti⁰nanoparticles. At T > 150°C, TiO₂is also formed by oxidation of Ti⁰with overheated water. Kinetic study highlights the importance of TiO₂nanocrystalline shell for H₂generation. Electrochemical impedance spectroscopy points out more efficient electron transfer for Ti@TiO₂nanoparticles in correlation with photocatalytic data. The apparent activation energy, E_a= (25–31) ± 5 kJ·mol⁻¹, assumes that photothermal effect arises from diffusion of glycerol oxidation intermediates or from water dynamics at the surface of catalyst. Under the heating, photocatalytic H₂emission is observed even in pure water.