Pollutants of emerging concern contaminate surface and ground water. Advanced oxidation processes treat these molecules and degrade them into smaller compounds or mineralization products. However, little information on coupled advanced oxidation techniques and on the degradation pathways of these pollutants is available to identify possible ecotoxic subproducts. In the present work, we investigate the ultrasound assisted photocatalytic degradation pathway of the herbicide Isoproturon. We worked in batch mode in a thermostatic glass reactor. We compared the activity of nanometric TiO 2 P25 with that of Kronos 1077, a micrometric TiO 2. We discuss the individual, additive and synergistic degradation action of photolysis, sonolysis, sonophotolysis, and sonophotocatalysis by varying catalyst loading and/or ultrasound power for the last three techniques. With 0.1 g L −1 catalyst, photocatalysis and sonophotopcatalysis completely degrade Isoproturon within 240 min and 60 min, respectively (> 99 % conversion). Sonophotocatalysis breaks Isoproturon down into smaller molecules than photocatalysis alone.

Advanced oxidation processes (AOPs) are technologies to degrade organic pollutants to carbon dioxide and water with an eco-friendly approach to form reactive hydroxyl radicals. Photocatalysis is an AOP whereby TiO2 is the most adopted photocatalyst. However, TiO2 features a wide (3.2 eV) and fast electron-hole recombination. When Mn is embedded in TiO2, it shifts the absorption wavelength towards the visible region of light, making it active for natural light applications. We present a systematic study of how the textural and optical properties of Mn-doped TiO2 vary with ultrasound applied during synthesis. We varied ultrasound power, pulse length, and power density (by changing the amount of solvent). Ultrasound produced mesoporous MnOx-TiO2 powders with a higher surface area (101–158 m2 g−1), pore volume (0-13–0.29 cc g−1), and smaller particle size (4–10 µm) than those obtained with a conventional sol-gel method (48–129 m2 g−1, 0.14–0.21 cc g−1, 181 µm, respectively). Surprisingly, the catalysts obtained with ultrasound had a content of brookite that was at least 28%, while the traditional sol-gel samples only had 7%. The samples synthesized with ultrasound had a wider distribution of the band-gaps, in the 1.6–1.91 eV range, while traditional ones ranged from 1.72 eV to 1.8 eV. We tested activity in the sonophotocatalytic degradation of two model pollutants (amoxicillin and acetaminophen). The catalysts synthesized with ultrasound were up to 50% more active than the traditional samples.

Highlights Highest pectin yield was at a pH 2 and an ultrasonic power density of 0.24 W ml −1 . Pectin yield from navel orange peels increases with ultrasonic power/amplitude. Acids are ideal pectin extractors as they hydrolyze protopectin from the cell wall. Pulsing ultrasound is less energy-intensive (80 kJ vs. 190 kJ) for similar yields.

Biolubricants synthesized from vegetable oils with oleic acid and 1,3-propanediol possess better cold flow properties and have a smaller environmental footprint than mineral-based lubricants. However, their synthesis is lengthy (>6 h) and requires temperatures above 120 °C. We applied ultrasound (US) to synthesize long-chain diesters (biolubricants): an ultrasonic horn delivered rated powers of 500 and 750 W at a frequency of 20 kHz to a solution of oleic acid and 1,3-propanediol. Amberlyst15-H esterified the acid to the diester biolubricant. US horns with powers of 750 and 500 W increased the reaction rate by factors of 2 and 1.2−1.5, respectively. A temperature of 100 °C is necessary to convert oleic acid to >50%. A partial factorial experimental design confirmed that temperature, US power, and initial molar ratio of reactants affect reaction rate and oleic acid conversion (p-value of <0.05). The 500 W horn is 17% less expensive than the 750 W horn.