Tim Sidnell

Dr Tim Sidnell

Postgraduate Research Student
Master of Engineering Chemical Engineering
Mon-Fri, 9:30-6:00


My research project


Research interests


Tim Sidnell, Angel J. Caceres Cobos, Jake Hurst, Judy Lee, Madeleine J. Bussemaker (2023)Flow and temporal effects on the sonolytic defluorination of perfluorooctane sulfonic acid, In: Ultrasonics sonochemistry101106667
Richard James Wood, Tim Sidnell, Ian Ross, Jeff McDonough, Judy Lee, Madeleine Bussemaker (2020)Ultrasonic degradation of perfluorooctane sulfonic acid (PFOS) correlated with sonochemical and sonoluminescence characterisation, In: Ultrasonics Sonochemistry Elsevier

Sonolysis has been proposed as a promising treatment technology to remove per- and polyfluoroalkyl substances (PFASs) from contaminated water. The mechanism of degradation is generally accepted to be high temperature pyrolysis at the bubble surface with dependency upon surface reaction site availability. However, the parametric effects of the ultrasonic system on PFAS degradation are poorly understood, making upscale challenging and leading to less than optimal use of ultrasonic energy. Hence, a thorough understanding of these parametric effects could lead to improved efficiency and commercial viability. Here, reactor characterisation was performed at 44, 400, 500 and 1000 kHz using potassium iodide (KI) dosimetry, sonochemiluminescence (SCL), and sonoluminescence (SL) in water and PFOS solution. Then the degradation of PFOS (10 mg / L in 200 mL solution) was investigated at these four frequencies. At 44 kHz, no PFOS degradation was observed. At 400, 500 and 1000 kHz the amount of degradation was 96.9, 93.8 and 91.2%, respectively, over four hours and was accompanied by stoichiometric fluoride release, indicating mineralisation of the PFOS molecule. Close correlation of PFOS degradation trends with KI dosimetry and SCL intensity was observed, which suggested degradation occurred under similar conditions to these sonochemical processes. At 1000 kHz, where the overall intensity of collapse was significantly reduced (measured by SL), PFOS degradation was not similarly decreased. Discussion is presented that suggests a solvated electron degradation mechanism for PFOS may occur in ultrasonic conditions.