Ultrafast photodegradation of isoxazole and isothiazolinones by UV254 and UV254/H2O2 photolysis in a microcapillary reactor

Kinetic Modeling of Advanced Oxidation Processes Using Microreactors: Challenges and Opportunities for Scale-Up

“…Intrinsic kinetic studies for the UVC/H 2 O 2 system in a photo-microreactor have been carried out by Russo et al in a series of papers published over the last five years [11,23,[51][52][53]. In this case, the reactor is substantially different from the one used for studies with immobilized solid photocatalysts.…”

“…A detailed mechanistic study with the identification, isolation, and investigation of by-products can be used for further detailed mechanistic models and better parameter estimation. Under these simplified assumptions, the kinetic model for the plug flow reactor assumption can be written as [52]:…”

“…At present, there are no models including axial dispersion in microreactors for the estimation of intrinsic kinetic constants for UVC/H 2 O 2 processes. The above-mentioned model, under PFR assumption, was used to estimate the quantum yield of photolysis and the constants k HO for several micropollutants, including benzoylecgonine [23,53], acyclovir [51], stavudine, zidovudine [11], isoxazole, and isothiazolinones [52], and was validated through the estimation of parameters for known compounds such as caffeine [23]. The papers highlighted the ultrafast experimental campaigns associated with the use of this experimental set-up, allowing for exceptionally fast degradation and minimum produced waste.…”

“…Finally, in the case of homogeneous processes, intermediates generated by UV-C/H 2 O 2 were identified for benzoylecgonine and benzisothiazolinone [52,69] using LC-MS/MS analysis and samples generated during kinetic investigation with a microcapillary photoreactor. Samples easily generated at different reaction times by using the above-mentioned experimental set-up were also used to investigate eco-toxicological effects on target aquatic organisms [11,51,53], demonstrating that toxic degradation products can persist in treated water even when the target compounds are fully degraded, and longer residence times are needed to reduce eco-toxicological responses.…”

“…Although some authors suggested the possibility of direct use of these devices for water treatment by numbering up units [25,42], this seems a fairly unrealistic and antieconomic scenario, with very few possible niche applications in the treatment of small volumes of water for specific applications. Only a limited number of papers have addressed the use of microreactors for the estimation of intrinsic parameters and mechanism identification, which can be used for the scale-up of AOPs for wastewater treatment, which, in fact, is the most promising application [9,11,12,23,[43][44][45][46][47][48][49][50][51][52][53][54]. In this sense, there is still extensive room for improvement and exploitation of this technology for the design and scale-up of such tertiary treatments.…”