Mechanistic Model and Optimization of the Diclofenac Degradation Kinetic for Ozonation Processes Intensification

Abstract

This work focused on estimating the rate constants for three ozone-based processes applied in the degradation of diclofenac. The ozonation (Oz) and its intensification with catalysis (COz) and photocatalysis (PCOz) were studied. Three mathematical models were evaluated with a genetic algorithm (GA) to find the optimal values for the kinetics constants. The Theil inequality coefficient (TIC) worked as a criterion to assess the models’ deviation. The diclofenac consumption followed a slow kinetic regime according to the Hatta number (Ha<0.3). However, it strongly contrasted with earlier studies. The obtained values for the volumetric rate of photon absorption (VRPA) corresponding to the PCOz process (1.75×10−6 & 6.54×10−7 Einstein L−1 min−1) were significantly distant from the maximum (2.59×10−5 Einstein L−1 min−1). The computed profiles of chemical species proved that no significant amount of hydroxyl radicals was produced in the Oz, whereas the PCOz achieved the highest production rate. According to this, titanium dioxide significantly contributed to ozone decomposition, especially at low ozone doses. Although the models’ prediction described a good agreement with the experimental data (TIC<0.3), the optimization algorithm was likely to have masked the rate constants as they had highly deviated from already reported values.

Analysis of the Applications of Particle Swarm Optimization and Genetic Algorithms on Reaction Kinetics: A Prospective Study for Advanced Oxidation Processes

“…According to Table 3, most of the research was focused on the study of kinetic parameters from photocatalytic and electrochemical oxidation processes; meanwhile, no investigation related to the UV/H 2 O 2 kinetics was found. At the same time, there were not independent studies on the reaction kinetics of pure ozonation and Fenton processes, instead, these were intensified with photocatalysis [87] and electrochemical processes, [180] respectively.…”

“…[84][85][86] In addition, if a solid catalyst is included, adsorption phenomena should be considered. [87][88][89] Furthermore, the kinetic of the gas-liquid interactions is highly dependent on the target pollutants and their concentration, thus, the kinetic regime of the ozone consumption should be characterized in terms of the Hatta number (Ha) to accurately model the ozone transport from the gas to the liquid phase. [90] Ultraviolet/Hydrogen Peroxide Processes It has been observed that the presence of UV in combination to hydrogen peroxide can promote the generation of HO * radicals by means of the Haber-Weiss mechanism.…”

“…As ozone‐based AOPs for water treatment involve at least two phases interaction (gas – liquid reactions), mathematical models need to involve the mass transfer of the ozone from the gas to the liquid phase [84–86] . In addition, if a solid catalyst is included, adsorption phenomena should be considered [87–89] . Furthermore, the kinetic of the gas‐liquid interactions is highly dependent on the target pollutants and their concentration, thus, the kinetic regime of the ozone consumption should be characterized in terms of the Hatta number (Ha) to accurately model the ozone transport from the gas to the liquid phase [90]…”

O3 decomposition to O2 on surfaces of Silicon nanocage and Carbon nanocage as effective catalysts

“…Researchers demonstrated that the metal doped nanostructures and nano-compounds are increased and improved their catalytic activity and ability for adsorption of toxic gas molecules [23]. The metal doped on surfaces of nanostructures are catalytic positions and possible sites for adsorption of toxic gas molecules [24,25].…”