Efficiency of the H2O2 consumption by the mineralization of hydrochlorothiazide via photo-Fenton UVA: a time dependent analysis

In the photochemical conversion of hydrogen peroxide (H 2 O 2 ) into radical ·OH, the rule of radiation dose (the quantum yield) on the oxidation kinetics is well known. In contrast, the H 2 O 2 dose mostly remains an attempt-and-error variable. Here, we propose a method to estimate the efficiency of H 2 O 2 dose consumption by the mineralization micro-kinetics that enables a generalist strategy for a more cost-effective dose of the oxidant. It needs the time-dependent H 2 O 2 , micropollutant, and product (CO 2 ) measure. Photo-Fenton (FP) hydrochlorothiazide (HCT) oxidation using a tubular photo-reactor and UVA radiation assisted in demonstrating the method. The average value of ~ 38% was on top of the best efficiencies associated with some of the fastest mineralization rates. Such efficiencies depend on the stochiometric concentration of the oxidant. Here, the variable stoichiometric H 2 O 2 excess for mineralization is proposed as a universal metric to quantify the (under-) over-dose of H 2 O 2 . Overall, H 2 O 2 excess between 2 and 5 leads to H 2 O 2 consumption efficiencies above 30%, together with a fast rate of CO 2 formation (mineralization). In contrast, any value below one invariably leads to a sluggish oxidation rate, leading even to the total depletion of the oxidant. Besides proposing a selection criterion for the most cost-effective H 2 O 2 -dose and providing some examples, this work carefully analyzes the commitment of the H 2 O 2 excess concerning the energy costs (EEO).