A kinetic study for the Fenton and photo-Fenton paracetamol degradation in an annular photoreactor

Abstract

A kinetic model describing Fenton and photo-Fenton degradation of paracetamol (PCT) and consumption of hydrogen peroxide (HO) was proposed. A set of Fenton and photo-Fenton experiments (18 runs in total) was performed by fixing the initial concentration of PCT to 40 mg L and varying the initial concentrations of HO and ferrous ion, Fe. The experimental set-up was a well-stirred annular photoreactor equipped with an actinic BL TL-DK 36 W/10 1SL lamp. Experimental results highlighted that PCT is no more detected by HPLC analysis within a minimum reaction time of 2.5 and a maximum reaction time of 15.0 min. Besides, a maximum conversion of total organic carbon (TOC) of 68.5% was observed after 75 min of reaction in case of using UV radiation and the highest concentrations of the Fenton reagents. The experimental data were used to fit the kinetic model. The radiation field inside the reactor was taken into account through the local volumetric rate of photon absorption, evaluated by assuming a line source model with spherical and isotropic emission. The kinetic parameters were estimated by using a non-linear least-squares regression procedure and root mean square errors (RMSE) were calculated in order to validate the feasibility of the proposed model. A good agreement between experimental and predicted data was observed and the lowest values of RMSE resulted in 5.84 and 9.59% for PCT and HO normalized concentrations, respectively.

A novel modeling approach for a generalizable photo-Fenton-based degradation of organic compounds

“…It must be noticed that the model by Audino et al was fitted to the same pilot plant described in Fig. 2 and using the same experimental results described in Table 2. As can be observed, the proposed PPS model, compared with the more accurate FPM by Audino et al (2019), slightly overestimates the PCT degradation both in the photo-Fenton (Fig. 8a) and in the Fenton (Fig.…”

“…This shows the difference between experimental and predicted values by the proposed model (named PPS model in Fig. 8) and by FPM from Audino et al (2019), represented in a bar diagram. It must be noticed that the model by Audino et al was fitted to the same pilot plant described in Fig.…”

“…RMSE resulted in 30% for PCT, 7% for TOC, and 11% for H 2 O 2 , and showed the acceptable prediction of the model. In addition, a comparative study illustrating the differences between the proposed model and a FPM developed by Audino et al (2019), for two specific experiments (the Fenton experiment EXP8 and the photo-Fenton experiment EXP18 in Table 2), is shown in Fig. 8a and b, respectively.…”

“…However, the proposed PPS model produces differences below 1% in the photo-Fenton case and below 5% in the Fenton case, for a short time interval (2-5 min), and correctly describes the early removal of PCT. In addition, [Fe 2+ ] 0 = 0.09 mmol L −1 ; [H 2 O 2 ] 0 = 5.56 mmol L −1 under dark (empty symbols and dashed lines, a, c, e) and irradiated (solid symbols and lines, b, d, f) conditions the proposed PPS model is also able to model TOC for the whole treatment span, which is not available in the FPM by Audino et al (2019). The TOC modeling represents a very significant advantage of the proposed methodology since, as already underlined, it allows describing the overall quality of wastewater which can be composed of many targets.…”

“…On the other hand, Alfano et al (1986) implemented a modeling approach based on rigorous radiation models to compute the spatial distribution of the absorbed photons inside the reactor and on simplified kinetic reaction schemes. Following this line, a recent work by Audino et al (2019) has proposed a kinetic study describing Fenton and photo-Fenton degradation of paracetamol in an annular photo-reactor, including the local volumetric rate of photon absorption effect. The work by Soriano-Molina et al (2018) proposed a mechanistic model of solar photo-Fenton.…”