Performance of a pilot-scale BDD reactor by numerical analysis of reaction rate parameters and additional numbers for mass transfers.

The performance of a pilot-scale boron-doped diamond (BDD) reactor through a numerical analysis of reaction rate parameters and enhanced mass transfer has been investigated. The main objective of this research is to evaluate the efficiency of the reactor in mineralizing and degrading caffeine as an emerging contaminant. Based on the kinetic mechanisms and mass transport correlations reported in the literature, two reaction rate kinetic models for caffeine degradation are proposed and analyzed. The models consider different electrolytes (NaCl and Na2SO4) and applied current densities. The kinetic fitting process utilizes the gradient-maximal electrochemical approach, together with orthogonal placement methods, fourth-order Runge-Kutta (RK4) methods, and Nelder & Mead methods for optimization of kinetic parameters and spatial discretization of the material balance. Experimental data obtained from a factorial design with four factors and two levels (24) validate the proposed kinetic models. Caffeine degradation is achieved with NaCl and Na2SO4 electrolytes at concentrations of 60 ppm and 100 ppm, respectively. The corresponding applied loads are 1.5 AhL-1 and 3 AhL-1. Na2SO4 exhibits superior performance with a total organic carbon (TOC) removal efficiency of 99.13%, while NaCl achieves 31.47% mineralization. The behavior of caffeine degradation under the operational and scale conditions demonstrates that NaCl, as a support electrolyte, enables controlled charge transfer (current density) during the degradation process. In contrast, Na2SO4 as a support electrolyte introduces a mixed control of charge and mass transfer. The pilot-scale kinetic parameters obtained in this study provide valuable insights into the support electrolyte dynamics and current density dynamics in BDD-based Electrooxidation (EO) systems, particularly in complex matrix applications. Furthermore, the observed electrical consumption supports the potential application of EO as a viable technology for industrial-scale tertiary wastewater treatment, specifically for caffeine removal.

A novel high rotation bubble reactor for the treatment of a model pollutant in ozone/goethite/H2O2 and UV/goethite coupled processes.

This work proposes a novel approach for the coupling of ozonation and Fenton processes using a new prototype of a high rotation bubble reactor (HRBR), which improves utilization of the ozone and hydrogen peroxide through bubble generation and axial and radial dispersion of the flow. The HRBR integrates the rotor and the diffuser in the same device facilitating the generation and dispersion of the ozone bubbles inside the reaction tank. Thus, the mass transfer to the liquid phase is enhanced. Most of the experiments were carried out under neutral pH and 1580 rpm of agitation during the 20 min of reaction. Total ibuprofen degradation was achieved within 20 min of operation for most of the couplings and individual processes evaluated. It was successfully demonstrated that the HRBR can be used as a reactive system for heterogeneous Fenton and ozonation coupling because it presents a high synergy. For the ozonation process, the reactor also displayed a good performance because the residual ozone in the gas is lower than 0.4 mg/L, which indicates that there is a suitable ozone utilization. Ibuprofen degradation by other processes like oxidation direct by H2O2 and heterogeneous Fenton was 28.0% and 73.1%, respectively. It was determined that the reaction rate, synergy, OUI (ozone utilized index), and consumption of electrical energy (EE/O) of the coupled processes could be improved by using the HRBR depending on the experimental conditions.

Experimental data on synthesis and characterization of WO3/TiO2 as catalyst.

WO3/TiO2 is a composite photocatalyst that is being widely used in heterogeneous photocatalysis because it presents better photocatalytic properties than TiO2. For example, the probability of recombination of the electron/hole pairs is diminished and a more range of the solar spectrum is used for its excitation. However, this depend of variables such as tungsten oxide concentration, calcination temperature and synthesis method. This work is focused in establish the effect of WO3 on the morphological and structural characteristics of TiO2. WO3/TiO2 was synthesized by sol-gel method at different calcination temperatures and at different concentrations of tungsten oxide. The surface area, the possible transition between valence band and conduction band, particle size, elemental analysis and crystallography were examined through the BET, DRS, SEM-EDS and XRD analysis.