Hydroxyapatite Fenton-like catalysis for methyl violet degradation. Effect of operating parameters and kinetic study

Behind the various properties and application of Hydroxyapatite (HA), we demonstrate in this work its crucial role in hydroxyl radical HO center dot regeneration by Fenton like process for the Methyl Violet (MV) degradation. The as-synthesized catalyst was examined by various techniques such as XRD, SEM, FT-IR, XPS, PL and EIS. The effects of the initial solution pH, hydrogen peroxide (H2O2) concentration, catalyst dose and reaction temperature, on the degradation process were investigated. It outcomes that HO center dot formed from the reaction between HA and H2O2 was the main active specie for the MV degradation. Furthermore, the electrochemical impedance spectroscopy (EIS) shows that the electron charges transfer across HA increases in the presence of H2O2 and MV/H2O2. The degradation kinetic follows a first-order and BMG models, while the activation energy (E-a) and the thermodynamic parameters namely standard enthalpy (Delta H*(0)), entropy (Delta S*(0)) and free energy (Delta G*(0)) revealed that the degradation reaction is an endothermic and non-spontaneous process.

Automated summary

In this study, the crucial role of Hydroxyapatite (HA) in the regeneration of hydroxyl radical (HO·) by a Fenton-like process for the degradation of Methyl Violet (MV) was demonstrated. The synthesized catalyst was characterized using various techniques, and the effects of pH, H2O2 concentration, catalyst dose, and reaction temperature on the degradation process were investigated. The main active species for MV degradation was found to be HO· formed through the reaction between HA and H2O2. Moreover, electrochemical impedance spectroscopy (EIS) showed an increase in electron charge transfer across HA in the presence of H2O2 and MV/H2O2.