Photodegradation of 4-chloropehol in aqueous media using LaBO3 (B = Fe, Mn, Co) perovskites: Study of the influence of the transition metal ion in the photocatalytic activity

The UV-light irradiation of the perovskite particles, dispersed in the solution of the organic pollutant, provokes the generation of electron-hole pairs. The photoinduced holes oxidize to OH− ions and water molecules that are adsorbed in the surface of the catalyst, generating OH radicals. These last species, rapid attack the organic pollutant, causing its degradation. To avoid the recombination of the charge carriers, O2 is bubbling into the solution. [Display omitted] •The cation B (Fe, Mn, Co) in the La containing perovskite determines their physicochemical properties and their catalytic activity.•The cation B determines the temperature at which the materials forms a crystalline structure.•The generation of OH radicals by the synthesized perovskites was corroborated by the terephtalic method. Three LaBO3 (B = Fe, Mn, Co) perovskitas were synthesized by the Pechini method using as raw materials ethylene glycol, citric acid and nitrates of the metal ions. The precursors so obtained, underwent to heat treatment to 600 and 700 °C. The catalysts were characterized by XRD, physisorption of N2, UV–vis diffuse reflectance and TEM microscopy. The results showed materials that exhibit a pure perovskite phase, low specific surface area (6.6998-15.7117 m2/g) and band gap energies in the range of 0.606–2.90 eV. The catalytic activity of the synthesized perovskites was evaluated in the photodegradation of 4-chlorophenol in aqueous media. Although all the photocatalysts degraded more than 35 % of the organic pollutant, the Mn-containing sample showed the major photocatalytic activity with a degrade percentage of approximately 80 after two hours of reaction. Fluorescence tests suggest the generation of OH radicals as the oxidative species of the target pollutant.