Effective photocatalytic mechanism on dye decolorization in different water matrices with phenolic resins as a photocatalyst under visible LED irradiation

[Display omitted] •A new model for reactive species contribution in photocatalytic processes is proposed.•Phenolic resins showed low scattering albedo under LED irradiation.•Electron-hole pair plays the major role on methyl orange decolorization.•Decolorization of methylene blue show a variable mechanism depending on the water matrix.•Bicarbonate alkalinity enhances the photocatalytic decolorization of methylene blue. In this research, a new approach for estimating the effective physicochemical mechanism via reactive oxygen species on photocatalytic degradation processes is proposed. The model was validated experimentally in three different water matrices (tap water, acidified tap water, and deionized water), evaluating acidic and alkalinity aspects. Phenolic resins were employed as a semiconductor for the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) under a LED irradiation source. It was demonstrated that phenolic resins are active on the visible light range and the recombination reaction process is diminished with LED irradiation because scattering of light is lower than 50% of the incident radiation. Findings also demonstrated that bicarbonate alkalinity enhances the photocatalytic degradation of MB, in contrast with MO. The mechanistic contribution, obtained from the effective photocatalytic mechanism (EPM) model, shows a synergistic effect on the transformation of MB and MO. Despite the photocatalytic degradation of MB has a variable mechanism as a function of the reactive media, hole oxidation mechanism prevailed as the main contribution on the decolorization of MO in the three different water matrices. The EPM model depicts the photocatalytic mechanisms satisfactorily and could be extended to other semiconductors and water matrices.