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In this study, Ag-modified natural zeolite catalyst (Z-Ag red ) was synthesized by chemical activation prior to the ion exchange and followed by a silver reduction with sodium boron hydride. The surface characterization of Z-Ag red has been investigated by X-ray diffraction, FT-IR spectroscopy, SEM microscopy and EDX analysis. Also, UV-VIS diffuse reflectance (DRUV-VIS) spectroscopy was used to determine the light absorption properties of the catalyst. The effect of silver reduction was noticed by comparison with the characterization of silvermodified natural zeolite by ion-exchange without the reduction stage. The photocatalytic performance of Z-Ag red catalyst was proved by photocatalysis application for the decolorisation and degradation of Methylene Blue (MB) dye containing wastewater under visible irradiation. The optimum operating parameters were determined based on the assessment of the photocatalytic process efficiency as a function of the catalyst dose, the initial pH, and the initial concentration of dye. The good results regarding the photocatalytic degradation of MB dye using Z-Ag red catalyst claim it as a potential for the real photocatalysis application in MB-containing wastewater under solar light.

The aim of this study was to investigate photocatalytic activity of a silver doped TiO 2 modified zeolite (Z-TiO 2 -Ag) in the photocatalytic degradation of Reactive Yellow 125 (RY 125) azo dye. The operational conditions using photocatalyst dose of 1g·L -1 at pH 6 were established as optimal conditions for photocatalysis application in RY 125 dye solution degradation. The photocatalyst exhibited a good performance for discoloration at all studied concentrations (25, 50 and 100 mgL -1 ). A good efficiency regarding the aromatic ring-opening process was achieved especially at low concentrations of the dye. However, an effective mineralization did not occur even at low concentrations of dye (25 mgL -1 ). The results of photocatalyst activity under VIS irradiation revealed a practical utility of the silver doped TiO 2 modified zeolite for the RY 125 dye degradation at low concentrations.

In this study, the adsorption mechanism of a reactive azo dye, Reactive Yellow 125 (RY 125), onto a nitrogen doped TiO 2 modified zeolite (Z-TiO 2-N) has been examined in order to identify the affinity of the material for the investigated pollutant envisaging its degradation by heterogeneous photocatalysis. Equilibrium experiments were performed and the data obtained were fitted with different isotherm equations, i.e., Langmuir, Freundlich, and Dubinin-Radushkevich (D-R). The Freundlich isotherm gave the best description of the adsorption process with a correlation coefficient of 0.8963. Adsorption kinetics has been studied in terms of pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The results showed that pseudo-secondorder kinetic model is the most appropriate to describe the uptake process satisfactorily. All determined equilibrium and kinetic parameters showed that the process is mainly governed by a physical mechanism rather than an electrostatic attraction, as confirmed by Zeta potential measurements.