Simultaneous Adsorption and Photocatalysis Processes Based on Ternary TiO2–CuxS–Fly Ash Hetero-Structures

Abstract

Ternary composites of TiO2–CuxS–fly ash were used in simultaneous adsorption and photocatalysis processes for the removal of organic (dye) pollutants. Composites of semiconductor (TiO2, CuxS) nanomaterials hosted within matrices of fly ash, such as film heterostructures, are promising materials for advanced wastewater treatment. The combination of adsorption and photocatalysis processes was investigated in the removal of methylene blue (MB), considered as a standard in photocatalysis. Ternary film heterostructures obtained by doctor blade technique allows overcoming the separation step of particles from treated wastewater. The comparison between the adsorption and photodegradation tests performed with TiO2–CuxS–fly ash showed that in dark conditions, the MB removal was 75% after 360 min, while in the presence of UV radiation, almost total dismissal of MB was achieved in the same treatment period. The degradation rate of MB, when H2O2 is used as an electron acceptor, could reach 90% in adsorption and 99% in simultaneous adsorption/photocatalysis processes. The adsorption isotherm was found to follow the Langmuir and Freundlich models.