Nanomaterials and photocatalysis for environment: Applications and characterization

This paper is devoted to recent works developed on the heterogeneous photocatalysis and the different parameters affecting the catalysis efficiency in the adsorption capacity of the organic pollutants for the wide applications in water treatment. The heterogeneous photocatalysis based on titanium dioxide is increasing and growing. The choice of titanium dioxide as a photocatalytic material is due to its stability, availability and low cost. Some new results on the surface physicochemical properties of the titanium dioxide were here presented. Inverse gas chromatography at infinite dilution was used to determine the specific interactions of n-alkanes and polar probes adsorbed on the titanium dioxide. This technique is based on the experimental determination of the net retention time tn of organic molecules adsorbed on the solid surface that allows to obtain the retention volume Vn and therefore the free enthalpy of adsorption. By varying the temperature, it will be possible to evaluate the dispersive and specific interactions, and the specific enthalpy and entropy of adsorption by using the representation of RTlnVn = f(logP0) for all adsorbed molecules. The acid base constants of the titanium dioxide nanoparticles in Lewis terms were calculated by using Hamieh's model that allowed to better characterizing the amphoteric properties of the solid surface. It was proved that the titanium dioxide nanoparticles are four times more basic than acidic.