Photocatalytic activity of hybrid Silica - waste derived substances for phenols abatement in aqueous solution

Photochemical transformations play an important role in the abiotic degradation of harmful organic matters in the soil and aquatic environments. In the last 30 years, many studies about humic substances, as photosensitizers, were carried out. Actually, these ubiquitous natural materials strongly absorb solar light, photoinducing the transformation of non-absorbing organic chemicals [1]. Recently, humic-like substances from biorefuses [2], have been employed as auxiliaries in formulations for textile dyeing, detergency and environmental decontamination processes. In this work, the photoactivity of substances isolated from biomass obtained by the green fraction of refuses (Soluble Biorganic Substances, SBO) was evaluated in removal of phenol-based pollutant. Previous study demonstrated that SBO is effective in the homogeneous monoclorophenols photodegradation [3]. Nevertheless, heterogeneization step is required in order to prepare a more efficient catalyst, due to the possibility of an easier recycle. SBO was immobilized on different types of silica [4] both amorphous and with ordered mesoporosity (HMS and SBA-15). The obtained hybrid organic-inorganic materials (SBO-Silica) were characterized by N2 adsorption, FT-InfraRed Spectroscopy, Transmission Electron Microscopy, Thermogravimetric Analysis and Small Angle X-Ray Scattering. The photocatalytic activity of SBO-Silica was tested for the abatement of 4-methylphenol, chosen as model substrate. The experiments were performed in aqueous solution irradiated by simulated solar light. The effect of the catalyst concentration was studied and the performances of the different materials were compared in order to identify possible structure-properties relationships. The stability of the materials upon irradiation and the possibility to re-use them is, at the present time, under investigation. References 1 L. Carlos, B. W. Pedersen, P.R. Ogilby, D. O. Martire, Photochem. Photobiol. Sci., 2011, 10, 1080-1086. 2 E. Montoneri, V. Boffa, P. Quagliotto, R. Mendichi, M. Chierotti, R. Gobetto, C.Medana, BioResources, 2008, 3(1), 123-141. 3 P. Avetta, F. Bella, A. Bianco Prevot, E. Laurenti, E. Montoneri, A. Arques, L. Carlos, ACS Sustainable Chem. Eng., 2013, 1, 1545-1550. 4 M.L. Testa, V. La Parola and A.M. Venezia, Catal. Today, 2014, 223, 115-121.