Environmental application of ecofriendly photosensitizers: degradation of pollutants by hybrid waste-derived substances.

Over the last few years, urban wastes have become a major source of contamination of soil, water and air, especially when they are not properly disposed. Recycling and reusing of wastes have therefore become mandatory for the sustainable development of our society. In this context, several papers reported that the recalcitrant lignin-like fraction of fermented urban biowastes is a cost effective source of soluble bio-based substances (SBO). These ones bear chemical similarities with humic substances, showing surfactant behaviour and photosensitizing properties. For example, it has been demonstrated that SBO are quite effective in enhancing photodegradation of water pollutants. Most of the published papers deal with CVT230, a SBO isolated from urban public park trimming and home gardening residues aged, under aerobic conditions, for 230 days. [1] This product has been tested with promising results as homogenous photosensitizer for the degradation of phenolic compounds. [1] In this work, soluble CVT230 was turned into an insoluble form by immobilizing it within a silica support, [2] obtaining organic-inorganic hybrid materials. The aim of this research is to exploit the photoactivity of these new compounds toward wastewaters cleaning, as well as to take advantage of the CVT230 heterogenization in order to recycle the material and perform repeated photodegradation cycles. This ecofriendly perspective offers considerable advantages for the engineering of remediation systems operating in a real environment. The CVT230-Silica hybrid materials were deeply characterized by several techniques and the photosensitizing activity was evaluated using, for example, 4-methylphenol as probe under simulated solar light irradiation with satisfactory results in terms of pollutant degradation, stability and reusability. [1] P. Avetta, F. Bella, A. Bianco Prevot, E. Laurenti, E. Montoneri, A. Arques and L. Carlos, ACS Sustainable Chem Eng., 2013, 1, 1545-1550 [2] M. L. Testa, M. L. Tummino, S. Agostini, P. Avetta, A. B. Prevot, F. Deganello, E. Montoneri and G. Magnacca. RSC Adv., 2015, Accepted Manuscript; DOI: 10.1039/C5RA03164H.