New insights on the photodegradation of caffeine in the presence of bio-based substances; from homogeneous to heterogeneous process

Waste-derived bio-based substances (BBS) isolated from urbancomposted biowaste are supramolecular aggregates structurally similar to soil humic substances, showing amphiphilic properties. Moreover BBS can produce reactive species, under UV-vis irradiation, and they have been already tested as photosensitizer for the degradation of several organic substrates, among them caffeine as representative of contaminants of emerging concern. Here we report new insights on BBS performance for caffeine photodegradation in both homogeneous system and as hybrid magnetic nanoparticles in heterogeneous system. The effect of pH, the possibility to recover and re-use the nanoparticles and the assessment of the reaction mechanism have been studied and discussed.