Remediation of imidacloprid and carbamazepine in polluted soil using TiO2 with LED lamps

Imidacloprid and carbamazepine are recognised as emerging contaminants (ECs) due to their ubiquitous presence in environmental compartments and their potential to cause undesirable ecological effects. Wastewater treatment plants are relevant routes for these compounds to enter environment since they are continuously released through treated wastewater. The progressively more extended custom of reusing treated wastewater for agricultural irrigation has also enlarged the risks for ECs accumulation in soil and their translocation to crops, posing a constant threat to both humans and wildlife. This work is aimed to study the behaviour of imidacloprid and carbamazepine and its main transformation products generated in soil during photocatalytic treatments using commercial TiO2 (Degussa P25) and ultraviolet light emitting diode (UV-LED) lamps as light source. Prior to remediation trial, the influence of catalyst load and soil moisture content in ECs degradation was studied. Experiments were performed using a photochemical reactor equipped with LED lamps running at 365 nm, exposing polluted soils to different treatments in presence and absence of photocatalyst. A significant degradation (93.4 and 96.2% for imidacloprid and carbamazepine, respectively) was observed after 4 days of photocatalytic treatment. The main transformation products were identified during the different treatments. Our results suggest that TiO2-photocatalytic treatment combined with UV-LED could be considered a promising technology to remove ECs from soils.