SrSnO3/g-C3N4 and sunlight: Photocatalytic activity and toxicity of degradation byproducts

The presence of organic pollutants in the environment, especially in water, is recognized as a continuing threat to environmental stability. Therefore, the development of new materials for the removal of organic pollutants in water are of fundamental importance. In this paper, a heterojunction SrSnO3/g-C3N4 photocatalytic system was synthesized and its photocatalytical performance for Rhodamine-B (RhB) degradation has been tested. For this purpose, in situ luminescence measurements were carried out for the first time here, for monitoring the photodegradation process in real time under real reaction conditions performance. The degradation profiles of RhB using the SrSnO3/g-C3N4 composite and pure g-C3N4 showed that the degradation of the dye occurs through different mechanisms including four processes: N-de-ethylation, chromophore cleavage, opening-ring and mineralization. The results demonstrate that the SrSnO3/g-C3N4 ratio 1:1 (SSO3) and 1:2 (SSO4) provide high photocatalytic activity under solar light. Best results were observed for composite SSO3, which displayed TOC removal of 97.3 ± 0.03 % after 4 h of solar exposure, while SSO4 and pure g-C3N4 obtained a rate of 72.4 ± 0.03 % and 44.6 ± 0.04 %, respectively. Result of in situ experiments showed that composite SSO3 was 1.7 times more efficient in the RhB degradation than pure g-C3N4. The toxicity of phototreated solution was evaluated by Fish Embryo Test (FET) showing the successful photodegradation of RhB to non-toxic species.