Synthesis and characterization of SnO NPs for photodegradation of eriochrome black-T using response surface methodology.

The domestic and industrial sewage contains an extensive range of various organic compounds. Due to the toxicity of these materials, their degradation is considered one of the great environmental challenges. To address this problem, SnO nanoparticles (NPs) were synthesized via a green route, and they were used as an efficient catalyst for the degradation of an organic dye. In the stage of synthesis of nanoparticles, Thymus vulgaris L. extract acted as an efficient capping agent and renewable reducing agent, and SnO NPs were synthesized without addition of any hazardous surfactants. The successful synthesis of SnO NPs was confirmed by XRD, FT-IR, SEM, EDX, and TEM. The photocatalytic performance of SnO NPs was examined for the degradation of eriochrome black-T (ECBT) as a toxic organic dye in aqueous medium under ultraviolet irradiation. Furthermore, the response surface methodology (RSM) with central composite design (CCD) model was carried out to study of the effects of three different operational parameters on degradation of ECBT. In this design, initial pH of solution (3-11), reaction time (0.5-4 h), and the catalyst loading (0.05-0.12 g) were selected as three factors, whereas the degradation efficiency was chosen as the response. The results of the experimental design indicated that initial pH and catalyst loading were highly significant factors, whereas the reaction time was less important than other factors. Also, recyclability of catalyst was investigated, and the obtained results showed that SnO NPs could be easily recovered and reused for at least 4 cycles without any significant decrease in their activity.