Photodegradation of chloramphenicol and paracetamol using PbS/TiO2 nanocomposites produced by green synthesis

The present study describes the photocatalytic potential of the successfully synthesized nanocrystalline PbS/TiO2 nanocomposites in the photodegradation of chloramphenicol and paracetamol. PbS and PbS/TiO2 nanoparticles were synthesized using biological sulphide produced by sulphate-reducing bacteria in batch and in a coupled bioremediation system (upflow anaerobic packed-bed reactor) for acid mine drainage treatment, yielding near-complete metal precipitation (similar to 100-99%, respectively). The PbS and PbS/TiO2 composites obtained using sulphide generated in batch have an average particle size ranging from 17 to 25 nm and 15 to 20 nm, respectively, while in bioreactor, both PbS and PbS/TiO2 particles have a similar size range from 20 to 50 nm. All the produced particles presented crystalline cubic structure. The specific surface area of TiO2 and PbS/TiO2 was estimated to be 46.559 m(2)/g and 38.005 m(2)/g, respectively. Chloramphenicol removal by photolysis was about 61% after 60 min of Hg irradiation and 36% under sunlight exposition. Chloramphenicol photodegradation using PbS/TiO2 as catalyst was successfully performed in a photoreactor (Hg medium pressure, 450 W) and under solar exposition with a high drug removal efficiency of 96% and 93% after 60 min and 240 min irradiation, respectively. Using TiO2 as a catalyst for photodegradation achieved 98% removal for both Hg and sunlight irradiation (UV index ranging 7-8) after 60 min and 240 min, respectively. Paracetamol removal by photolysis was about 18%. Drug's photocatalytic degradation using PbS/TiO2 was successfully performed under sunlight exposition with a high removal efficiency of 93%, while in the presence of TiO2, the removal was complete, after 235 min irradiation.