Fabrication of new composite NCuTiO2/CQD for photocatalytic degradation of ciprofloxacin and pharmaceutical wastewater treatment: degradation pathway, toxicity assessment.

In this research, the photocatalytic degradation of CIP from aqueous solutions using CQD decorated on N-Cu co-doped titania (NCuTCQD) was made during two synthesis steps by sol-gel and hydrothermal methods. The fabricated catalysts were analyzed using various techniques, including XRD, FT-IR, BET, FESEM, EDX, and DRS. The results showed that N and Cu atoms were doped on TiO2 and CQD was well deposited on NCuT. The investigation of effective operational parameters demonstrated that the complete removal of ciprofloxacin (CIP: 20 mg/L) could be achieved at pH 7.0, NCuTCQD4wt%: 0.8 g/L, and light intensity: 100 mW/cm2 over 60 min reaction time. The O2•- and OH˙ radicals were identified as the primary reactive species during the decontamination process. The synthesized photocatalyst could be recycled after six consecutive cycles of CIP decomposition with an insignificant decrease in performance. Pharmaceutical wastewater was treated through the optimum degradation conditions which showed the photocatalytic degradation eliminated 89% of COD and 75% of TOC within 180 min. In the effluent toxicity evaluation, the EC50 values for treated and untreated pharmaceutical wastewater increased from 62.50% to 140%, indicating that the NCuTCQD4wt%/Vis system can effectively reduce the toxic effects of pharmaceutical wastewater on aquatic environments.

Synthesis of new hybrid composite based on TiO2 for photo-catalytic degradation of sulfamethoxazole and pharmaceutical wastewater, optimization, performance, and reaction mechanism studies.

In this study photo-catalytic degradation of sulfamethoxazole (SMX) from aqueous solutions using carbon quantum dot (CQD)-decorated Cu-TiO2 was investigated. The as-prepared photo-catalyst samples were characterized by various FTIR, XRD, FE-SEM, TEM, EDX, BET, and DRS techniques. The investigation of effective photo-catalytic operational parameters confirmed that the complete removal of SMX (20 mg/L) can be accomplished at pH: 6.0 and light intensity: 75 mW/cm2 over a 30-min reaction time. DRS analysis demonstrated adding CQD to the Cu-TiO2 reduced its bandgap energy from 2.97 to 2.90 eV. The photo-catalytic degradation kinetics of SMX fit well with the pseudo-first-order model. The radical trapping experiment indicates that HO• and O2•- active species were more effective species for SMX degradation, and the higher inhibition effect on the SMX degradation efficiency was assigned to O2•- ions. The water matrix species-inhibited effect in SMX removal was as follows: SO42- > Cl- > NO3- > CO3- > no ions. The synthesized photo-catalyst could be recycled after six consecutive cycles of SMX degradation with an insignificant decrease in performance. The total organic carbon (TOC) analysis suggested the mineralization of SMZ by composite photo-catalysts. The minimum inhibitory concentration (MIC) for Escherichia coli remained at 12.5 mg L-1 SMX. A possible mechanism and pathway of SMX degradation in the photo-catalytic system was presented.

Catalytic potential of CuFe2O4/GO for activation of peroxymonosulfate in metronidazole degradation: study of mechanisms.

Application of magnetite nanoparticles (CuFe2O4/GO) were anchored on graphene oxide (GO), as a Heterogeneous nanocomposite for activating of peroxymonosulfate (PMS) into Metronidazole (MNZ) destruction. The effect of solution pH, reaction time, effectiveness of water matrix components and trapping factors, different catalyst concentrations, PMS and contaminants were evaluated as operating factors on the efficiency of MNZ degradation. Also, mineralization, stability, reactivity and Recycling tests of the catalyst, and the degradation kinetics were performed. MNZ degradation and mineralization were obtained under optimal conditions (0.2 g/L catalyst, pH = 5, 30 mg/L MNZ and 2 mM PMS), 100% and 41.02%, respectively over 120 min. Leaching of Fe and Cu was found <0.2 mg/L for CuFe2O4/GO showed a high stability of catalyst, and a significant recyclability was achieved CuFe2O4/GO within 5 times consecutive use. MNZ degradation affected by anions was reduced as follows: HCO3 - > NO3 - > Cl- > SO4 2-. The experimental data were very good agreement with pseudo-first-order kinetic model, and during quenching tests SO4 •- radicals played a dominant role in the degradation process of MNZ. As a result, the CuFe2O4/GO/PMS system can be described as a promising activation of PMS in MNZ degradation, due to its high stability, reusability and good catalyst reactivity, and the production of reactive species simultaneously.