Pharmaceutical effluent degradation using hydrogen peroxide-supported zerovalent iron nanoparticles catalyst

Abstract

Pharmaceutical effluents generated during drugs production and application are often times released into the water systems with little or no treatment, which could pose potential danger to the ecosystem. Advanced oxidation processes for organic pollutants treatment have gained wide consideration due to their effectiveness. In this work, hydrogen peroxide (H₂O₂) and hydrogen peroxide-supported nano zerovalent iron (H₂O₂@nZVIs) were deployed to study pharmaceutical effluents (PE) degradation via batch experiments, under various reaction time, (H₂O₂) and (H₂O₂@nZVIs) concentrations, pH, PE concentration, and temperature. The nZVIs was prepared from the green synthesis of Vernonia amygdalina leaf extract and characterized using different analytical tools such as Fourier Transform-Infrared Spectroscopy (FT-IR), Gas Chromatography Mass Spectroscopy (GC-MS), Scanning Electron Microscopy (SEM), and X-Ray Diffraction Spectroscopy (XRD). The FT-IR results showed the presence of -C = O, -NH, -OH, -C = C and, -C-O functional groups, SEM report showed that the morphology of the nZVIs is round in shape, while GC-MS revealed the presence of several phytochemicals. When the concentration of the effluent was increased from 10 to 30 ml, the percentage decolourization decreased from 74.74 to 51.96% and from 80.36 to 54.38% for H₂O₂ and H₂O₂@nZVI respectively, whereas when the contact time was increased from 10 to 60 min, the percentage decolourization rose from 70.39 to 83.49% for H₂O₂ and from 85.19 to 89.73% when H₂O₂@nZVI was used. When the effect of pH was assessed, it was observed that on increasing the pH from 2 to 10, the percentage decolourization rose from 74.5 to 80.25% for H₂O₂, however, with H₂O₂@nZVI, the percentage decolourization decreased from 81.50 to 68%. Maximum percentage decolourization of 57.10% and 94.56% for H₂O₂ and H₂O₂@nZVI was achieved at catalyst volume of 25 ml. For all the parameters tested, the H₂O₂@nZVIs performed much better indicating that the nZVIs enhanced the decolourization ability of the H₂O₂. The kinetic results showed that the decolorization of pharmaceutical effluent by both catalysts fitted very well with the second-order model, while thermodynamic properties of enthalpy change were found to be 10.025 and 27.005 kJ/mol/K for H₂O₂ and H₂O₂@nZVIs respectively suggesting that the oxidation process is endothermic in nature. This technique employed in using hydrogen peroxide-supported zero valent iron, proved to be highly efficient not only for pharmaceutical effluent degradation but also in the elimination of lead from the effluent.