Giuseppina Iervolino

Facile method to immobilize ZnO particles on glass spheres for the photocatalytic treatment of tannery wastewater

In order to apply the photocatalytic processes on a real scale for the treatment of industrial wastewaters, the use of slurry reactors employing suspended photocatalysts is not suitable due to the need for an uncomfortable and expensive separation phase of photocatalyst. To overcome this disadvantage, the photocatalyst particles must be immobilized on a transparent support: our work proposes, for this reason, a simple and cost effective method for the deposition of ZnO photocatalyst on glass spheres in order to formulate a structured photocatalyst effective in the treatment of aqueous solutions containing various organic dyes, commonly used in the tannery industries and in the treatment of a real wastewater at high COD content (11 g/L) coming from the refining unit of the tanning process. In particular, ZnO was immobilized on glass spheres (ZnO/GS) with a simple dip coating method, starting from zinc acetate aqueous solution, without using complexing agent and strong basic compounds. The optimization of ZnO amount on glass spheres was evaluated employing Acid Blue 7 dye, as model pollutant. In particular, it was found that best performances in terms of discoloration and mineralization of the target dye were obtained using the photocatalyst with a ZnO loading equal to 0.19 wt% (ZnO_ac1), prepared through only one dip-coating step. Moreover, the ZnO_ac1 photocatalyst can be easily separated from the reaction mixture, maintaining excellent photocatalytic activity and durability even after several reuse cycles. Finally, ZnO_ac1 showed a high photocatalytic activity in the treatment of the real wastewater, obtaining a COD removal equal to 70% after 180 min of UV light irradiation.

Inactivation of an urban wastewater indigenous Escherichia coli strain by cerium doped zinc oxide photocatalysis

Heterogeneous photocatalysis (HPC) is a subset of Advanced Oxidation Processes (AOPs) with potential future applications in water disinfection. Herein, a zinc oxide photocatalyst was doped with cerium at various atomic ratios ranging from 0 to 0.1 Ce : Zn. Keeping in mind that the application of HPC is often limited by its cost of use, a simple and easy to upscale method, that is the hydroxide induced hydrolysis of zinc nitrate in the presence of Ce3+ followed by calcination at 300 °C, was used to synthesise the catalysts. The catalysts have been characterized by different techniques such as X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis DRS) and Raman spectroscopy. XRD results showed that Ce3+ ions were successfully incorporated into the ZnO lattice. UV-vis DRS spectra evidenced that Ce–ZnO samples present band-gap values of about 2.97 eV, lower than those of undoped ZnO (3.21 eV). These various photocatalysts, at 0.1 g L−1 in saline 0.85%, were used to inactivate Escherichia coli previously isolated from an urban wastewater treatment plant. Higher atomic ratios of Ce in the ZnO lattice, as confirmed by XRD and Raman spectroscopy, showed significant improvements to the inactivation rate; the resulting recommended optimum cerium loading of 0.04 : 1 Ce : Zn gave multiple orders of magnitude higher rate of inactivation after 60 min of treatment when compared to un-doped ZnO. This optimum loading of cerium was faster than the de facto literature standard TiO2-P25 tested under identical conditions.

Enhanced photocatalytic hydrogen production from glucose on Rh-doped LaFeO3

The aim of this work was to evaluate effect of different amount of rhodium used for the doping of LaFeO3 prepared through solution combustion synthesis in the photocatalytic hydrogen production from glucose solution. The process efficiency was evaluated in terms of both glucose degradation and hydrogen production during the irradiation time. Characterization results showed the formation of orthorhombic perovskite type structure and the absence of rhodium oxide crystallites up to Rh loading of 1.16 mol %. Photocatalytic results showed that the highest value of H2 production (1835 μmol/L) was achieved on 0.70%Rh photocatalyst after 4 h irradiation time. The substitutional doping generated by the replacement of Fe with Rh promotes the separation of charge carriers efficiently, and consequently enhancing the photocatalytic activity.

Photocatalytic Conversion of Glucose to H2 over Lafeo3 Perovskite Nanoparticles

Photocatalytic Conversion of Glucose to H2 over LaFeO3 Perovskite Nanoparticles Giuseppina Iervolino, Vincenzo Vaiano, Diana Sannino, Luigi Rizzo, Paolo Ciambelli a Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy b Department of Civil Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA) Italy giiervolino@unisa.it