Olga Sacco

Photocatalytic Degradation of Organic Dyes under Visible Light onN-Doped Photocatalysts

This study was focused on the application of white and blue light emitting diodes (LEDs) as sources for the photocatalytic degradation of organic dyes in liquid phase with visible light. The photocatalytic activity of N-doped titanium dioxide, synthesized by direct hydrolysis of titanium tetraisopropoxide with ammonia, was evaluated by means of a batch photoreactor. The bandgap energy of titanium dioxide was moved in the visible range from 3.3 eV to 2.5 eV. The visible light responsive photocatalysts showed remarkably effective activity in decolorization process and in the removal of total organic carbon. Methylene blue was also used as a model dye to study the influence of several parameters such as catalyst weight and initial concentration. The effect of dye on the photocatalytic performance was verified with methyl orange (MO). The results demonstrated that the right selection of operating conditions allows to effectively degrade different dyes with the N-doped TiO2 photocatalysts irradiated with visible light emitted by LEDs.

Influence of the photoreactor configuration and of different light sources in the photocatalytic treatment of highly polluted wastewater

Abstract In this study, a highly polluted wastewater from tannery industry is treated by photocatalysis using home-made N-doped TiO2 as catalyst. The doping by nitrogen of titania particles leads to a reduction in the absorption threshold from 3.2 to 2.5 eV, permitting the absorption of radiation characterized by a wavelength in the visible spectrum.Experiments were carried out by using different light sources, in particular white LEDs, blue LEDs, and UV lamps, with the aim to evaluate the process efficiency at different operating conditions. The obtained performances were compared with those using an undoped commercial TiO2 catalyst (Degussa P25).Moreover, a simplified mathematical model capable to correlate the power input of the used light sources, the geometrical properties of the reactor, and emitting sources spectra with the performances of the photocatalytic reaction was developed.

Successful Integration of Membrane Technologies in a Conventional Purification Process of Tannery Wastewater Streams

The aim of this work is to design and integrate an optimized batch membrane process in a conventional purification process used for the treatment of tannery wastewater. The integration was performed by using two spiral wound membrane modules in series, that is, nanofiltration and reverse osmosis, as substitutes to the biological reactor. The membrane process was designed in terms of sensible fouling issues reduction, which may be observed on the nanofiltration membrane if no optimization is performed. The entity of the fouling phenomena was estimated by pressure cycling measurements, determining both the critical and the threshold flux on the nanofiltration membrane. The obtained results were used to estimate the need of the overdesign of the membrane plant, as well as to define optimized operating conditions in order to handle fouling issues correctly for a long period of time. Finally, the developed membrane process was compared, from a technical and economic point of view, with the conventional biological process, widely offered as an external service near tannery production sites, and, here, proposed to be substituted by membrane technologies.

Surface water disinfection by chlorination and advanced oxidation processes: Inactivation of an antibiotic resistant E. coli strain and cytotoxicity evaluation.

The release of antibiotics into the environment can result in antibiotic resistance (AR) spread, which in turn can seriously affect human health. Antibiotic resistant bacteria have been detected in different aquatic environments used as drinking water source. Water disinfection may be a possible solution to minimize AR spread but conventional processes, such as chlorination, result in the formation of dangerous disinfection by-products. In this study advanced oxidation processes (AOPs), namely H2O2/UV, TiO2/UV and N-TiO2/UV, have been compared with chlorination in the inactivation of an AR Escherichia coli (E. coli) strain in surface water. TiO2 P25 and nitrogen doped TiO2 (N-TiO2), prepared by sol-gel method at two different synthesis temperatures (0 and -20°C), were investigated in heterogeneous photocatalysis experiments. Under the investigated conditions, chlorination (1.0 mg L(-1)) was the faster process (2.5 min) to achieve total inactivation (6 Log). Among AOPs, H2O2/UV resulted in the best inactivation rate: total inactivation (6 Log) was achieved in 45 min treatment. Total inactivation was not observed (4.5 Log), also after 120 min treatment, only for N-doped TiO2 synthesized at 0°C. Moreover, H2O2/UV and chlorination processes were evaluated in terms of cytotoxicity potential by means of 3-(4,5-dime-thylthiazol-2-yl)-2,5-diphenylte-trazolium colorimetric test on a human-derived cell line and they similarly affected HepG2 cells viability.

Photocatalytic removal of phenol by ferromagnetic N-TiO2/SiO2/Fe3O4 nanoparticles in presence of visible light irradiation

Photocatalytic Removal of Phenol by Ferromagnetic NTiO2/SiO2/Fe3O4 Nanoparticles in presence of Visible Light Irradiation Vincenzo Vaiano, Olga Sacco, Diana Sannino, Marco Stoller, Paolo Ciambelli, Angelo Chianese Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy Department of Chemical Material Environmental Engineering, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome, Italy. vvaiano@unisa.it

Long afterglow green phosphors functionalized with Fe-N doped TiO2 for the photocatalytic removal of emerging contaminants

Long Afterglow Green Phosphors Functionalized with Fe-N Doped TiO2 for the Photocatalytic Removal of Emerging Contaminants Olga Sacco , Vincenzo Vaiano, Changseok Han, Diana Sannino, Dionysios D. Dionysiou, Paolo Ciambelli Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy. Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 10 45221-0012, USA vvaiano@unisa.it

Optimized design of Wastewater stream treatment processes by membrane technologies

Optimized Design of Wastewater Stream Treatment Processes by Membrane Technologies Marco Stoller*, Javier Miguel Ochando Pulido, Olga Sacco a Department of Chemical Materials Environmental Engineering, ‘La Sapienza’ University of Rome, Rome, Italy b Department of Chemical Engineering, University of Granada, Granada, Spain c Department of Chemical Engineering, University of Salerno, Salerno, Italy marco.stoller@uniroma1.it

Photocatalytic removal of Eriochrome Black T dye over ZnO nanoparticles doped with Pr, Ce or Eu

Wastewaters coming from textile industries produce serious problems because they contain a lot of pollutants such as organic dyes. Heterogeneous photocatalysis is a promising and efficient approach to remove dye pollutants from wastewater. ZnO is an excellent and promising photocatalytic material to decompose organic pollutants by transforming them into CO2 and H2O. In order to enhance the photocatalytic activity, ZnO could be doped with metal and non-metal ions. In this work, the doping with chemical elements belonging to the lanthanide group, such as praseodymium (Pr), cerium (Ce) and europium (Eu) is reported. ZnO nanoparticles doped with Pr or Ce or Eu were prepared by a modified precipitation method. The chemical-physical characterization data evidenced that that dopant ions were successfully incorporated into the ZnO lattice because the doped ZnO samples presented band-gap values of about 3.0 eV, lower than undoped ZnO (3.3 eV). Photocatalytic activities of the synthesized samples under UV or visible irradiation were investigated in the degradation of Eriochrome Black T (EBT) in aqueous solutions. Photocatalytic results showed that the total EBT discoloration was reached after 120 min under UV irradiation for all the photocatalysts and the complete mineralization was achieved after 180 min only for the Pr and Ce doped ZnO samples. The best photocatalytic performances in terms of EBT discoloration and mineralization have been found for Pr doped- ZnO photocatalyst, both under UV and visible light.

Determination of Optimal Operating Condition in Nanofiltration (nf) and Osmosis Reverse (ro) During the Treatment of a Tannery Wastewater Stream

Determination of Optimal Operating Condition in Nanofiltration (NF) and Reverse Osmosis (RO) During the Treatment of a Tannery Wastewater Stream Diana Sannino* a ,Olga Sacco ,Angelo Chianese b a University of Salerno, Department of Industrial Engineering, Via Ponte don Melillo, 84084 Fisciano (SA), Italy b University of Rome “La Sapienza”, Department of Chemical Engineering, Via Eudossiana 18, 00184 Rome, Italy dsannino@unisa.it

Photocatalytic reactor with multiphase digital control of luminous radiation

This paper investigates the effect of controlled periodic illumination by visible LEDs on the performances of a visible-light-active N-doped TiO2 photocatalyst (N — TiO2) immobilized on glass spheres for wastewater treatment, using Methylene Blue (MB) dye as a model pollutant. Different LED dimming techniques are investigated and compared, including a classical Pulse Width Modulation (PWM) technique and a novel proposed Variable-Peak PWM technique. A modulation of dimming duty-cycle is adopted as well, which allows to control the light irradiation in a new way with respect to previously used methods. Experimental results highlight the improvement in MB photocatalytic degradation process obtained by using the proposed modulation techniques.