Susana Silva-Martínez

Photoelectrocatalytic inactivation of fecal coliform bacteria in urban wastewater using nanoparticulated films of TiO2 and TiO2/Ag

ABSTRACT Photocatalysis has shown the ability to inactivate a wide range of harmful microorganisms with traditional use of chlorination. Photocatalysis combined with applied bias potential (photoelectrocatalysis) increases the efficiency of photocatalysis and decreases the charge recombination. This work examines the inactivation of fecal coliform bacteria present in real urban wastewater by photoelectrocatalysis using nanoparticulated films of TiO2 and TiO2/Ag (4%w/w) under UV light irradiation. The catalysts were prepared with different thicknesses by the sol-gel method and calcined at 400°C and 600°C. The urban wastewater samples were collected from the sedimentation tank effluent of the university sewage treatment facility. The rate of bacteria inactivation increases with increasing the applied potential and film thicknesses; also, the presence of silver on the catalyst surface annealed at 400°C shows better inactivation than that at 600°C. Finally, a structural cell damage of Escherichia coli (DH5α), inoculated in water, is observed during the photoelectrocatalytic process.

Recent Overview of Solar Photocatalysis and Solar Photo-Fenton Processes for Wastewater Treatment

This literature research, although not exhaustive, gives perspective to solar-driven photocatalysis, such as solar photo-Fenton and solar photocatalysis, reported in the literature for the degradation of aqueous organic pollutants. Parameters that influence the degradation and mineralization of organics like catalyst preparation, type and load of catalyst, catalyst phase, pH, applied potential, and type of organic pollutant are addressed. Such parameters may also affect the photoactivity of the catalysts used in the studied solar processes. Solar irradiation is a renewable, abundant, and pollution-free energy source for low-cost commercial applications. Therefore, these solar processes represent an environmentally friendly alternative mainly because the use of electricity can be decreased/avoided.

Prediction of global solar radiation by artificial neural network based on a meteorological environmental data

AbstractThis paper describes a model based on artificial neural network (ANN) for the estimation of global solar radiation (GSR) on a horizontal surface. The GSR is the primary renewable energy in the nature. The estimation of GSR is decisive; there are many researches that need such estimation since they do not have the required instruments. A simple algorithm with ANN modeling is proposed. The configuration of the back propagation neural network giving the mean square error was a three-layer ANN (5-30-1 neurons) with tangent sigmoid transfer function at the hidden layer, sigmoid transfer function at output layer, and Levenberg–Marquardt algorithm. The sensitivity analysis was developed and showed that all studied variables (time, temperature, relativity humidity, wind speed, and atmospheric pressure) have effect in the prediction of GSR. The results showed that the ANN modeling could simulate the behavior of GSR.

Elimination of bio-refractory chlorinated herbicides like atrazine, alachlor, and chlorbromuron from aqueous effluents by Fenton, electro-Fenton, and peroxi-coagulation methods

AbstractAlachlor, atrazine (broad-leaf herbicides), and chlorbromuron (photosynthesis inhibitor) have been used worldwide to control weeds in crops. Their extensive use have led to widespread contamination of soils, and water which has consequently led to increasing concern about the environmental fate of these substances, since these herbicides are persistent in the environment and exhibit relatively slow rate of decomposition. Several advanced oxidation processes have been used to degrade such bio-refractory organic contaminants present in wastewater. The Fenton process is classified among these processes and has been used for the removal of many hazardous organics from wastewater efficiently. This study reports the removal of alachlor, atrazine, and chlorbromuron from aqueous effluents by classical Fenton, electro-Fenton, peroxi-coagulation, and photoperoxi-coagulation processes in slightly acidic aqueous solutions. A UV lamp was used to assist the peroxi-coagulation process. Herbicide concentration de...

Fenton Process Coupled to Ultrasound and UV Light Irradiation for the Oxidation of a Model Pollutant

The Fenton process coupled to photosonolysis (UV light and Us), using Fe2O3 catalyst supported on Al2O3, was used to oxidize a model pollutant like acid green 50 textile dye (AG50). Dye degradation was followed by AG50 concentration decay analyses. It was observed that parameters like iron content on a fixed amount of catalyst supporting material, catalyst annealing temperature, initial dye concentration, and the solution pH influence the overall treatment efficiency. High removal efficiencies of the model pollutant are achieved. The stability and reusability tests of the Fe2O3 catalyst show that the catalyst can be used up to three cycles achieving high discoloration. Thus, this catalyst is highly efficient for the degradation of AG50 in the Fenton process.

Design and experimental analysis of low-cost heat water solar collectors

Abstract Owing to fossil fuels’ consumption and environmental pollution, it is necessary to make efficient use of energy based on the different renewable energy sources such as solar energy. The present research has focused on the design, construction, and assembly of a train of solar energy collectors consisting of five concentrators, which individually have significant differences in the arrangements focus tube reflective surface and the greenhouse effect. The collectors are operated under the same environmental conditions. In the analysis presented on the train of solar energy collectors, a theoretical–experimental study was performed on the different reflecting surfaces of each collector, such as the mirrors’ reflecting surface, reflecting surface of the 316 L stainless-steel mirror polished, reflecting surface of the aluminum foil’s reflective surface with an aluminum paint, surface reflective type 304 stainless steel-mirror polish. The present study was developed to analyze and discuss the increase ...

Modeling methylene blue oxidation by means of Fenton chemistry enhanced by UV irradiation at mild conditions

AbstractTaking into account that Fenton chemistry can be enhanced under UV radiation, a systematic activation of different H2O2 concentrations (7–50 mM) in 0.05 M Na2SO4 (pH 2 adjusted with H2O4) was carried out, in the presence of UV/Fe2+ in a photochemical reactor. From the experimental results, a simple empirical correlation between the H2O2 activation velocity (AV) and its concentration was derived, as a result, a chemical model for the production was obtained. Considering that the attractiveness of the Fenton chemistry is its near-stoichiometric generation of a strong oxidant, it is possible to model the oxidation of organic matter under mild conditions. In this way, the fraction of H2O2 produced/consumed provides a measure of the efficiency of the oxidation process. The chemical model was tested in the photochemical reactor with several methylene blue (MB) concentrations (0.1–0.3 mM). Experimentally and theoretically, it was found that 0.1, 0.2, and 0.3 mM MB can be oxidized in 85, 90, and 100 min, ...