Effective degradation of phenacetin in wastewater by (photo)electro-Fenton processes: Investigation of variables, acute toxicity, and intermediates

Electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) processes were employed at different scales to degrade phenacetin (PNT), the first synthetic analgesic. EF experiments were conducted at lab scale, whereas SPEF experiments were performed in an 8 L pre-pilot plant using an electrochemical filter-press cell. Under optimal conditions (25 mg L−1 PNT, 25.3 mg L−1 Fe2+, and current density of 59.5 mA cm−2), EF resulted in degradation and mineralization degrees of 83.9% and 45.2% at 14 and 230 min, respectively. Similarly, PNT was spiked into real wastewater from a municipal secondary treatment plant, resulting in degradation of 68.0% and mineralization of 39.4%, with an energy consumption of 7.0 kWh g−1. The optimal conditions of SPEF (16.8 mg L−1 Fe2+ and current density of 45.9 mA cm−2) led to degradation and mineralization degrees of 55.9% and 37.1% at 36 and 181 min, respectively, with a low energy consumption of 0.142 kWh g−1. Both processes effectively detoxified the solutions, as demonstrated by tests with Artemia salina and Lactuca sativa. Three distinct degradation pathways were proposed based on the identification of eleven reaction intermediates formed upon •OH attack. In conclusion, the low energy cost of the SPEF process underscores its potential for pharmaceutical degradation in wastewater

Synthesis, characterization, and photocatalytic activity of pure and N-, B-, or Ag- Doped TiO2

This article reports the synthesis and characterization of pure and N-, B-, and Ag-doped TiO2 and the ability of these oxides to photodegrade methylene blue (MB) under sunlight or UV-ABC radiation. The compounds were synthesized using the sol-gel method and characterized by scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Photocatalytic efficiency was significantly increased by N-doping, resulting in 98% MB decomposition under UV-ABC irradiation for 180 min. Ag- and B-doped TiO2 lowered MB degradation rates to 52 and 73%, respectively, compared with pure TiO2. The same behavior was observed with exposure to UV-Vis, with 88, 65, 60, and 42% MB removal with N-doped, pure, B-doped, and Ag-doped TiO2, respectively. Under visible light alone, N-doped TiO2 exhibited higher photocatalytic efficiency than commercial P25-type TiO2. Photocatalysis with N-doped TiO2 proved to be a promising alternative for MB degradation, given the potential of employing solar energy, thus minimizing operating costs

Use of natural rubber membranes as support for powder TiO2 and Ag/TiO2 photocatalysts

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The purpose of this study was to synthesize TiO2-polymer composites able to act as photocatalyst membranes. TiO2 catalysts were prepared using the sol-gel method to contain 0.0, 0.5, 1.0, and 2.0 wt.% of embedded Ag particles, subsequently incorporated into natural rubber latex at a weight fraction of 15%. Samples of these ceramic powders were suspended in a latex emulsion (natural rubber), cast in Petri dishes and slowly dried in an oven. The resulting materials were evaluated by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, diffuse reflectance spectroscopy, differential scanning calorimetry, thermogravimetry, and photocatalytic assaying using methylene blue as an organic pollutant reference. All composite membranes exhibited good photoactivity conferred by TiO2 powder, with 98% dye fading after 300 min of ultraviolet irradiation.The purpose of this study was to synthesize TiO2-polymer composites able to act as photocatalyst membranes. TiO2 catalysts were prepared using the sol-gel method to contain 0.0, 0.5, 1.0, and 2.0 wt.% of embedded Ag particles, subsequently incorporated in273575583CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFUNDECT - FUNDAÇÃO DE APOIO AO DESENVOLVIMENTO DO ENSINO, CIÊNCIA E TECNOLOGIA DO ESTADO DE MATO GROSSO DO SUL |Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)sem informaçãosem informaçãosem informaçãosem informaçãoThe authors wish to thank the Brazilian funding agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and Fundação de Apoio ao Desenvolvimento do Ensino, Ciênci

Bio-based substances from urban waste as auxiliaries for solar photo-Fenton treatment under mild conditions: Optimization of operational variables

The use of soluble bio-based organic substances (SBO) obtained from urban wastes to expand the pH region where the photo-Fenton process can be applied has been investigated in this study. For this purpose, a mixture of six pollutants, namely acetaminophen, carbamazepine, amoxicillin, acetamiprid, clofibric acid and caffeine, at an initial concentration of 5 mg L-1 each, has been employed. Surface response methodology, based on the Doehlert matrix, has shown to be a useful tool to determine the effect of pH (in the range 3-7), concentration of SBO (15-25 mg L-1) and iron (2-6 mg L-1) on the performance of the photodegradation of the studied pollutants, measured by their half-life. Results indicate that, at high SBO concentration, the optimum pH shifts in most cases to a higher value (between 3 and 4) and that a significant loss of efficiency of the process was only observed at pH values above 5. An iron concentration of 4-5 mg L-1 and an amount of SBO of 19-22 mg L-1 have been determined to be the optimal conditions for the degradation of most of the studied pollutants at pH = 5. (C) 2014 Elsevier B.V. All rights reserved.The authors want to thank the financial support of the European Union (PIRSES-GA-2010-269128, EnvironBOS) and Spanish Ministerio de Educacion y Ciencia (CTQ2012-38754-C03-02). Juan Gomis would like to thank UPV for his FPI grant (2010-07).Gomis Vicens, J.; Carlos, L.; Bianco Prevot, A.; Teixeira, ACSC.; Mora Carbonell, M.; Amat Payá, AM.; Vicente Candela, R.... (2015). Bio-based substances from urban waste as auxiliaries for solar photo-Fenton treatment under mild conditions: Optimization of operational variables. Catalysis Today. 240(Part A):39-45. https://doi.org/10.1016/j.cattod.2014.03.034S3945240Part

Gaining further insight into photo-Fenton treatment of phenolic compounds commonly found in food processing industry

A mixture of eight phenolic compounds, namely 2,4-dinitrophenol, tannic, ellagic, gallic, protocatechuic, vanillic, syringic and sinapic acids, have been treated by means of a photo-Fenton process under simulated and real sunlight. An experimental design methodology, based in Doehlert matrixes, was employed to check the effect of the concentration of Fe(II) and H2O2, as well as pH. Response surfaces show that photo-Fenton can be extended to pH values clearly above 2.8, probably due to complexation of iron with the phenolic substances. Experiments performed under solar irradiation at pH = 3.9 showed that complete removal of the monitored pollutants was achieved in less than 3 min; mineralisation was also efficient, although some organics remained in the solution. Toxicity was monitored according to Pseudokirchneriella subcapitata and Daphnia magna bioassays; Recombinant Yeast Assay (RYA) was employed to assess estrogenic and dioxin-like activities. 2,4-Dinitrophenol was demonstrated to be the major concern and, in general, photo-Fenton resulted in a detoxification of the solution. Finally, excitation emission matrix (EEM) fluorimetry was employed to obtain complementary information on the behaviour of organic matter. Most peaks associated with the parent pollutants disappeared after short irradiation periods and, at 12 min of irradiation chromophores were destroyed, what can be associated with the removal of complex molecules. (C) 2015 Elsevier B.V. All rights reserved.The authors want to thank the financial support of the Spanish Ministerio de Education y Ciencia (CTQ2012-38754-C03-02) and Generalitat Valenciana (GV/2015/074). Sara Garcia-Ballesteros would like to thank Spanish Ministerio de Economia y Competitividad for her fellowship (BES-2013-066201).García Ballesteros, S.; Mora Carbonell, M.; Vicente Candela, R.; Sabater Marco, C.; Castillo López, MÁ.; Arques Sanz, A.; Amat Payá, AM. (2016). Gaining further insight into photo-Fenton treatment of phenolic compounds commonly found in food processing industry. Chemical Engineering Journal. 288:126-136. https://doi.org/10.1016/j.cej.2015.11.031S12613628

The relationship between local structure and photo-Fenton catalytic ability of glasses and glass-ceramics prepared from Japanese slag

Local structure and the photo-Fenton reactivity of iron-containing glasses and glass-ceramics prepared from Japanese domestic waste slag were investigated. The largest rate constant (k) of (2.8 ± 0.08) × 10−2 min−1 was recorded for the methylene blue degradation test by using H2O2 with a heat-treated ‘model slag’. The 57Fe Mössbauer spectrum was composed of a paramagnetic doublet with isomer shift of 0.18 ± 0.01 mm s−1 attributed to distorted FeIIIO4 tetrahedra. These results indicate that the paramagnetic Fe3+ provided strong photo-Fenton catalytic ability, and that waste slag can thus be recycled as an effective visible-light activated photocatalyst

Photolysis of ferric ions in the presence of sulfate or chloride ions: implications for the photo-Fenton process

The photo-Fenton process (Fe(2+)/Fe(3+), H(2)O(2), UV light) is one of the most efficient and advanced oxidation processes for the mineralization of the organic pollutants of industrial effluents and wastewater. the overall rate of the photo-Fenton process is controlled by the rate of the photolytic step that converts Fe(3+) back to Fe(2+). in this paper, the effect of sulfate or chloride ions on the net yield of Fe(2+) during the photolysis of Fe(3+) has been investigated in aqueous solution at pH 3.0 and 1.0 in the absence of hydrogen peroxide. A kinetic model based on the principal reactions that occur in the system fits the data for formation of Fe(2+) satisfactorily. Both experimental data and model prediction show that the availability of Fe(2+) produced by photolysis of Fe(3+) is inhibited much more in the presence of sulfate ion than in the presence of chloride ion as a function of the irradiation time at pH 3.0.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundacao Univ Fed Grande Dourados, Fac Ciencias Exatas & Tecnol, BR-79804970 Mato Grosso, MS, BrazilUniversidade Federal de São Paulo, BR-09972270 Diadema, SP, BrazilUniv São Paulo, Dept Quim, Fac Filosofia Ciencias & Letras Ribeirao Pret, BR-14040901 Ribeirao Preto, SP, BrazilUniv São Paulo, Inst Quim, BR-05513970 São Paulo, BrazilUniversidade Federal de São Paulo, BR-09972270 Diadema, SP, BrazilWeb of Scienc

Photo-Fenton oxidation of phenol and organochlorides (2,4-DCP and 2,4-D) in aqueous alkaline medium with high chloride concentration

A highly concentrated aqueous saline-containing solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2.4-DCP) was treated by the photo-Fenton process in a system composed of an annular reactor with a quartz immersion well and a medium-pressure mercury lamp (450 W). The study was conducted under special conditions to minimize the costs of acidification and neutralization, which are usual steps in this type of process. Photochemical reactions were carried out to investigate the influence of some process variables such as the initial concentration of Fe2+ ([Fe2+](0)) from 1.0 up to 2.5 mM, the rate in mmol of H2O2 fed into the system (F-H2O2,F-in) from 3.67 up to 7.33 mmol of H2O2/min during 120 min of reaction time, and the initial pH (pH(0)) from 3.0 up to 9.0 in the presence and absence of NaCl (60.0 g/L). Although the optimum pH for the photo-Fenton process is about 3.0, this particular system performed well in experimental conditions starting at alkaline and neutral pH. The results obtained here are promising for industrial applications, particularly in view of the high concentration of chloride, a known hydroxyl radical scavenger and the main oxidant present in photo-Fenton processes. (C) 2012 Elsevier Ltd. All rights reserved.CAPESCAPESCNPqCNPqANPANPFAPESPFAPESPFUNDECTFUNDEC