Life cycle assessment of solar photo-Fenton and solar photoelectro-Fenton processes used for the degradation of aqueous α-methylphenylglycine

A comparative Life Cycle Assessment (LCA) of solar photo-Fenton and solar photoelectro-Fenton, two solar-driven advanced oxidation processes (AOPs) devoted to the removal of non-biodegradable pollutants in water, is performed. The study is based on the removal, at laboratory scale, of the amino acid α-methylphenylglycine, a good example of soluble and non-biodegradable target pollutant. The system under study includes chemicals, electricity, transport of all raw materials to the plant site, and the generation of emissions, but it does not take into account the impact of the infrastructure needed to build a hypothetical solar plant. Nine environmental impact categories are included in the LCA: global warming potential, ozone depletion potential, aquatic eutrophication potential, acidification potential, human toxicity potential, photochemical ozone formation potential, fresh water aquatic ecotoxicity potential, marine aquatic ecotoxicity potential, and terrestrial ecotoxicity potential and abiotic resource depletion potential. Although previous experimental results show that both AOPs are able to efficiently degrade the pollutant, the LCA indicates that solar-driven photo-Fenton is the most environmentally friendly alternative, mainly because the use of electricity in solar photoelectro-Fenton experiments involves high environmental impacts.     

Photoelectro-Fenton treatment of pesticide triclopyr at neutral pH using Fe(III)–EDDS under UVA light or sunlight

Environmental Science and Pollution Research - One of the main challenges of electrochemical Fenton-based processes is the treatment of organic pollutants at near-neutral pH. As a potential...     

Electro-Fenton degradation of the antibiotic sulfanilamide with Pt/carbon-felt and BDD/carbon-felt cells. Kinetics,reaction intermediates,and toxicity assessment

The degradation of 230 mL of a 0.6-mM sulfanilamide solution in 0.05 M Na₂SO₄ of pH 3.0 has been studied by electro-Fenton process. The electrolytic cell contained either a Pt or boron-doped diamond (BDD) anode and a carbon-felt cathode. Under these conditions, organics are oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between initially added (and then electrochemically regenerated) Fe²⁺ and cathodically generated H₂O₂. From the decay of sulfanilamide concentration determined by reversed-phase liquid chromatography, an optimum Fe²⁺ concentration of 0.20 mM in both cells was found. The drug disappeared more rapidly using BDD than Pt, and, in both cases, it was more quickly removed with raising applied current. Almost total mineralization was achieved using the BDD/carbon-felt cell, whereas the alternative use of Pt anode led to a slightly lower mineralization degree. In both cells, the degradation rate was accelerated at higher current but with the concomitant fall of mineralization current efficiency due to the greater increase in rate of the parasitic reactions of hydroxyl radicals. Reversed-phase liquid chromatography allowed the identification of catechol, resorcinol, hydroquinone, p-benzoquinone, and 1,2,4-trihydroxybenzene as aromatic intermediates, whereas ion exclusion chromatography revealed the formation of malic, maleic, fumaric, acetic, oxalic, formic, and oxamic acids. NH₄ ⁺, NO₃ ^?, and SO₄ ^2? ions were released during the electro-Fenton process. A plausible reaction sequence for sulfanilamide mineralization involving all detected intermediates has been proposed. The toxicity of the solution was assessed from the Vibrio fischeri bacteria luminescence inhibition. Although it acquired its maximum value at short electrolysis time, the solution was completely detoxified at the end of the electro-Fenton treatment, regardless of the anode used.     

Chronic risk assessment of exposure to volatile organic compounds in the atmosphere near the largest Mediterranean industrial site

This study focuses on characterising the risk of exposure to volatile organic compounds (VOCs) by means of inhalation in people living in the vicinity of the largest chemical production site in the Mediterranean area. Eighty-six VOCs were initially selected for this study based on their adverse environmental and health effects. The monitoring campaign was conducted for 276 days in three different locations around the chemical site. The analytical method used for the characterisation was based on European standard method EN-14662-2, which consists of the active sampling of air for 24 h in charcoal tubes, followed by extraction with carbon disulphide and GC-MS analysis. Forty-four VOCs with toxicological data available concerning their carcinogenic and non-carcinogenic health effects were quantified during the monitoring campaign. None of the quantified VOCs showed average concentrations exceeding their chronic reference concentrations and, therefore, no non-carcinogenic health effects are expected as a result of this exposure. However, the global average cancer risk due to VOC exposure in the area (3.3 × 10^− 4) was found to be above the values recommended by the WHO and USEPA.The influence of the analytical method was also evaluated by comparing cancer risk estimates using a thermal desorption (TD) method based on method EN-14662-1. The results of the 24-h samples for the solvent extraction method were compared with the average of 12 daily samples of 2-h for the TD method for 24 sampling days. Although the global estimated lifetime cancer risk was statistically comparable for both methods, some differences were found in individual VOC risks.To our knowledge, this is the first study that estimates the carcinogenic and non-carcinogenic risks posed by the inhalation of VOCs in people living near a chemical site of this size, and compares the estimated cancer risk obtained using two different standard analytical methods.     

Water consumption in Barcelona and its regional environmental imprint: a long-term history (1717–2008)

We present the evolution of urban water withdrawal and consumption of Barcelona from the eighteenth to the twenty-first centuries. The boundaries of the urban system have been set into the limits of the current municipality, adjusting the data of earlier periods to include the estimated consumption in former municipalities aggregated to the city. Different sorts of water flows have been either recorded or estimated from scant and indirect information, such as local groundwater extractions obtained from a hydrological model calibrated with historical data on variations in the water table. The changes experienced in catching infrastructures, the regional ecological imprint of the domestic or industrial water consumed together with the rates of growth in population, economic activity and water intensity have been taken into account as driving forces. The series obtained reveal an overall increase in accessibility to safe freshwater, and a corresponding extension of water terrestrial imprints of Barcelona over the Catalan river basins, up to the peak reached in 1967?C1970 both for per capita and total water withdrawn. The subsequent downward trend, mainly driven by a lesser water intensity of the local economy, a halt in population growth, and a recently link to the emergence of a New Sustainable Water Culture in Catalan society, stands out against the alleged need for new transfers from farthest basins such as the Ebro or Roine rivers.     

Degradation of clofibric acid in acidic aqueous medium by electro-Fenton and photoelectro-Fenton

Acidic aqueous solutions of clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid), the bioactive metabolite of various lipid-regulating drugs, have been degraded by indirect electrooxidation methods such as electro-Fenton and photoelectro-Fenton with Fe(2+) as catalyst using an undivided electrolytic cell with a Pt anode and an O(2)-diffusion cathode able to electrogenerate H(2)O(2). At pH 3.0 about 80% of mineralization is achieved with the electro-Fenton method due to the efficient production of oxidant hydroxyl radical from Fenton's reaction between Fe(2+) and H(2)O(2), but stable Fe(3+) complexes are formed. The photoelectro-Fenton method favors the photodecomposition of these species under UVA irradiation, reaching more than 96% of decontamination. The mineralization current efficiency increases with rising metabolite concentration up to saturation and with decreasing current density. The photoelectro-Fenton method is then viable for treating acidic wastewaters containing this pollutant. Comparative degradation by anodic oxidation (without Fe(2+)) yields poor decontamination. Chloride ion is released during all degradation processes. The decay kinetics of clofibric acid always follows a pseudo-first-order reaction, with a similar rate constant in electro-Fenton and photoelectro-Fenton that increases with rising current density, but decreases at greater metabolite concentration. 4-Chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol, along with carboxylic acids such as 2-hydroxyisobutyric, tartronic, maleic, fumaric, formic and oxalic, are detected as intermediates. The ultimate product is oxalic acid, which forms very stable Fe(3+)-oxalato complexes under electro-Fenton conditions. These complexes are efficiently photodecarboxylated in photoelectro-Fenton under the action of UVA light.