Alejandro Medel
Universitat of Barcelona

Environmental Engineering

PhD
7.68

Publications

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    Alejandro Medel
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    ABSTRACT: During the crude oil refining process, NaOH solutions are used to remove H2S, H2Saq, and sulfur compounds from different hydrocarbon streams.The residues obtained are called “spent caustics.” These residues can be mixed with those obtained in other processes, adding to its chemical composition naphthenic acids and phenolic compounds, resulting in one of the most dangerous industrial residues. In this study, the use of electrochemical technology (ET), using BDDwith Ti as substrate (Ti/BDD), is evaluated in electrolysis of spent caustic mixtures, obtained through individual samples from different refineries. In this way, the Ti/BDD’s capability of carrying out the electrochemical destruction of spent caustics in an acidic medium is evaluated having as key process a chemical pretreatment phase. The potential production of ∙OHs, as themain reactive oxygen species electrogenerated over Ti/BDD surface, was evaluated in HCl and H2SO4 through fluorescence spectroscopy, demonstrating the reaction medium’s influence on its production. The results show that the hydrocarbon industry spent caustics can be mineralized to CO2 and water, driving the use of ET and of the Ti/BDD to solve a real problem, whose potential and negative impact on the environment and on human health is and has been the environmental agencies’ main focus.
    Full-text · Article · Jul 2015 · International Journal of Photoenergy
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    Alejandro Medel
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    ABSTRACT: This research evaluated two electrokinetic remediation systems (EKR) for separating phenanthrene from bentonite and its electrochemical destruction by using a Boron Doped Diamond (BDD) electrode. The effect of the electrochemical potential for the oxidation of phenanthrene in liquid phase with Ti/BDD was analyzed by Normal Pulse Voltammetry and Hydroxyl Radical (●OH) analysis using the Spin Trapping Technique. The results showed that 70% of phenanthrene was removed from bentonite through EKR by applying 20 mA for 4 h in alkaline conditions, and that phenanthrene in solution was 100% degraded with Ti/BDD by applying 2.3 V vs Hg|Hg2SO4, for 2.5 h. These results demonstrate the potential application of the electrochemical technology in treating soils contaminated with highly toxic compounds, such as Polyaromatic Hydrocarbons (PAHs) and their final destruction using the EKR-BDD process.
    Full-text · Article · Mar 2015 · Environmental engineering and management journal
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    Alejandro Medel · Erika Bustos · Luis M Apátiga · Yunny Meas
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    ABSTRACT: C-sp 2 (graphite) impurities are undesirable in syn-thetic diamond electrodes (C-sp 3), because they can affect the electrochemical response. In this work, we demonstrate that C-sp 3 surfaces can be activated successfully by applying an anodic current density corresponding to sufficiently high po-tential where the hydroxyl radicals (● OH) are generated. The effectiveness of this activation process was verified by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and cyclic voltammetry.
    Full-text · Article · Sep 2013 · Electrocatalysis
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    ABSTRACT: Electrochemical incineration using boron-doped diamond electrodes was applied to samples obtained from a refinery and compared to the photo-electro-Fenton process in order to selectively eliminate the phenol and phenolic compounds from a complex matrix. Due to the complex chemical composition of the sample, a pretreatment to the sample in order to isolate the phenolic compounds was applied. The effects of the pretreatment and of pH on the degradation of the phenolic compounds were evaluated. The results indicate that the use of a boron-doped diamond electrode in an electrochemical incineration process mineralizes 99.5% of the phenolic sample content. Working in acidic medium (pH = 1), and applying 2 A at 298 K under constant stirring for 2 hours, also results in the incineration of the reaction intermediates reflected by 97% removal of TOC. In contrast, the photo-electro-Fenton process results in 99.9% oxidation of phenolic compounds with only a 25.69% removal of TOC.
    Full-text · Article · Sep 2012 · International Journal of Photoenergy

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