This paper presents a comparative analysis of three carbon-based electrodes: bare multiwalled carbon nanotubes (MWCNT), SnO2/MWCNT, and PbO2/graphene-nanoribbons (PbO2/GNR) composites, as anodes for ...the electrooxidative degradation of Rhodamine B as a model organic pollutant. Anodic electrooxidation of Rhodamine B was performed on all three electrodes, and the decolorization efficiency was found to increase in the order MWCNT < PbO2/GNR < SnO2/MWCNT. The electrodes were characterized by X-ray photoelectron spectroscopy (XPS) and linear sweep voltammetry (LSV). It was proposed that, in the 0.1 M Na2SO4 applied as electrolyte, observed decolorization mainly occurs in the interaction of Rhodamine B with OH radical adsorbed on the anode. Finally, the obtained results were complemented with Density Functional Theory (DFT) calculations of OH-radical interaction with appropriate model surfaces: graphene(0001), SnO2(001), and PbO2(001). It was found that the stabilization of adsorbed OH-radical on metal oxide spots (SnO2 or PbO2) compared to carbon is responsible for the improved efficiency of composites in the degradation of Rhodamine B. The observed ability of metal oxides to improve the electrooxidative potential of carbon towards organic compounds can be useful in the future design of appropriate anodes.
Electrochemical removal of organic pollutants represents an attractive methodology in water depollution. The key challenges for researchers comprise finding simple, affordable electrode materials ...with satisfactory efficiency in all ranges of pollutant concentration. Electrochemical oxidation of a mixture of phenol-based dyes: bromocresol green (BCG), cresol red (CR), and thymol blue (TB), in sulphate medium, at total concentration not exceeding 15 ppm, has been performed using simply prepared, low-cost composite electrodes, based on graphene nanoplatelets (GNP) and metallic oxides (TiO2 and SnO2) loaded on stainless steel substrate: GNP@SS, SnO2/GNP@SS, and TiO2/GNP@SS. Electrodes were characterised by XRD, FTIR, and electrochemical techniques. The degradation kinetics of initial dyes was tracked with UPLC and GC-MS chromatography for 6 h, at a current density of 10 mA/cm2. GC-MS analysis of the degradation products revealed oxidised aromatic compounds as the main products, while TOC analysis confirmed a total mineralisation extent in the range of 30–35%. The proposed degradation mechanism involves the attack of OH-radical, as the main oxidising agent, to the hydroxyl oxygens of dye phenolic rings. Obtained results provide useful information for the further development of affordable laboratory-scale and industrial systems for the complete removal of phenol-based compounds.
In this work the electrochemical behavior of cobalt ethylendiamine complexes
(Co(en)), at pH 12 has been investigated by cyclic voltammetry (CV),
potentiostatic pulse technique and polarization curve ...measurements at
stationary and rotating glassy carbon (GC) electrode. It was shown that
sixteen different species can be formed in the solution containing Co(en)3
ligand, with the most stable one at all pH values being Co(en)33+. The
reduction of Co(en)33+ into Co(en)32+ was shown to be totally
irreversible, one-electron exchange reaction. Further reduction of
Co(en)32+ was found to be complex process leading to a cobalt deposition
at the potentials more negative than -1.45 V vs. SCE. The process of
Co(en)32+ oxidation was also complex and most probably coupled with the
chemical reaction.
Last decade, a growing emphasis on developing sustainable and environmentally friendly technologies for electro-oxidative wastewater treatment has catalyzed innovation and spurred research efforts ...worldwide. Researchers may explore the use of renewable energy sources to drive electrochemical processes, as well as the development of eco-friendly electrode materials for wastewater treatments. The integration of nanostructured anodes into the electrolytic system for wastewater treatment has led to significant advancements in the removal of pollutants via electro-oxidation. Despite the great number of research articles related to the development and use of nanostructured anodes for electro-oxidative wastewater treatment, to our knowledge, no bibliometric analysis has been published in this domain. Therefore, this work presents a bibliometric study of publications on the designated theme, retrieved from the Web of Science Core Collection database, which were published over the last decade. The visual and network analysis of co-authorship among authors, organizations, countries, co-citation of authors, citation of documents and sources, as well as the co-occurrence of author keywords was performed using two compatible pieces of scientometric software, namely VOSviewer (version 1.6.18) and CiteSpace (version 6.2.R4). From 2013 to 2023, there has been a gradual increase in the number of publications regarding the development and use of nanostructured anodes for electro-oxidative wastewater treatment. It suggests a steady advancement in this field. The People’s Republic of China emerges as the most productive country, and it is a leader in international collaborations. Also, the United States of America, South Korea, and European Union countries have significant impacts on the research in this domain. The development and application of nanostructured materials for urea electro-oxidation is a main and prospective research theme. This bibliometric analysis allowed for the visualization of the present landscape and upcoming trends in this research field, thereby facilitating future collaborative research endeavors and knowledge exchange.
Polycyclic aromatic hydrocarbons (PAH) have been listed by the United States Environmental Protection Agency (US EPA) and by the European Community as priority environmental pollutants. The removal ...of PAHs from soils, sediments and waste water has attracted attention of scientists and engineers for several decades. Electrochemical oxidation of PAH compounds in water, is receiving increasing attention, due to its convenience and simplicity. In this study we performed electrochemical oxidation of 16 EPA PAHs mixture in 10% NaCl aqueous solution in potentiostatic conditions, at voltage 1 V. Decrease of concentration of some individual PAHs, up to 70% referred to their starting concentration, after 60 min of electrolysis, was confirmed by UPLC/PDA analysis. In further work investigation was extrapolated to in situ removal of PAHs from concrete, as the medium where, to our knowledge, such way of PAH removal has not been investigated before.
High concentrations of PAH contamination occurred in the concrete structure of the residential buildings in Belgrade in 2014. Application of DC voltage of 50 V between nickel and stainless steel electrodes packed in the concrete wall, moisturized with the 10% NaCl solution, led to considerable removal of the pollutants by oxidation process throughout the concrete.
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•Concrete pollution with PAHs determined.•Electrochemical oxidation of PAH water solution examined.•Substantial oxidation of PAH in concrete achieved.
Application of DC voltage between electrodes packed in the concrete wall, led to considerable removal of the pollutants by oxidation process throughout the concrete.
Bisphenol A (BPA) is an organic pollutant that is widely spread in waterbody with effluents as a result of its extensive use in the plastics industry. It posses to the class of compounds that are ...endocrine disruptors and has a great negative impact on living organisms. Therefore, the progress in development of green technology for BPA removal from the aquatic media is crucial for environmental protection. This paper presents BPA removal by electrochemical oxidation on SnO2-MWCNT (tin dioxide-multi walled carbon nanotube) nanocomposite anode. The nanocomposite was structural and morphological characterized by X-ray powder diffraction and transmission electron microscopy. Electrochemical properties of the SnO2-MWCNT anode were investigated using cyclic voltammetry, linear sweep voltammetry and electrical impedance spectroscopy. The electrochemical behavior of anodes toward BPA in sodium sulfate solutions has shown that BPA is oxidized by indirectly mechanism via hydroxyl radicals (verified by quenching tests). Electrolysis of BPA has been done in galvanostatic regime at current densities 2.5, 5.0, 10.0, 15.0 and 20.0 mA cm−2 in 0.1 M sodium sulfate supported electrolyte pH 4.0. Complete degradation of BPA was accomplished after 5 h of electrolysis at a current density of 20 mA cm−2. The proposed electrochemical technology using a low-cost SnO2-MWCNT electrode is promising for wastewater BPA removal.
•Analysis of the 16 EPA PAHs in new matrix was presented.•Simultaneous identification and quantification of PAHs in concrete by UPLC-PDA.•Suitable for control testing of concrete in ...buildings.•Conducive method for monitoring PAHs removal from concrete.
Human exposure to persistent organic contaminants, from building materials, negatively affects people’s health and overall quality of life. This paper presents the validation and uncertainty assessment of the analytical method, developed for the simultaneous determination of 16 EPA polycyclic aromatic hydrocarbons (PAHs) in solid–solid concrete by ultra-performance liquid chromatography with photo diode-array detector. Linearity of calibration curves was good over the whole range of calibration. Limits of detection varied between 0.2 and 2.9μgkg−1. The accuracy in terms of recovery of the validated method is within the range from 54 to 106%. The developed method proved to be appropriate for analysis of PAHs and can be used for the quality control testing of concrete during the construction of new buildings, the old residences and related buildings associated with sick-building syndrome. In addition, this is the first reported method described for the evaluation of PAHs in solid–solid concrete.
This manuscript presents contribution on the improved efficiency of the alkaline electrolytic production of hydrogen by in situ adding activating compounds directly into the electrolyte during the ...electrolytic process. New electrode material, ternary system, Ni–Cu–Mo, was applied as activating compound i.e. ionic activator. The energy requirements per mass unit of hydrogen produced is reduced for more than 10%, compared to non-activated, 30 wt. % KOH electrolyte system. Energy saving is higher at higher temperatures and at higher current densities. During the electrolytic process, the ionic activators develop nanosized porous structure deposits on the surface of the Ni electrode. Presented results point out a strong possibility of the usage of ternary ionic activators in industrial applications.
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•Ternary Ni(en)Cu(ox)Mo system used as ionic activator.•Highly developed surface of electrode, sponge pattern with needle like nanometar structure.•Energy saving in electrolytic hydrogen production more than 10%.
Policiklični aromatični ugljovodonici (engl. Polycyclic Aromatic Hydrocarbons, PAHs) predstavljaju grupu organskih jedinjenja koja se sastoje od dva ili više kondenzovanih benzenovih prstenova. ...Istraživanja ukazuju da PAH-ovi imaju kancerogen i mutagen uticaj na ljude i druge žive organizme. Perzistentni su i bioakumulativni i kao takvi predstavljaju opasnost po životnu okolinu.Dodatni problem predstavljaju proizvodi degradacije policikličnih aromatičnih ugljovodonika, koji nastaju tokom prirodne transformacije ili fizičko-hemijskih tretmana za njihovo uklanjanje. Novoformirana jedinjenja često imaju izraženiji toksični uticaj na ljude i druge žive organizme u poređenju sa polaznim jedinjenjem. Zato se posebna pažnja posvećuje razvoju novih metoda za njihovo što bezbednije uklanjanje. Do sada su razvijene metode za analizu sledećih kontaminiranih medijuma: voda, zemljište, vazduh, sedimenti i dr. Kako je zagađenost PAH-ovima u životnoj sredini rasla, uglavnom usled antropogenih faktora, tako su se pojavili i na drugim mestima, poput betona u stambenim zgradama.Cilj istraživanja doktorske disertacije je razvijanje nove, efikasne, neinvazivne metode za uklanjanje PAH-ova iz betona, koja je zasnovana na elektrohemijskoj oksidaciji. Da bi se osigurala bezbednost metode za praktičnu primenu, posebna pažnja posvećena je proceni toksičnosti PAH-a i njihovih produkata razgradnje nastalih tokom procesa elektrooksidacije.Kao laboratorijski model sistem za elektrohemijsku degradaciju PAH-ova koristi se elektrolitička ćelija sa niklenim elektrodama. Praćenje koncentracije PAH-ova u betonu izvedeno je primenom novopostavljene i validirane metode na uređaju tečni hromatograf ultravisokih performansi sa fotodiodnim detektorom (UPLCPDA). Efikasnost uklanjanja za pojedine PAH-ove dostiže vrednost i preko 90 %. Za procenu toksičnosti elektrohemijskog tretmana određuje se citotoksični i genotoksični potencijal na limfocitima i eritrocitima periferne krvi čoveka. Testoviobuhvataju određivanje učestalosti mikronukleusa i proliferacioniog potencijala ćelija, ispitivanje antioksidativne zaštite enzima (katalaze) kao i uticaja na oksidativni stres (određivanjem sadržaja malondialdehida).Rezultati ispitivanja potvrđuju toksičnost početne smeše PAH-ova - pre elektrohmijske oksidacije - uzrokujući značajno povećanje niva DNK oštećenja, smanjujući potencijal ćelija za deobu i indukujući oksidativni stres što se ogleda kroz povećanje malondialdehida u procesu lipidne peroksidacije ćelijskih membrana i povećanju aktivnosti katalaze, enzima antioksidativne odbrane. Procesom elektrohemijske oksidacije PAH-ova nastaju produkti koji ispoljavaju različit stepen citotoksičnosti zavisno od vremena nastanka. Najtoksičniji efekti su utvrđeni u prvih 15 minuta što se manifestuje kroz povećanje učestalosti genomskih ozleda, suprimiranje proliferativnog potencijala i/ili indukciju oksidativnog stresa, kao i značajanu modifikaciju aktivnosti enzima antioksidativne zaštite. Nakon 60 minuta produkti oksidacije su manje citotoksični u odnosu na početno jedinjenje, ali i dalje su toksičniji u poređenju sa netretiranom kontrolom.
The aim of this study is to evaluate the size and stability of radiolytically produced silver clusters. The clusters obtained by the gamma irradiation of a mixture of a silver salt and polyvinyl ...alcohol (PVA) were studied both theoretically and by mass spectrometry. MALDI TOF mass spectrometry of the Agn clusters showed the presence of clusters containing between 5 and 29 atoms. Both the theoretical and experimental results of this paper show that the most stable clusters are small clusters with an odd number of atoms. The stability of these clusters is correlated with the cluster's electronic configuration.
► The size and the stability of radiolytically produced silver clusters were examined. ► The clusters were studied by mass spectrometry and theoretically. ► Mass spectrometry showed the presence of clusters containing 5–29 atoms. ► The most stable clusters are the small clusters with an odd number of atoms.
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