Removal of emerging contaminants, such as antibiotics, from wastewater by adsorption is a simple, low-cost, and high-performance process; however, regeneration and reuse of the exhausted adsorbent are necessary to make the process economically viable. This study aimed to investigate the possibility of electrochemical-based regeneration of clay-type materials. For this, the calcined Verde-lodo (CVL) clay was saturated with the antibiotics ofloxacin (OFL) and ciprofloxacin (CIP) in one-component systems by an adsorption process and then subjected to photo-assisted electrochemical oxidation (0.45 A, 0.05 mol/L NaCl, UV-254 nm, and 60 min), which promotes both pollutant degradation and adsorbent regeneration. The external surface of the CVL clay was investigated by X-ray photoelectron spectroscopy before and after the adsorption process. The influence of regeneration time was evaluated for the CVL clay/OFL and CVL clay/CIP systems, and the results demonstrate high regeneration efficiencies after 1 h of photo-assisted electrochemical oxidation. Clay stability during regeneration was investigated by four successive cycles in different aqueous matrices (ultrapure water, synthetic urine, and river water). The results indicated that the CVL clay is relatively stable under the photo-assisted electrochemical regeneration process. Furthermore, CVL clay was able to remove antibiotics even in the presence of natural interfering agents. The hybrid adsorption/oxidation process applied here demonstrated the electrochemical-based regeneration potential of CVL clay for the treatment of emerging contaminants, since it can be operated quickly (1h of treatment) and with lower consumption of energy (3.93 kWh kg-1) than the traditional method of thermal regeneration (10 kWh kg-1).
Bentonite , Water Pollutants, Chemical , Clay/chemistry , Bentonite/chemistry , Ciprofloxacin , Ofloxacin , Adsorption , Anti-Bacterial Agents , Water , Water Pollutants, Chemical/analysis , Kinetics
The degradation of the chemotherapeutic drug cyclophosphamide in artificial urine was evaluated by Electrochemical Advanced Oxidation Processes (EAOP). The system consisted of an electrochemical flow reactor with a commercial DSA® electrode (nominal composition Ti / Ru0,3Ti0,7O2) and Ti-mesh cathode. In order to assess the best parameters, the effect of current density, time and flow rate were analyzed using an initial 23 factorial design. The chosen response variable was the energy efficiency to produce free chlorine species (HClO/ClO-). After obtaining the most significant factors, the Central Composite Design (CCD) was performed, where the optimum conditions were determined for the current density range (11.714â mAâ cm-2 and 66.57â mAâ cm-2), flow rate (31.33â mLâ min-1) and time range (19 and 37â min). Under an optimized condition, the efficiency of other combined methods (photo-assisted electrochemical, photochemical, sonoelectrochemical and photo-assisted sonoelectrochemical) was evaluated. The efficiency of degradation processes was determined by removal of Chemical Oxygen Demand (COD), creatinine and urea. Analysis by HPLC demonstrates that the cyclophosphamide was substantially removed during the treatment process of â¼77%. Based on these results, it can be observed that the coupling between electrochemical and photochemical processes is a promising alternative for the treatment of this effluent, as a marked reduction of organic matter is observed (63, 94% of creatinine, 29.62% of urea, 39.1% of TOC) and a low treatment cost ratio.
Water Pollutants, Chemical , Creatinine/analysis , Water Pollutants, Chemical/chemistry , Oxidation-Reduction , Chlorine/analysis , Chlorine/chemistry , Electrodes , Urea
The efficiency of electrolysis (EC/Cl2) and photo-assisted electrolysis (EC/UV/Cl2) methods, in the presence of chloride, for the abatement of real dairy waste from a producer in the Triangulo Mineiro region of Brazil, was evaluated. A complete 23 factorial design was performed for the variables time, pH and current. After determining the ideal pH, a Central Compound Design (CCD) was performed, where the applied current (533.42 mA) and treatment time (60.45 minutes) were maximized. The effluent was subsequently submitted to prolonged EC/Cl2 and EC/UV/Cl2 treatment in order to evaluate the behaviour of specific environmental parameters over time. The EC/UV/Cl2 method was more efficient than simple EC/Cl2 treatment. The EC/UV/Cl2 method resulted in a reduction of all environmental parameters investigated to levels within legal standards for effluent discharge. A relatively low cost of treatment is obtained with Energy per Order (EEO) values of 0.89 and 1.22 kWh m-3 order-1 for the EC/UV/Cl2 and EC/Cl2 treatments, respectively. The electrochemical production of free chlorine species followed by subsequent photolysis and production of radical species can convert a simple electrochemical process into an advanced oxidation process (AOP).
Water Pollutants, Chemical , Water Purification , Brazil , Chlorides , Electrolysis , Oxidation-Reduction , Waste Disposal, Fluid , Wastewater
The aim of the present study was to investigate the electrochemical formation of free chlorine species (HOCl/ClO-) and their subsequent use for the degradation of the pesticide atrazine. Initially, the process of electrochemical-free chlorine production was investigated using a bench-scale electrochemical flow-cell. The most significant variables (electrolyte concentration ([NaCl]) and inter-electrode gap) of the process were obtained using a 23 factorial design and the optimum process conditions (1.73â molâ L-1 and 0.56â cm) were determined by a central composite design. Following optimization of free chlorine production, three degradation techniques were investigated, individually and in combination, for atrazine degradation: electrochemical, photochemical and sonochemical. The method using the techniques in combination was denominated sono-photo-assisted electrochemical degradation. Constant current assays were performed and the sono-photo-assisted electrochemical process promoted more efficient removal of atrazine, achieving total organic carbon removal of â¼98% and removal of atrazine to levels below the detection limit (>99%) in under 30â min of treatment. Furthermore, the combination of three techniques displayed lower energy consumption, and phytotoxicity tests (Lactuca sativa) showed that there was no increase in toxicity.
Atrazine , Water Pollutants, Chemical , Water Purification , Chlorine , Electrochemical Techniques , Oxidation-Reduction , Ultraviolet Rays
The present paper presents the study of (1) the optimization of electrochemical-free chlorine production using an experimental design approach, and (2) the application of the optimum conditions obtained for the application in photo-assisted electrochemical degradation of simulated textile effluent. In the experimental design the influence of inter-electrode gap, pH, NaCl concentration and current was considered. It was observed that the four variables studied are significant for the process, with NaCl concentration and current being the most significant variables for free chlorine production. The maximum free chlorine production was obtained at a current of 2.33â A and NaCl concentrations in 0.96â molâ dm-3. The application of the optimized conditions with simultaneous UV irradiation resulted in up to 83.1% Total Organic Carbon removal and 100% of colour removal over 180â min of electrolysis. The results indicate that a systematic (statistical) approach to the electrochemical treatment of pollutants can save time and reagents.
Environmental Pollutants , Water Pollutants, Chemical , Chlorine , Electrolysis , Oxidation-Reduction , Research Design , Textile Industry
ABSTRACT: The effect of the incorporation of cinnamon (Cinnamomum cassia) and nut meg (Myristicafragrans) essential oils in alginate-based edible coatings that were applied on minimally processed apples, is reported. The minimum inhibitory concentrations were 1.25mg.mL-1 (cinnamon) and 2.50mg.mL-1 (nutmeg), against both Escherichia coli and Penicillium commune. Over storage periods there was a significant reduction in the E. coli and P. commune counts compared to the control. The extent of enzymatic browning was also significantly reduced in the coated samples. In the coated minimally processed apples sensory tests, the flavor had the lowest rating of the properties analyzed, for both treatments, followed by aroma and firmness.
RESUMO: O efeito da incorporação dos óleos essenciais de canela (Cinnamomum cassia) e noz-moscada (Myristicafragrans) em revestimentos comestíveis à base de alginato, aplicados em maçãs minimamente processadas é apresentado. As concentrações inibitórias mínimas foram de 1,25mg.mL-1 (canela) e 2,50mg.mL-1 (noz-moscada), contra Escherichia colie Penicillium commune. Durante o armazenamento, houve redução significativa nas contagens de E.coli e P. Commune em comparação com o controle. A extensão do escurecimento enzimático também foi significativamente reduzida nas amostras revestidas. Nas análises sensoriais, o sabor dos óleos essenciais apresentou a menor classificação das propriedades analisadas, tanto para os óleos essenciais, quanto para aroma e firmeza.
ABSTRACT: Medicated wound dressings are important barriers to avoid contamination and, when they contain antimicrobial additives, can be used as treatment for infected wounds. There are several types of polysaccharide materials that serve as matrices for medicated wound dressings, among them, sodium alginate. For the preparation of the films studied in this paper, sodium alginate was employed in combination with essential oils/oleoresins (EO/OL) of six peppers that are commonly used in cooking. The EO/OL were incorporated at three different concentrations (low, intermediate and high). Most of the films prepared had better dispersion of the EO/OL at the intermediate concentration. All films studied in this research were dissolved in water at different rates. The antibacterial activity of the prepared films showed significant results against Escherichia coli, Staphylococcus aureus and Bacillus cereus, and demonstrated that the films studied may be a new alternative for medicated wound dressings.
RESUMO: Os curativos medicamentosos são importantes barreiras para se evitar contaminação e ainda, quando contém aditivos antimicrobianos, servem como tratamento para ferimentos infectados. Existem vários tipos de materiais polissacarídicos que servem como matrizes para curativos medicamentosos, dentre eles, destaca-se o alginato de sódio. Para a preparação dos filmes estudados neste trabalho, utilizou-se alginato de sódio e incorporou-se óleos essenciais/oleoresinas (OE/OL) de seis pimentas utilizadas na culinária, em três diferentes concentrações. A maioria dos filmes preparados apresentou melhor dispersão dos OE/OL na concentração intermediária destes. Todos os filmes estudados neste trabalho apresentam solubilidade em água, em uma certa extensão. A atividade antibacteriana dos filmes preparados mostra resultados significantes contra Escherichia coli, Staphylococcus aureus e Bacillus Cereus, mostrando que os filmes estudados podem ser uma nova alternativa como curativos medicamentos.
ABSTRACT: Essential oils are the most important compounds produced during secondary metabolism in aromatic plants. Essential oils are volatile, have characteristic odor and are used as defensive agents by plants. In pepper, it is possible to say that essential oils are the “flavor fingerprint” of each species. In the present article, eight species of pepper were studied in order to extract their essential oils and oleoresins, test their antibacterial and antifungal activities and also to identify the compounds present in the most bioactive samples. Results demonstrated that two essential oils [Pimenta dioica (L.) Merr. and Schinus terebinthifolius] and three oleoresins (Schinus terebinthifolius and Piper nigrum white and black) recorded significant antimicrobial activity. These active essential oils and oleoresins are interesting for use in biotechnological processes employed in food, pharmaceutical and other industries.
RESUMO: Os óleos essenciais são os compostos mais importantes produzidos durante o metabolismo secundário de plantas aromáticas. No caso das pimentas, é possível afirmar que os óleos essenciais são a “impressão digital do sabor” de cada espécie. No presente artigo, oito espécies de pimenta foram estudadas a fim de extrair seus óleos essenciais e oleoresinas, testar a sua atividade antibacteriana e antifúngica, bem como, identificar os compostos presentes nas amostras mais ativas. Os resultados obtidos mostram que dois óleos essenciais (Pimenta dioica e Schinus terebinthifolius) e três oleoresinas (Schinus terebinthifolius e Piper nigrum branco e preto) apresentaram atividade antimicrobiana significativa. Esses óleos essenciais e oleoresinas bioativos mostram-se interessantes para a utilização em processos biotecnológicos empregados na indústria alimentar, farmacêutica e outras indústrias.
The influence of chloride ion concentration during the photo-assisted electrochemical degradation of simulated textile effluent, using a commercial Ti/Ru0.3Ti0.7O2 anode, was evaluated. Initially, the effect of applied current and supporting electrolyte concentration on the conversion of chloride ions to form reactive chlorine species in 90 min of experiment was analyzed in order to determine the maximum production of reactive chlorine species. The optimum conditions encountered (1.5 A and 0.3 mol dm(-3) NaCl) were subsequently employed for the degradation of simulated textile effluent. The efficiency of the process was determined through the analysis of chemical oxygen demand (COD), total organic carbon (TOC), of the presence of organochlorine products and phytotoxicity. Photo-assisted electrochemical degradation was more efficient for COD and TOC removal than the electrochemical technique alone. With simultaneous UV irradiation, a reduced quantity of reactive chlorine was produced, indicating that photolysis of the chlorine species led to the formation of hydroxyl radicals. This fact turns a simple electrochemical process into an advanced oxidation process.
Chlorine/chemistry , Electrolysis/methods , Photolysis , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/chemistry , Industrial Waste , Oxidation-Reduction , Textile Industry , Water Pollutants, Chemical/radiation effects
