Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 139
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Sensors (Basel) ; 20(9)2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-32397177

RESUMO

Threatened preterm labor (TPL) is the most common cause of hospitalization in the second half of pregnancy and entails high costs for health systems. Currently, no reliable labor proximity prediction techniques are available for clinical use. Regular checks by uterine electrohysterogram (EHG) for predicting preterm labor have been widely studied. The aim of the present study was to assess the feasibility of predicting labor with a 7- and 14-day time horizon in TPL women, who may be under tocolytic treatment, using EHG and/or obstetric data. Based on 140 EHG recordings, artificial neural networks were used to develop prediction models. Non-linear EHG parameters were found to be more reliable than linear for differentiating labor in under and over 7/14 days. Using EHG and obstetric data, the <7- and <14-day labor prediction models achieved an AUC in the test group of 87.1 ± 4.3% and 76.2 ± 5.8%, respectively. These results suggest that EHG can be reliable for predicting imminent labor in TPL women, regardless of the tocolytic therapy stage. This paves the way for the development of diagnostic tools to help obstetricians make better decisions on treatments, hospital stays and admitting TPL women, and can therefore reduce costs and improve maternal and fetal wellbeing.


Assuntos
Trabalho de Parto , Trabalho de Parto Prematuro , Tocólise , Útero , Feminino , Humanos , Recém-Nascido , Monitorização Fisiológica , Trabalho de Parto Prematuro/diagnóstico , Trabalho de Parto Prematuro/tratamento farmacológico , Gravidez , Prognóstico , Contração Uterina
2.
J Environ Manage ; 262: 110364, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32250826

RESUMO

In this work, a three-step process (adsorption-desorption-electrolysis) is evaluated as an interesting approach for the removal of organochlorinated compounds (clopyralid, lindane and perchloroethylene) with different physical properties (solubility and vapor pressure) from low concentrated wastewater. First steps are based on the adsorptive capacity of granular active carbon (GAC) particles to retain organics and on the solvent capacity of methanol to extract them to concentrated solution and regenerate GAC. In the last step of electrolysis with conductive diamond electrodes, the degradation of pesticide is projected, as well as the recovery of methanol. Results show that clopyralid, lindane and PCE are efficiently retained in GAC, although adsorption efficiency depend on pollutant/GAC ratio and physicochemical properties of pollutant. Pretreatment allows the concentration of clopyralid and PCE solutions up to 8 times, but worse results are obtained in case of lindane solutions. Electrolysis of concentrated methanol solution seems to be more efficient than electrolysis of diluted aqueous wastes, mainly in the case of clopyralid. In all cases, electrochemical degradation fits a first order kinetics confirming mixed oxidation mechanisms with diffusion control of the direct processes and mediated oxidation. Results obtained in terms of current efficiency and energy consumption of electrolysis step point out the lower operation cost of concentrated liquid wastes and encourage further works on the development of cost-effective combined processes for the treatment of diluted solutions polluted with polar compounds (such as clopyralid).


Assuntos
Poluentes Químicos da Água , Adsorção , Eletrodos , Eletrólise , Oxirredução , Águas Residuárias
3.
J Environ Manage ; 265: 110566, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32275236

RESUMO

This work focuses on disinfection of water using electrolysis with diamond coatings avoiding or minimizing the formation of hazardous chlorates and perchlorates using a special type of commercial cells designed by CONDIAS (Itzehoe, Germany) in two different sizes: the CabECO and the MIKROZON cells. In these cells, the electrolyte that separates the anode and cathode is a proton exchange membrane. This helps to minimize the production of perchlorate and this behavior is enhanced in the smallest cell for which the very low contact times between the electrodes and the water allows to avoid the production of perchlorates when operating in a single-pass mode, which becomes a really remarkable point. In this paper, we report tests in which we demonstrate this outstanding performance and we also explain the differences observed in the two cells operating with the same water.


Assuntos
Cloratos , Poluentes Químicos da Água , Diamante , Desinfecção , Eletrodos , Alemanha , Oxirredução , Percloratos
4.
J Environ Manage ; 233: 768-773, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30318156

RESUMO

This work focuses on the evaluation of the electrochemical dewatering of sludge polluted with model hazardous species. To do this, two sludge samples taken from the outlet of the anaerobic digesters of the municipal Wastewater Treatment Facility of Ciudad Real were polluted with herbicide clopyralid (CP) and with antibiotics amoxicillin (AMX) and ampicillin (AMP), respectively. These sludge samples underwent first dewatering by press filtration and then, the dewatering continued by the application of an electrochemically assisted driven process with increasing electric fields (1.0, 2.0 and 3.0 V cm-1). Results demonstrate that the electrochemically-assisted process can help to exhaust the pollutant adsorbed onto the sludge and attain a supplemental removal (up to 15%) of water in both cases. This is a highly important result, because it can help to develop technologies for sludge treatment that avoid the diffusion of hazardous pollution during the land application of the sludge. No reactivity of the pollutants was observed during the tests.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Eletricidade , Filtração , Águas Residuárias , Água
5.
J Environ Manage ; 231: 570-575, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30388654

RESUMO

This work presents a techno-economic study of the scaling-up of the electrochemically-assisted soil remediation (EASR) process of polluted soil. Four scales have been selected for the study: laboratory, bench, pilot and prototype, with a capacity of treating a volume of soil of 1 × 10-4, 2 × 10-3, 0.11 and 21.76 m3, respectively. This study analyses the technical information produced by studies carried out at each scale, and informs about the fixed costs (construction of the electrokinetic remediation reactor, installation of auxiliary services and purchase of analytical equipment) and variable costs (start-up, operation and dismantling of the test) derived from running a test at each of the evaluated scales. The information discussed in based on the experience gained with many evaluations carried out over the last decade at these scales. This information can provide useful guidance for developing a scaling-up of the EASR for many researchers starting on the evaluation of this important environmental remediation technology.


Assuntos
Recuperação e Remediação Ambiental , Poluentes do Solo , Poluição Ambiental , Solo
6.
J Environ Manage ; 222: 135-140, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29807263

RESUMO

This work presents the design and evaluation of a new concept of pre-disinfection treatment that is especially suited for highly polluted surface water and is based on the combination of coagulation-flocculation, lamellar sedimentation and filtration into a single-column unit, in which the interconnection between treatments is an important part of the overall process. The new system, the so-called PREDICO (PRE-DIsinfection Column) system, was built with low-cost consumables from hardware stores (in order to promote in-house construction of the system in poor countries) and was tested with a mixture of 20% raw wastewater and 80% surface water (in order to simulate an extremely bad situation). The results confirmed that the PREDICO system helps to avoid fouling in later electro-disinfection processes and attains a remarkable degree of disinfection (3-4 log units), which supplements the removal of pathogens attained by the electrolytic cell (more than 4 log units). The most important sizing parameters for the PREDICO system are the surface loading rate (SLR) and the hydraulic residence time (HRT); SLR values under 20 cm min-1 and HRT values over 13.6 min in the PREDICO system are suitable to warrant efficient performance of the system.


Assuntos
Águas Residuárias , Purificação da Água , Desinfecção , Filtração , Poluição da Água
7.
J Environ Manage ; 195(Pt 2): 216-223, 2017 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-27530074

RESUMO

Wastewater produced in pharmaceutical manufacturing plants (PMPs), especially the one coming from organic-synthesis facilities, is characterized by its large variability due to the wide range of solvents and chemical reagents used in the different stages of the production of medicines. Normally, the toxicity of the organic compounds prevent the utilization of biological processes and more powerful treatments are needed becoming advanced oxidation processes (AOPs) a valid alternative. In this work, the efficiency in abatement of pollution by Fenton oxidation (FO) and conductive-diamond electro-oxidation (CDEO) are compared in the treatment of 60 real effluents coming from different processes carried out in a pharmaceutical facility, using standardized tests. In 80% of the samples, CDEO was found to be more efficient than FO and in the remaining 20%, coagulation was found to exhibit a great significance in the COD abatement mechanism during FO, pointing out the effectiveness of the oxidation promoted by the electrochemical technology. Mean oxidation state of carbon was found to be a relevant parameter to understand the behavior of the oxidation technologies. It varied inversely proportional to efficiency in FO and it showed practically no influence in the case of CDEO.


Assuntos
Diamante/química , Eliminação de Resíduos Líquidos , Indústria Farmacêutica , Peróxido de Hidrogênio/química , Ferro/química , Oxirredução , Poluentes Químicos da Água
8.
J Clin Pharm Ther ; 41(2): 203-8, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26916590

RESUMO

WHAT IS KNOWN AND OBJECTIVE: It is well known that medication reconciliation at discharge is a key strategy to ensure proper drug prescription and the effectiveness and safety of any treatment. Different types of interventions to reduce reconciliation errors at discharge have been tested, many of which are based on the use of electronic tools as they are useful to optimize the medication reconciliation process. However, not all countries are progressing at the same speed in this task and not all tools are equally effective. So it is important to collate updated country-specific data in order to identify possible strategies for improvement in each particular region. Our aim therefore was to analyse the effectiveness of a computerized pharmaceutical intervention to reduce reconciliation errors at discharge in Spain. METHODS: A quasi-experimental interrupted time-series study was carried out in the cardio-pneumology unit of a general hospital from February to April 2013. The study consisted of three phases: pre-intervention, intervention and post-intervention, each involving 23 days of observations. At the intervention period, a pharmacist was included in the medical team and entered the patient's pre-admission medication in a computerized tool integrated into the electronic clinical history of the patient. The effectiveness was evaluated by the differences between the mean percentages of reconciliation errors in each period using a Mann-Whitney U test accompanied by Bonferroni correction, eliminating autocorrelation of the data by first using an ARIMA analysis. In addition, the types of error identified and their potential seriousness were analysed. RESULTS AND DISCUSSION: A total of 321 patients (119, 105 and 97 in each phase, respectively) were included in the study. For the 3966 medicaments recorded, 1087 reconciliation errors were identified in 77·9% of the patients. The mean percentage of reconciliation errors per patient in the first period of the study was 42·18%, falling to 19·82% during the intervention period (P = 0·000). When the intervention was withdrawn, the mean percentage of reconciliation errors increased again to 27·72% (P = 0·008). The difference between the percentages of pre- and post-intervention periods was statistically significant (P = 0·000). Most reconciliation errors were due to omission (46·7%) or incomplete prescription (43·8%), and 35·3% of which could have caused harm to the patient. WHAT IS NEW AND CONCLUSION: A computerized pharmaceutical intervention is shown to reduce reconciliation errors in the context of a high incidence of such errors.


Assuntos
Análise de Séries Temporais Interrompida/métodos , Sistemas Computadorizados de Registros Médicos , Erros de Medicação/prevenção & controle , Reconciliação de Medicamentos/métodos , Serviço de Farmácia Hospitalar/métodos , Idoso , Idoso de 80 Anos ou mais , Prescrições de Medicamentos , Feminino , Hospitalização , Humanos , Masculino , Admissão do Paciente , Alta do Paciente , Farmacêuticos , Espanha
9.
J Environ Manage ; 171: 128-132, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26861224

RESUMO

In this work, it is studied a wind-powered electrokinetic soil flushing process for the removal of pesticides from soil. This approach aims to develop an eco-friendly electrochemical soil treatment technique and to face the in-situ treatment of polluted soils at remote locations. Herbicide 2,4 dichlorophenoxyacetic acid (2,4-D) is selected as a model pollutant for the soil treatment tests. The performance of the wind-powered process throughout a 15 days experiment is compared to the same remediation process powered by a conventional DC power supply. The wind-powered test covered many different wind conditions (from calm to near gale), being performed 20.7% under calm conditions and 17% under moderate or gentle breeze. According to the results obtained, the wind-powered soil treatment is feasible, obtaining a 53.9% removal of 2,4-D after 15 days treatment. Nevertheless, the remediation is more efficient if it is fed by a constant electric input (conventional DC power supply), reaching a 90.2% removal of 2,4-D with a much lower amount of charge supplied (49.2 A h kg(-1) and 4.33 A h kg(-1) for wind-powered and conventional) within the same operation time.


Assuntos
Ácido 2,4-Diclorofenoxiacético/análise , Técnicas Eletroquímicas/métodos , Recuperação e Remediação Ambiental/métodos , Herbicidas/análise , Poluentes do Solo/análise , Vento , Concentração de Íons de Hidrogênio , Solo/química
10.
J Environ Manage ; 158: 36-9, 2015 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-25950835

RESUMO

In the search for greener treatment technologies, this work studies the coupling of a wind turbine energy supply with an electrolytic cell (CWTEC device) for the remediation of wastewater polluted with pesticide 2,4-dichlorophenoxyacetic acid (2,4-D). The discontinuous and unforeseeable supply of energy is the main challenge inspiring this new proposal, which aims at reducing the environmental impact of electrolytic treatment by using a green energy supply. The results obtained using the coupled technologies are compared with those obtained by powering the electrolyser with a traditional power supply with a similar current intensity. The mineralisation of wastewater can be accomplished independently of how the electrolytic cell is powered, although differences in performance are clearly observed in the total organic carbon (TOC) and 2,4-D decays. These changes can be explained in terms of the changing profile of the current intensity, which influences the concentrations of the oxidants produced and thereby the mediated electrolytic process.


Assuntos
Técnicas Eletroquímicas , Herbicidas/química , Águas Residuárias/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Vento , Boro , Diamante , Eletrodos , Humanos
11.
Genet Mol Res ; 12(2): 2138-47, 2013 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-23913391

RESUMO

Brazil has only one public genetic pool of Bombyx mori strains, which was established in 2005 at Universidade Estadual de Maringá, Maringá, Paraná State. This genetic bank has been maintained, and the strains have been characterized using genetic and morphological tools. The quantitative and qualitative traits, directly or indirectly related to productivity, were evaluated in 14 silkworm strains. In addition to biological and productivity analyses, DNA markers related to susceptibility to the B. mori nucleopolyhedrovirus (BmNPV) were analyzed. BmNPV is a major cause of production loss and is a serious problem for Paraná sericulture. The silkworm strains from diverse geographic origins were found to have different characteristics, including body weight, larval stage duration, cocoon weight, and other biological traits. In terms of productivity, the raw silk percentages were almost uniform, with an overall average of 16.28%. Overall, the Chinese strain C37 gave the best performance in many of the quantitative traits, and it surpassed the other strains in productivity traits. Therefore, it can be used as one of the strains that compose the elite germplasm for silkworm breeding programs. Additionally, genetic molecular markers were efficient in discriminating between B. mori strains that had been identified based on their geographical origin. We found that all Japanese strains produced a 400-bp molecular marker that has been associated with susceptibility to BmNPV.


Assuntos
Bombyx/genética , Bombyx/fisiologia , Marcadores Genéticos , Nucleopoliedrovírus/fisiologia , Animais , Bancos de Espécimes Biológicos , Bombyx/anatomia & histologia , Bombyx/virologia , Brasil , Cruzamento , Bases de Dados Genéticas , Larva/anatomia & histologia , Larva/genética , Larva/fisiologia , Característica Quantitativa Herdável , Seda , Têxteis
12.
Drug Dev Ind Pharm ; 39(2): 310-20, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23323873

RESUMO

Due to their crystalline nature, the encapsulation of hydrophobic corticosteroids within polymeric nanoparticles by o/w solvent evaporation method is often difficult to achieve. The aim of this study was to evaluate the effect of both process and formulation parameters on the encapsulation of a model corticosteroid: methylprednisolone (MP). For this purpose, a 3(2)factorial design was performed evaluating the effects of the concentration of emulsifiers and sonication time on the manufactured nanoparticles, followed by a multiresponse optimization. The study also included the evaluation of other parameters such as the type of organic solvent used, polymer characteristics and the initial mass of drug. The optimal nanoparticle formulation using 0.25% (w/v) of emulsifying agent (Polyvinyl-alcohol, PVA) and 5 min of sonication was then characterized. The highest encapsulation was obtained with an organic phase consisting of acetone: dichloromethane (1:1), polyD,L-lactide-co-glycolide (PLGA) 50:50 as polymer and an initial mass of 6.6 mg of methylprednisolone. Nanoparticles size and ζ potential of optimized formulation were respectively around 230 nm and -14 mV. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) demonstrated that the drug was molecularly dispersed within the nanoparticles. Release study showed that MP-loaded nanoparticles sustained drug release for up to 120 h. This study reflects the importance of factorial design to optimize the manufacture of nanoparticles encapsulating hydrophobic drugs.


Assuntos
Anti-Inflamatórios/química , Metilprednisolona/química , Nanopartículas/química , Biodegradação Ambiental , Composição de Medicamentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Polímeros/química
14.
Behav Anal Pract ; 16(1): 93-101, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37006437

RESUMO

Parents and caregivers of individuals with autism spectrum disorders (ASD) are faced with a vast array of treatment options, which vary greatly in evidence-based merits, and it is unclear what factors affect their final selections. Understanding the factors that influence family decisions can shed light on avenues for more effectively communicating the importance of selecting empirically supported treatments. In this article, we conducted a systematic literature review on how parents select evidence-based treatments for their children with ASD. We categorized treatment types using a combination of established resources, such as the National Standards Project (NSP), to determine the validity of research evidence for different ASD treatments. We reported the various treatment types, decision-making factors, and sources of recommendations across the literature, and compared those with earlier systematic literature reviews. The results of the present review indicate that parents' decisions are influenced by the accessibility of treatment, trust of practitioners, and alignment on factors such as parental values and the child's specific needs. We conclude with suggestions for practitioners and researchers on future research and wider adoption of evidence-based treatments (EBTs).

15.
Chemosphere ; 287(Pt 3): 132334, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34563766

RESUMO

In previous works, a low-cost predisinfection column that combined coagulation-flocculation and GAC filtration was proposed for combination with electrodisinfection in the successful treatment of highly faecal polluted surface water. In this work, this column is adapted for the treatment of pore water by transforming the coagulation chamber into a chemical reactor with lime and replacing the GAC of the filter with ion exchange resins. This adapted system can soften water, remove nitrate and condition water for very efficient electrochemical disinfection, where 4 logs and 3 logs in the removal of E. coli and P. aeruginosa, respectively, were reached using commercial electrochemical cells, i.e., CabECO ® or MIKROZON®. The availability and low cost of the technology are strong points for usage in poor areas of developing countries.


Assuntos
Água Potável , Poluentes Químicos da Água , Purificação da Água , Desinfecção , Escherichia coli , Filtração , Poluentes Químicos da Água/análise
16.
Chemosphere ; 289: 133141, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34871614

RESUMO

This work focuses on increasing the TRL of electro-ozonizer technology by evaluating the effect of electrolyte composition and operation conditions on the production of ozone, using an actual commercial cell, CONDIAPURE®, in conditions similar to what could be expected in a real application. Not only is attention paid to the changes in the concentration of ozone in the liquid phase, but also to those observed in the gas phase. The electrolyte and its recirculation flowrate, as well as operation temperatures and pressures are found to have significant influence on production rates. The most efficient way to produce ozone is operating at low temperatures and high pressures. In this work, 0.25 and 0.21 mg O3/min were obtained operating at 10 A in electrolytes consisting of aqueous solutions of perchloric and sulfuric acid, respectively, in tests carried out at 13 °C and 2 bars of gauge pressure. The negative effect of scavengers that appear electrochemically along the production of ozone is very important and seems to be partially compensated when organics are present in the solution due to the competition between the reaction of these scavengers with ozone or organics.


Assuntos
Ozônio , Poluentes Químicos da Água , Tecnologia , Temperatura , Água , Poluentes Químicos da Água/análise
17.
Br J Anaesth ; 107(4): 593-600, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21743068

RESUMO

BACKGROUND: The performance of eight currently available paediatric propofol pharmacokinetic models in target-controlled infusions (TCIs) was assessed, in healthy children from 3 to 26 months of age. METHODS: Forty-one, ASA I-II children, aged 3-26 months were studied. After the induction of general anaesthesia with sevoflurane and remifentanil, a propofol bolus dose of 2.5 mg kg(-1) followed by an infusion of 8 mg kg(-1) h(-1) was given. Arterial blood samples were collected at 1, 2, 3, 5, 10, 20, 40, and 60 min post-bolus, at the end of surgery, and at 1, 3, 5, 30, 60, and 120 min after stopping the infusion. Model performance was visually inspected with measured/predicted plots. Median performance error (MDPE) and the median absolute performance error (MDAPE) were calculated to measure bias and accuracy of each model. RESULTS: Performance of the eight models tested differed markedly during the different stages of propofol administration. Most models underestimated propofol concentration 1 min after the bolus dose, suggesting an overestimation of the initial volume of distribution. Six of the eight models tested were within the accepted limits of performance (MDPE<20% and MDAPE<30%). The model derived by Short and colleagues performed best. CONCLUSIONS: Our results suggest that six of the eight models tested perform well in young children. Since most models overestimate the initial volume of distribution, the use for TCI might result in the administration of larger bolus doses than necessary.


Assuntos
Anestésicos Intravenosos/farmacocinética , Propofol/farmacocinética , Algoritmos , Anestésicos Intravenosos/sangue , Calibragem , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Fenda Labial/cirurgia , Fissura Palatina/cirurgia , Interpretação Estatística de Dados , Feminino , Humanos , Lactente , Masculino , Modelos Estatísticos , Monitorização Intraoperatória , Propofol/sangue , Estudos Prospectivos , Valores de Referência , Reprodutibilidade dos Testes
18.
J Hazard Mater ; 417: 126078, 2021 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-33992923

RESUMO

This work aims to shed light on the scale-up a combined electrokinetic soil flushing process (EKSF) with permeable reactive barriers (PRB) for the treatment of soil spiked with clopyralid. To do this, remediation tests at lab (3.45 L), bench (175 L) and pilot (1400 L) scales have been carried out. The PRB selected was made of soil merged with particles of zero valent iron (ZVI) and granular activated carbon (GAC). Results show that PRB-EKSF involved electrokinetic transport and dehalogenation as the main mechanisms, while adsorption on GAC was not as relevant as initially expected. Clopyralid was not detected in the electrolyte wells and only in the pilot scale, significant amounts of clopyralid remained in the soil after 600 h of operation. Picolinic acid was the main dehalogenated product detected in the soil after treatment and mobilized by electro-osmosis, mostly to the cathodic well. The transport of volatile compounds into the atmosphere was promoted at pilot scale because of the larger soil surface exposed to the atmosphere and the electrical heating caused by ohmic losses and the larger interelectrode gap.


Assuntos
Recuperação e Remediação Ambiental , Herbicidas , Poluentes do Solo , Carvão Vegetal , Solo , Poluentes do Solo/análise
19.
Chemosphere ; 279: 130525, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33866102

RESUMO

This work focuses on the treatment of gaseous perchloroethylene (PCE) using electro-scrubbing with diamond electrodes and cobalt mediators. PCE was obtained by direct desorption from an aqueous solution containing 150 mg L-1, trying to a real pollution case. The electro-scrubber consisted of a packed absorption column connected with an undivided electrochemical cell. Diamond anodes supported on two different substrates (tantalum and silicon) were used and the results indicated that Ta/BDD was more successful in the production of Co (III) species and in the degradation of PCE. Three experimental systems were studied for comparison purposes: absorbent free of Co (III) precursors, absorbent containing Co (III) precursors, and absorbent containing Co (III) precursors undergoing previous electrolysis to the electro-scrubbing to facilitate the accumulation of oxidants. The most successful option was the last, confirming the important role of mediated electrochemical processes in the degradation of PCE. Trichloroacetic acid (TCA) and carbon tetrachloride (CCl4) were found as the primary reaction products and ethyl chloroacetate esters were also identified. A comprehensive mechanism of the processes happening inside electro-scrubber is proposed.


Assuntos
Tetracloroetileno , Poluentes Químicos da Água , Cobalto , Diamante , Eletrodos , Eletrólise , Gases , Oxirredução
20.
Chemosphere ; 238: 124854, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31549676

RESUMO

This work focusses on the production of hydrogen peroxide and in the removal of bromacil by the electro-Fenton process using two different electrochemical cells: mixed tank cell (MTC) and flow-through cell (FTC). Both cells use boron doped diamond (BDD) as anode and carbon felt as cathode to promote the formation of hydrogen peroxide. In the case of the MTC, two surface area ratios, Acathode/Aanode, have been used. Results show that the H2O2 produced by MTC and FTCPSC increases with the time until a stabilization state. For the FTCPSC, the average hydrogen peroxide concentration produced increases progressively with the current, while for MTC the maximum values are found in applying very low current densities. In addition, the FTCPSC provides higher concentrations of hydrogen peroxide for the same current density applied. Regarding the MTC, it can be stated that the higher the area of the cathode, the higher is the amount of H2O2 produced and the lower is the cell voltage (because of a more efficient current lines distribution). The initial oxidation of bromacil is very efficiently attained being rapidly depleted from wastewater. However, the higher production of hydrogen peroxide obtained by the FTCPSC cell does not reflect on a better performance of the electro-Fenton process. Thus, bromacil is better mineralized using the MTC cell with the lowest cathode area. This observation has been explained because larger concentrations of produced hydrogen peroxide seems to benefit the oxidation of intermediates and not the mineralization.


Assuntos
Bromouracila/análogos & derivados , Diamante/química , Peróxido de Hidrogênio/síntese química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Boro/química , Bromouracila/análise , Carbono/química , Condutividade Elétrica , Ferro/química , Oxirredução
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA