RESUMOA contaminação de águas por espécies tóxicas ou recalcitrantes gera grandes impactos ambientais. Nesse contexto, os Processos Oxidativos Avançados (POAs), tecnologias que utilizam principalmente o radical hidroxila (HO • ) para a oxidação dos poluentes, têm se destacado como métodos alternativos promissores no tratamento de águas residuais e efluentes industriais. Os POAs têm sido considerados uma estratégia eficaz do ponto de vista técnico, econômico e ambiental para a degradação de poluentes presentes em águas residuais e efluentes industriais, apesar de possuir limitações como alto custo das fontes de energia, desenvolvimento de novos materiais catalíticos de baixo custo e construção de reatores em escala real. Há uma grande relevância na aplicação desses processos em escala industrial mediante a otimização desses fatores de eficácia. Sendo assim, o objetivo deste trabalho foi realizar um levantamento bibliográfico sobre os POAs e apresentar dados a respeito da eficiência desses processos na degradação de poluentes, comparando os embasamentos teóricos e a sua aplicação industrial. Diante disso, os fundamentos e aplicações dos principais POAs (químicos, fotoquímicos, eletroquímicos, sonoquímicos, sonoeletroquímico e processos baseados em ozônio), bem como suas vantagens e desvantagens foram descritos nesta revisão da literatura.
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 2 factorial design and the optimum process conditions (1.73 mol L and 0.56 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 ∼98% and removal of atrazine to levels below the detection limit (>99%) in under 30 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.
The present work had as its objective, the evaluation of the combination of electrochemical, photochemical and sonrochemical techniques (sono-electrochemical photoassisted) applied to degradation of cytarabine (chemotherapeutic drug) in a simulated urine that continues with creatinine and laboratory research. The paper involved laboratory research with both a qualitative and quantitative approach. A continuous-flow filter-press electrochemical reactor was employed using Dimensionally Stable Anode (DSA® - Ti/Ru0.3Ti0.7O2) as the electrode material. A 23 factorial design was used to optimize the degradation of organic compounds contained in artificial urine (creatinine and urea) together with cytarabine, varying applied current, retention time and flow rate, the response variable was total organic carbon (TOC) removal. Additionally, UHPLC analyses demonstrated the removal of ancitabine (precursor of cytarabine), corroborating with the data obtained by the from the experimental design. The use of artificial urine as an electronic support interferes with the electrochemical process, taking TOC to high levels. However, it was observed that there was significant removal of the organic load present in the effluent solution, even when a more complex degradation matrix is used (artificial urine).
The objective of this paper was to examine the adsorption of the antibiotic ciprofloxacin (CIP) in a calcined Verdelodo (CVL) clay-packed fixed-bed system. The characterization study of the fresh and contaminated clay indicated filling of the clay pores by the CIP (pore volume decreased from 65.4 to 31.1 cm 3 g −1 ) and did not evidence significant changes in the clay texture. The fixed-bed system reached a breakthrough adsorption capacity of 0.038 mmol g −1 (12.6 mg g −1 ) and a mass transfer zone of 4.29 cm. Five mathematical models were fitted to the breakthrough curves, and the dual-site diffusion displayed the best fit to the experimental data (R 2 > 0.98). The adsorption performance of CIP was compared to that of the antibiotic ofloxacin, reported in the literature, in which density functional theory (DFT) computations were performed to clarify the particularities of the adsorption of both compounds onto CVL clay.
IntroductionThe inflation pressure of the endotracheal tube cuff can cause ischemia of the
tracheal mucosa at high pressures; thus, it can cause important tracheal morbidity
and tracheal microaspiration of the oropharyngeal secretion, or it can even cause
pneumonia associated with mechanical ventilation if the pressure of the cuff is
insufficient.ObjectiveIn order to investigate the effectiveness of the RUSCH® 7.5 mm endotracheal tube
cuff, this study was designed to investigate the physical and mechanical aspects
of the cuff in contact with the trachea.MethodsFor this end, we developed an in vitro experimental model to assess the flow of
dye (methylene blue) by the inflated cuff on the wall of the artificial material.
We also designed an in vivo study with 12 Large White pigs under endotracheal
intubation. We instilled the same dye in the oral cavity of the animals, and we
analyzed the presence or not of leakage in the trachea after the region of the
cuff after their deaths (animal sacrifice). All cuffs were inflated at the
pressure of 30 cmH2O.ResultsWe observed the passage of fluids through the cuff in all in vitro and in vivo
experimental models.ConclusionWe conclude that, as well as several other cuff models in the literature, the
RUSCH® 7.5 mm tube cuffs are also not able to completely seal the trachea and thus
prevent aspiration of oropharyngeal secretions. Other prevention measures should
be taken.
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.
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