Visible-Light-Driven AO7 Photocatalytic Degradation and Toxicity Removal at Bi-Doped SrTiO3.

In this study, Bi-doped SrTiO3 perovskites (Sr1-xBixTiO3, x = 0, 0.03, 0.05, 0.07 and 0.1) were synthesized using the solid-state method, characterized, and tested as photocatalysts in the degradation of the azo dye acid orange 7 (AO7) under visible light. The perovskites were successfully synthesized, and XRD data showed a predominant, well-crystallized phase, belonging to the cubic perovskite symmetry. For the doped samples, a minority phase, identified as bismuth titanate, was detected. All doped samples exhibited improved photocatalytic activity under visible light, on the degradation of AO7 (10 mg L-1), when compared with the undoped SrTiO3, with an increase in relative Abs484 nm decay from 3.7% to ≥67.8% after 1 h, for a powder suspension of 0.2 g L-1. The best photocatalytic activity was exhibited by the Sr0.95Bi0.05TiO3 perovskite. Reusability studies showed no significant loss in photocatalytic activity under visible light. The final solutions showed no toxicity towards D. magna, proving the efficiency of Sr0.95Bi0.05TiO3 as a visible-light-driven photocatalyst to degrade both the AO7 dye as well as its toxic by-products. A degradation mechanism is proposed.

Drug resistance and phylogenetic grouping of bacteria isolated from visitors' hands in a secondary-care hospital.

INTRODUCTION: Dynamic movement in the hospital environment promotes the transmission of nosocomial pathogens and multidrug resistance mechanisms through the dissemination of organisms that carry genetic determinants. Healthcare workers play an important role in the spread of pathogens; however, the role of visitors in this environment is poorly understood. OBJECTIVE: This study aimed to molecularly identify and examine the antibiotic resistance of the palmar microbiota of patients' companions in a hospital waiting room. METHODOLOGY: Twenty-five palmar surface and interdigital space sample swabs were randomly collected and cultured on blood agar plates, and 19 colonies with different macro- and microscopic characteristics were isolated. The V4 and V6 hypervariable regions of the 16S rRNA gene from each isolate were amplified by PCR and sequenced. Maximum likelihood- and Bayesian inference-based phylogenetic analyses were performed to determine taxonomic relationships. Antibiotic resistance was evaluated by disk diffusion and broth microdilution. RESULTS: Among the isolates, 52.6% were related to Bacillus, 36.8% to Staphylococcus, 5.3% to Enterococcus and 5.3% to Atlantibacter. All of the isolates exhibited ampicillin and penicillin resistance, while 94.7% also exhibited dicloxacillin resistance. Staphylococcus aureus was resistant to penicillins but sensitive to the remaining drugs. Bacteria identified as Bacillus subtilis (MLM14B99), Bacillus pumilus (MLM23B07 and MLM25B06), Staphylococcus epidermidis (MLM24S31 and MLM29S04), and Enterococcus (MLM22E08) showed resistance to at least 46.7% of the antibiotics. CONCLUSIONS: To decrease the transmission of pathogenic bacteria with an antibiotic resistance profile, re-evaluation of hand cleaning measures and their application by people who visit hospital centres is needed.

Sunlight-Driven AO7 Degradation with Perovskites (La,Ba)(Fe,Ti)O3 as Heterogeneous Photocatalysts.

Perovskites of the (La,Ba)(Fe,Ti)O3 family were prepared, characterized, and utilized as heterogeneous photocatalysts, activated by natural sunlight, for environmental remediation of Acid Orange 7 (AO7) aqueous solutions. Catalysts were prepared by the ceramic (CM) and the complex polymerization (CP) methods and characterized by XRD, SEM, EDS, and band gap energy. It was found that catalytic properties depend on the synthesis method and annealing conditions. In the photocatalytic assays with sunlight, different AO7 initial concentrations and perovskite amounts were tested. During photocatalytic assays, AO7 and degradation products concentrations were followed by HPLC. Only photocatalysis with BaFeO3-CM and BaTiO3-CP presented AO7 removals higher than that observed for photolysis. However, photolysis leads to the formation of almost exclusively amino-naphthol and sulfanilic acid, whereas some of the perovskites utilized form less-toxic compounds as degradation products, such as carboxylic acids (CA). Partial substitution of Ba by La in BaTiO3-CM does not produce any change in the photocatalytic properties, but the replacement of Ti by Fe in the La0.1Ba0.9TiO3 leads to reduced AO7 removal rate, but with the formation of CAs. The best AO7 removal (92%) was obtained with BaFeO3-CM (750 mg L-1), after 4 h of photocatalytic degradation with solar radiation.

Electro-Persulfate Processes for the Treatment of Complex Wastewater Matrices: Present and Future.

Complex wastewater matrices present a major environmental concern. Besides the biodegradable organics, they may contain a great variety of toxic chemicals, heavy metals, and other xenobiotics. The electrochemically activated persulfate process, an efficient way to generate sulfate radicals, has been widely applied to the degradation of such complex effluents with very good results. This review presents the fundamentals of the electro-persulfate processes, highlighting the advantages and limitations, followed by an exhaustive evaluation on the application of this process for the treatment of complex industrial effluents. An overview of the main relevant experimental parameters/details and their influence on the organic load removal is presented and discussed, having in mind the application of these technologies at an industrial scale. Finally, the future perspectives for the application of the electro-persulfate processes in the treatment of complex wastewater matrices is outlined.

Treatment of tannery effluent by chemical coagulation combined with batch-recirculated electro-oxidation at different anode materials.

The aim of this work was to evaluate the pollutant load from tannery effluents treated by chemical coagulation (CC) followed by electro-oxidation (EO), performed in two different experimental batch-recirculated setups, one with a BDD anode and the other with Ti/Pt/PbO2 and Ti/Pt/SnO2-Sb2O4 anodes (PS). Results were compared with those obtained from EO of the raw sample. CC was performed with a Fe3+ concentration of 0.25 g L-1, and the applied current densities for EO in each setup were 60 mA cm-2 for BDD and, in the PS setup, 20 and 40 mA cm-2 for Ti/Pt/SnO2-Sb2O4 and Ti/Pt/PbO2, respectively. During CC, removals of 27% in chemical oxygen demand (COD), 14% in total nitrogen, 100% in sulfide, and 73% in Cr(VI) were observed. COD removal in the EO of the raw sample was higher than that obtained for the combined CC + EO, for both setups, showing that the organic compounds removed by CC are mainly those that would be more easily removed by EO. For most of the other parameters related with carbon and nitrogen, the removals for CC + EO were higher than for EO alone. During EO, sulfide is converted to sulfate, especially with BDD. Concerning Cr(VI) concentration, it increases during EO, in particular for PS setup. Combined treatment, with both setups, proved to be an effective choice to treat tannery effluents.

Diclofenac photodegradation with the Perovskites BaFeyTi1-yO3 as catalysts.

Perovskite oxides BaFeyTi1-yO3, with y = 0, 0.6, 0.8 and 1, were prepared by ceramic (CM) and complex polymerization methods (CPM) and utilized in UV-LED (365 nm) photocatalytic degradation assays of 25 mg L-1 diclofenac (DIC) model solutions. BaTiO3-CM was also used in the photocatalytic degradation test of a real mineral water for human consumption spiked with 2 mg L-1 DIC. The XRD patterns of the synthesized perovskites showed cubic structure for those prepared by CPM, with distortions of the cubic lattice to hexagonal or tetragonal when prepared by CM, except for BaTiO3. All the perovskites showed good catalytic activity, higher than photolysis, except BaFeO3-CM that presented similar results. BaTiO3-CM and CPM and BaFeO3-CPM were also utilized in UV-LED photocatalytic DIC degradation assays with peroxydisulfate addition. BaFeO3-CPM and BaTiO3-CPM showed better ability to persulfate activation, but the highest mineralization degree was obtained with BaTiO3-CM. This last perovskite was also able to perform DIC degradation in a real matrix. The studied oxides show potentiality for photocatalytic degradation of organic compounds, with or without persulfate addition. A degradation mechanism is proposed.

Methiocarb Degradation by Electro-Fenton: Ecotoxicological Evaluation.

This paper studies the degradation of methiocarb, a highly hazardous pesticide found in waters and wastewaters, through an electro-Fenton process, using a boron-doped diamond anode and a carbon felt cathode; and evaluates its potential to reduce toxicity towards the model organism Daphnia magna. The influence of applied current density and type and concentration of added iron source, Fe2(SO4)3·5H2O or FeCl3·6H2O, is assessed in the degradation experiments of methiocarb aqueous solutions. The experimental results show that electro-Fenton can be successfully used to degrade methiocarb and to reduce its high toxicity towards D. magna. Total methiocarb removal is achieved at the applied electric charge of 90 C, and a 450× reduction in the acute toxicity towards D. magna, on average, from approximately 900 toxic units to 2 toxic units, is observed at the end of the experiments. No significant differences are found between the two iron sources studied. At the lowest applied anodic current density, 12.5 A m-2, an increase in iron concentration led to lower methiocarb removal rates, but the opposite is found at the highest applied current densities. The highest organic carbon removal is obtained at the lowest applied current density and added iron concentration.

Emerging contaminants removal from effluents with complex matrices by electrooxidation.

The electrooxidation of methiocarb and bisphenol A was studied in complex matrices, namely, simulated and real sanitary landfill leachate samples, using a boron-doped diamond anode. With simulated sanitary landfill leachate samples, the influence of the type and ratio of carbon source (glucose/humic acid) and electrolyte (NaCl or Na2SO4) on the emerging contaminants removal was assessed. Using real sanitary landfill leachate, the influence of current density was evaluated. The experimental results showed that electrooxidation, using a boron-doped diamond anode, can be successfully utilized to degrade methiocarb and bisphenol A when present in complex matrices, such as sanitary landfill leachate, and that methiocarb is more easily oxidized than bisphenol A. Furthermore, it was found that the presence of chloride and high humic acid content increases emerging contaminants removal rate, showing that electrooxidation at boron-doped diamond is particularly adequate to solve the problems raised by sanitary landfill leachate, even when contaminated with emerging contaminants.

Performance of Electrochemical Processes in the Treatment of Reverse Osmosis Concentrates of Sanitary Landfill Leachate.

Electrochemical technologies have been broadly applied in wastewaters treatment, but few studies have focused on comparing the performance of the different electrochemical processes, especially when used to treat highly-polluted streams. The electrochemical treatment of a reverse osmosis concentrate of sanitary landfill leachate was performed by means of electrocoagulation (EC), anodic oxidation (AO) and electro-Fenton (EF) processes, and the use of different electrode materials and experimental conditions was assessed. All the studied processes and experimental conditions were effective in organic load removal. The results obtained showed that EC, with stainless steel electrodes, is the cheapest process, although it presents the disadvantage of sludge formation with high iron content. At high applied current intensity, AO presents the best treatment time/energy consumption ratio, especially if the samples' initial pH is corrected to 3. However, pH correction from natural to 3 deeply decreases nitrogen-containing compounds' removal. For longer treatment time, the EF process with a carbon-felt cathode and a BDD anode, performed at natural iron content and low applied current intensity, is the most favorable solution.

Ecotoxicological evaluation of electrochemical oxidation for the treatment of sanitary landfill leachates.

In this study, the efficiency of electrochemical oxidation to treat a sanitary landfill leachate was evaluated by the reduction in physico-chemical parameters and in ecotoxicity. The acute toxicity of the sanitary landfill leachates, before and after treatment, was assessed with the model organism Daphnia magna. Electrochemical oxidation treatment was effective in the removal of organic load and ammonium nitrogen and in the reduction of metal ions concentrations. Furthermore, a reduction of 2.5-fold in the acute toxicity towards D. magna after 36 h of treatment was noticed. Nevertheless, the toxicity of the treated leachate is still very high, and further treatments are necessary in order to obtain a non-toxic effluent to this aquatic organism. Toxicity results were also compared with others described in the literature for different leachate treatments and test organisms.

Electro-Fenton oxidation of reverse osmosis concentrate from sanitary landfill leachate: Evaluation of operational parameters.

The electro-Fenton oxidation of a concentrate from reverse osmosis of a sanitary landfill leachate, with an initial chemical oxygen demand (COD) of 42 g L-1, was carried out using a carbon-felt cathode and a boron doped diamond anode. The influence of the applied current intensity, initial pH and dissolved iron initial concentration on the electro-Fenton process was assessed. For the experimental conditions used, results showed that the initial pH is the parameter that more strongly influences the current efficiency of the electro-Fenton process, being this influence more pronounced on the oxidation rate than on the mineralization rate of the organic matter. The increase in iron initial concentration was found to be detrimental, since the natural amount of iron present in the effluent, 73 mg L-1 of total iron and 61 mg L-1 of dissolved iron, was sufficient to ensure the electro-Fenton process at the applied intensities - 0.2-1.4 A. For the more favourable conditions studied, initial pH of 3 and natural iron concentration, it was found an increase in the organic load and nitrogen removals with the applied current intensity. For the highest current intensity applied, a COD removal of 16.7 g L-1 was achieved after 8-h experiments.

Electrochemical treatment of concentrate from reverse osmosis of sanitary landfill leachate.

Conventional sanitary landfill leachate treatment has recently been complemented and, in some cases, completely replaced by reverse osmosis technology. Despite the good quality of treated water, the efficiency of the process is low and a large volume of reverse osmosis concentrate has to be either discharged or further treated. In this study, the use of anodic oxidation combined with electro-Fenton processes to treat the concentrate obtained in the reverse osmosis of sanitary landfill leachate was evaluated. The anodic oxidation pretreatment was performed in a pilot plant using an electrochemical cell with boron-doped diamond electrodes. In the electro-Fenton experiments, a boron-doped diamond anode and carbon-felt cathode were used, and the influence of the initial pH and iron concentration were studied. For the experimental conditions, the electro-Fenton assays performed at an initial pH of 3 had higher organic load removal levels, whereas the best nitrogen removal was attained when the electrochemical process was performed at the natural pH of 8.8. The increase in the iron concentration had an adverse impact on treatment under natural pH conditions, but it enhanced the nitrogen removal in the electro-Fenton assays performed at an initial pH of 3. The combined anodic oxidation and electro-Fenton process is useful for treating the reverse osmosis concentrate because it is effective at removing the organic load and nitrogen-containing species. Additionally, this process potentiates the increase in the biodegradability index of the treated effluent.

Electrochemical wastewater treatment: influence of the type of carbon and of nitrogen on the organic load removal.

Boron-doped diamond (BDD) and Ti/Pt/PbO2 anodes were utilized to perform the electrodegradation of synthetic samples containing humic acid in the presence of different organic and inorganic carbon-containing and nitrogen-containing compounds. The influence of the chloride ion in the degradation process of the different synthetic samples was also assessed. The results showed that the anodic oxidation process can efficiently degrade recalcitrant compounds such as humic acid. The presence of carbonate in solution enhances the nitrogen removal, whereas it hinders the oxidation of the organic compounds. When organic nitrogen is present, it is converted to NH4+, which in turn is oxidized to nitrate and to volatile nitrogen compounds. Hydroxyl radicals are more prone to oxidize the organic nitrogen than the ammonium nitrogen. The presence of chloride enhances the organic matter and nitrogen removal rates, BDD being the anode material that yields the highest removals.

Ti/ß-PbO2 versus Ti/Pt/ß-PbO2: Influence of the platinum interlayer on the electrodegradation of tetracyclines.

The behaviors of the electrodes Ti/PbO2 and Ti/Pt/PbO2 as anodes in the electro-oxidation of two antibiotics-tetracycline and oxytetracycline-were evaluated at different applied current densities, to evaluate the influence of the Pt interlayer. In the preparation of the electrodes, the electrodeposited ß-PbO2 phase was homogeneous; no Ti or Pt peaks were detected in the diffractograms. The ß-PbO2 surface presented significant roughness when deposited over the Pt interlayer, which also conferred significant conductivity to the material. In the electro-oxidation assays, the COD, TOC and absorbance removals increased with the current density due to an increase in the concentration of hydroxyl radicals, for both electrode materials and antibiotics tested. Slightly better results were obtained with Ti/PbO2. The primary differences observed in the antibiotics concentration decay consisted of zero-order kinetics at the Ti/Pt/PbO2 anode and first-order kinetics at the Ti/PbO2 anode with a higher oxytetracycline concentration decay than the tetracycline concentration decay. A greater amount of total nitrogen was eliminated with the Ti/PbO2 electrode. At the Ti/Pt/PbO2 anode, the organic nitrogen primarily transformed into NH4(+) and the total nitrogen remained unchanged. The specific energy consumption with the Ti/Pt/PbO2 anode was significantly lower than the specific energy consumption with the Ti/PbO2 anode due to the higher electrical conductivity of the Ti/Pt/PbO2 anode. Both anode materials were also utilized in the electro-oxidation of a leachate sample collected at sanitary landfill and spiked with tetracycline, and the complete elimination of the antibiotic molecule was observed.

Electrochemical treatment of cork boiling wastewater with a boron-doped diamond anode.

Anodic oxidation at a boron-doped diamond anode of cork boiling wastewater was successfully used for mineralization and biodegradability enhancement required for effluent discharge or subsequent biological treatment, respectively. The influence of the applied current density (30-70 mA/cm2) and the background electrolyte concentration (0-1.5 g/L Na2SO4) on the performance of the electrochemical oxidation was investigated. The supporting electrolyte was required to achieve conductivities that enabled anodic oxidation at the highest current intensities applied. The results indicated that pollutant removal increased with the applied current density, and after 8 h, reductions greater than 90% were achieved for COD, dissolved organic carbon, total phenols and colour. The biodegradability enhancement was from 0.13 to 0.59 and from 0.23 to 0.72 for the BOD/COD ratios with BOD of 5 and 20 days' incubation period, respectively. The tests without added electrolyte were performed at lower applied electrical charges (15 mA/cm2 or 30 V) with good organic load removal (up to 80%). For an applied current density of 30 mA/cm2, there was a minimum of electric conductivity of 1.9 mS/cm (corresponding to 0.75 g/L of Na2SO4), which minimized the specific energy consumption.

[Continuous paravertebral block as an analgesic method in thoracotomy]. / Eficacia del bloqueo paravertebral continuo como método analgésico en la toracotomía.

INTRODUCTION: Open thoracotomy is one of the surgical procedures that is still very painful in the postoperative period, which, in this type of surgery can have on respiratory function and subsequent recovery of the patient. PATIENTS AND METHOD: The aim of the study is to assess continuous paravertebral thoracic block as an analgesic technique in thoracotomy. A total of 139 patients undergoing pulmonary resection surgery by posterolateral thoracotomy received postoperative analgesia using a 1.5% lidocaine infusion (7-10 ml/h) through a thoracic paravertebral catheter for at least 48 h. Pain intensity measured on the visual analogue scale (VAS) both at rest (passive VAS) and during stimulated cough (active VAS) was recorded at time of discharge from the Recovery Unit, and on the second, third and fourth day post-surgery. Postoperative complications and the need for analgesic rescue were studied. RESULTS: On discharge from recovery, 98.6% of the patients had mild pain (passive VAS <3), 1.4% had moderate pain (passive VAS 4-6) and none with severe pain (EVA >6); on the 2nd day post-surgery, 97.9% had mild pain, and 1.2% moderate pain; on the third day 98.6% had mild pain and 0.7% moderate pain; and on the 4th day 100% had mild pain. There were no complications arising from the analgesic technique. CONCLUSIONS: Continuous thoracic paravertebral analgesia is effective and safe in controlling post-thoracotomy pain.

Eficacia del bloqueo paravertebral continuo como método analgésico en la toracotomía / Continuous paravertebral block as an analgesic method in thoracotomy

Introducción: La toracotomía abierta es uno de los procedimientos quirúrgicos con postoperatorio más doloroso, hecho que en este tipo de cirugía puede repercutir sobre la función respiratoria y posterior recuperación del paciente. Paciente y método: El propósito del estudio es evaluar el bloqueo paravertebral contínuo torácico como técnica analgésica en la toracotomía. Ciento treinta y nueve pacientes sometidos a cirugía de resección pulmonar mediante toracotomía posterolateral recibieron analgesia postoperatopria mediante infusión de lidocaína al 1,5% (7–10ml/h) a través de un catéter paravertebral torácico y durante un mínimo de 48h. La intensidad del dolor mediante la escala analógica visual (EVA) tanto en reposo (EVA pasivo) como durante la tos incentivada (EVA activo), fue registrada al alta de la unidad de reanimación, al segundo, tercer y cuarto día postoperatorio. Se estudiaron las complicaciones postoperatorias y la necesidad de analgesia de rescate. Resultados: Al alta de reanimación un 98,6% de los pacientes presentaron un dolor leve (EVA pasivo <3 un 1 4 dolor moderado eva pasivo ndash 6 y 0 severo 6); en el 2.° día postoperatorio un 97,9% tuvieron un dolor leve, y un 1,2% dolor moderado; en el 3.er día un 98,6% un dolor leve y un 0,7% dolor moderado; y al 4° día un 100% presentaron dolor leve. No se encontraron complicaciones derivadas de la técnica analgésica. Conclusiones: La analgesia paravertebral torácica contínua es efectiva y segura en el control del dolor postoracotomía (AU)

Introduction: Open thoracotomy is one of the surgical procedures that is still very painful in the postoperative period, which, in this type of surgery can have on respiratory function and subsequent recovery of the patient. Patients and method: The aim of the study is to assess continuous paravertebral thoracic block as an analgesic technique in thoracotomy. A total of 139 patients undergoing pulmonary resection surgery by posterolateral thoracotomy received postoperative analgesia using a 1.5% lidocaine infusion (7–10ml/h) through a thoracic paravertebral catheter for at least 48h. Pain intensity measured on the visual analogue scale (VAS) both at rest (passive VAS) and during stimulated cough (active VAS) was recorded at time of discharge from the Recovery Unit, and on the second, third and fourth day post-surgery. Postoperative complications and the need for analgesic rescue were studied. Results: On discharge from recovery, 98.6% of the patients had mild pain (passive VAS <3 1 4 had moderate pain passive vas ndash 6 and none with severe eva 6); on the 2nd day post-surgery, 97.9% had mild pain, and 1.2% moderate pain; on the third day 98.6% had mild pain and 0.7% moderate pain; and on the 4th day 100% had mild pain. There were no complications arising from the analgesic technique. Conclusions: Continuous thoracic paravertebral analgesia is effective and safe in controlling post-thoracotomy pain (AU)