Enhanced degradation of Direct Red 80 dye via Fenton-like process mediated by cobalt ferrite: generated superoxide radicals and singlet oxygen.

Azo dyes, widely used in the textile industry, contribute to effluents with significant organic content. Therefore, the aim of this work was to synthesize cobalt ferrite (CoFe2O4) using the combustion method and assess its efficacy in degrading the azo dye Direct Red 80 (DR80). TEM showed a spherical structure with an average size of 33 ± 12 nm. Selected area electron diffraction and XRD confirmed the presence of characteristic crystalline planes specific to CoFe2O4. The amount of Co and Fe metals were determined by ICP-OES, indicating an n(Fe)/n(Co) ratio of 2.02. FTIR exhibited distinct bands corresponding to Co-O (455 cm-1) and Fe-O (523 cm-1) bonds. Raman spectroscopy detected peaks associated with octahedral and tetrahedral sites. For the first time, the material was applied to degrade DR80 in an aqueous system, with the addition of persulfate. Consistently, within 60 min, these trials achieved nearly 100% removal of DR80, even after the material had undergone five cycles of reuse. The pseudo-second-order model was found to be the most fitting model for the experimental data (k2 = 0.07007 L mg-1 min-1). The results strongly suggest that degradation primarily occurred via superoxide radicals and singlet oxygen. Furthermore, the presence of UV light considerably accelerated the degradation process (k2 = 1.54093 L mg-1 min-1). The material was applied in a synthetic effluent containing various ions, and its performance consistently approached 100% in the photo-Fenton system. Finally, two degradation byproducts were identified through HPLC-MS/MS analysis.

Green synthesis of Fe0 nanoparticles using Eucalyptus grandis leaf extract: Characterization and application for dye degradation by a (Photo)Fenton-like process.

Zero-valent iron nanoparticles (EGnZVI) were synthesized using Eucalyptus grandis (EG) leaf extract as a reducing/stabilizing agent. The studied materials (EG leaves, extract and EGnZVI) were characterized using the XRD, FTIR, Raman spectroscopy, SEM, TEM/EDS techniques. The results indicate that several organic compounds, including phenolics, present in the EG leaves were successfully extracted and incorporated into the structure of the material, possibly promoting the capping and stabilization of the formed zero-valent iron particles. The EGnZVI presented low crystallinity, varied size (50-500 nm), approximately spherical shape, and formed aggregates. The EGnZVI were utilized in the removal of the Direct Red 80 (DR80), an azo dye. The effects of the temperature (15-35 °C), initial DR80 concentration (10-250 mg L-1), initial pH (2.5-8.5), the doses of H2O2 (0.5-5 mmol L-1) and EGnZVI (0.2-10 mg L-1), and the incidence of UV-light were evaluated. The EGnZVI did not present reactivity towards the DR80 in the absence of H2O2. However, in the presence of H2O2, the EGnZVI was highly efficient at removing the DR80 at slightly acidic pH0 values (4 and 5.5). Under these pH0 conditions, the EGnZVI/Fenton process proved to be more effective than the classic homogenous Fenton. Finally, in the presence of the UV-light, the process was highly efficient throughout the studied pH0 interval, with increased removal rates. Therefore, the nZVI/Fenton process, using the synthesized material, presents itself as a promising alternative for the degradation of organic pollutants, and the incidence of UV light can considerably improve its efficiency.

Reuse of iron ore tailings as an efficient adsorbent to remove dyes from aqueous solution.

In this work, an iron ore tailings sample (IOT), collected from a tailings dam in Minas Gerais, Brazil, was characterized. The IOT presented point of zero charge of ∼ 6, specific surface area of 4 m2 g-1, and was mainly composed of hematite and quartz. Subsequently, experiments were performed to evaluate the adsorption of an anionic dye, Direct Red 80 (DR80), and a cationic dye, Methylene Blue (MB), by the IOT, studying the effects of its dose (doseIOT) and the solution initial pH (pH0). The DR80 removal increased with the decrease of the pH0 while the opposite effect occurred in the experiments with the MB, suggesting the process is governed by the adsorption resulting from electrostatic forces. The increase in the doseIOT increased the DR80 and MB removal, which can be attributed to the greater availability of adsorption sites. Pseudo-second order kinetic (R2 > 0.9994) and the Langmuir equilibrium isotherm (R2 > 0.9842) models described well the DR80 adsorption by the IOT, being the reaction rate and maximum adsorption capacity higher at lower pH0. In a regeneration experiment, it was possible to desorb almost entirely the DR80 using a NaOH solution. Additionally, the regenerated IOT was able to adsorb the DR80, demonstrating its reusability. In a preliminary assay, the IOT decreased the colour of the textile wastewater sample at pH0 3. Therefore, the results indicate the potential use of IOT for removing electric-charged pollutants by adsorption, especially anionic ones under acidic conditions.

Urotelio versus mucosa intestinal en ampliación vesical con sigmoide desmucosado: resultados de histopatología de largo plazo / Comparison between intestinal mucosa and urothelium in the setting of bladder augmentation: long term results

La ampliación vesical (AV) con sigmoide desmucosado ha mostrado grandes beneficio como reducción del mucus urinario y sus complicaciones. El objetivo de este estudio es determinar los cambios histológicos que acompañan a esta observación clínica, evaluando las transformaciones del epitelio de revestimiento del parche implantado; en distintos periodos post ampliación. Métodos: En 35 pacientes operados de AV (1998-2005), se realizaron aleatoriamente 24 exámenes endoscópicos con sus respectivas biopsias. La biopsia se tomó en tres puntos distintos del parche de ampliación desmucosado (9-12 y 3hrs). En aquellos niños con cierre de cuello, se utilizó un trocar trans-vesical. Los resultados histopatológicos (HP) se compararon entre diferentes períodos, con mucosa intestinal normal y con 2 biopsias realizadas sin parche desmucosado (>10 años). Resultados: La edad promedio al momento de la biopsia fue de 12 años (rango 4 a 15). El periodo de toma de biopsia tiene una mediana de 39 meses (rango 12-84 meses) post ampliación. La descripción macroscópica mostró dos grupos; en el periodo menor a 3 años el intestino se ve recubierto con urotelio con algunas zonas de mucosa intestinal (“estrellado”), y en muestras mayores a 3 años el parche estaba completamente cubierto con mucosa intestinal pero más pálido. La HP de las biopsias efectuadas precozmente (< 36 meses) demostraron que el implante presenta mayoritariamente urotelio con pequeñas “estrellas” de mucosa sigmoidea normal con algunas glándulas atróficas. En la totalidad de las muestras > 36 meses se informó parche recubierto mayoritariamente con mucosa sigmoidea con glándulas rodeadas por tejido fibroso, mayoritariamente atróficas y ausencia de urotelio. En los 2 pacientes con ampliación vesical sin parche desmucosado las glándulas intestinales mostraron estructura normal. Conclusión: Podría plantearse la existencia de un fenómeno de regeneración y expansión de mucosa histológicamente...

Bladder augmentation (BA) using demucosalized sigmoid has showed excellent benefices as mucus reduction and its complications. The aim of this study is to determinate the histological changes of this clinical observation, evaluating the coating epithelium of the patch in different periods postaugmentation. Methods: There were 24 random endoscopies exams and biopsies performed in 35 cases who underwent a BA between 1998 and 2005. Biopsy was done in 3 different points of the augmentedpatch (9-12-3 o’clock). In those children with bladder neck surgery a trans-vesical trocar was used. Histopathology (HP) results were compared among different post augmented periods, with normal intestinal mucosa and with biopsies done in 2 cases of BA where sigmoid without demucosalized was used (>10 years). Results: The mean age at biopsy was 12 years (range 4-15 y) and the period of biopsy has a median post BA of 39 months (range 12-84 m). Macroscopic description showed 2 groups; one (< 3 years) where the intestine was covered by urothelium with some small areas of intestinal mucosa (“stars”), and the other over 3 years where the patch was covered completely with intestinal mucosa. HP results in the early biopsies (< 36 months) showed that the patch was mostly covered with urothelium with some small “stars” of sigmoid mucosa, but with atrophic glands. In the group > 36 months the patch was mostly covered with intestinal mucosa with atrophic glands surrounded by fibrotic tissue and no signs of urothelium. In the 2 cases of BA with sigmoid without demucosalized the intestinal glands were completely normal. Conclusion: It could be affirmed that there is a regenerative and expansive process of mucosa histologically similar to a normal sigmoid mucosa (< 3 years), which could begin from intestinal mucosa remnants (“stars”). While the glandular structure would be atrophic in the patch, it was normal in those cases augmented with sigmoid without...