Explore the vast range of titles available.

El presente documento describe el proceso realizado para sintetizar nanopartículas de magnetita Fe3O4 a partir de extracto de cáscara de papaya mediante una reacción simple y ecológica. Para la realización de la síntesis se verifica la cantidad de glucosa presente en las cáscaras puesto que este carbohidrato es indispensable como agente reductor en la reacción, el procedimiento se realiza para tres muestras diferentes las cuales son evaluadas por medio de microscopia infrarroja FTIR y comparadas con una muestra comercial, por otro lado, se evidencia por medio de una prueba SEM si el tamaño de los productos obtenidos corresponden a material nanométrico y si la morfología efectivamente corresponde a magnetita; posterior a esto se realiza la degradación de colorantes azoicos dando resultados positivos para el colorante azul brillante E-133 mostrando transparencia en el medio lo que se verifica de manera cuantitativa por medio de espectroscopia UV-Vis.

Synthetic colorants are widely used globally by different industries for the dyeing process. However, these chemicals pollute the environment and affect human health by causing allergies, hives, dermatitis, and cancer. This study aims to compare the effectiveness of duckweed (Lemna minor) in the removal of the Methylene Blue (MB) and Congo red (CR) dyes at different concentrations (1 mg/L, 5 mg/L, 10 mg/L, and 15 mg/L). Absorbance values were determined at 665 nm for MB and 497 nm for CR after 96 hours. The results show higher removal of MB compared to CR for all concentrations (95.49 % vs. 59.32%, 1 mg/L; 97.24% vs. 39.43%, 5mg/L; 91.30% vs 28.47%, 10mg/L; y 85.42% vs 20.27%, 15mg/L). The removal of MB was observed after 30 min of contact with duckweed, while the removal of CR was observed after 24 hours in all concentrations.

En el presente estudio, se produjeron carbones activados (CA) derivados de la maleza Bidens pilosa (BPW) tratada químicamente mediante pirólisis tradicional. Los CA se utilizaron para tratar colorantes, por ejemplo, rodamina B (RhB), naranja de metilo (MO) y rojo de metilo (MR) a partir de soluciones acuosas. La influencia de las proporciones de impregnación (1:0.5, 1:1, 1:1.5 y 1:2) de hidróxido de potasio (KOH) y ácido fosfórico (H₃PO₄) como agentes químicos de activación sobre la eficiencia de adsorción fue investigada. Según los resultados, para todos los colorantes investigados, el carbón activado por el agente H₃PO₄ en una proporción de impregnación de 1:2 (ACH4) presentó el mejor adsorbente para la eliminación del colorante. Transcurridos 300 minutos de experimentos de adsorción, la adsorción alcanzó el equilibrio, con eficiencias de adsorción del 98.6%, 95.5% y 96.0% para RhB, MO y MR, respectivamente. Se analizó el ACH4 mediante espectroscopia infrarroja con transformada de Fourier (FTIR) y microscopía electrónica de barrido (SEM). La imagen SEM reveló un desarrollo progresivo de poros resultante de la eliminación de sustancias volátiles e impurezas. El análisis FTIR indicó el predominio de grupos funcionales ácidos en la superficie, lo que favoreció el proceso de adsorción. Por lo tanto, el ACH4 preparado a partir de la maleza Bidens pilosa es un adsorbente prometedor para la eliminación de colorantes de soluciones acuosas.  

Industrial textile effluents containing azo dyes pose a major environmental challenge due to their persistence and toxicity. This study evaluated the capacity of a native white-rot fungus (Lentinus sp.) to treat a real textile effluent polluted with an azo dye (Red 40) in a packed-bed bioreactor. Fungal biomass was immobilized on low-cost lignocellulosic supports (Luffa cylindrica), and pine sawdust was added as a biological inducer to stimulate ligninolytic enzyme production. Treatment conditions were first optimized in Erlenmeyer flasks (0.15 L), achieving 94.0 ± 0.1 % decolorization. Under scaled-up conditions (6 L, 30 ◦C, 12-day hydraulic retention time, batch mode, no agitation), the system removed 61.5 ± 0.2 % of dye color and reduced chemical oxygen demand (COD) by 99.0 ± 0.3 %. Enzymatic assays revealed manganese peroxidase activity, while laccase was not detected. Nuclear magnetic resonance (NMR) analysis confirmed structural modifications of the dye through azo bond cleavage. These findings demonstrate the potential of native ligninolytic fungi as sustainable and cost-effective biotechnological tools to treat azo dye-polluted industrial effluents, supporting their applicability at larger scales.

The aim of this in vitro study is to investigate the effects of acidic beverages on the discoloration of bulk-fill composites with different viscosities. 144 disc-shaped specimens (8mm diameter × 2mm thick) were prepared from four different composite resins including a nanohybrid (Filtek Ultimate), two packable bulk-fill (Filtek Bulk Fill, Tetric N Ceram Bulk Fill), and a flowable bulk-fill composite (Tetric N Flow Bulk Fill). The specimens of each group were divided into 3 subgroups and submerged in distilled water, orange juice and coke (n=12). Color difference (∆E) were measured using CIELab color space and a compact spectrophotometer (VITA Easyshade) at baseline and after 30 days of immersion. Data were analyzed using two-way ANOVA and Tukey's HSD post-hoc tests (P<0.05). Two-way ANOVA revealed that both material type and staining solution significantly influenced ∆E values (P<0.001). Immersion in orange juice resulted in greater and significant discoloration over time in comparison to distilled water and coke (P<0.05). Tetric N Ceram (∆E=7.0) and Tetric N Flow (∆E=7.7) bulk-fill restoratives showed highest color change values after 30 days of immersion in orange juice. This study suggests that a discoloration above the clinically acceptable threshold (∆E>2.7) was observed for all bulk-fill composites tested. It can be speculated that orange juice has a more negative effect on the color stability compared to coke. Additionally, flowable bulk-fill composite was more prone to discoloration than condensable bulk-fill composites. El objetivo de este estudio fue investigar los efectos de las bebidas ácidas en la decoloración de resinas compuestas tipo Bulk con diferentes viscosidades. Se prepararon 144 muestras en forma de disco (8mm de diámetro x 2mm de grosor) a partir de cuatro resinas compuestas diferentes que incluyen un nanohíbrido (Filtek Ultimate), dos de pasta condensables tipo Bulk (Filtek Bulk Fill, Tetric N Ceram Bulk Fill) y una fluida (Tetric N Flow Bulk Fill). Las muestras de cada grupo se dividieron en 3 subgrupos y se sumergieron en agua destilada, jugo de naranja y Coca-Cola (n=12). La diferencia de color (∆E) se midió utilizando el CIELab y un espectrofotómetro compacto (VITA Easyshade) al inicio y después de 30 días de inmersión. Los datos se analizaron mediante ANOVA bidireccional y pruebas post-hoc HSD de Tukey (P<0,05). El ANOVA bidireccional reveló que tanto el tipo de material como la solución de tinción influyeron significativamente en los valores de ∆E (P<0,001). La inmersión en jugo de naranja resultó en una decoloración mayor y significativa con el tiempo en comparación con el agua destilada y la Coca-Cola (P<0.05). Las resinas Tetric N Ceram (∆E=7.0) y Tetric N Flow (∆E=7.7) mostraron los valores más altos de cambio de color después de 30 días de inmersión en jugo de naranja. En este estudio se observó una decoloración por encima del umbral clínicamente aceptable (∆E>2,7) para todos los materiales resinosos. Se puede especular que el jugo de naranja tiene un efecto más negativo sobre la estabilidad del color en comparación con la Coca-Cola. Además, la resina fluida fue más propensa a la decoloración que las resinas condensables.

Abstract The deterioration of the environment is a matter of great concern today and has led to the development of research to remedy the harmful effects caused by man with his industrial activity overflowing. Water bodies are being affected by pollutant discharges from industries using dyes and pigments, as it is an alteration to aquatic systems by the interference in the passage of light and potentially toxic particles that have effects not only on the aquatic organisms but also possible indirect effects on human health. This research is developed to know and choose the most appropriate toxicity measurement techniques to evaluate the impact of these effluents loaded with dyes and pigments for their subsequent application to real residual water samples. A bibliographic review of different techniques for aquatic toxicity evaluation is carried out and the importance of the application of these tests in the evaluation of the advantages, and the efficiency of the color removal treatments is emphasized.

In Colombia, sugarcane represents the second product with a large area of cultivation. It is estimated that from sugar mills about 6 million tons of sugarcane bagasse, SCB, are produced, of which 5 million are inefficiently used for burning boilers. SCB is mainly composed of cellulose, hemicellulose and lignin, allowing its use as a potential adsorbent. Particularly, the aim of this work was to evaluate the viability of using SCB for the adsorption of basic red 46, BR46, in aqueous solution. The effect of factors such as point of zero charge, solution pH, particle size, adsorbent dosage, initial dye concentration, contact time and ionic strength was evaluated using a statistical design of experiments. A removal of 86.4 % was obtained and the further optimization of the process through a response surface design, allowed to achieve a maximum adsorption of 95.0 %. These results suggest SCB is a promising alternative of a non-conventional adsorbent that could be applied for treating dyed effluents.

A novel, rapid, and reliable ultra-high performance supercritical fluid chromatography (UHPSFC) method was developed to correctly separate and quantitatively determine Sudan dyes in chilli products. The effect of different separation parameters on the retention characteristics of Sudan dyes was investigated. The results showed that diode array detection of Sudan I-II was accomplished at 480 nm, and that of Sudan III-IV at 500 nm. In the analysis of Sudan dyes, the whole analysis time was less than 10 minutes, the method had a limit of detection and limit of quantification of 0.25 μg/mL and 0.50 μg/mL, respectively. All calibration curves had good linearity (r 2  > 0.9989) within the tested concentration ranges. The method had intra- and inter-day precision of less than 3.5% and 4.1%, respectively, with a recovery between 96.58% and 104.50%, and a relative standard deviation of less than 4.4%. The method was successfully applied to analyze chilli product sample.

The nutritional properties of subterranean termite exuviae (shed exoskeletons) are not well-known because obtaining the large quantities necessary for investigation is difficult. A method for collecting large numbers of exuviae is reported here for the Asian subterranean termite, Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae), an invasive and economically important tropical termite species. In this study, groups of 1,000 C. gestroi workers from 4-yr-old laboratory colonies (n = 3) were allowed to feed on a media pad dyed with Nile Blue A for 2 d. Approximately 16% of the original 1,000 workers did not uptake dye. These individuals were then placed into a Petri dish with dyed filter paper and checked hourly (10:00 A.M. to 10:00 P.M.) for 7 d. Newly molted workers and those individuals that started turning blue were removed to prevent feeding on exuviae. An average of 14 workers molted per d that yielded an average of 12 exuviae with an overall mean of 86 exuviae collected over the 7 d study period. We also found the number of individuals that acquired dye during the study significantly decreased by d. However, variables such as the number of exuviae, newly molted individuals, and cadavers were not correlated with d of collection because termites molt asynchronously.

Context: Agricultural residues have become unconventional adsorbents of great interest due to their wide availability, minimum cost, and high efficiency. In this work, the adsorbent capacity of rice husk by-product (RH) in the Red 40 (R40) anionic dye removal was evaluated under a discontinuous system. Method: For determining the best conditions for the removal of this dye, a factorial design 23 was implemented, which allows to achieving a removal of 75.6% at pH = 2.0, an initial concentration of 15 mg/L, dosage of 8.0 g/L, and contact time of 18 hours. Results: The equilibrium, kinetics and thermodynamic properties of the process were evaluated. It was found that the Langmuir model best represents the experimental results with qmax of 2.74 mg/g and an adjustment coefficient of R2=0.987. Regarding kinetics, the pseudosecond order model with qt of 1.09 mg/g presented the best fit (R2 = 0.970). Finally, Gibbs free energy (ΔG = -1.11 KJ/mol) and entropy (ΔS = 23.9 J/mol*K) indicate a spontaneous process, while enthalpy showed that the removal of R40 constitutes an endothermic process, with ΔH = 6.71 KJ/mol. Furthermore, the activation energy of 14.1 KJ/mol suggests that the mechanism of adsorption of the R40 takes place through a physi-adsorption. Conclusions: These results indicate that the rice husk offers a adequate adsorbent capacity for the retention of azo dye off contaminated effluents; besides, scaling up this process is feasible given its thermodynamic characteristics.