Integrated ozonation-enzymatic hydrolysis pretreatment of sugarcane bagasse: enhancement of sugars released to expended ozone ratio

Producción CientíficaThe combined effects of three key ozonation process parameters on the integrated ozonation-enzymatic hydrolysis pretreatment of sugarcane bagasse (SCB) were investigated, with emphasis on the relationship between sugar release and ozone consumption. A lab-scale fixed bed reactor was employed for ozonation at varying ozone doses (50, 75 and 100 mg O3/g SCB), particle sizes (420, 710 and 1000 µm) and moisture contents (30, 45 and 60% w/w) in multifactorial experiments, keeping a residence time of 30 min. The ozonated SCB showed a reduction in the content of acid-insoluble lignin from 26.6 down to 19.1% w/w, while those of cellulose and hemicellulose were retained above 45.5 and 13.6% w/w, with recoveries of 100–89.9 and 83.5–72.7%, respectively. Ozone-assisted enzymatic hydrolysis allowed attaining glucose and xylose yields as high as 45.0 and 37.8%, respectively. The sugars released/ozone expended ratio ranged between 2.3 and 5.7 g sugars/g O3, being the higher value achieved with an applied ozone input of 50 mg O3/g SCB and SCB with 420 µm particle size and 60% moisture. Such operating conditions led to efficient ozone utilization (<2% unreacted ozone) with a yield of 0.29 g sugars/g SCB. Overall, the amount of sugars released relative to the ozone consumed was improved, entailing an estimated cost of ozonation of USD 34.7/ton of SCB, which could enhance the profitability of the process.Consejo Nacional de Ciencia y Tecnología (CONACYT) - (Project-CB-SEP-133791

Time delay evaluation on thewater-leaving irradiance retrieved from empirical models and satellite imagery

Temporal delays and spatial randomness between ground-based data and satellite overpass involve important deviations between the empirical model output and real data; these are factors poorly considered in the model calibration. The inorganic matter-generated turbidity in Lake Chapala (Mexico) was taken as a study case to expose the influence of such factors. Ground-based data from this study and historical records were used as references. We take advantage of the at-surface reflectance from Landsat-8, sun-glint corrections, a reduced NIR-band range, and null organic matter incidence in these wavelengths to diminish the physical phenomena-related radiometric artifacts; leaving the spatio-temporal relationships as the principal factor inducing the model uncertainty. Non-linear correlations were assessed to calibrate the best empirical model; none of them presented a strong relationship (<73%), including that based on hourly delays. This last model had the best predictability only for the summer-fall season, explaining 71% of the turbidity variation in 2016, and 59% in 2017, with RMSEs < 24%. The instantaneous turbidity maps depicted the hydrodynamic complexity of the lake, highlighting a strong component of spatial randomness associated with the temporal delays. Reasonably, robust empirical models will be developed if several dates and sampling-sites are synchronized with more satellite overpasses.</p

Propuesta de ruta de degradación del BPA durante la reacción del ozono

Endocrine-disrupting compounds (EDC) are present in surface water bodies that supply water to the population. One of them is bisphenol A (BPA), which is listed as a carcinogen. This research addresses its degradation through the ozone reaction and presents a likely pathway established by analyzing products and degradation products using gas chromatography-mass spectrometry (GC-MS). BPA degradation was carried out under pseudo-first-order conditions, where liquid phase ozone was the limiting reactive, in doses of ≈2.29 × 10-4 M and BPA doses of 1.25 × 10-4, 17.5 × 10-4, and 35.0 × 10-4 M, looking to have molar ratios [BPA]> [O3]; the oxidation reaction was carried out in a stopped-flow system that allows obtaining results in the order of seconds. The degradation pathway obtained shows the rupture of one of the benzene rings, decreasing the phenolic toxicity of the BPA compound. The proposed pathway can contribute to the understanding of the degradation of BPA in the environment and tertiary treatment processes with the use of ozone. Likewise, it is intended to contribute with new data to the issues of drinking water treatment to offer safe water to the population

Revista de la Facultad de Ciencias Médicas de la Universidad de Cuenca

Se presenta un estudio retrospectivo de carácter descriptivo, de 100 pacientes operados por obesidad con diferentes técnicas en el Hospital Enrique Garcés de la ciudad de Quito, el cual nos muestra la tendencia actual al predominio del Bypass Gástrico y Gastrectomía vertical en manga, a quienes durante el seguimiento, se les aplicó el SCORE DE BAROS, evidenciando una mejoría integral de la calidad de vida que complementa a la disminución del peso y entes.A retrospective descriptive study of 100 patients operated by obesity with different techniques in the Enrique Garcés Hospital of the City of Quito, which shows the actual trend of the prevalence of gastric bypass and vertical sleeve gastrectomy, to which during monitoring were applied the SCORE OF BAROS evidencing a comprehensive improvement in the quality of life that complements weight reduction and resolution of comorbidities in patients.Cuencavolumen 32; no

Assessment of the kinetics of oxidation of some steroids and pharmaceutical compounds in water using ozone

[EN] Emerging contaminants are present in surface and ground water, generating a potential risk for the public health of surrounding populations that consume contaminated water. However, their elimination using conventional treatment methods has not been an easy task. The aim of this research was the assessment of the kinetics of oxidation of four emerging contaminants in water two steroids: estradiol (E2) and ethynilestradiol (EE2) and two pharmaceutical drugs: naproxen (NPX) and ibuprofen (IBP) ¿ by using an ozonation process. The stoichiometry and the second order rate constants for the four compounds were obtained. The method of competitive kinetics was established to assess the kinetics of oxidation of steroids and NPX and the absolute rate constant under pseudo-first-order conditions method for IBP. The second order rate constants for E2, EE2, NPX were in the order of 104 to 105 L/(mol s) and for IBP the value was 101 L/(mol s). An oxidation kinetic model for the steroids and pharmaceutical drugs at different doses of ozone was obtained from the rate constants, and validated with the experimental values. In addition, the half-life of the selected compounds for each experimental ozone dose was obtained, which serves to predict the behavior of oxidation of emerging contaminants, knowing the initial concentration of ozone. This research is focused toward a project for water treatment with the presence of emerging contaminants on a semi-pilot scale in continuous operation. 2014 Elsevier Ltd. All rights reserved.Vallejo Rodríguez, R.; Murillo Tovar, M.; Navarro-Laboulais, J.; León Becerril, E.; López López, A. (2014). Assessment of the kinetics of oxidation of some steroids and pharmaceutical compounds in water using ozone. Journal of Environmental Chemical Engineering. 2:316-323. doi:10.1016/j.jece.2013.12.024S316323

Compuestos emergentes: implementación de métodos analíticos para extraer y cuantificar 17β-estradiol, 17⍺-etinilestradiol, ibuprofeno y naproxeno en agua

Los métodos implementados permitieron la cuantificación de dos esteroides (17β-estradiol y 17⍺-etinilestradiol) y dos fármacos (ibuprofeno y naproxeno) utilizando extracción en fase sólida (EFS) y cromatografía de líquidos de alta resolución con detector de arreglo de diodos (CLAR-DAD). Las condiciones de EFS con cartuchos C18 se evaluaron variando los tipos y las cantidades de disolvente de elución, condiciones de pH y la masa de muestra en el cartucho. La eficiencia se evaluó mediante la fortificación de muestras de agua con cantidades conocidas de los analitos en tres niveles de concentración distintos. Las recuperaciones encontradas indican que la eficiencia de los métodos es independiente de la cantidad de analito tratada en el rango de ensayo (p > 0.05) con recobros (promedio ± desviación estándar) para 17β-estradiol (86.9% ± 4.2), 17⍺-etinilestradiol (87.1% ± 6.1), ibuprofeno (89.4% ± 5.3) y naproxeno (85.9% ± 15), que reúnen criterios de aceptación suficientes para el control de calidad de futuras aplicaciones. Por lo tanto, los métodos propuestos son confiables para ser aplicados a muestras acuosas. Sin embargo será necesario probar su desempeño y ajustar sus condiciones cuando se analicen muestras más complejas

Time delay evaluation on thewater-leaving irradiance retrieved from empirical models and satellite imagery

Temporal delays and spatial randomness between ground-based data and satellite overpass involve important deviations between the empirical model output and real data; these are factors poorly considered in the model calibration. The inorganic matter-generated turbidity in Lake Chapala (Mexico) was taken as a study case to expose the influence of such factors. Ground-based data from this study and historical records were used as references. We take advantage of the at-surface reflectance from Landsat-8, sun-glint corrections, a reduced NIR-band range, and null organic matter incidence in these wavelengths to diminish the physical phenomena-related radiometric artifacts; leaving the spatio-temporal relationships as the principal factor inducing the model uncertainty. Non-linear correlations were assessed to calibrate the best empirical model; none of them presented a strong relationship (<73%), including that based on hourly delays. This last model had the best predictability only for the summer-fall season, explaining 71% of the turbidity variation in 2016, and 59% in 2017, with RMSEs < 24%. The instantaneous turbidity maps depicted the hydrodynamic complexity of the lake, highlighting a strong component of spatial randomness associated with the temporal delays. Reasonably, robust empirical models will be developed if several dates and sampling-sites are synchronized with more satellite overpasses.</p