REMOCIÓN DEL COLORANTE INDUSTRIAL AZUL DE METILENO UTILIZANDO EL ALGA PARDA FUCUS VESICULOSUS

El presente estudio tuvo como objetivo evaluar la eficiencia de remoción del colorante azul de metileno (AM), utilizando como biosorbente alga parda Fucus vesiculosus (sargazo vesiculoso). Se caracterizó el alga mediante la determinación del punto cero de carga. Se consideraron los efectos de los siguientes parámetros sobre la eficiencia de remoción del colorante: pH y temperatura del medio acuoso, concentración del colorante, tiempo de contacto, así como la dosis de biomasa. Se encontró que las condiciones óptimas de remoción del colorante fueron para los valores de pH entre 8 y 12. Se obtuvo una eficiencia de remoción del 92.8% a un pH de 12. El alga parda removió mejor el AM conforme aumentó la temperatura. A una temperatura de 60 °C se logró una eficiencia de remoción del 72.5%. Los resultados mostraron que el comportamiento de adsorción fue mejor descrito por el modelo de Langmuir. El alga Fucus vesiculosus presentó una capacidad máxima de adsorción de 555.56 mg/g del colorante. Con respecto a la cinética de adsorción, los datos obtenidos mostraron un buen ajuste a ambos modelos (pseudo primer y segundo orden). La cantidad óptima de biomasa fue de 0.1g y con ella se logró remover el 99.1% de AM

Sorption of Cd(II), Ni(II) and Zn(II) on natural, sodium-, and acid-modified clinoptilolite-rich tuff

Sorption of Cd2+, Ni2+and Zn2+ions on natural (ZPCli), sodium modified (ZPCliNa) and acid modified (ZPCliH) zeolites have been investigated in function of the contact time, pH, and metal concentration by the batch technique. The characterization of ZPCIi, ZPCliNa, and ZPCliH materials was performed using X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. The surface area (BET) and the pHpzcwere also determined. The pH in the point of the zero charge of ZPCli, ZPCliNa, and ZPCliH zeolites was 8.25, 8.00, and 2.05, respectively. The kinetic sorption data for ZPCli, ZPCliNa and ZPCliH were well fitted to the pseudo-second order model (R2> 0.99). The linear model described the Cd, Ni and Zn sorption isotherms for ZPCliH, while for ZPCliNa and ZPCliH it was the Freundlich model. The unmodified and modified zeolitic materials showed the highest sorption capacity for Cd2+, lower for Zn2+ and Ni2+

Structural and Electric Properties of the Ru0.9M0.1Sr2GdCu2O8 System with M = Zr, Mo, and Mn

The superconducting properties of the RuSr2GdCu2O8 ceramic system depend strongly on the synthesis conditions and the ionic substitutions. In this work, we studied the structural and electrical properties of the Ru0.9M0.1Sr2GdCu2O8 system, with M = Zr, Mo, and Mn. The samples were prepared by solid-state reaction at ambient pressure in air, using temperatures between 980 °C and 1020 °C. X-ray powder diffraction patterns indicate that all samples crystallize in a tetragonal symmetry (S.G. P4/mmm, No. 123). The structural data of each sample was refined by the Rietveld method, showing that the Cu-O (1) and Ru-O (1) bond lengths vary with the substituted ionic radii of Zr, Mo, and Mn ions. Electrical resistance measurements indicate that the samples annealed in flowing oxygen at 1050 °C and 1055 °C for 5 days exhibit a semiconductor like behavior for M = Mo and Mn, whereas the samples with M = Zr and Ru show superconducting behavior

Composite of methyl polysiloxane and avocado biochar as adsorbent for removal of ciprofloxacin from waters

Two carbon composite materials were prepared by mixing avocado biochar and methyl polysiloxane (MK). Firstly, MK was dissolved in ethanol, and then the biochar was added at different times. In sample 1 (R1), the time of adding biochar was immediately after dissolving MK in ethanol, and in sample 2 (R2), after 48 h of MK dissolved in ethanol. The samples were characterized by nitrogen adsorption/desorption measurements obtaining specific surface areas (SBET) of 115 m2 g−1 (R1) and 580 m2 g−1 (R2). The adsorbents were further characterized using scanning electron microscopy, FTIR and Raman spectroscopy, adsorption of vapors of n-heptane and water, thermal analysis, Bohem titration, pHpzc, and C H N elemental analysis. R1 and R2 adsorbents were employed as adsorbents to remove the antibiotic ciprofloxacin from the waters. The t1/2 and t0.95 based on the interpolation of Avrami fractional-order were 20.52 and 246.4 min (R1) and 14.00 and 157.6 min (R2), respectively. Maximum adsorption capacities (Qmax) based on the Liu isotherm were 10.77 (R1) and 63.80 mg g−1 (R2) for ciprofloxacin. The thermodynamic studies showed a spontaneous and exothermic process for both samples, and the value of ΔH° is compatible with physical adsorption

Raman Spectroscopy and Chemometric Modeling to Predict Physical-Chemical Honey Properties from Campeche, Mexico

In this work, 10 chemometric models based on Raman spectroscopy were constructed to predict the physicochemical properties of honey produced in the state of Campeche, Mexico. The properties of honey studied were pH, moisture, total soluble solids (TSS), free acidity, lactonic acidity, total acidity, electrical conductivity, Redox potential, hydroxymethylfurfural (HMF), and ash content. These proprieties were obtained according to the methods described by the Association of Official Analytical Chemists, Codex Alimentarius, and the International Honey Commission. For the construction of the chemometric models, 189 honey samples were collected and analyzed in triplicate using Raman spectroscopy to generate the matrix data [X], which were correlated with each of the physicochemical properties [Y]. The predictive capacity of each model was determined by cross validation and external validation, using the statistical parameters: standard error of calibration (SEC), standard error of prediction (SEP), coefficient of determination of cross-validation (R2cal), coefficient of determination for external validation (R2val), and Student’s t-test. The statistical results indicated that the chemometric models satisfactorily predict the humidity, TSS, free acidity, lactonic acidity, total acidity, and Redox potential. However, the models for electric conductivity and pH presented an acceptable prediction capacity but not adequate to supply the conventional processes, while the models for predicting ash content and HMF were not satisfactory. The developed models represent a low-cost tool to analyze the quality of honey, and contribute significantly to increasing the honey distribution and subsequently the economy of the region

Physical and Chemical Properties of Biodiesel Obtained from Amazon Sailfin Catfish (Pterygoplichthys pardalis) Biomass Oil

Amazon sailfin catfish (Pterygoplichthys pardalis) is considered one of the greatest threats to the biodiversity of continental aquatic systems, causing serious economic and environmental problems in the regions. In this work, the production of biodiesel from Amazon sailfin catfish biomass oil is studied. The physical and chemical properties of biofuel produced were evaluated under the specifications of the European standard EN-14214 by using gas chromatography-mass spectrometry, infrared spectroscopy, and atomic absorption spectrometry analyses. The results show that the biodiesel complies with all the specifications of the standard, except the content of polyunsaturated methyl esters. The yields obtained from oil and biodiesel were 9.67 and 90.71% (m/m), respectively. The methyl ester concentrations study identified 17 components where 47.003% m/m corresponded to methyl esters with saturated chains, whereas 34.394% m/m was attributed to monosaturated methyl esters and the remaining (18.624% m/m) to polysaturated methyl esters. Finally, mineral analysis by atomic absorption showed the absence of heavy metals Cd, Ni, and Pb, as well as low concentrations of Ni, Fe, Cu, and Zn, demonstrating that the quality of the fuel is not compromised. The study indicates the feasibility of manufacturing biodiesel using Amazon sailfin catfish biomass oil as a low-cost raw material. It represents an environmental option to mitigate a global problem of atmospheric pollution, and at the same time, it shows a commercial alternative to reduce the ecological impact caused by this fish in the diverse ecosystems to which it has spread. In addition, the great adaptability of this fish provides the possibility of a profitable process to have very high rates of reproduction and growth, allowing the generation of large amounts of biomass for the production of biodiesel