No abstract

Cocoa pod husks are a waste generated during the processing of cocoa beans. We aimed to explore the enzymatic extraction of pectin using cellulases. The extraction process was optimized using a central composite design (CCD) and analyzed by response surface methodology (RSM). The parameters optimized were feedstock concentration (%), enzyme dosage (µL/g), and time (h). Three dependent variables were studied: pectin yield (g/100 g dry husk) (R2 = 97.02), galacturonic acid content (g/100 g pectin) (R2 = 96.90), and galacturonic acid yield (g/100 g feedstock) (R2 = 95.35). The optimal parameters were 6.0% feedstock concentration, 40 µL g−1 of enzyme, and 18.54 h, conditions that produced experimentally a pectin yield of 10.20 g/100 g feedstock, 52.06 g galacturonic acid/100 g pectin, and a yield 5.31 g galacturonic acid/100 g feedstock. Using the chemical extraction method, a yield of 8.08 g pectin/100 g feedstock and a galacturonic acid content of 60.97 g/100 g pectin were obtained. Using assisted sonication, a pectin yield of 8.28 g/100 g feedstock and a galacturonic acid content of 42.77 g/100 g pectin were obtained. Enzymatically optimized pectin has rheological and physicochemical features typical of this biomaterial, which provides an interesting alternative for the valorization of cocoa husks.

The existence of water hyacinth proliferation in wetlands of the Canal del Dique (Department of Bolívar, Colombia) causes environmental problems because there is no final disposal of these. Therefore, it is necessary to study alternatives for its use. The objective of the study was to evaluate the behavior of the aquatic hyacinth as an adsorbent of Cr (VI) (VI) and Hg (II) (II) in a synthetically prepared solution. The lignocellulosic material was dried at 80°C for 24 h to remove moisture; then crushed and sieved with meshes of different particle sizes; characterized by elemental analysis to check for the presence of cellulose, hemicellulose, and lignin, as well as by Fourier Transform Infrared Spectrometry to verify the existence of functional groups responsible for the adsorption process. It was found that the best particle size was 1 mm, with a removal percentage of 73,4 and 79,3% for Cr (VI) and Hg (II), respectively. When establishing the adsorption kinetics, it was verified that the elimination percentage increases with time up to 5,5 h of contact with the Hg (II) solution and 3,8 h with the Cr (VI) solution.

Summary The aim of this paper was to estimate fermentation kinetic parameters to develop a mathematical model of the bioethanol production under magnetic field effect. Thus, a non‐structured mathematical model was developed considering three non‐lineal kinetic models typically known as Levenspiel, Aiba, Jerusalimsky, which take into account inhibitory effects of the high product concentration on yeasts. The non‐lineal differential equations system solution was carried out by MatLab software using the Runge–Kutta fourth‐order multivariable method. This method was improved through a replication scheme coupled with Newton–Raphson method modified with a damping Broyden parameter. Experimental data on substrate consumption, biomass formation and ethanol production were collected at magnetic field intensities (H) of 414, 796 and 1216 A/cm during 16 h of fermentation. Consequently, the adjusted model for biomass, consumed substrate and bioethanol produced allowed us to correlate fermentation kinetic parameters with the magnetic field. The best result was observed when Jerusalimsky model modified with a magnetic field parameter was considered, because the RMSD order and R‐square correlation coefficient were around 10−3 and higher than 0.95, respectively. These results are important to understand the phenomenological behavior of this unconventional bioprocess and be helpful to further sensibility analysis and scale up of the bioethanol production assisted by electromagnetic field. Copyright © 2016 John Wiley & Sons, Ltd.

Cáscara de cacao fue empleada como bioadsorbente natural para remover cromo6+ en soluciones acuosas con concentraciones equivalentes a las generadas en procesos de curtiembre. Un análisis por FTIR del material antes y después del proceso de adsorción ratifica la presencia de grupos funcionales (lignina, celulosa, hemicelulosa), que favorecen la adsorción de los iones metálicos del cromo. El efecto de la temperatura y el diámetro de partícula sobre el porcentaje de metal adsorbido fue estudiado. La concentración del metal en la solución fue detectada por adsorción atómica. Obteniendo una adsorción máxima de 24.7% a temperatura de 28ºC y 0.8mm diámetro de partícula. La Isoterma de Sips fue el modelo que mejor ajustó los datos de equilibrio. Los datos cinéticos fueron ajustados, encontrándose un mayor coeficiente de correlación para el modelo de pseudo segundo orden. La biomasa contaminada con cromo fue encapsulada mediante la técnica estabilización/solidificación para su disposición final.