Experimental determination of dynamic pseudo-equilibrium moisture content: A practical limit for the drying process

Simulation and rigorous design of industrial dryers combine a large number of models, which feed three fundamental balances: (1) mass; (2) energy; and (3) quantity of movement of the material through the dryer. Many of these models represent physical phenomena affecting the three balances at the same time, which makes these calculations extremely complex, hence, accurate models are essential. The hypothesis that the kinetic stage of drying of any material culminates in the thermodynamic moisture equilibrium between solid and drying gas has been in effect for many years. However, recent findings show that there is a transition stage between the kinetic stage and the thermodynamic equilibrium, which, experimentally, looks like an equilibrium. The beginning of this transition stage or dynamic pseudo-equilibrium stage would mark the end of the drying kinetics models, which has been named as the dynamic pseudo-equilibrium moisture contents (Xdpe). The non-observance of this phenomenon presupposes a model limited in its prediction capacity, especially in the last stages of drying and even more so at low drying temperatures. As a consequence, sizes of industrial dryers could be underestimated during the simulation and rigorous design process, or underestimate drying times, in batch dryers. On the other hand, the optimal conditions may never be found, during the optimization of existing industrial drying processes. The objective of this work is to present the procedure to determine Xdpe, during the experimental determination of drying curves of any material. Likewise, to propose the practical moisture ratio, which uses Xdpe, instead of the equilibrium moisture, to be used in the modeling of the drying kinetics. • The drying process is divided into three stages: kinetic, transition, and equilibrium. • The dynamic pseudo-equilibrium moisture content divides the kinetic and the transition stages. • The practical moisture ratio should be used in rigorous industrial dryer design calculations

Biorefinación del fruto del Prosopis juliflora para producción de etanol. Evaluación de las etapas de acondicionamiento y pretratamiento

The fruits of Prosopis juliflora have the potential to be raw material in the production of bioethanol due to its high carbohydrate and fiber content, and its high productivity in arid localities. P. juliflora fruits were characterized chemically, its sun drying kinetics was modeled and 2 physicochemical pretreatments were evaluated. The fruits showed a moisture content of 12.51% on a wet basis (wb), 14.84% protein, 2.27% fat, 20.15% fiber, 58.49% Nitrogen Free Extract (NFE) and 4.25% of ash, on dry basis (db). The prediction sun drying of Faneite-Suárez model was the best, within the range of prevailing weather conditions. The acid pretreatment (6% of sulfuric acid, for 20 min, at 121 ° C) got the highest content of reducing sugars, 37.85%. The evaluated fruits can be used in the production of bioethanol through a technically feasible and sustainable processing route.Los frutos del Prosopis juliflora, tienen el potencial de ser materia prima en la producción de bioeta­nol debido a su elevado contenido de carbohidratos y fibra, y su alta productividad en localidades áridas. Frutos de P. juliflora fueron caracterizados químicamente, fue modelada su cinética de secado al sol y fueron evaluados 2 pretratamientos fisicoquímicos. Las frutos resultaron tener 12,51% de Humedad en base húmeda (bh), 14,84% de proteínas, 2,27% de grasa, 20,15% de fibra, 58,49% de Extracto libre de nitrógeno (ELN) y 4,25% de ceniza, en base seca (bs). El modelo Faneite-Suárez es el que mejor predice el secado al sol, dentro del rango de condiciones meteorológicas imperan­tes. El pretratamiento ácido (6% de ácido sulfúrico, por 20 min, a 121oC) fue con el que se obtuvo el mayor contenido de azúcares reductores, un 37,85%. Los frutos evaluados pueden ser usados en la producción de bio-etanol mediante una ruta de procesamiento técnicamente factible y sostenible

Biorefinación del fruto del Prosopis juliflora para producción de etanol. Evaluación de las etapas de acondicionamiento y pretratamiento

The fruits of Prosopis juliflora have the potential to be raw material in the production of bioethanol due to its high carbohydrate and fiber content, and its high productivity in arid localities. P. juliflora fruits were characterized chemically, its sun drying kinetics was modeled and 2 physicochemical pretreatments were evaluated. The fruits showed a moisture content of 12.51% on a wet basis (wb), 14.84% protein, 2.27% fat, 20.15% fiber, 58.49% Nitrogen Free Extract (NFE) and 4.25% of ash, on dry basis (db). The prediction sun drying of Faneite-Suárez model was the best, within the range of prevailing weather conditions. The acid pretreatment (6% of sulfuric acid, for 20 min, at 121 ° C) got the highest content of reducing sugars, 37.85%. The evaluated fruits can be used in the production of bioethanol through a technically feasible and sustainable processing route.Los frutos del Prosopis juliflora, tienen el potencial de ser materia prima en la producción de bioeta­nol debido a su elevado contenido de carbohidratos y fibra, y su alta productividad en localidades áridas. Frutos de P. juliflora fueron caracterizados químicamente, fue modelada su cinética de secado al sol y fueron evaluados 2 pretratamientos fisicoquímicos. Las frutos resultaron tener 12,51% de Humedad en base húmeda (bh), 14,84% de proteínas, 2,27% de grasa, 20,15% de fibra, 58,49% de Extracto libre de nitrógeno (ELN) y 4,25% de ceniza, en base seca (bs). El modelo Faneite-Suárez es el que mejor predice el secado al sol, dentro del rango de condiciones meteorológicas imperan­tes. El pretratamiento ácido (6% de ácido sulfúrico, por 20 min, a 121oC) fue con el que se obtuvo el mayor contenido de azúcares reductores, un 37,85%. Los frutos evaluados pueden ser usados en la producción de bio-etanol mediante una ruta de procesamiento técnicamente factible y sostenible

Biorefinación del fruto del Prosopis juliflora para producción de etanol. Evaluación de las etapas de acondicionamiento y pretratamiento

The fruits of Prosopis juliflora have the potential to be raw material in the production of bioethanol due to its high carbohydrate and fiber content, and its high productivity in arid localities. P. juliflora fruits were characterized chemically, its sun drying kinetics was modeled and 2 physicochemical pretreatments were evaluated. The fruits showed a moisture content of 12.51% on a wet basis (wb), 14.84% protein, 2.27% fat, 20.15% fiber, 58.49% Nitrogen Free Extract (NFE) and 4.25% of ash, on dry basis (db). The prediction sun drying of Faneite-Suárez model was the best, within the range of prevailing weather conditions. The acid pretreatment (6% of sulfuric acid, for 20 min, at 121 ° C) got the highest content of reducing sugars, 37.85%. The evaluated fruits can be used in the production of bioethanol through a technically feasible and sustainable processing route.Los frutos del Prosopis juliflora, tienen el potencial de ser materia prima en la producción de bioeta­nol debido a su elevado contenido de carbohidratos y fibra, y su alta productividad en localidades áridas. Frutos de P. juliflora fueron caracterizados químicamente, fue modelada su cinética de secado al sol y fueron evaluados 2 pretratamientos fisicoquímicos. Las frutos resultaron tener 12,51% de Humedad en base húmeda (bh), 14,84% de proteínas, 2,27% de grasa, 20,15% de fibra, 58,49% de Extracto libre de nitrógeno (ELN) y 4,25% de ceniza, en base seca (bs). El modelo Faneite-Suárez es el que mejor predice el secado al sol, dentro del rango de condiciones meteorológicas imperan­tes. El pretratamiento ácido (6% de ácido sulfúrico, por 20 min, a 121oC) fue con el que se obtuvo el mayor contenido de azúcares reductores, un 37,85%. Los frutos evaluados pueden ser usados en la producción de bio-etanol mediante una ruta de procesamiento técnicamente factible y sostenible

Biological Characterization and Instrumental Analytical Comparison of Two Biorefining Pretreatments for Water Hyacinth (Eichhornia crassipes) Biomass Hydrolysis

Water hyacinth is a rapidly growing troublesome aquatic weed plant, which causes eutrophication in water bodies and irreversible damage to the ecological system. In this work, we have investigated the water hyacinth biomass (WHB) hydrolysis efficacy of dilute alkaline (DA) pretreatment followed by biological pretreatment with white-rot fungus Alternaria alternata strain AKJK-2. The effectiveness of the dilute alkaline (DA) and biological pretreatment process on WHB was confirmed by using X-ray Diffraction (XRD) and Fourier Transform Infrared Spectrophotometer (FTIR), and was further visualized by Scanning Electron Microscope (SEM) and Confocal Laser Scanning Microscopy (CLSM). XRD spectra showed the increase in the crystallinity of pretreated samples, attributed to the elimination of amorphous components as lignin and hemicellulose. FTIR peak analysis of pre-treated WHB showed substantial changes in the absorption of cellulose functional groups and the elimination of lignin signals. Scanning electron microscopy (SEM) images showed firm, compact, highly ordered, and rigid fibril structures without degradation in the untreated WHB sample, while the pretreated samples exhibited loose, dispersed, and distorted structures. XRD indices (Segal, Landis, and Faneite), and FTIR indices [Hydrogen bond intensity (HBI); Total crystallinity index (TCI); and Lateral order crystallinity (LOI)] results were similar to the aforementioned results, and also showed an increase in the crystallinity both in alkaline and biological pretreatments. Alkaline pretreated WHB, with these indices, also showed the highest crystallinity and a crystalline allomorphs mixture of cellulose I (native) and cellulose II. These results were further validated by the CLSM, wherein fluorescent signals were lost after the pretreatment of WHB over control. Overall, these findings showed the significant potential of integrated assessment tools with chemical and biological pretreatment for large-scale utilization and bioconversion of this potential aquatic weed for bioenergy production