Angel Gonzalez-Delgado

Potential for degradation of lignocellulosic biomass via alkaline pretreatment using corn crop residual biomass

The increasing interest in the development of renewable energy sources such as biogas or bioethanol has led to study different lignocellulosic biomass as feedstock. In this work, corn biomass (stalk and leaf) was used to obtain total reducing sugar (TRS) and evaluate its suitability as feedstock for biofuels production. Biomass characterization was carried out by high performance liquid chromatography (HPLC) technique in order to determine main components (cellulose, hemicellulose, and lignin). For TRS quantification, different biomass particle size (0.5 mm, 1 mm, 2 mm, and in natura) were considered and the effect of alkaline pretreatment was studied in corn stalk, corn leaf, and corn stalk/leaf biomasses. It was found that corn cultivation wastes biomass exhibited high cellulose content of 28.38 g/L and 19.02 g/L for stalk and leaf, respectively. In addition, the highest concentration of TRS (28.89 g/L) was achieved using pretreated stalk/leaf biomass with 0.5 mm particle size indicating that alkaline pretreatment improves the TRS concentration. These results suggested that corn crop residues are an attractive feedstock for producing biofuels.

Kinetic and dynamic study of Cr (VI) adsorption onto chemically modified corn cob

Low-cost materials have been widely investigated to be used for removing water pollutants as heavy metals. The kinetic and dynamic of adsorption Cr (VI) onto corn cob and chemically modified corn cob biosorbents were studied. Batch adsorption experiments were performed under solution pH=2 and the results were used for determining kinetic model (pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion) that best describes adsorption process over time. In addition, adsorption process was carried out in packed-bed columns to construct concentration-like profile and calculate parameters of dynamic models as Thomas, Adams-Bohart, Yoon-Nelson and dose-response. Desorption-adsorption cycles were also performed to analysis capacity of biomass to be regenerated. It was found that pseudo-second order best fitted experimental data for corn cob biomass with k2 = 0.00098 g/mg min and qe,2 = 15.05 mg/g. The reduction in adsorption capacity after chemical modification indicated that corn cob biosorbent is recommended for further studies. Dynamic process using corn cob biosorbent obeyed Thomas model with kTh = 0.039 mL/mg min and qo = 2.1 mg/g. The desorption study revealed that this biomass can be regenerated and reused in consecutive cycles, which make it attractive for being applied in industrial-scale processes. 1384 Ángel Villabona-Ortíz et al.

Computer-aided exergy analysis of agar production process from macroalgae Gracilaria sp.

In this work, an agar production process from macroalgae Gracilaria sp. is analyzed using exergy analysis methodology in order to quantify the physical and chemical exergies of the species involved, total irreversibilities, exergy from utilities and wastes generated, and overall exergy efficiency of the process. Results show that for an 8,670 t/year of Gracilaria sp. algae plant, the Filtration III and Evaporation stages have a great improvement opportunity since the use of waste streams such as water vapor, water and filter cake increase the exergy efficiency from 18.7 to 39.4%. Finally, it is suggested an improved topology to optimize the process by the implementation of an energy integration to reduce exergy of industrial services as well as operating costs.

Obtención de lípidos y carbohidratos a partir de microalgas mediante el diseño de medios de cultivo selectivos

La produccion sostenible de biorrefinerias a partir de microalgas presenta varias complicaciones tecnicas a diferentes niveles, entre los que se encuentra la maximizacion de la productividad de bloques energeticos, como carbohidratos y lipidos, que sean materia prima para biodiesel y bioetanol. Una alternativa para aumentar la productividad de bloques energeticos es el uso de cultivos alternativos a los medios quimicos tradicionales, los cuales se han basado en fuentes de carbono, fosforo, nitrogeno y microelementos. Este trabajo presenta el diseno de dos medios de cultivo mixotrofico con diferentes fuentes de carbono, nitrogeno y fosforo, a fin de evaluar la produccion de carbohidratos y lipidos a partir de Chlorella vulgaris. Los medios de cultivo se disenaron a diferentes concentraciones de nitrato de sodio, fosfato de potasio y acetato de sodio/carbonato de amonio como fuente de carbono. Ademas, se realizaron diagramas de Pareto y Superficies de Respuesta utilizando el software estadistico STATISTICA 7.0, a fin de conocer la influencia significativa de las variables de estudio sobre la produccion de metabolitos. Los resultados mostraron que la concentracion de los nutrientes en los cultivos mixotroficos afecta la produccion de metabolitos, para el caso de la obtencion de carbohidratos, el acetato, el carbonato y el fosfato ejercieron un efecto positivo en su produccion. Para la produccion de lipidos, cuando el medio de cultivo contenia acetato, no se presento variable alguna que influyera significativamente, mientras que, para el cultivo con carbonato de amonio, el nitrato y las interacciones carbonato-fosfato, nitrato-fosfato ejercieron una influencia significativa en la produccion de este metabolito.

Simulation of bioethanol production process from residual microalgae biomass

Abstract Microalgae biomass is been evaluated mostly for biodiesel production, however, this feedstock has the potential of be used for production of bioethanol owing to its percentage of cellulosic material, in this work was performed the evaluation of three alternative technologies for the production of bioethanol from microalgae cake (biomass of microalgae lipid-free) in large scale, using the methodology of process simulation. Simultaneous Saccharification and Co-fermentation SSCF (route 1), Simultaneous Saccharification and Fermentation SSF (route 2), and Separate Saccharification and fermentation using acid hydrolysis SHF (route 3), technological routes were simulated based on experimental information using the software Aspen Plus 7.1. Results of simulation shows that Route 1 (SSCF) presents a bioethanol yield of 23.6%, being the highest of the routes evaluated, SSF route gives a yield of 20.1% and SHF 18.5%. This study shows the potential of enzymatic technologies for microalgal bioethanol production.