R. López

Bio: R. López is an academic researcher from University of León. The author has contributed to research in topics: Soil water & Biomass. The author has an hindex of 7, co-authored 24 publications receiving 216 citations.

Thermogravimetric analysis of lignocellulosic and microalgae biomasses and their blends during combustion

Abstract: Thermogravimetric analysis was used to study and compare the combustion of different blends of corn bioresidues with sunflower, rape and algae bioresidues. Non-isothermal thermogravimetric data were used to obtain the combustion kinetics of these bioresidues. This paper reports on the application of the Vyazovkin and Ozawa–Flynn–Wall isoconversional methods for the evaluation of kinetic parameters (energy activation, pre-exponential factor and order of reaction) for the combustion of the biomasses studied. Differences were found in the TG curves in accordance with the proximate analysis results for the cellulose, hemicellulose and lignin content of biomasses. The activation energy obtained from combustion (E ~ 151.6 kJ mol−1) was lower than that from the blends (similar values were obtained for corn–sunflower, E ~ 160.5 kJ mol−1 and corn–rape, E ~ 156.9 kJ mol−1) whereas the activation energy obtained from the microalgae was higher (E ~ 171.5 kJ mol−1). Both the Vyazovkin and Ozawa–Flynn–Wall methods yielded similar results.

Co-Digestion of Swine Manure and Crude Glycerine: Increasing Glycerine Ratio Results in Preferential Degradation of Labile Compounds

Abstract: Co-digestion of swine manure and crude glycerine from biodiesel production has been successfully attempted by many authors reporting substantial increments in biogas production. However, the effectiveness of this approach has been questioned recently. The addition of glycerol may cause an improvement in biogas production but at the expense of disturbing the degradation of manure. In the present paper, the organic transformations undergone in the anaerobic digestion of pig manure at increasing amounts of glycerine (2–8 % (v/v)) were analysed using spectroscopy techniques (Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR)). An increase in biogas production was observed with the addition of glycerine up to 8 %, resulting in a volumetric production of methane per litre of reactor (Lr) of 1.4 L CH4/Lr d. However, the subsequent failure of the system was observed at this glycerine content due to the inhibitory effect caused by high H2S concentration and foam formation. FTIR and 1H NMR analysis performed on digestate samples showed that the addition of the co-substrate also caused the preferential degradation of glycerine and accumulation of proteins and aliphatic compounds. A post-stabilisation stage was necessary to complete the degradation process. Modifications in organic matter continued under this last stage although in the previous digestion period, a competition for substrate between sulphate reducing bacteria and methanogens was observed.

Remediation of Potential Toxic Elements from Wastes and Soils: Analysis and Energy Prospects

Abstract: The aim of this study is to evaluate the application of the main hazardous waste management techniques in mining operations and in dumping sites being conscious of the inter-linkages and inter-compartment of the contaminated soils and sediments. For this purpose, a systematic review of the literature on the reduction or elimination of different potential toxic elements was carried out, focusing on As, Cd and Hg as main current contaminant agents. Selected techniques are feasible according to several European countries’ directives, especially in Spain. In the case of arsenic, we verified that there exists a main line that is based on the use of iron minerals and its derivatives. It is important to determine its speciation since As (III) is more toxic and mobile than As (V). For cadmium (II), we observed a certain predominance of the use of biotic techniques, compared to a variety of others. Finally, in mercury case, treatments include a phytoremediation technique using Limnocharis flava and the use of a new natural adsorbent: a modified nanobiocomposite hydrogel. The use of biological treatments is increasingly being studied because they are environmentally friendly, efficient and highly viable in both process and energy terms. The study of techniques for the removal of potential toxic elements should be performed with a focus on the simultaneous removal of several metals, since in nature they do not appear in isolation. Moreover, we found that energy analysis constitutes a limiting factor in relation to the feasibility of these techniques.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Characterization and comparative study of pyrolysis kinetics of the rice husk and the elephant grass

Abstract: A comparative evaluation of different biomasses allows the choice that presents the best potential as fuel for energy production. The knowledge of the thermal and kinetics parameters of the biomass in the process of thermal conversion is fundamental as their chemical and physical characterization. Various methodologies have been developed for the determination of kinetic parameters as apparent activation energy and reaction order from the thermogravimetric analysis. In this work, the apparent activation energy needed to break the bonds of hemicelluloses and cellulose of rice husk and elephant grass during the thermal conversion was evaluated according to the kinetics models of Flynn and Wall and Model Free Kinetics developed by Vyazovkin. The biomass elephant grass and rice husk were characterized for moisture, ash and volatile matter by ASTM E871, ASTM E1755, ASTM E872, respectively, and fixed carbon by difference. The percentage of carbon, hydrogen, nitrogen, and oxygen were determined by ultimate analysis. The elephant grass showed to be more suitable for production of bio-oil through pyrolysis due to the higher percentage of volatile, less ash content and less energy required to break the bonds of hemicellulose and cellulose than rice husk in the thermal conversion process.

A Combined Overview of Combustion, Pyrolysis, and Gasification of Biomass

Abstract: From the conventional use of biomass in the form of heating to the modern day use of biomass in the form of electricity generation and biofuel production, biomass has always been part of the evolution of mankind Modern day use of biomass is gradually becoming more complex, and engineering played an important role in defining different directions This review provides an overall view of biomass utilization through thermal treatment including combustion, pyrolysis, and gasification Efficient use of biomass with the desired output and minimizing the drawbacks are the core of the research, and marginal focus is being held on developing new techniques The variety of composition and uptake of different elements throughout the lifespan of biomass produces a mixture of results In general, it can be seen that the optimization was observed either in the form of chemical looping combustion to prevent greenhouse gas emission or in upgrading of bio-oil to produce biofuels The significant factor is the reaction co

Utilization of the residual glycerol from biodiesel production for renewable energy generation

Abstract: A rapid growth in biodiesel production has naturally led to a surplus of crude glycerol generated. Due to the impurities present in the crude glycerol, expensive refining processes are often necessary in order for the crude glycerol to be used in the same applications as pure glycerol. As a result, the demand for crude glycerol is quite low, and biodiesel producers must find ways to dispose it. Disposal can be costly, detrimental to the environment, and wasteful. Exploration of crude glycerol utilization is of significance for not only reducing the negative impact on the environment but also for increasing the economic benefits of biodiesel production. This paper reviewed a number of valuable and practical applications of crude glycerol in the sector of renewable energy generation through processes such as fermentation, digestion, gasification, pyrolysis, liquefaction, combustion, and steam reforming. Studies indicated that an integration of crude glycerol to other systems for energy production is a promising option despite the impurities in crude glycerol, and some processes even benefit from their presence.