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Garcia-Dominguez M.T.,Agrifood Campus of International Excellence CeiA3 | Garcia-Dominguez J.C.,University of Huelva | Lopez F.,University of Huelva | De Diego C.M.,Acciona | Diaz M.J.,University of Huelva
Environmental Progress and Sustainable Energy | Year: 2015

The autohydrolysis process as a method for selective extraction of hemicelluloses and conversion to furfural was proposed for lignocellulosic raw materials. Samples of wheat straw (WS) and Eucalyptus globulus (EG) were subjected to nonisothermal autohydrolysis, defined by temperature 180-240°C. Within a biorefinery scheme for the selected materials, the aim of this study is both (a) to optimize furfural processing technology to enable higher yields and improved productivity from EG and WS by autohydrolysis and (b) to not excessively degrade the remaining polymeric constituents (glucan) in solid to facilitate a potential later use. Differences in the rate of the dehydration reaction of xylose to furfural have been observed, and it is faster in the case of WS with respect to that observed for eucalyptus. In that form, 4.25 g/100 g raw material (26% of the initial xylan in WS) could be found at 220°C, and an increase in the temperature (240°C) yielded 4.54 g/100 g raw material, 28% of the initial xylan. In EG, the increase in the hydrolysis temperature (240°C) yielded liquor with higher contents of furfural (4.45 g/100 g raw material, 25% of the initial xylan) and acetic acid (4.49 g/100 g raw material) and smaller contents of arabinose and xylan. In WS, a faster dehydration is found. © 2015 American Institute of Chemical Engineers Environ Prog. Source


Lopez F.,University of Huelva | Trinidad Garcia M.,Agrifood Campus of International Excellence CeiA3 | Mena V.,University of Huelva | Mauricio Loaiza J.,University of Huelva | And 2 more authors.
BioResources | Year: 2015

This study investigates the operating conditions used in the soda-anthraquinone pulping of Eucalyptus globulus wood after autohydrolysis pretreatment on the yield, kappa number, and brightness of the resulting unbleached pulp. Moreover, strength-related properties of the resulting handsheets was examined to identify the best pulping conditions and compare the outcome with that of a conventional soda-anthraquinone pulping process. The paper strength properties of the pulp were similar to or better than papers made from soda-AQ delignified pulps conducted in a single step. Also, a liquid fraction with a substantial content in hemicellulosic extracts was recovered in the simplified process. Autohydrolysis of the raw material facilitates carrying out soda-AQ pulping under milder conditions. In addition, autohydrolysis improves other properties relative to paper from raw cellulose pulp. Yield, kappa number, and brightness for pulp from solid residues of autohydrolysed eucalyptus wood were similar to those for pulp from untreated eucalyptus wood. Source


Lopez F.,University of Huelva | Garcia M.T.,Agrifood Campus of International Excellence CeiA3 | Feria M.J.,University of Huelva | Garcia J.C.,University of Huelva | And 3 more authors.
Chemical Engineering Journal | Year: 2014

The aim of this study was to optimize the production of furfural by hydrolysis with dilute acid of Eucalyptus globulus wood in two stages, using a factorial experimental design and multiple regression models to maximize furfural yields. The two-stage process could provide a solid phase with less degraded cellulose and older applications that the solid phase of a conventional acid hydrolysis. The selectivity for furfural of the process was increased by effect of the glucan and lignin fractions being efficiently removed after the first acid hydrolysis stage.The operational ranges are especially suitable for the extraction of xylose, which was virtually quantitative at 170. °C and virtually independent of the operation time. It is therefore advisable to use non-isothermal conditions or short times. This is quite important if one considers the low acid concentration used. The liquid phase obtained after autohydrolysis of the raw material under the optimum conditions contained 2.3% glucose, 9.8% xylose, 2.5% xylo-oligomers, 0.6% arabinose, 1.1% furfural and 0.1% 5-OH methyl furfural.After the residual solid from the first hydrolysis stage is removed, the acid concentration is the most influential variable on the conversion of xylo-oligomers or xylose into furfural. Conversions to furfural were quite substantial (greater than 10. g/L). Hemicelluloses in the raw material were extracted by 32-57.7% and xylan by 40.5-84%. The highest conversions to furfural were obtained by using a medium operation time (15. min) and low temperature (170. °C) and pH. =. 2.The process additionally provides hemicellulose derivatives that are scarcely contaminated with cellulose derivatives. The concentrations of gluco-oligomers were very low and those of glucose in the region of 3% of the raw material. © 2013 Elsevier B.V. Source


Sanchez-Quesada C.,University of Jaen | Lopez-Biedma A.,University of Jaen | Warleta F.,University of Jaen | Campos M.,University of Jaen | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

Oleanolic acid, maslinic acid, uvaol, and erythrodiol are the main triterpenes present in olives, olive tree leaves, and virgin olive oil. Their concentration in virgin olive oil depends on the quality of the olive oil and the variety of the olive tree. These triterpenes are described to present different properties, such as antitumoral activity, cardioprotective activity, anti-inflammatory activity, and antioxidant protection. Olive oil triterpenes are a natural source of antioxidants that could be useful compounds for the prevention of multiple diseases related to cell oxidative damage. However, special attention has to be paid to the concentrations used, because higher concentration may lead to cytotoxic or biphasic effects. This work explores all of the bioactive properties so far described for the main triterpenes present in virgin olive oil. © 2013 American Chemical Society. Source


Contreras J.I.,Institute of Research and Training in Agriculture and Fishery IFAPA | Segura M.L.,Institute of Research and Training in Agriculture and Fishery IFAPA | Lao M.T.,Agrifood Campus of International Excellence CeiA3 | Lao M.T.,University of Almeria
Acta Horticulturae | Year: 2015

The purpose of this trial was to study the nutritional status of the root-zone, using the substrate solution obtained with the suction cup method as related to growth and quality of plants of Syngonium podophyllum. For such purpose some sources of fertilizers were tested. The trial was carried out in a type INSOLE greenhouse (Buried Solar Greenhouse), from 19 April to 19 September, 2004. There were four mineral fertilizer treatments: (SLF) a standard liquid feeding, (LFSF) a fertilizer (17-8-14) containing nitrate (NO3 -), ammonium (NH4 +) and a nitrification inhibitor (3,4-dimethylpyrazole phosphate, DMPP) and (CRF) two coated controlled release fertilizers (Basacote Plus (16-8-12) plus half concentration of SLF and Osmocote Plus (16-8-12) plus half concentration of SLF). The nutrient substrate solutions showed important differences, especially when CRF were incorporated to the substrate. Substrate buffers the system, avoiding a high pH lowering. Electrical conductivity was highest in CRF, due to the nitrate concentration, a fact suggesting that the use of controlled release fertilizers should be reconsidered in tropical crops. Basacote treatment showed a good-excellent plant quality; plants treated with LFSF and Osmocote treatments also showed a good quality, while SLF depressed the quality of plants. The efficiency of different ways of fertilization has been studied globally, LFSF being significantly higher. Source

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