A major proportion of the organic matter contained by domestic wastewater is mainly formed by lip... more A major proportion of the organic matter contained by domestic wastewater is mainly formed by lipids, proteins and carbohydrates. Hydrolytic enzymes like proteases and lipases are produced by microorganisms to degrade this organic matter. In the present study protease and lipase were extracted from activated sludge using ultrasound disintegration combined with a non ionic detergent. It was observed that the concentration of Triton X100 has a strong influence for the extraction of protease, while it has a negligible effect for the extraction of lipase. Samples obtained after ultrasound disintegration using 0% and 2% (v/v) Triton X100 were further purified by precipitation with ammonium sulphate and dialysis. The samples were frozen and lyophilised to recover them in powder form. Lipase activity was tested after all the purification steps, finding that the optimal process was a combination of ultrasound treatment (without any detergent) followed by dialysis and lyophilisation. This process allowed recovering up to 23 lipase units/g solid.
Partially O-acetylated xylo-oligosaccharides (DXO) isolated from almond shells by autohydrolysis ... more Partially O-acetylated xylo-oligosaccharides (DXO) isolated from almond shells by autohydrolysis as well as their de-acetylated form (DeXO) were subjected to chemical, molecular, and structural analyses. They represent a mixture of neutral and acidic oligomers and low-molecular weight polymers related to (4-O-methyl-D-glucurono)-D-xylan. DXO and DeXO showed direct mitogenic activity and enhancement of the T-mitogen-induced proliferation of rat thymocytes, indicating the immunostimulatory potential of the almond shell xylo-oligosaccharides.
ABSTRACT Xylose-based oligosaccharides produced from xylan-rich hemicelluloses (xylo-oligomers) a... more ABSTRACT Xylose-based oligosaccharides produced from xylan-rich hemicelluloses (xylo-oligomers) are carbohydrates with potential food and pharmaceutical uses. Autohydrolysis of lignocellulosic biomass is an efficient way to produce xylo-oligomers in a reasonable yield and a wide variety of compositions (anhydroarabinose/anhydroxylose and acetyl/anhydroxylose mass ratios). In this work, we develop a kinetic model for the autohydrolysis of xylan in lignocellulosic biomass that describes the yields of the different reaction products and explains the changes in the chemical composition of the xylo-oligomers due to reaction temperature and time. This model assumes that xylan is made up of three monomers (xylose, arabinose, and acetic acid) and that there are two xylan fractions with different compositions and reactivities toward hydrolysis. Both fractions are hydrolyzed to xylo-oligomers, which are hydrolyzed to xylose, arabinose, and acetic acid. Finally, monosaccharides dehydrate to furfural and degradation products. The model is validated with experimental data obtained for the autohydrolysis of corncobs in a batch reactor system at temperatures from 150 to 190 °C. The amount and composition of each xylan fraction, as well as the activation energies and frequency factors for all the reactions, are calculated from the experimental data. This model provides a satisfactory interpretation of the experimental data.
... Ethers and esters prepared from xylan and xylo-oligosaccharides have been synthesized and use... more ... Ethers and esters prepared from xylan and xylo-oligosaccharides have been synthesized and used as thermoplastic compounds for biodegradable plastics, water soluble films, coatings, capsules, and tablets (Glasser, Jain, & Sjöstedt, 1995), also for the preparation of xylan ...
Process intensification is one of the most promising areas in chemical engineering. Related to me... more Process intensification is one of the most promising areas in chemical engineering. Related to membranes, it means that the reac-tion and separation/purification steps are combined in a new single unit. This can be carried out in enzymatic membrane reactors (EMRs), which ...
Process intensification is one of the most promising areas in chemical engineering. Related to me... more Process intensification is one of the most promising areas in chemical engineering. Related to membranes, it means that the reac-tion and separation/purification steps are combined in a new single unit. This can be carried out in enzymatic membrane reactors (EMRs), which ...
Almond shells are agricultural residues with a high content of xylan that are produced abundantly... more Almond shells are agricultural residues with a high content of xylan that are produced abundantly in some regions with a Mediterranean climate. We have studied the production of xylo-oligosaccharides from almond shells by autohydrolysis at 150-190°C. The yield, composition, and molar mass distribution of the xylo-oligosaccharides were dependent on temperature and time: the maximum yield of xylo-oligosaccharides increased from 42% at 150°C and 300 min to 63% at 190°C and 19 min, while their anhydroarabinose-to-anhydroxylose and acetyl-toanhydroxylose mass ratios were 0.039 and 0.076 at 150°C and 0.129 and 0.125 at 190°C, respectively. Experimental data was used to fit the parameters of a kinetic model for xylan autohydrolysis, which describes the yields of the different reaction products and accounts for the changes in the chemical composition of xylan and xylo-oligosaccharides. The recovery of the xylo-oligosaccharides by spray drying was also evaluated. Spray drying of the autohydrolysis liquor obtained at 179°C and 23 min gave a yield of nonvolatile products of 29.4 g/(100 g of dry almond shells). The composition of this product was 58.3% xylo-oligosaccharides, 2.4% xylose, 1.5% arabinose, 0.78% glucose, 0.27% HMF, 16% Klason-type lignin, 4.8% ash, and 14.9% nonidentified products, which probably included organic extractives and protein present in almond shells, and products formed by the degradation of carbohydrates.
Ultrafiltration using commercial thin-film polymeric membranes was studied to purify the xylo-oli... more Ultrafiltration using commercial thin-film polymeric membranes was studied to purify the xylo-oligosaccharides (XOs) obtained by autohydrolysis of almond shells. Almond shells are agricultural residues with a high content of xylan that are produced abundantly in some regions with Mediterranean climate. Autohydrolysis was performed at 179 • C for 23 min in a 10 L stirred batch reactor at an almond shells-to-water mass ratio of 1-6, and the crude XOs were recovered by spray drying. Xylo-oligosaccharides only accounted for 58.3% of the recovered non-volatile products, and the rest was composed of low molar mass lignin (16.0%), monosaccharides (4.95%), inorganic compounds (or ashes, 4.80%) and a 15.0% of other unidentified impurities originated from the extractives of the almond shells. The product had a wide distribution of molar mass, ranging from around 0.1 kDa (monomers) to 70 kDa (dextran-equivalent). Ultrafiltration of the XOs solution was studied with commercial membranes (Osmonix, G-series) of molecular weight cut-off (MWCO) of 1, 2.5, 3.5 and 8 kDa, at pressures from 2.6 to 9 bar. The selectivity towards preferential permeation of the lignin-related impurities was larger for the 1 kDa membrane, and it decreased linearly with the flux of permeate (or trans-membrane pressure) for all membranes. The flux of lignin-related impurities varied between 10 g/h m 2 for the 1 kDa membrane at 2.7 bar and 264 g/h m 2 for the 8 kDa membrane at 8.6 bar, while the flux of xylo-oligosaccharides changed from 19 to 579 g/h m 2 at the same conditions. The apparent MWCO of the membranes, determined from GPC analysis of the XOs in the permeate, were above their nominal values. The 1 kDa membrane had an apparent MWCO of 2.75 ± 0.70 kDa, and for the 8 kDa membrane it was 10.9 ± 0.5. Membranes had a good resistance to fouling; water permeability for the used membranes was close to 93% of that of a new, unused membrane.
... Daniel Montané,* Débora Nabarlatz, Anna Martorell, Vanessa Torné-Fernández, and Vanessa Fierr... more ... Daniel Montané,* Débora Nabarlatz, Anna Martorell, Vanessa Torné-Fernández, and Vanessa Fierro. Departament d'Enginyeria Química, ETSEQ Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona (Catalunya), Spain. Ind. Eng. Chem. Res. ...
Enzymatic membrane reactors based on a polymeric matrix and activated carbon loaded with dextrana... more Enzymatic membrane reactors based on a polymeric matrix and activated carbon loaded with dextranase were synthesized to separate and purify dextrans. The steps carried out were: (1) testing the activity of the enzyme with a 40 kDa commercial dextran to obtain oligomers with low degree of polymerization, avoiding the production of monomer, (2) adsorbing the enzyme by the activated carbon considering concentration and pH as variables, as well as testing the activity of the loaded activated carbon obtained, (3) synthesizing the enzymatic membrane reactors, (4) characterizing them by SEM and IFME ® software and (5) testing their performance in a flat membrane module at ultrafiltration pressures. Results show a proper activity of the enzyme and the loaded activated carbon, and optimal conditions for the adsorption of enzyme by the activated carbon were found (pH 5). Related to the enzymatic membrane reactors, the larger activated carbon-enzyme loading, the closer porous structure was obtained. Since a very specific enzyme was used, changes in the loading of the activated carbon-enzyme leads to a change on the mean value of degree of polymerization of the produced compounds, but not on the amount of a specific-in-size product obtained. By using 4 wt.% of activated carbon-enzyme loading in the preparation of the enzymatic membrane reactor it is possible to obtain, as purified reaction products, oligomers from 200 Da.
A major proportion of the organic matter contained by domestic wastewater is mainly formed by lip... more A major proportion of the organic matter contained by domestic wastewater is mainly formed by lipids, proteins and carbohydrates. Hydrolytic enzymes like proteases and lipases are produced by microorganisms to degrade this organic matter. In the present study protease and lipase were extracted from activated sludge using ultrasound disintegration combined with a non ionic detergent. It was observed that the concentration of Triton X100 has a strong influence for the extraction of protease, while it has a negligible effect for the extraction of lipase. Samples obtained after ultrasound disintegration using 0% and 2% (v/v) Triton X100 were further purified by precipitation with ammonium sulphate and dialysis. The samples were frozen and lyophilised to recover them in powder form. Lipase activity was tested after all the purification steps, finding that the optimal process was a combination of ultrasound treatment (without any detergent) followed by dialysis and lyophilisation. This process allowed recovering up to 23 lipase units/g solid.
Partially O-acetylated xylo-oligosaccharides (DXO) isolated from almond shells by autohydrolysis ... more Partially O-acetylated xylo-oligosaccharides (DXO) isolated from almond shells by autohydrolysis as well as their de-acetylated form (DeXO) were subjected to chemical, molecular, and structural analyses. They represent a mixture of neutral and acidic oligomers and low-molecular weight polymers related to (4-O-methyl-D-glucurono)-D-xylan. DXO and DeXO showed direct mitogenic activity and enhancement of the T-mitogen-induced proliferation of rat thymocytes, indicating the immunostimulatory potential of the almond shell xylo-oligosaccharides.
ABSTRACT Xylose-based oligosaccharides produced from xylan-rich hemicelluloses (xylo-oligomers) a... more ABSTRACT Xylose-based oligosaccharides produced from xylan-rich hemicelluloses (xylo-oligomers) are carbohydrates with potential food and pharmaceutical uses. Autohydrolysis of lignocellulosic biomass is an efficient way to produce xylo-oligomers in a reasonable yield and a wide variety of compositions (anhydroarabinose/anhydroxylose and acetyl/anhydroxylose mass ratios). In this work, we develop a kinetic model for the autohydrolysis of xylan in lignocellulosic biomass that describes the yields of the different reaction products and explains the changes in the chemical composition of the xylo-oligomers due to reaction temperature and time. This model assumes that xylan is made up of three monomers (xylose, arabinose, and acetic acid) and that there are two xylan fractions with different compositions and reactivities toward hydrolysis. Both fractions are hydrolyzed to xylo-oligomers, which are hydrolyzed to xylose, arabinose, and acetic acid. Finally, monosaccharides dehydrate to furfural and degradation products. The model is validated with experimental data obtained for the autohydrolysis of corncobs in a batch reactor system at temperatures from 150 to 190 °C. The amount and composition of each xylan fraction, as well as the activation energies and frequency factors for all the reactions, are calculated from the experimental data. This model provides a satisfactory interpretation of the experimental data.
... Ethers and esters prepared from xylan and xylo-oligosaccharides have been synthesized and use... more ... Ethers and esters prepared from xylan and xylo-oligosaccharides have been synthesized and used as thermoplastic compounds for biodegradable plastics, water soluble films, coatings, capsules, and tablets (Glasser, Jain, & Sjöstedt, 1995), also for the preparation of xylan ...
Process intensification is one of the most promising areas in chemical engineering. Related to me... more Process intensification is one of the most promising areas in chemical engineering. Related to membranes, it means that the reac-tion and separation/purification steps are combined in a new single unit. This can be carried out in enzymatic membrane reactors (EMRs), which ...
Process intensification is one of the most promising areas in chemical engineering. Related to me... more Process intensification is one of the most promising areas in chemical engineering. Related to membranes, it means that the reac-tion and separation/purification steps are combined in a new single unit. This can be carried out in enzymatic membrane reactors (EMRs), which ...
Almond shells are agricultural residues with a high content of xylan that are produced abundantly... more Almond shells are agricultural residues with a high content of xylan that are produced abundantly in some regions with a Mediterranean climate. We have studied the production of xylo-oligosaccharides from almond shells by autohydrolysis at 150-190°C. The yield, composition, and molar mass distribution of the xylo-oligosaccharides were dependent on temperature and time: the maximum yield of xylo-oligosaccharides increased from 42% at 150°C and 300 min to 63% at 190°C and 19 min, while their anhydroarabinose-to-anhydroxylose and acetyl-toanhydroxylose mass ratios were 0.039 and 0.076 at 150°C and 0.129 and 0.125 at 190°C, respectively. Experimental data was used to fit the parameters of a kinetic model for xylan autohydrolysis, which describes the yields of the different reaction products and accounts for the changes in the chemical composition of xylan and xylo-oligosaccharides. The recovery of the xylo-oligosaccharides by spray drying was also evaluated. Spray drying of the autohydrolysis liquor obtained at 179°C and 23 min gave a yield of nonvolatile products of 29.4 g/(100 g of dry almond shells). The composition of this product was 58.3% xylo-oligosaccharides, 2.4% xylose, 1.5% arabinose, 0.78% glucose, 0.27% HMF, 16% Klason-type lignin, 4.8% ash, and 14.9% nonidentified products, which probably included organic extractives and protein present in almond shells, and products formed by the degradation of carbohydrates.
Ultrafiltration using commercial thin-film polymeric membranes was studied to purify the xylo-oli... more Ultrafiltration using commercial thin-film polymeric membranes was studied to purify the xylo-oligosaccharides (XOs) obtained by autohydrolysis of almond shells. Almond shells are agricultural residues with a high content of xylan that are produced abundantly in some regions with Mediterranean climate. Autohydrolysis was performed at 179 • C for 23 min in a 10 L stirred batch reactor at an almond shells-to-water mass ratio of 1-6, and the crude XOs were recovered by spray drying. Xylo-oligosaccharides only accounted for 58.3% of the recovered non-volatile products, and the rest was composed of low molar mass lignin (16.0%), monosaccharides (4.95%), inorganic compounds (or ashes, 4.80%) and a 15.0% of other unidentified impurities originated from the extractives of the almond shells. The product had a wide distribution of molar mass, ranging from around 0.1 kDa (monomers) to 70 kDa (dextran-equivalent). Ultrafiltration of the XOs solution was studied with commercial membranes (Osmonix, G-series) of molecular weight cut-off (MWCO) of 1, 2.5, 3.5 and 8 kDa, at pressures from 2.6 to 9 bar. The selectivity towards preferential permeation of the lignin-related impurities was larger for the 1 kDa membrane, and it decreased linearly with the flux of permeate (or trans-membrane pressure) for all membranes. The flux of lignin-related impurities varied between 10 g/h m 2 for the 1 kDa membrane at 2.7 bar and 264 g/h m 2 for the 8 kDa membrane at 8.6 bar, while the flux of xylo-oligosaccharides changed from 19 to 579 g/h m 2 at the same conditions. The apparent MWCO of the membranes, determined from GPC analysis of the XOs in the permeate, were above their nominal values. The 1 kDa membrane had an apparent MWCO of 2.75 ± 0.70 kDa, and for the 8 kDa membrane it was 10.9 ± 0.5. Membranes had a good resistance to fouling; water permeability for the used membranes was close to 93% of that of a new, unused membrane.
... Daniel Montané,* Débora Nabarlatz, Anna Martorell, Vanessa Torné-Fernández, and Vanessa Fierr... more ... Daniel Montané,* Débora Nabarlatz, Anna Martorell, Vanessa Torné-Fernández, and Vanessa Fierro. Departament d'Enginyeria Química, ETSEQ Rovira i Virgili University, Av. Països Catalans 26, 43007 Tarragona (Catalunya), Spain. Ind. Eng. Chem. Res. ...
Enzymatic membrane reactors based on a polymeric matrix and activated carbon loaded with dextrana... more Enzymatic membrane reactors based on a polymeric matrix and activated carbon loaded with dextranase were synthesized to separate and purify dextrans. The steps carried out were: (1) testing the activity of the enzyme with a 40 kDa commercial dextran to obtain oligomers with low degree of polymerization, avoiding the production of monomer, (2) adsorbing the enzyme by the activated carbon considering concentration and pH as variables, as well as testing the activity of the loaded activated carbon obtained, (3) synthesizing the enzymatic membrane reactors, (4) characterizing them by SEM and IFME ® software and (5) testing their performance in a flat membrane module at ultrafiltration pressures. Results show a proper activity of the enzyme and the loaded activated carbon, and optimal conditions for the adsorption of enzyme by the activated carbon were found (pH 5). Related to the enzymatic membrane reactors, the larger activated carbon-enzyme loading, the closer porous structure was obtained. Since a very specific enzyme was used, changes in the loading of the activated carbon-enzyme leads to a change on the mean value of degree of polymerization of the produced compounds, but not on the amount of a specific-in-size product obtained. By using 4 wt.% of activated carbon-enzyme loading in the preparation of the enzymatic membrane reactor it is possible to obtain, as purified reaction products, oligomers from 200 Da.
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Papers by Debora Nabarlatz