Browsing by Author "Lorenzo, Leire"
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Item Purification and concentration of formic acid from formic acid/gluconic acid mixtures by two successive steps of nanofiltration and reactive liquid-liquid extraction(2022-04-01) Roncal, Tomás; Lorenzo, Leire; Prieto-Fernández, Soraya; Ochoa-Gómez, José R.; Tecnalia Research & Innovation; BIOECONOMÍA Y CO2; GENERALA downstream process for the purification and concentration of formic acid (FA) from FA/gluconic acid (GA) mixtures, obtainable by a coupled biocatalytic reaction of CO2 reduction and glucose oxidation, has been developed. The process involved two technologies: i) a first nanofiltration (NF) step to separate FA and GA, and ii) a second reactive liquid-liquid extraction (RLLE) step to concentrate FA. The NF process, using a Synder NFX membrane, consisted of three NF steps separated into two divergent lines, named permeate and retentate pathways. The first NF was common for both pathways, resulting in a permeate strongly enriched in FA and depleted in GA, and a retentate with opposite characteristics. In the permeate pathway, this first permeate was subjected to a second NF to obtain a 99.6% pure FA permeate. In the retentate pathway, an additional NF step on the first retentate resulted in a concentrated 99.4% pure GA retentate. The final diluted FA permeate was concentrated by RLLE using tri-N-octylamine as extractant in n-octanol, and a final back-extraction with NaOH. The optimized RLLE process involved a 100-fold volume decrease and resulted in a final FA solution (as sodium formate) of 174.5 g/L, 78 times more concentrated than the feed.Item Removal of cooper (II) ions from aqueous solution by the use of biopolymers(2005) Villarán, M. Carmen; Valle, Beatriz; Bilbao, Ainhoa; Lorenzo, Leire; De Apodaca, Elena Díaz; Gugliotta, Vito; Gaballah, I.; Mishra, B.; Solozabal, R.; Tanaka, M.; Alimentación Sostenible; Tecnalia Research & InnovationChelation with bio-polymers is recognized as an emerging technique for the treatmente os wastewater containing heavy metals. In a first step of this study, the chelatmg kinetics of bio-polymers as alginic acid, calcium alginate, carrageenan and chitosan in relation with the Cu(II) at different pH and metal concentration, has been investigated. The chitosan was crosslinked with different chemicals and at different concentrations, to improve its stability at several pH. The used technologies for the regeneration of each polymer were ionic exchange and electrodeposition. Only with a combination of both technologies has been possible to obtain values of regeneration up to 95%.Item Two-step oxidation of glycerol to glyceric acid catalyzed by the Phanerochaete chrysosporium glyoxal oxidase(2012-02-10) Roncal, Tomás; Muñoz, Carmen; Lorenzo, Leire; Maestro, Belén; Díaz de Guereñu, María del Mar; BIOECONOMÍA Y CO2; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSGlyoxal oxidase of P. chrysosporium is a radical copper oxidase that catalyzes oxidation of aldehydes to carboxylic acids coupled to dioxygen reduction to H 2O 2. In addition to known substrates, glycerol is also found to be a substrate for glyoxal oxidase. During enzyme turnover, glyoxal oxidase undergoes a reversible inactivation, probably caused by loss of the active site free radical, resulting in short-lasting enzyme activities and undetectable substrate conversions. Enzyme activity could be extended by including two additional enzymes, horseradish peroxidase and catalase, in addition to a redox chemical activator, such as Mn(III) (or Mn(II)+H 2O 2) or hexachloroiridate. Using this three-enzyme system glycerol was converted in glyceric acid in a two-step reaction, with glyceraldehyde as intermediate. A possible operation mechanism is proposed in which the three enzymes would work coordinately allowing to maintain a sustained glyoxal oxidase activity. In the course of its catalytic cycle, glyoxal oxidase alternates between two functional and interconvertible reduced and oxidized forms resulting from a two-electron transfer process. However, glyoxal oxidase can also undergo an one-electron reduction to a catalytically inactive form lacking the active site free radical. Horseradish peroxidase could use glyoxal oxidase-generated H 2O 2 to oxidize Mn(II) to Mn(III) which, in turn, would reoxidize and reactivate the inactive form of glyoxal oxidase. Catalase would remove the excess of H 2O 2 generated during the reaction. In spite of the improvement achieved using the three-enzyme system, glyoxal oxidase inactivation still occurred, which resulted in low substrate conversions. Possible causes of inactivation, including end-product inhibition, are discussed.