RESUMEN
The main objective of this work was to assess Eucalyptus globulus lignin as an adsorbent and compare the results with kraft lignin, which has previously been demonstrated to be an effective adsorbent. Eucalypt lignin was extracted (by the dioxane technique), characterised, and its adsorption properties for Cr(VI) ions were evaluated. The monomeric composition of both types of lignin indicated a high content of guaiacyl (G) and syringyl (S) units but low content of p-hydroxyphenyl (H), with an H:G:S ratio of 1:50:146 (eucalypt lignin) and 1:16:26 (kraft lignin), as determined by Py-GC/MS. According to elemental analysis, sulphur (2%) and sodium (1%) were found in kraft lignin, but not in eucalypt lignin. The adsorption capacity of the eucalypt lignin was notably higher than the kraft lignin during the first 8 h, but practically all the ions had been absorbed by both the eucalypt and kraft lignin after 24 h (93.4% and 95%, respectively). Cr(VI) adsorption onto both lignins fitted well using the Langmuir adsorption isotherm model, with capacities of 256.4 and 303.0 mg/g, respectively, for eucalypt and kraft. The study's overall results demonstrate the great potential of eucalypt lignin as a biosorbent for Cr(VI) removal from aqueous solutions.
Asunto(s)
Cromo , Contaminantes Químicos del Agua , Adsorción , Dioxanos , Concentración de Iones de Hidrógeno , Iones , Cinética , Lignina , Sodio , AzufreRESUMEN
Statistical models concerning partitioning of pectinase in polyethylene glycol 1000/Na2SO4 aqueous two-phase system were established with response surface methodology. Concentrations of polyethylene glycol 1000 and Na2SO4 were selected as independent variables to evaluate their impact on parameters of partitioning in aqueous two-phase system--the partition coefficient of pectinase, purification factor and pectinase yield. An experimental space where over 2.5-fold purification was achieved, followed by over 90% yield of pectinase. The established models showed good prediction of partitioning parameters.
Asunto(s)
Modelos Estadísticos , Polietilenglicoles/química , Poligalacturonasa/aislamiento & purificación , Sulfatos/química , Adenosina Trifosfato/metabolismo , Poligalacturonasa/metabolismo , AguaRESUMEN
A selection of best combination of adequate immobilization support and efficient immobilization method is still a key requirement for successful application of immobilized enzymes on an industrial level. Eupergit® supports exhibit good mechanical and chemical properties and allow establishment of satisfactory hydrodynamic regime in enzyme reactors. This is advantageous for their wide application in enzyme immobilization after finding the most favorable immobilization method. Methods for enzyme immobilization that have been previously reported as efficient considering the obtained activity of immobilized enzyme are presented: direct binding to polymers via their epoxy groups, binding to polymers via a spacer made from ethylene diamine/glutaraldehyde, and coupling the periodate-oxidized sugar moieties of the enzymes to the polymer beads. The modification of the conventionally immobilized enzyme with ethylenediamine via the carbodiimide route seems to be a powerful tool to improve its stability and catalytic activity.
Asunto(s)
Candida/enzimología , Enzimas Inmovilizadas/química , Compuestos Epoxi/química , Etilenodiaminas/química , Glutaral/química , Lipasa/química , Polímeros/química , Acrilamidas/química , Aminación , Candida/química , Candida/metabolismo , Estabilidad de Enzimas , Enzimas Inmovilizadas/metabolismo , Lipasa/metabolismo , Metacrilatos/química , Oxidación-ReducciónRESUMEN
A selection of the best combination of adequate immobilization support and efficient immobilization method is still a key requirement for successful application of immobilized enzymes on the industrial level. Eupergit) supports exhibit good mechanical and chemical properties and allow establishment of satisfactory hydrodynamic regime in enzyme reactors. This is a good recommendation for their wide application in enzyme immobilization after finding the most favorable immobilization method. Methods for enzyme immobilization that have been previously reported as efficient, considering the obtained activity of immobilized enzyme are presented: direct binding to polymers via their epoxy groups, binding to polymers via a spacer made from ethylene diamine/glutaraldehyde, and coupling the periodate-oxidized sugar moieties of the enzymes to the polymer beads.