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- Berglund, Per, et al.
(author)
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Enantiorecognition of Chiral Acids by Candida rugosa Lipase : Two Substrate Binding Modes Evidenced in an Organic Medium
- 2001
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In: Applied Biocatalysis in Speciality Chemicals and Pharmaceuticals. - : American Chemical Society (ACS). - 0841236798 ; 776, s. 263-273
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Conference paper (peer-reviewed)abstract
- We have identified the existence of different modes of binding the enantiomers of 2-methyl-branched carboxylic acids to a lipase active site by rational substrate engineering. Similar to hydrolysis, previously investigated, we have now evidence for differential binding modes in the Candida rugosa lipase-catalyzed esterifications in cyclohexane. The relevance of considering two different binding modes to understand lipase enantiorecognition is demonstrated by introducing bulky substituents on a chiral carboxylic acid which impose a different orientation of the substrate acyl chain in the active site of Candida rugosa lipase. With this substrate engineering approach based on molecular modeling it is thus possible to markedly alter the enantioselectivity of the lipase. Examples from hydrolysis and new results from esterifications in an organic solvent are presented and discussed.
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- Dupaul, Gabriel, et al.
(author)
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Fiberbanks as substrate and feedstock for biological remediation : A practical analytical method development for organic pollutants analysis
- 2020
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In: Book of Abstracts. - : ABA Publishing. - 9789189081031
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Conference paper (peer-reviewed)abstract
- Fiberbanksfrom the pulp and paper industry are typically contaminated with a wide range ofchlorinated aromatic and aliphatic toxins such as HCB and other chlorinated benzenes, PCB,HCH, DDT, PCDD, PCDF and Chlorophenols. This poses a formidable challenge for theanalyst to develop appropriate analytical methodology for the monitoring of the progress ofremediation.In preparation to this undertaking, an examination of a practical analytical method using oneextraction method, one clean-up and one analysis method for the aforementioned targetcompounds found in the fibrous sediment. This method was performed using acceleratedsolvent extraction (ASE), a modified silica gel column and GC-FID/ECD. Additionally,an assessment of the levels of organic pollutants was conducted,with the purposeofmeasuringthe potential alteration in contaminantswhenfreeze-drying, air-drying andautoclavingpretreatments are applied to the sediment samples, prior to be used as a media forbiological remediation.The results showed that the ASE is a very fast and reliable method of extraction, with yieldscomparableorhigher than the reference Soxhlet extraction method. Theactivatedsilica gelcolumn demonstrated adequate purification of the sediment extract for analysisusingthe twodetectors, FID and ECD, whichwere able to identify the target analytes fromonlyone purifiedextract. The method employed in this study has the potentialto reduceboth processing timeand materialusedfor analytical sample preparation. Lastly, some modifications inconcentrations anddistribution of target analyteswere revealedin thesediments pre-treated byautoclave and air-driedwhencompared withthefreeze-dried sediments, which can helpunderstanding the development of the biological remediation process.
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- Haller, Henrik, 1977-, et al.
(author)
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Polluted lignocellulose waste as a resource for marketable products
- 2020
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In: Proceedings Linnaeus ECO-TECH 2020. - 9789189081031
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Conference paper (peer-reviewed)abstract
- Fiberbanks and fiber-rich sediments are legacies of the previously unregulated wastewater discharge from the pulp and paper industry that have accumulated large quantities of toxic organic waste on the Baltic Sea floor and on the bottom of rivers and lakes. Several km2 are covered with deposits of fibrous residues that are, typically, heavily polluted with a number of organic and inorganic substances, posing a serious threat to human and ecological health. High toxicity and the large volume of the polluted material are challenges for remediation endeavors. However, since the fibrous material is a bioresource with a high energy density, the sheer quantity of it could appeal to commercialization as feedstock for various marketable products. This study sets out to explore the potential of using this polluted material as a resource for industrial production, by reviewing and synthesizing data about modern production methods or reuse alternatives for lignocellulose material that can be adapted to a polluted feedstock. Biochemical methods such as composting, anaerobic digestion, as well as, thermochemical methods, for instance, HTC, HTL, pyrolysis, gasification etc. have been assessed. Potential end products from fiber bank material include biochar, liquid and gaseous biofuels, growth media, and fatty acids and proteins produced by white-rot fungi.
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- Högberg, Ida, et al.
(author)
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The Interaction Parameter in Binary Surfactant Mixtures of a Chelating Surfactant and a Foaming Agent.
- 2010. - 138
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In: TRENDS IN COLLOID AND INTERFACE SCIENCE XXIV. - Berlin : Springer. - 9783642190377 ; , s. 17-20
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Conference paper (peer-reviewed)abstract
- The micellisation in binary mixed surfactant systems of a chelating surfactant and a foaming agent has been studied by surface tension measurements in order to calculate the interaction parameter (beta). 2-dodecyldiethylenetriamine pentaacetic acid, 4-C(12)-DTPA, is an amphoteric chelating surfactant applicable for removing disturbing metal ions from industrial processes, or for heavy metal decontamination of soil or leachate. 4-C(12)-DTPA contains multiple donor atoms and forms very stable coordination complexes with metal ions. The metal complexes can easily be recovered from water by flotation, if the foaming is enhanced by a foaming agent with strong interactions to the chelating surfactant. Two foaming agents were examined, one cationic and one anionic. As expected, strong interactions were found between the negatively charged 4-C(12)-DTPA and the cationic dodecyltrimethylammonium chloride, DTAC. The influence of metal ion chelation, as well as pH, on the interaction parameter was also investigated.
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