Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Fermentations great promise
    Smid, E.J. - \ 2019
    biobased economy - microorganisms - bacteria - chemicals - food - fatty acids - kerosene - fermentation
    'Veelbelovend en bijna marktrijp' : onderzoek door Wageningen Universiteit Research naar biobased bindmiddelen in verf
    Haveren, J. van - \ 2017
    residual streams - biobased economy - chemicals - biobased chemicals - research - biobased chemistry - binding agents - biopolymers - paints
    Microbial electrosynthesis of biochemicals : innovations on biocatalysts, electrodes and ion-exchange for CO2 supply, chemicals production and separation
    Bajracharya, S. - \ 2016
    Wageningen University. Promotor(en): Cees Buisman; David Strik; Deepak Pant. - Wageningen : Wageningen University - ISBN 9789462578531 - 181
    carbon dioxide - biofuels - chemicals - biocatalysis - ion exchange - electrodes - kooldioxide - biobrandstoffen - chemicaliën - biokatalyse - ionenuitwisseling - elektrodes

    Microbial electrosynthesis (MES) is an electricity-driven production of chemicals from low-value waste using microorganisms as biocatalysts. MES from CO2 comprises conversion of CO2 to multi-carbon compounds employing microbes at the cathode which use electricity as an energy source. This thesis presents innovations on MES from CO2 using anaerobic mixed-cultures, circumventing the methane generation. Acetate was the primary product but other products including ethanol, butyrate were also produced. Establishment of active biocathode at the graphite felt cathode was achieved under long-term operation which led to the acetate accumulation up to 7-10 g L-1 at -1 V/Ag/AgCl cathode potential. CO2 reduction in MES requires continuous availability of CO2 and low cathode potential to ensure the supply of reducing equivalents/hydrogen. Use of gas diffusion biocathode doubled the CO2 mass-transfer rate which enhanced the production rates, reaching. Furthermore, a sustainable technology for manufacturing biochemicals/biofuels was demonstrated in this thesis by integrating the product separation in MES. The electricity-driven production of chemicals/biofuels from CO2/waste products and subsequent product recovery studies prospect an integration of microbial electrosynthesis with biorefineries for the up-scaling of both technologies.

    Assessing the effects of chemicals on aquatic microbial ecosystems
    Rocha Dimitrov, M. - \ 2016
    Wageningen University. Promotor(en): Hauke Smidt; Paul van den Brink. - Wageningen : Wageningen University - ISBN 9789462576667 - 264
    aquatic ecosystems - microorganisms - macroinvertebrates - microbial ecology - aquatic fungi - chemicals - tebuconazole - fungicide residues - pesticides - marine sediments - toxicity - enrofloxacin - fluoroquinolones - zooplankton - phytoplankton - antibiotic resistance - periphyton - bacteria - ecological risk assessment - aquatische ecosystemen - micro-organismen - macroinvertebraten - microbiële ecologie - waterschimmels - chemicaliën - tebuconazool - fungicidenresiduen - pesticiden - mariene sedimenten - toxiciteit - enrofloxacine - fluoroquinolonen - zoöplankton - fytoplankton - antibioticaresistentie - perifyton - bacteriën - ecologische risicoschatting
    Metabolic engineering of Escherichia coli for itaconate production
    Vuoristo, K.S. - \ 2016
    Wageningen University. Promotor(en): Gerrit Eggink; Johan Sanders, co-promotor(en): Ruud Weusthuis. - Wageningen : Wageningen University - ISBN 9789462576001 - 162
    fermentation - escherichia coli - aspergillus niger - biobased chemistry - bioengineering - acids - organic acids - glutamates - tca - production - chemicals - fermentatie - escherichia coli - aspergillus niger - chemie op basis van biologische grondstoffen - bioengineering - zuren - organische zuren - glutamaten - tca - productie - chemicaliën

    Interest in sustainable development together with limited amounts of fossil resources have increased the demand for production of chemicals and fuels from renewable resources. The market potential for bio-based products is growing and a transition from petrochemicals to biomass-based chemicals is ongoing. Itaconic acid is a C5-dicarboxylic acid which can be produced by microbial conversion processes. It can be easily polymerized and is an appealing building block for the chemical industry with many potential applications. However, biobased chemicals have to compete with their petrochemical counterparts, and yield and productivity of the microbial processes are therefore of the utmost importance. Traditionally itaconic acid is produced using the ascomycete Aspergillus terreus. This process is not competitive with petrochemical processes due to high production costs caused by low yields, and difficult and expensive product recovery. Maximizing product yield is important to lower production costs. This thesis looked at ways to reach theoretical maximum yield in a recombinant production host, Escherichia coli.

    Chapter 2 describes the construction of an itaconate biosynthesis pathway in E. coli. The key enzyme of microbial itaconate production is cis-Aconitate decarboxylase (CadA) that converts the citric acid cycle intermediate cis-aconitate into itaconate. We focused on optimizing heterologous expression of cadA from Aspergillus terreus in E. coli. Initially this resulted in low CadA activities and production of trace amounts of itaconate. CadA was primarily present as inclusion bodies, explaining the low activity. The activity was significantly improved by using lower cultivation temperatures and mineral medium and this resulted in enhanced itaconate titres. The itaconate titre was further increased in aerobic bioreactor cultures by introducing citrate synthase and aconitase from Corynebacterium glutamicum and by deleting genes encoding phosphate acetyltransferase and lactate dehydrogenase. The maximum itaconate yield from glucose obtained in this study was only 0.09 mol/mol, due to high flux of carbon to by-products such as acetate and pyruvate. Pyruvate is a precursor molecule for itaconate biosynthesis and its accumulation suggested that the activity of CadA might be one of the rate limiting steps. It was concluded that further optimization of cadA expression, and reduction of acetate formation should be achieved to obtain higher itaconate yield.

    As sufficient cis-aconitate decarboxylase activity is crucial for itaconate production, in chapter 3 ways to increase the activity of CadA were investigated. A recently characterized cis-aconitate decarboxylase of mammalian origin was therefore expressed in E.coli. The novel cis-aconitate decarboxylase from Mus musculus encoded by immunoresponsive gene 1 (irg1) produced comparable amounts of itaconate as CadA from A. terreus. In addition, the effects of codon optimization and harmonization on enzymatic activities of heterologously expressed cadA and irg1 were studied. Codon harmonization increased the activity of CadA in cell free extracts, but this did not result in higher itaconate production in bioreactor cultures. This suggests that other factors such as itaconate transport may limit the production.

    In chapter 4, proof of principle for an anaerobic fermentation process for the production of itaconic acid was obtained by using the mixed acid fermentation pathway of E. coli. Itaconic acid production was redox balanced by co-producing succinate or ethanol with H2 and CO2. Expression of cadA together with citrate synthase (gltA) and aconitase (acnA) from Corynebacterium glutamicum resulted in 0.66 mM (1.2 % Cmol) itaconate under anaerobic conditions. Unexpectedly, strains started to produce significant amounts of glutamate when the itaconate pathway was introduced. As glutamate production depends on the availability of nitrogen in the medium, a nitrogen-limited medium was tested to diminish glutamate production. This enhanced the production of itaconate to up to 2.9 mM (5.4 % C mol %). Here, anaerobic production of itaconate from glucose was reported for the first time. The observed itaconate yields and productivities were still modest. Eliminating the pathways to major by-products like glutamate, succinate, and acetate, and enhancing the pathway between pyruvate and itaconate is crucial to obtain a cost-competitive anaerobic itaconic acid process production.

    To investigate how itaconate production can be improved, the insights from the previous chapters together with existing scientific literature were combined with our pathway design proposals in chapter 5. The tricarboxylic acid (TCA) cycle is an important source of precursors for biobased chemicals. The opinion article takes a closer look at the metabolic engineering of TCA cycle for the production of chemicals high yield. For most TCA cycle products the maximum pathway yield is much lower than the theoretical maximum yield. For succinate, this was solved by creating two pathways to the product, using both branches of the TCA cycle, connected by the glyoxylate shunt. A similar solution cannot be applied directly for production of compounds from the oxidative branch of the TCA cycle because irreversible reactions are involved: the conversion of acetyl-CoA and glyoxylate to malate in the glyoxylate shunt and the conversion of 2-oxoglutarate into succinyl-CoA in the TCA cycle. This way, the pathway yield for products originating from the oxidative TCA cycle branch such as citrate, itaconate and L-glutamate becomes identical to the theoretical maximum. Future research should focus on implementing these solutions in suitable production hosts, and increasing the ATP yield of the production pathways. This will minimize the oxygen requirement of the process, or even allow for anaerobic operation, and should lead to reduced operational costs and maximal product yields.

    In chapter 6 the implications of the overall results of this thesis for the current research status of itaconate production are presented. Solutions to optimize itaconate production strains and production process were proposed.

    Probabilistic dietary exposure models : relevant for acute and chronic exposure assessment of adverse chemicals via food
    Boon, Polly E. ; Voet, H. van der - \ 2015
    Bilthoven : RIVM (RIVM letter report 2015-0191) - 41
    exposure assessment - exposure - models - chemicals - toxic substances - intake - food consumption - food safety - probabilistic models - blootstellingsbepaling - blootstelling - modellen - chemicaliën - toxische stoffen - opname (intake) - voedselconsumptie - voedselveiligheid - waarschijnlijkheidsmodellen
    Exposure models are used to calculate the amount of potential harmful chemicals ingested by a human population. Examples of harmful chemicals are residues of pesticides, chemicals entering food from the environment (such as dioxins, cadmium, lead, mercury), and chemicals that are generated via heating (such as acrylamide and furans). In this report we describe the characteristics of two types of models: the first for calculating the short term-intake, and the second for calculating long-term intake. These models currently result in the most realistic estimation of chemical intake via food.
    Sediment toxicity testing and prospective risk assessment of organic chemicals
    Diepens, N.J. - \ 2015
    Wageningen University. Promotor(en): Bart Koelmans, co-promotor(en): Paul van den Brink. - Wageningen : Wageningen University - ISBN 9789462574991 - 346
    sediment - toxiciteit - testen - sedimenttest - verontreinigde sedimenten - chemicaliën - risicoschatting - ecotoxicologie - sediment - toxicity - testing - sediment test - contaminated sediments - chemicals - risk assessment - ecotoxicology

    While providing an option for development in coastal areas, shrimp farming is usually associated with high environmental cost due to the loss of mangrove forest and high social cost as farmers suffer heavy financial losses due to disease outbreaks. Planning shrimp farming requires to integrate risk as well as social and environmental cost. This thesis, using the Mekong Delta as a case, presents an approach to investigate, with local stakeholders, options to plan a resilient and sustainable shrimp farming sector. First, Olivier Joffre analyzed the different shrimp production systems from economic point of view before analyzing farmer’s strategies and providing insights on drivers that will push or, at the opposite, constraint farmers to choose integrated mangrove shrimp systems. This knowledge was integrated in an Agent Based Model (ABM) that was calibrated using Role Playing Games (RPG).

    The effect of future scenarios and different policies on the farmers’ decisions was tested using a combination of RPG and ABM. For one coastal district of the Mekong Delta, the results showed that promotion of intensification of shrimp production has a high social cost and decreases the total production in the study area after 10 years. Policies for supporting the spread of integrated mangrove-shrimp systems, such as Payment for Ecosystem Services, or access to an organic value chain, are not strong enough to influence farmers’ decision toward adopting these systems. Without any adaptation to climate change a sharp decrease of the production is expected. The approach brought local farmers’ knowledge to the attention of decision makers.

    Twee vliegen in één klap : duurzame vervangers voor zorgwekkende stoffen zijn kansrijk
    Zundert, M. van; Es, D.S. van - \ 2015
    Chemie Magazine 57 (2015)7/8. - ISSN 1572-2996 - p. 28 - 29.
    chemicaliën uit biologische grondstoffen - biobased economy - marktverkenningen - vervangmiddelen - chemicaliën - biobased chemicals - biobased economy - market surveys - substitutes - chemicals
    De lijst van zeer zorgwekkende stoffen is lang. Onderzoeker Daan van Es van de Wageningen UR liep de lijst door en ziet goede kansen voor biobased vervangers.
    Accurate assessment of the biodegradation of cationic surfactants in activated sludge reactors (OECD TG 303A)
    Geerts, R. ; Ginkel, C.G. van; Plugge, C.M. - \ 2015
    Ecotoxicology and Environmental Safety 118 (2015). - ISSN 0147-6513 - p. 83 - 89.
    sewage-treatment - treatment-plant - ammonium-salts - fate - model - chemicals
    The continuous-fed activated sludge test (OECD TG 303A) was used to predict the removal of cationic surfactants from wastewater in activated sludge plants. However, a method to differentiate between adsorption and biodegradation is not provided in these guidelines. Assessment of removal by biodegradation was possible with analysis of the surfactant present in mixed liquid suspended solids in combination with a simple equation. This equation was derived from the mass balance of the activated sludge unit in steady state. The removal by biodegradation of decylamine, tetradecylamine, octadecylamine, dioctadecylmethylamine and dioctadecyldimethylammonium chloride that have different capacities to adsorb was >99.9%, >99.9%, 98.2%, 94.2%, and 69.0%, respectively. The total removal of all five cationic surfactants from the influent was =98.8%. The removal of octadecylamine spiked at different influent concentrations indicated first order kinetics
    Use of methylene blue uptake for assessing cell viability of colony-forming microalgae
    Lemos Bicas, J. ; Kleinegris, D.M.M. ; Barbosa, M.J. - \ 2015
    Algal Research 8 (2015). - ISSN 2211-9264 - p. 174 - 180.
    botryococcus-braunii - yeast cells - race-b - biomass - hydrocarbons - extraction - chemicals - dyes
    During the past few years, interest in microalgae has grown, mainly because of their potential for biofuel production. Botryococcus braunii, a green microalga that can accumulate more than half of its dry weight as hydrocarbons, is one of the most important examples. This microorganism grows in colonies and there has been no reliable viability protocol reported for this species as yet. Knowing the number of dead cells in cultures is essential for the development of efficient bioprocesses such as non-destructive extraction procedures (“milking”) to obtain lipid soluble substances from microalgal biomass. Our study presents a simple colorimetric method to determine the proportion of living to dead cells in cultures, based on the uptake of methylene blue in solution by dead B. braunii cells. The main parameters influencing this process were investigated and used to develop a protocol. This technique was validated using flow cytometry and Neochloris oleoabundans, and appears not to be limited to use with B. braunii.
    Liver DNA methylation analysis in adult female C57BL/6JxFVB mice following perinatal exposure to bisphenol A
    Esterik, J.C. van; Vitins, A.P. ; Hodemaekers, H.M. ; Kamstra, J.H. ; Legler, J. ; Pennings, J.L.A. ; Steegenga, W.T. ; Lute, C. ; Jelinek, J. ; Issa, J.P. ; Dollé, M.E.T. ; Ven, L.T.M. van der - \ 2015
    Toxicology Letters 232 (2015)1. - ISSN 0378-4274 - p. 293 - 300.
    endocrine disruptors - disease - bpa - xenoestrogens - association - epigenetics - expression - nutrition - evolution - chemicals
    Bisphenol A (BPA) is a compound released from plastics and other consumer products used in everyday life. BPA exposure early in fetal development is proposed to contribute to programming of chronic diseases like obesity and diabetes, by affecting DNA methylation levels. Previously, we showed that in utero and lactational exposure of C57BL/6JxFVB hybrid mice via maternal feed using a dose range of 0–3000 µg/kg body weight/day resulted in a sex-dependent altered metabolic phenotype in offspring at 23 weeks of age. The most univocal effects were observed in females, with reduced body weights and related metabolic effects associated with perinatal BPA exposure. To identify whether the effects of BPA in females are associated with changes in DNA methylation, this was analyzed in liver, which is important in energy homeostasis. Measurement of global DNA methylation did not show any changes. Genome-wide DNA methylation analysis at specific CpG sites in control and 3000 µg/kg body weight/day females with the digital restriction enzyme analysis of methylation (DREAM) assay revealed potential differences, that could, however, not be confirmed by bisulfite pyrosequencing. Overall, we demonstrated that the observed altered metabolic phenotype in female offspring after maternal exposure to BPA was not detectably associated with liver DNA methylation changes. Still, other tissues may be more informative.
    Mechanistic modelling of toxicokinetic processess within Mytiophyllum
    Heine, S. ; Schmitt, W. ; Schaffer, A. ; Gorlitz, G. ; Buresova, H. ; Arts, G. ; Preuss, T.G. - \ 2015
    Chemosphere 120 (2015). - ISSN 0045-6535 - p. 292 - 298.
    partition-coefficients - cuticular membranes - risk-assessment - aquatic macrophytes - water permeability - plant cuticles - sensitivity - diffusion - chemicals - linuron
    Effects of chemicals are, in most cases, caused by internal concentrations within organisms which rely on uptake and elimination kinetics. These processes might be key components for assessing the effects of time-variable exposure of chemicals which regularly occur in aquatic systems. However, the knowledge of toxicokinetic patterns caused by time-variable exposure is limited, and gaining such information is complex. In this work, a previously developed mechanistic growth model of Myriophyllum spicatum is coupled with a newly developed toxicokinetic part, providing a model that is able to predict uptake and elimination of chemicals, as well as distribution processes between plant compartments (leaves, stems, roots) of M. spicatum. It is shown, that toxicokinetic patterns, at least for most of the investigated chemicals, can be calculated in agreement with experimental observations, by only calibrating two chemical- specific parameters, the cuticular permeability and a plant/water partition coefficient. Through the model-based determination of the cuticular permeabilities of Isoproturon, Iofensulfuron, Fluridone, Imazamox and Penoxsulam, their toxicokinetic pattern can be described with the model approach. For the use of the model for predicting toxicokinetics of other chemicals, where experimental data is not available, equations are presented that are based on the log (Poct/wat) of a chemical and estimate parameters that are necessary to run the model. In general, a method is presented to analyze time-variable exposure of chemicals more in detail without conducting time and labour intensive experiments.
    The MCRA model for probabilistic single-compound and cumulative risk assessment of pesticides
    Voet, H. van der; Boer, W.J. de; Kruisselbrink, J.W. ; Goedhart, P.W. ; Heijden, G.W.A.M. van der; Kennedy, M.C. ; Boon, P.E. ; Klaveren, J.D. van - \ 2015
    Food and Chemical Toxicology 79 (2015). - ISSN 0278-6915 - p. 5 - 12.
    dietary exposure - carbamate insecticides - 21st-century roadmap - chemicals - food - organophosphorus - framework - residues - project
    Pesticide risk assessment is hampered by worst-case assumptions leading to overly pessimistic assessments. On the other hand, cumulative health effects of similar pesticides are often not taken into account. This paper describes models and a web-based software system developed in the European research project ACROPOLIS. The models are appropriate for both acute and chronic exposure assessments of single compounds and of multiple compounds in cumulative assessment groups. The software system MCRA (Monte Carlo Risk Assessment) is available for stakeholders in pesticide risk assessment at We describe the MCRA implementation of the methods as advised in the 2012 EFSA Guidance on probabilistic modelling, as well as more refined methods developed in the ACROPOLIS project. The emphasis is on cumulative assessments. Two approaches, sample-based and compound-based, are contrasted. It is shown that additional data on agricultural use of pesticides may give more realistic risk assessments. Examples are given of model and software validation of acute and chronic assessments, using both simulated data and comparisons against the previous release of MCRA and against the standard software DEEM-FCID used by the Environmental Protection Agency in the USA. It is shown that the EFSA Guidance pessimistic model may not always give an appropriate modelling of exposure.
    Actieve biologische Monitoring Zoete Rijkswateren: microverontreinigingen in zoetwatermosselen - 2015
    Kotterman, M.J.J. - \ 2014
    IJmuiden : IMARES (IMARES / Rapport C085/15) - 37
    monitoring - waterbeheer - waterbeleid - watersystemen - mytilidae - chemicaliën - biologische monitoring - microbiële besmetting - waterverontreiniging - mossels - binnenwateren - monitoring - water management - water policy - water systems - mytilidae - chemicals - biomonitoring - microbial contamination - water pollution - mussels - inland waters
    Rijkswaterstaat van het Ministerie van Infrastructuur en Milieu is in 1992 gestart met de uitvoering van het monitoringprogramma “Monitoring Zoete Rijkswateren”. Dit vormt een onderdeel van de “Monitoring van de Waterstaatkundige Toestand des Lands” (MWTL). Doelstellingen van de metingen zijn: - het signaleren van langjarige ontwikkelingen in de biologische toestand van watersystemen (trend). - periodieke toetsing van de toestand aan criteria die voortvloeien uit de toegekende functies van wateren (controle). De opdracht is gebaseerd op het werkdocument “Actieve monitoring chemische stoffen zoetwatermosselen, projectplan chemisch meetnet MWTL 2014”, van 28 augustus 2014 en is uitgevoerd door IMARES. De uit te voeren werkzaamheden betroffen het bemonsteren van zoetwatermosselen en het analyseren van microverontreinigingen daarin. Dit rapport bevat zowel de analyseresultaten van quaggamosselen uit het oorspronkelijke onderzoek in 2014, als ook de resultaten van het aanvullende onderzoek betreffende driehoeksmosselen en quagga’s uit het Spaarne; op tijdstip 0 (niet uitgehangen) en tijdstip 1 (na uithangen, alleen locatie Keizersveer).
    Lignin pyrolysis for profitable lignocellulosic biorefineries
    Wild, P.J. de; Gosselink, R.J.A. ; Huijgen, W.J.J. - \ 2014
    Biofuels Bioproducts and Biorefining 8 (2014)5. - ISSN 1932-104X - p. 645 - 657.
    wheat-straw - organosolv lignin - biomass - phenols - separation - valorization - pretreatment - hydrolysis - conversion - chemicals
    Bio-based industries (pulp and paper and biorefineries) produce > 50 Mt/yr of lignin that results from fractionation of lignocellulosic biomass. Lignin is world's second biopolymer and a major potential source for production of performance materials and aromatic chemicals. Lignin valorization is a key-issue for enhanced profitability of sustainable bio-based industries. Despite a myriad of potential applications for lignin and decades of research, its heterogeneity and recalcitrance still preclude commercial value-added applications. Most lignin is utilized for heat and power. Unconventional solutions are needed to better exploit lignin's potential. Organosolv lignins are especially suitable as feedstock for high-value chemicals. At ECN, a lignin biorefinery approach (LIBRA) has been developed, involving a dedicated lignin pyrolysis protocol that is robust, continuous, and capable of processing different lignins. Typical product yields are 20% gas, 35% char, and 45% oil. The oil contains approximately 45% oligomeric phenolic substances, 23% monomeric phenols, and 33% water. The future perspective is scale-up of the process to produce larger lignin pyrolysis oil samples for separation, purification, and industrial application tests. Presently, small lignin pyrolysis oil samples are investigated as feedstock for extracting high-value chemicals, as a substitute for phenol in several applications, and as a feedstock for hydrotreating. The biochar is tested as growth enhancer and as substitute for carbon-black in rubber. Regarding the large lignin side streams from (future) bio-based industries, the LIBRA pyrolysis technology has ample potential to increase the profitability of lignocellulosic biorefineries provided that for both the liquid product and the solid char value-added applications are developed.
    Characteristics of Wheat Straw Lignins from Ethanol-based Organosolv Treatment
    Huijgen, W.J.J. ; Telysheva, G. ; Arshanitsa, A. ; Gosselink, R.J.A. ; Wild, P.J. de - \ 2014
    Industrial Crops and Products 59 (2014). - ISSN 0926-6690 - p. 85 - 95.
    industrial applications - enzymatic-hydrolysis - technical lignins - kraft lignin - fractionation - pretreatment - biomass - chemicals - bagasse
    Non-purified lignins resulting from ethanol-based organosolv fractionation of wheat straw were characterized for the presence of impurities (carbohydrates and ash), functional groups (hydroxyl, carboxyl and methoxyl), phenyl-propanoid structural moieties, molar mass distribution and thermal behavior. In accordance with its herbaceous nature, the syringyl/guaiacyl-ratio of the wheat straw lignins was substantially lower than of Alcell lignin. In addition, the content of p-hydroxyphenyl and carboxyl groups is substantially higher for the wheat straw lignins. The non-purified organosolv lignins had a high purity with 0.4–5.2% carbohydrate impurities, both originating from lignin to carbohydrate complexes and residual organosolv liquor. The use of H2SO4 in the organosolv process improved the lignin yield, but at low acid doses increased the carbohydrate impurities. For applications where a low amount of carbohydrates is important, lignin from a high-temperature autocatalytic organosolv process was found to be preferred. The highest content of total hydroxyl groups was determined when lignins were produced using 30 mM H2SO4 as catalyst or 50% w/w aqueous ethanol as solvent for the organosolv process. Aliphatic hydroxyl groups, the most predominant type of hydroxyl groups present originating for a substantial part from residual carbohydrates, were found to decrease with reaction time and ethanol proportion of the organosolv solvent. The correlations between organosolv process conditions and lignin characteristics determined can facilitate the use of organosolv lignins in value-added applications such as in polymers and resins and as a feedstock for bio-based aromatics.
    Comparing population recovery after insecticide exposure for four aquatic invertebrate species using models of different complexity
    Baveco, H. ; Norman, S. ; Roessink, I. ; Galic, N.G. ; Brink, P.J. van den - \ 2014
    Environmental Toxicology and Chemistry 33 (2014)7. - ISSN 0730-7268 - p. 1517 - 1528.
    ecological risk-assessment - competition delays recovery - individual-based model - potential application - pesticides - dynamics - chemicals - chlorpyrifos - ecosystems - arthropod
    Population models, in particular individual-based models (IBMs), are becoming increasingly important in chemical risk assessment. They can be used to assess recovery of spatially structured populations after chemical exposure that varies in time and space. The authors used an IBM coupled to a toxicokinetic-toxicodynamic model, the threshold damage model (TDM), to assess recovery times for 4 aquatic organisms, after insecticide application, in a nonseasonal environment and in 3 spatial settings (pond, stream, and ditch). The species had different life histories (e.g., voltinism, reproductive capacity, mobility). Exposure was derived from a pesticide fate model, following standard European Union scenarios. The results of the IBM-TDM were compared with results from simpler models: one in which exposure was linked to effects by means of concentration-effect relationships (IBM-CE) and one in which the IBM was replaced by a nonspatial, logistic growth model (logistic). For the first, exposure was based on peak concentrations only; for the second, exposure was spatially averaged as well. By using comparisons between models of different complexity and species with different life histories, the authors obtained an understanding of the role spatial processes play in recovery and the conditions under which the full time-varying exposure needs to be considered. The logistic model, which is amenable to an analytic approach, provided additional insights into the sensitivity of recovery times to density dependence and spatial dimensions.
    RIVM ZZS-2-BIO project : the biobased replacement potential of hazardous substances
    Es, D.S. van - \ 2014
    Wageningen : Wageningen UR - Food & Biobased Research (Report / Wageningen UR Food & Biobased Research no. 1506) - ISBN 9789462573529 - 74
    chemicaliën uit biologische grondstoffen - biobased economy - marktverkenningen - vervangmiddelen - chemicaliën - biobased chemicals - biobased economy - market surveys - substitutes - chemicals
    A quick scan of the ZZS (zeer zorgwekkende stoffen) list of 371 substances of very high concern shows that there is significant potential in biobased replacement of part of the list. It is shown that in many cases easily implementable biobased alternatives are already available or in advanced stages of development. However, in some cases safe, biobased alternatives are still in early development. This in spite of a growing need for replacement, as is the case for e.g. high polarity aprotic solvents such as DMF, or NMP. Since solvents like NMP enable the manufacturing of environmentally friendly water borne coatings and paints, as well as the development of various carbohydrate based materials, finding effective substitutes should be given high priority. Unfortunately, currently there are no Dutch national science programs that could support or initiate this. Also more advanced, indirect type of replacement appears feasible. An example of possible short term implementation is the partial replacement of toxic ethylene oxide for the production of ethylene glycol by the hydrogenolysis of glucose to ethylene glycol and propylene glycol. Other advanced level replacements require more time, and deeper analysis in order to assess the impact on product/value chains. A shortlist of nine substances that could be replaced by biobased alternatives on short term is also presented in this quick scan report. The suggested biobased alternatives for this shortlist are either already commercially available or close to commercialisation. This quick scan results in a number of recommendations.
    Synthesis of bio-based methacrylic acid by decarboxylation of itaconic acid and citric acid catalyzed by solid transition-metal catalysts
    Notre, J.E.L. le; Witte-van Dijk, S.C.M. ; Haveren, J. van; Scott, E.L. ; Sanders, J.P.M. - \ 2014
    ChemSusChem 7 (2014)9. - ISSN 1864-5631 - p. 2712 - 2720.
    renewable resources - supercritical water - reaction pathways - fatty-acids - chemicals - biomass - decarbonylation - deoxygenation - conversion - plastics
    Methacrylic acid, an important monomer for the plastics industry, was obtained in high selectivity (up to 84%) by the decarboxylation of itaconic acid using heterogeneous catalysts based on Pd, Pt and Ru. The reaction takes place in water at 200–2508C without any external added pressure, conditions significantly milder than those described previously for the same conversion with better yield and selectivity. A comprehensive study of the reaction parameters has been performed, and the isolation of methacrylic acid was achieved in 50% yield. The decarboxylation procedure is also applicable to citric acid, a more widely available bio-based feedstock, and leads to the production of methacrylic acid in one pot in 41% selectivity. Aconitic acid, the intermediate compound in the pathway from citric acid to itaconic acid was also used successfully as a substrate.
    The ChimERA project: Coupling mechanistic exposure and effect models into an integrated platform for ecological risk assessment
    Laender, F. de; Brink, P.J. van den; Janssen, C.R. ; Guardo, A. Di - \ 2014
    Environmental Science and Pollution Research 21 (2014)9. - ISSN 0944-1344 - p. 6263 - 6267.
    stress ecology - insecticide - ecosystems - recovery - ecotoxicology - chemicals
    Current techniques for the ecological risk assessment of chemical substances are often criticised for their lack of environmental realism, ecological relevance and methodological accuracy. ChimERA is a 3-year project (2013-2016), funded by Cefic's Long Range Initiative (LRI) that aims to address some of these concerns by developing and testing mechanistic fate and effect models, and coupling of these models into one integrated platform for risk assessment. This paper discusses the backdrop against which this project was initiated and lists its objectives and planned methodology.
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