Studies of the complexation behaviour of transition metals applicable in membrane technologies

Many industrial processes make use of metal ions. These metal ions, however, end up in several effluent streams. Due to very strict discharge values, new technologies are constantly emerging for treating and purifying all kinds of wastewater. One of these innovative technologies is the Supported Liquid Membrane (SLM) technique. The SLM technology is a membrane-based solvent extraction method that uses a micro-porous hydrophobic membrane as supporting layer. This membrane is impregnated with an organic solvent containing the specific carrier molecules for metal ion extraction. In this study, the extractions of some metal complexes applicable in Supported Liquid Membranes were investigated in depth. The studies were mainly focused on the metal ions copper(II), nickel(II), cobalt(II), iron(III, II) and magnesium(II). As extractants, organophosphorous acids (D2EHPA, CYANEX 301, CYANEX 302 and CYANEX 272) and hydroxyoximes (LIX 860-I, LIX 84-I) were investigated either separately or in combination with a second extractant molecule in order to determine synergistic effects. Hexane and 1-decanol were applied as diluents in order to determine the effect of the polarity of the diluent on the extraction efficiency of the metal ions and to investigate if changes occur in the configuration of the metal complexes. Furthermore, the influence of the presence of acetate ions in the aqueous phase was investigated. Secondly, Job’s method was applied to determine the stoichiometry of the metal-organic complexes. This spectrophotometric method was compared with a water-free procedure. By following up the release of hydrogen chloride during complexation, a correlation is obtained with the number of extractant molecules participating in the complexes. Furthermore, a practical application of the Supported Liquid Membrane technology was evaluated, viz. recovery of nickel(II). The results on real effluent streams have shown hat nickel(II) can be recovered out of industrial effluents below the PARCOM value of 0.5 mg.L-1 with a mixture of LIX 860-I and CYANEX 302. Finally, an introduction has been given of the potential abilities of Polymer Inclusion Membranes (PIM) and Immobilized Liquid Membranes (ILM) as alternative wastewater treatment techniques. The results indicated however that it seems very doubtful that fluxes in the same order of magnitude will be reached as for Supported Liquid Membranes

Phenotypic evaluation of natural and industrial Saccharomyces yeasts for different traits desirable in industrial bioethanol production

Saccharomyces cerevisiae is the organism of choice for many food and beverage fermentations because it thrives in high-sugar and high-ethanol conditions. However, the conditions encountered in bioethanol fermentation pose specific challenges, including extremely high sugar and ethanol concentrations, high temperature, and the presence of specific toxic compounds. It is generally considered that exploring the natural biodiversity of Saccharomyces strains may be an interesting route to find superior bioethanol strains and may also improve our understanding of the challenges faced by yeast cells during bioethanol fermentation. In this study, we phenotypically evaluated a large collection of diverse Saccharomyces strains on six selective traits relevant for bioethanol production with increasing stress intensity. Our results demonstrate a remarkably large phenotypic diversity among different Saccharomyces species and among S. cerevisiae strains from different origins. Currently applied bioethanol strains showed a high tolerance to many of these relevant traits, but several other natural and industrial S. cerevisiae strains outcompeted the bioethanol strains for specific traits. These multitolerant strains performed well in fermentation experiments mimicking industrial bioethanol production. Together, our results illustrate the potential of phenotyping the natural biodiversity of yeasts to find superior industrial strains that may be used in bioethanol production or can be used as a basis for further strain improvement through genetic engineering, experimental evolution, or breeding. Additionally, our study provides a basis for new insights into the relationships between tolerance to different stressors

Fatty Acid and Amino Acid Profiles of Seven Edible Insects: Focus on Lipid Class Composition and Protein Conversion Factors

This study is based on the fatty acid and amino acid profiles of seven edible insect species: Acheta domesticus, Alphitobius diaperinus, Blaptica dubia, Galleria mellonella, Locusta migratoria, Tenebrio molitor, and Zophobas morio. The aim of the present study is to provide new data on the fatty acid distributions among lipid classes as well as the species-specific protein conversion factor (Kp) of a wide range of insects in order to further improve the nutritional characterisation of insects as food. Oleic acid was the predominant fatty acid in all insects except for A. domesticus, in which a significantly higher percentage of linoleic acid was found. The majority of the lipids were neutral lipids. A significant amount of α-linolenic acid in the phospholipid fraction of L. migratoria was shown, while in T. molitor, phospholipids were the only fraction in which a measurable amount of docosahexaenoic acid was found. Overall, in most insects, the phospholipid fraction had the highest polyunsaturated fatty acid content compared to the other classes, which may be protective in terms of auto-oxidative stability. Kp values in the range of 4.17 to 6.43 were obtained. Within the nutritional quality indices, all insects showed healthy fatty acids and high-quality amino acid profiles

Functional probiotic products based on fermented wort with Lactobacillus rhamnosus GG and Lactobacillus casei

status: accepte

Flax treatment with strategic enzyme combinations: Effect on chemical fiber composition and ease of fiber extraction

status: publishe

Extraction and spray drying of Class II hydrophobin HFBI produced by Trichoderma reesei

© 2018 Elsevier Ltd Hydrophobins are considered the strongest surface-active proteins from microbial origin. The amphiphilic proteins are produced by filamentous fungi and exhibit unique physicochemical properties. Self-assembly into membranes at hydrophobic-hydrophilic interfaces illustrate their unique properties, leading to a broad range of applications, from foam stabilization to protein immobilization. Due to insufficient production quantities of Class II hydrophobins using native fungal strains and limited long-term storage stability of liquid formulations, commercial availability remains lacking. Within this research, the potential of trehalose for stabilization and preservation of hydrophobins during spray drying was studied. Therefore, the Class II hydrophobin HFBI, expressed by Trichoderma reesei, was produced by submerged cultures in fed-batch mode and extracted from the mycelium. Extracts purified with FPLC were subsequently spray dried. Residual activity of 93.62 ± 5.07% was obtained with trehalose in a ratio of 2:1 (excipient:protein) to stabilize HFBI during spay drying, which demonstrates the huge potential of trehalose.status: publishe

Comparative study of the cellulose content of enzymatically treated flax by gravimetrical method and gas chromatography

status: publishe

Effect of enzymatic treatment of flax on fineness of fibers and mechanical performance of composites

The application of enzymes as alternative to dew retting of flax was studied in correlation to the characteristics of composites reinforced with these natural fibers. Fiber fineness and mechanical properties of biocomposites were evaluated. Furthermore, moisture absorption by biocomposites was studied and fracture surfaces were investigated using Scanning Electron Microscopy. Compared to dew retted fiber composites, improvements in mechanical performance can be observed for composites impregnated with fibers extracted after enzymatic treatments. All enzymatic treatments resulted in finer fibers than green fibers and led to biocomposites with a reduced equilibrium moisture content and lower diffusion coefficient. This study illustrates the high potential of enzymatic retting, in particular with polygalacturonase. Also, the manual extraction procedure used, produced fibers with an E-modulus up to 84 GPa and strength up to 800 MPa, likely due to reduced fiber damage, which illustrates the hidden potential of flax fibersstatus: Published onlin

Enzymatic treatment of flax for use in composites

Enzymes are highly advantageous compared to dew retting to reach fibers of high and consistent quality. However, no unambiguous insights have been retained from the research, i.e. lacking a clear directive of which enzyme activities are strictly needed. Methods for evaluating enzymatic retting should be standardized, with characterization of chemical, morphological and mechanical properties and analysis of the ease of extraction. Moreover, evaluation should not only be focused on the microscopic level of the fiber but the performance of the resulting composite materials should be assessed as well. The review also covers research challenges for introducing enzymatic treatment in large scale production as well as inherent limitations and economic aspects. Besides their high selectivity and environmentally-friendly processing conditions, applying enzymes may also result in a less severe mechanical post-treatment implying less fiber damage. Moreover, recycling of enzymes and utilization of byproducts may increase the economic feasibility of the process. Keywords: Flax fibers, Enzymatic extraction, Composite