A Novel Application of Oceanic Biopolymers — Strategic Regulation of Polymer Characteristics for Membrane Technology in Separation Engineering

Membranes prepared from oceanic biopolymers have a high potential in membrane separation processes and water purification. It is anticipated to result in more biocompatible and lower-cost materials compared with artificial polymers. This chapter describes the excellent performance of oceanic biopolymer membranes in separation engineering and the regulation factors controlling membrane properties. In particular, chitosan and alginate were picked up as intelligent membrane materials to provide the promised molecular size recognition and other membrane properties. Future prospective strategies for a simple methodology for preparing stable membranes from oceanic biopolymers and the development of selective separation processing were reviewed

Innovative Separation Technology Utilizing Marine Bioresources: Multifaceted Development of a Chitosan-Based System Leading to Environmentally-Friendly Processes

Chitosan, known as a most typical marine biological polymer, has a fruitful capability of biocompatible gel formation. Attempts of chitosan have been made to develop it from the multifaceted viewpoint of separation technology. The physicochemical properties of chitosan containing a lot of hydroxyl groups and reactive amino groups help to build the characteristic polymer networks. The deacetylation degree of chitosan is found as the most influential factor to regulate properties of chitosan hydrogels. The antibacterial activity of the chitosan membrane is one of its notable abilities because of its practical application. The chitosan, its derivatives, and the complex formation with other substances has been used for applications in filtration and membrane separation processes. Adsorption processes based on chitosan have been also developed widely. Moreover, complex of chitosan gel helps to immobilize adsorbent particles. The chitosan membrane immobilizing Prussian-Blue for cesium ion removal from the aqueous phase is one of the leading cases. To elaborate the adsorption behavior on the chitosan immobilizing adsorbent, the isothermal equilibrium and mass transfer characteristics can be discussed. The adsorption process using chitosan-based membranes in combination with filtration in a flow process is advantageous compared with the batch process. More advanced studies of chitosan aerogel and chitosan nanofibers have been proceeded recently, especially for adapting to water purification and air filtration

Effect of Template Type on the Trametes versicolor Laccase-Catalyzed Oligomerization of the Aniline Dimer p-Aminodiphenylamine (PADPA)

Many previous studies have shown that (i) the oxidation of aniline or the aniline dimer p-aminodiphenyl-amine (PADPA) in a slightly acidic aqueous solution can be catalyzed with heme peroxidases or multicopper laccases and that (ii) subsequent reactions lead to oligomeric or polymeric products, which resemble chemically synthesized polyaniline in its conductive emeraldine salt form (PANI-ES), provided that (iii) an anionic "template" is present in the reaction medium. Good templates are anionic polyelectrolytes, micelles, or vesicles. Under optimal conditions, their presence directs the reactions in a positive way toward the desired formation of PANI-ES-type products. The effect of four different types of anionic templates on the formation of PANI-ES-like products from PADPA was investigated and compared by using Trametes versicolor laccase (TvL) as a catalyst in an aqueous pH 3.5 solution at room temperature. All four templates contain sulfonate groups: the sodium salt of the polyelectrolyte sulfonated polystyrene (SPS), micelles from sodium dodecylbenzenesulfonate (SDBS), vesicles from a 1:1 molar mixture of SDBS and decanoic acid, and vesicles from sodium bis(2-ethylhexyl) sulfosuccinate (AOT). Although with all four templates, stable, inkjet-printable solutions or suspensions consisting of PANI-ES-type products were obtained under optimized conditions, considerably higher amounts of TvL were required with SDBS micelles to achieve comparable monomer conversion to PANI-ES-like products during the same time period when compared to those with SPS or the two types of vesicles. This makes SDBS micelles less attractive as templates for the investigated reaction. In situ UV/vis/near-infrared, electron paramagnetic resonance (EPR), and Raman spectroscopy measurements in combination with an high-performance liquid chromatography analysis of extracted reaction products, which were deprotonated and chemically reduced, showed seemingly small but significant differences in the composition of the mixtures obtained when reaching reaction equilibrium after 24 h. With the two vesicle systems, the content of unwanted substituted phenazine units was lower than in the case of SPS polyelectrolyte and SDBS micelles. The EPR spectra indicate a more localized, narrower distribution of electronic states of the paramagnetic centers of the PANI-ES-type products synthesized in the presence of the two vesicle systems when compared to that of the similar products obtained with the SPS polyelectrolyte and SDBS micelles as templates. Overall, the data obtained from the different complementary methods indicate that with the two vesicle systems structurally more uniform (regular) PANI-ES-type products formed. Among the two investigated vesicle systems, for the investigated reaction (oxidation of PADPA with TvL and O-2), AOT appears a somewhat better choice as it leads to a higher content of the PANI-ES polaron form

How experimental details matter. The case of a laccase-catalysed oligomerisation reaction

The Trametes versicolor laccase (TvL)-catalysed oligomerisation of the aniline dimer p-aminodiphenylamine (PADPA) was investigated in an aqueous medium of pH = 3.5, containing 80-100 nm-sized anionic vesicles formed from AOT, the sodium salt of bis(2-ethylhexyl)sulfosuccinic acid. If run under optimal conditions, the reaction yields oligomeric products which resemble the emeraldine salt form of polyaniline (PANI-ES) in its polaron state, known to be the only oxidation state of linear PANI which is electrically conductive. The vesicles serve as "templates" for obtaining products with the desired PANI-ES-like features. For this complex, heterogeneous, vesicle-assisted, and enzyme-mediated reaction, in which dissolved dioxygen also takes part as a re-oxidant for TvL, small changes in the composition of the reaction mixture can have significant effects. Initial conditions may not only affect the kinetics of the reaction, but also the outcome, i.e., the product distribution once the reaction reaches its equilibrium state. While a change in the reaction temperature from T approximate to 25 to 5 degrees C mainly influenced the rate of reaction, increase in enzyme concentration and the presence of millimolar concentrations of chloride ions were found to have significant undesired effects on the outcome of the reaction. Chloride ions, which may originate from the preparation of the pH = 3.5 solution, inhibit TvL, such that higher TvL concentrations are required than without chloride to yield the same product distribution for the same reaction runtime as in the absence of chloride. With TvL concentrations much higher than the elaborated value, the products obtained clearly were different and over-oxidised. Thus, a change in the activity of the enzyme was found to have influence not only on kinetics but also led to a change in the final product distribution, molecular structure and electrical properties, which was a surprising find. The complementary analytical methods which we used in this work were in situ UV/vis/NIR, EPR, and Raman spectroscopy measurements, in combination with a detailed ex situ HPLC analysis and molecular dynamics simulations. With the results obtained, we would like to recall the often neglected or ignored fact that it is important to describe and pay attention to the experimental details, since this matters for being able to perform experiments in a reproducible way

Language vs individuals in cross-linguistic corpus typology

Published as a special publication of Language Documentation & Conservation (No. 25).Peer reviewe

Synthesizing Polyaniline With Laccase/O-2 as Catalyst

The polymerization of aniline to polyaniline (PANI) can be achieved chemically, electrochemically or enzymatically. In all cases, the products obtained are mixtures of molecules which are constituted by aniline units. Depending on the synthesis conditions there are variations (i) in the way the aniline molecules are connected, (ii) in the average number of aniline units per molecule, (iii) in the oxidation state, and (iv) in the degree of protonation. For many possible applications, the synthesis of electroconductive PANI with para-N-C-coupled aniline units in their half-oxidized and protonated state is of interest. This is the emeraldine salt form of PANI, abbreviated as PANI-ES. The enzymatic synthesis of PANI-ES is an environmentally friendly alternative to conventional chemical or electrochemical methods. Although many studies have been devoted to the in vitro synthesis of PANI-ES by using heme peroxidases with added hydrogen peroxide (H2O2) as the oxidant, the application of laccases is of particular interest since the oxidant for these multicopper enzymes is molecular oxygen (O2) from air, which is beneficial from environmental and economic points of view. In vivo, laccases participate in the synthesis and degradation of lignin. Various attempts of synthesizing PANI-ES with laccase/O2 in slightly acidic aqueous media from aniline or the linear aniline dimer PADPA (p-aminodiphenylamine) are summarized. Advances in the understanding of the positive effects of soft dynamic templates, as chemical structure guiding additives (anionic polyelectrolytes, micelles, or vesicles), for obtaining PANI-ES-rich products are highlighted. Conceptually, some of these template effects appear to be related to the effect “dirigent proteins” exert in the biosynthesis of lignin. In both cases intermediate radicals are formed enzymatically which then must react in a controlled way in follow-up reactions for obtaining the desired products. These follow-up reactions are controlled to some extent by the templates or specific proteins.ISSN:2296-418

Modification of Copper (II) Ion-exchange Properties of Freestanding Alginate Membrane by Embedding with Zeolite

Insolubilized alginate membranes were obtained by crosslinking alginate with calcium ions, and alginate membranes embedded with zeolite in order to improve their ion exchange capacities were also successfully prepared. The alginate membranes were ion exchangeable due to the release of crosslinking ions, and showed an ion exchange capability for copper (II) ions that was comparable to that for alginate hydrogel beads. Additionally, while both the insolubilized alginate membranes and the zeolite-embedded membrane exhibited ion-exchange abilities, additional ion-exchange capacities was imparted by embedding zeolite in the latter. However, it was also found that embedding partially inhibits the ion-exchange capacities of the zeolite contained therein