Poly(glutaraldehyde)‐stabilized fish scale fibrillar collagen–some features of a new material for heavy metal sorption

In this work, fibrillar collagen on scales of Corvina fish (Micropogonias furnieri) was crosslinked and used as a new adsorbent for sorption of Cr(VI) from aqueous solutions. Characterization has suggested that the crosslinked collagen of Corvina scale has higher denaturation temperature in relation to the raw scales. In addition, electrostatic interactions between collagen positive charges and chromate negative charges constitute the majority of the interactions. Solution microcalorimetry experiments have indicated that water swelling of the crosslinked scales is slightly exothermic and increased with increasing temperature. Sorption of Cr(VI) by crosslinked scales increases with increasing initial Cr(VI) concentration in solution and decreases with temperature increasing. The kinetic data of Cr(VI) sorption on crosslinked scales were best fitted to a multilinear exponential model. The values of Cr(VI) diffusion constants increase with both temperature and initial Cr(VI) concentration in solution. The maximum sorption capacity of the new adsorbent for Cr (VI) was found at 39 mg g^?1 and is higher than some commercial adsorbent samples. So, chemically crosslinked Corvina scale is a promising adsorbent for sorption of Cr(VI) from aqueous solutions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A survey on data fusion: what for? in what form? what is next?

Journal of Intelligent Information Systems - Data fusion is the process of merging records from multiple sources which represent the same real-world object into a single representation. This review...     

Evaluation of production and characterization of polygalacturonase by Aspergillus niger ATCC 9642

The aim of our study was to evaluate polygalacturonase (PG) production and characterization by Aspergillus niger ATCC 9642. The maximum PG activity (51.82 U/mL) was obtained using pectin, l-asparagine, and, iron sulphate concentrations of 32 g/L, 2 g/L, 0.06 g/L and 1.0 g/L, respectively; 180 rpm of stirring rate, 25 °C and an initial pH of 4.0. The kinetic study showed that the highest enzyme activity was achieved at 27 h of fermentation. The evaluation of the optimum pH and temperature permitted us to observe that highest PG activities were achieved at 37 °C and pH of 5.5. The enzymatic extract presented higher stability at 55 °C and pH of 5.0. The results showed that at low temperatures the enzyme extract kept the initial activity until 40 days of storage. The experimental design methodology permitted us to optimize the PG activity and an important aspect of this study is the characterization of the PG in terms of optimum temperature and pH using experimental design technique and also, the characterization of enzyme stability at low temperature. Such studies are very scarce in the literature and should be helpful to understand the true potentialities of pectinases in its industrial applications.     

Mechanical properties of interfaces within a flax bundle – Part I: Experimental analysis

In order to model the tensile behaviour of flax fibre based composites, the properties of each of the constituents need to be determined. In addition to the fibres, the matrix and the fibre/matrix interface, the fibre/fibre interface present within a bundle of flax fibres is an element which is rather hard to characterize but whose properties also need to be taken into account to understand properly the deformation and rupture modes of the derived composites. In the first part of this study, the protocol used to determine these properties is described; the results of the mechanical tests and the microscopic observations carried out on pairs of fibres are given and exploited to lead to the fibre/fibre interface properties. In the second part, various cohesive zone models will be evaluated using these interface properties and numerical simulations will be performed for the purpose of validation.     

Voltammetric determination of the critical micellar concentration of surfactants by using a boron doped diamond anode

The electrochemistry of three surfactants has been studied by voltammetry at boron doped diamond (BDD) electrode in sodium sulphate solutions. The electrochemical behaviour of these surfactants is characterized by an oxidation signal (peak or wave) situated before the electrolyte oxidation. The anodic current is found to follow a linear relation with the concentration of the surfactants; the slope decreases abruptly above the critical micellar concentration (CMC) of the surfactants. The CMC values obtained for an anionic (sodium dodecylbenzenesulfonate, SDBS), a cationic (polyoxyethylene-23-dodecyl ether, BRIJ 35) and a neutral (1-(hexadecyl)trimethylammonium bromide, CTAB) surfactant are found in good agreement with those measured by the classical technique of surface tension. This voltammetric method has the advantage not to require the use of a redox active electrochemical probe.     

Electrochemical study in both classical cell and microreactors of flavin adenine dinucleotide as a redox mediator for NADH regeneration

The electrochemical reduction of flavin adenine dinucleotide (FAD) is studied in a classical electrochemical cell as well as in two types of microreactors: the first one is a one-channel reactor and the other one, a multichannel filter-press reactor. The ultimate goal is to use the reduced form of flavin (FADH₂), in the presence of formate dehydrogenase (FDH), in order to continuously regenerate the reduced form of nicotinamide adenine dinucleotide (NADH) for chiral syntheses. Various voltammetric and adsorption measurements were carried out for a better understanding of the redox behavior of the FAD as well as its adsorption on gold. Diffusivity and kinetic electrochemical parameters of FAD were determined.     

Investigation of premature aging of zeolites used in the drying of gas streams

Abstract

The presence of humidity in gas streams is usually associated to several problems in the performance of industrial unit operations. Therefore, gas drying is one of the most important primary stages in the process that is commonly carried out by adsorption, using hydrophilic porous materials. These materials are typically regenerated by temperature swings (TSA), which in the presence of contaminants in the gas stream, may lead to adsorbent degradation and reduced lifespan of the drying process. The objective of this study is to investigate the hydrothermal stability of a zeolitic material used in the process of natural gas drying, by means of an aging test developed to simulate the operating conditions of a typical TSA. The textural characteristics, elemental analysis, and H₂O/CO₂ adsorption capacity are determined along the heating/cooling cycles. The presence of hydrocarbons, represented by n-heptane, is the most significant factor that contributed to the aging of the adsorbent within the temperature and pressure ranges under study.