Characterization of a bacterioruberin-producing Haloarchaea isolated from the marshlands of the Odiel river in the southwest of Spain.

In this work, we describe the isolation, identification, pigment characterization, and optimization of the culture conditions for a haloarchaea strain isolated from salt evaporation ponds in the Odiel river, at Southwest of Spain. The haloarchaea belongs to the genus Halorobrum, as deduced from the analysis of its 16S rRNA encoding gene and has been designated as Halorubrum sp. SH1.

Studying the effects of laccase treatment in a softwood dissolving pulp: cellulose reactivity and crystallinity.

An enzymatic biobleaching sequence (LVAQPO) using a laccase from Trametes villosa in combination with violuric acid (VA) and then followed by a pressurized hydrogen peroxide treatment (PO) was developed and found to give high bleaching properties and meet dissolving pulp requirements: high brightness, low content of hemicellulose, satisfactory pulp reactivity, no significant cellulose degradation manifested by α-cellulose and HPLC, and brightness stability against moist heat ageing. The incorporation of a laccase-mediator system (LMS) to bleach sulphite pulps can be a good alternative to traditional bleaching processes since thermogravimetric analysis (TGA) showed that the laccase treatment prevented the adverse effect of hydrogen peroxide on fibre surface as observed during a conventional hydrogen peroxide bleaching treatment (PO). Although VA exhibited the best results in terms of bleaching properties, the performance of natural mediators, such as p-coumaric acid and syringaldehyde, was discussed in relation to changes in cellulose surface detected by TGA.

A new biobleaching sequence for kenaf pulp: influence of the chemical nature of the mediator and thermogravimetric analysis of the pulp.

This paper evaluates five phenolic compounds as mediators for kenaf pulp biobleaching by laccase. The results have been compared with the treatment using a non-phenolic mediator, 1-hydroxybenzotriole and laccase alone. The influence of the nature of the chemical mediators used on various pulp properties is discussed.

Investigating the structure-effect relationships of various natural phenols used as laccase mediators in the biobleaching of kenaf and sisal pulps.

Nine phenol derivatives, p-coumaric acid (PC), vanillin (V), acetovanillone (AV), acetosyringone (AS), syringaldehyde (SA), coniferaldehyde (CLD), ferulic acid (FRC), sinapic acid (SNC), and sinapyl aldehyde (SLD) were assayed as laccase redox mediators in the biobleaching of kenaf and sisal pulps. As a general behaviour, the phenolic mediators increased the kappa number (KN) and reduced the brightness of pulps. In particular, these changes were found to depend in a linear manner on the energy of the highest occupied molecular orbital (E(HOMO)) of the mediators.

Thermogravimetry study of xylanase- and laccase/mediator-treated eucalyptus pulp fibres.

Thermogravimetric analyses (TGA) was applied to study the effects of enzymatic bleaching of eucalyptus pulp with xylanase and a laccase-mediator system. The thermal degradation profile of the pulps was sensitive to the enzymatic treatments. Xylanase treatment produced an ordered and clean microfibril, whereas laccase oxidized surface cellulose chains and increased the amorphous (paracrystalline) cellulose content.

Use of thermogravimetric analysis to monitor the effects of natural laccase mediators on flax pulp.

The effects of 1-hydroxybenzotriazole (HBT) and the natural laccase mediators gallic acid, caffeic acid and p-hydroxybenzoic acid, on the enzymatic bleaching of flax pulp were compared. The treatment was performed under atmospheric air and oxygen pressure, and, for the first time, monitored by thermogravimetric analysis (TGA) for comparison with chemical analysis, FTIR and X-ray diffraction (XRD) spectroscopies. Thermogravimetric data were simulated by applying a nucleation kinetic equation to a combustion model based on four pseudo-components (hemicellulose, amorphous and crystalline cellulose, and lignin).

Simulation of the thermogravimetry analysis of three non-wood pulps.

In a study of three non-wood pulps (rice straw, EFB, and Hesperaloe), the standard pyrolysis model for biomass based on hemicellulose, cellulose, and lignin pseudo-components, was modified to include char volatilization. As a result, abnormally high values for lignin content have been avoided. On the other hand, the consideration of autocatalysis (Prout-Tompkins equation) for TGA data simulation under inert and oxidative atmospheres, allows obtaining a stable set of kinetic parameters that describe volatilization and char oxidation for different heating rates, including char ignition.

Effect of the previous composting on volatiles production during biomass pyrolysis.

Composting is a biological process of decomposition of organic materials in an aerobic environment, which modifies the chemical composition and the thermal behavior of biomass. During composting, fungi and bacteria promote the decomposition of hemicellulosic and cellulosic fractions, increasing the lignin proportion. Its product, compost, is usually used as an amendment to soil; however, its physicochemical characteristics turn it into an interesting feedstock in pyrolysis or gasification facilities.

Use of autocatalytic kinetics to obtain composition of lignocellulosic materials.

Non-isothermal thermogravimetric analysis (TGA) data of biomasses and pulps originating from non-wood and alternatives materials (i.e., Tagasaste or rice straw) have been fitted with refined models, which include autocatalytic kinetics.