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Laser-induced graphene (LIG) is a foam-like porous material consisting of few-layer graphene obtained by laser irradiation of a wide range of carbon-containing substrates. Among these, the ability to synthesize LIG from paper and other cellulose-related materials is particularly exciting, as it opens the door to a wide assortment of potential applications in the form of low-cost, flexible, and biodegradable devices. Here, the synthesis of this material, dubbed paper-LIG, on different types of filter papers and xylan biopolymer is discussed. In particular, we report the formation of paper-LIG by single-step irradiation, providing an improvement over the conventional multiple lasing approach and giving an explanation of the conditions that allow this simplified synthesis. All the relevant process parameters are covered, assessing their effect on the resulting electrical properties, structure, and morphology. Additionally, we demonstrate the application of LIG obtained from xylan, an abundant and often underutilized biopolymer, for temperature sensing. These results provide a better understanding of the conditions required for the synthesis of highly conductive LIG from paper and related materials, paving the way for its application, with reduced cost and low environmental impact, in fields ranging from biomonitoring to consumer electronics. published

The increasing demand for cellulosic fibres is continuously driven by the growing earth population and requirements of the textile industry. The annual cotton production of ca. 25 million tons is no longer enough to meet the market demands. This market gap of cellulosic fibres is progressively filled by regenerated cellulosic fibres derived from the dissolving pulp. The conventional industrial process of viscose production is far from being environmentally friendly due to the use of hazardous reagents. Alternatively, new trends in the production of regenerated fibres are related to the direct dissolution of cellulose in appropriate environmentally sound recyclable solvents, allowing high quality rayon fibres. This article reviews the sources of dissolving pulps used for the production of viscose and its quality parameters related to the performance of viscose production. The prospective cellulose regeneration processes, both commercialized and under development, are reviewed regarding current and future developments in the area.

A sensor consisting of an optical fibre with the exposed tip coated with the polyoxometalate salt [(C4H9)4N]4H[PMo10V2O40], specially designed to be insoluble in water, which UV–Vis spectrum changed in contact with formaldehyde, is presented. The sensor limit of detection for formaldehyde was 0.2 mg L−1, and the limit of quantification was 0.6 mg L−1, which were close to the conventional spectrophotometric method values of 0.2 mg L−1 and 0.5 mg L−1, respectively, and lower than the tolerable limit for ingested food. The sensor was tested for formaldehyde quantification in milk, as its deliberate addition is a matter of concern. The results obtained analysing formaldehyde in milk samples by the optical sensor and by the conventional method were not statistically different (α = 0.05).

This work studies the microwave-assisted extraction conditions for recovery of polysaccharides from spent coffee grounds, including their effect on arabinogalactans and galactomannans polymerization and branching structural features. Temperature (140, 170, and 200 °C) has the most significant impact on total extracted mass (ηtotal soluble solids) and sugars yield (ηsugars), arabinogalactans (ηAG) and galactomannans (ηGM), and polysaccharide mass ratio (ηAG/ηGM). Time (2, 5, and 10 min) and alkali (diluted 0.1 M NaOH) treatments have less influence. Alkali treatment and shorter time (2 min) provided a protective effect against polysaccharides degradation. At 170 °C, the yield of arabinogalactans was found to be significantly higher than that of galactomannans (ηAG/ηGM >1). Increasing temperature to 200 °C leads to decrease the polymerization of polysaccharides, promoting the formation of debranched polysaccharides and oligosaccharides. This study shows that the optimum conditions for polysaccharides extraction cannot be selected only by mass yield but need to be defined according to the desired structural features for the specific applications.

Bioethanol production potential from cardoon ( Cynara cardunculus ) and rockrose ( Cistus ladanifer ), pretreated by diluted acid hydrolysis (DAH), was studied and compared by both, separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes. DAH pretreatment allowed an increase of 5 fold to cardoon and 16 fold to rockrose in cellulose accessibility towards enzymatic hydrolysis. Both plants showed better overall fermentation efficiency and ethanol yield in SSF than in SHF also with shorter processing periods, 24 h against 72 + 24 h, respectively. Results obtained for rockrose are about half the concentration and volumetric productivity of ethanol and 60% of the overall fermentation efficiency of those obtained for cardoon. The recalcitrance of rockrose to enzymatic hydrolysis was explained by higher abundance of lignin and extractives than in cardoon. Comparing the steam explosion (SE) and DAH pretreatments, the former was more advantageous for the recalcitrant rockrose in terms of enzymatic saccharification yield., This research was funded by INALENTEJO 2007.2013/QREN (BioEcos Project – Valorização Integrada de Biomassa (ALENT-09-0140-FEDER-000705 (QREN)). The author’s thanks, FCT (Fundação para a Ciência e Tecnologia) under projects CICECO-Aveiro Institute of Materials (Ref.FCTUID/CTM/50011/2013) and ICAAM-Instituto de Ciências Agrárias e Ambientais Mediterrânicas (Ref.FCTUID/AGR/00115/2013). Agrarian School from Instituto Politécnico de Beja and Associação de Defesa do Património de Mértola, are greatly acknowledged for kindly supplying cardoon and rockrose, respectively.

The removal of graffiti causes irreversible deterioration of fair-faced concrete. The protective products are often selected without counting the properties of concrete surface leading to its insufficient protection. Chemical and micro-structural effects of anti-graffiti products on the concrete surface were analyzed in relation to its protection efficiency against graffiti paints. Contact angles and wetting envelope graphs were examined, allowing the understanding and prediction of wetting behavior of concrete surfaces. The obtained results revealed the changes on the concrete surface produced by graffiti, graffiti protection and graffiti removal products, showing the advantage of permanent protection coating over sacrificial one., CICECO – Institute of Materials (Portugal) for the financing of this work within the scope of the FCT (Portugal) grant PEst-C/QUI/UI0062/2013

In this work, the successful derivatization of a beechwood xylan (BX) by carboxymethylation and hydroxypropylation was achieved aimed to produce bio-based films. Carboxymethyl xylan (CMX) and hydroxypropyl xylan (HPX) with a substitution degree of 0.3 and 1.1, respectively, as determined by H-1 NMR, were synthesised. The xylan's characterization by thermogravimetric analysis showed that HPX is thermally more stable than CMX or BX. The ability of the xylan derivatives to form films and the effect of the glycerol addition on the films performance were evaluated. Tensile strength, Young's modulus and water vapour permeability of self-supporting CMX films were higher and the elongation at break lower than those of the corresponding HPX films. The water vapour barrier properties of CMX and HPX films were improved with 10% glycerol addition. Oxygen barrier property was exceptionably good for a CMX film plasticized with 25% of glycerol (oxygen permeability of 0.5 cm(3) mu m m(-2) d(-1) kPa(-1)) while higher oxygen permeability values were obtained for HPX films. Favourable characteristics were found that may enable the use of these films in, e.g., coatings for packaging. (C) 2016 Elsevier B.V. All rights reserved.

Electrochemical impedance spectroscopy was applied to the study of conducting lignin-derived polymers to be used in all-solid-state potentiometric chemical sensors. Conducting polymers were produced by step-growth polymerization of modified eucalyptus kraft lignin with isocyanate and doped by multi-wall carbon nanotubes (MWCNTs). Lignin possesses ion-exchange properties due to the presence of a variety of functional groups, which makes it an attractive active substance for chemical sensing. Co-polymerization allows fixing lignin inside polymer matrix ensuring high stability of the resulting material. Doping of the lignin-based polyurethane with multi-wall carbon nanotubes (MWCNTs) was adopted as a mean to obtain electrically conductive system with low mass of filler. The direct current (DC) electrical conductivity and the dielectric properties of the conducting polymers have been evaluated at MWCNTs contents from 0 to 0.72% (wt.) at the frequencies between 40 Hz and 100 MHz in the temperature range −100 to 100 °C. The percolation model theory was used to describe DC and the low frequency behaviour, where the electrical conductivity and the dielectric constant were expressed by scaling laws near the threshold conduction. The lignin-based polyurethane presented low critical concentration of MWCNTs around 0.18 wt.%. The dielectric analysis was carried out using the modulus formalism and the dielectric relaxation behaviour was modelled using the Cole–Cole expression.

Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, 41080-Seville, Spain and CICECO and University of Aveiro, Department of Chemistry,3810-193 Aveiro, Portugal E-mail address: gisela@irnase.csic.es (G. Marques), The heteroxylan from sisal (Agave sisalana), an O-acetyl-(4-O-methylglucurono)xylan with a molecular weight (Mw) of 18 kDa, was isolated by extraction of peracetic holocellulose with Me2SO and thoroughly characterized by wet chemistry, and NMR spectroscopy. The heteroxylan backbone is composed of (1→4)-linked β-D-xylopyranosyl units (Xylp) partially branched with terminal (1→2)-linked 4-O-methyl-α-D-glucuronosyl (MeGlcpA, 9%mol.) and a small proportion of α-D-glucuronosyl (GlcpA, This study has been supported by the Spanish Projects AGL2005-01748 and AGL2008-00709 and the EU BIORENEW project (NMP2-CT-2006-26456). We thank CELESA (Tortosa, Spain) for providing the samples. G.M. thanks the Spanish Ministry of Education for a FPI fellowship.

Dioxane lignins from two fractions of banana plant ‘Dwarf Cavendish’ stalk (floral stalk (DL FS ) and rachis (DL R )) were structurally characterized by a set of spectroscopic (Ultraviolet (UV), FTIR, solid- and liquid-state NMR) and chemical degradation (permanganate (PO) and nitrobenzene oxidation (NO)) techniques. Despite both lignins are of HGS-type, strong structural differences were observed between them. Thus, DL FS showed almost twice the abundance of H and G units and almost half of the abundance of S units when compared to DL R . DL R possessed significantly higher amount of β- O -4′ structures (0.32/C 6 against 0.12/C 6 ) and the molecular weight (5400 Da against 3750 Da) than those of DL FS . About 72% of the condensed structures in DL FS are of β-5 and 5–5′ types, whereas 4- O -5′-diaryl ether structures were the most abundant condensed structures in DL R . Most of H units in both lignins are terminal phenolic coumarates linked to lignin substructures by ester bonds. Both lignins are structurally associated with suberin-like components in cell wall tissues. Structural features of stalk lignin were discussed in terms of possible restrictions for the kraft pulping of integral stem material.

The chemical composition of the dichloromethane extracts of different morphological parts of banana plant “Dwarf Cavendish”, cultivated in Madeira Island (Portugal), were studied by gas chromatography–mass spectrometry. The five different morphological fractions in study have a similar qualitative chemical composition. Fatty acids and sterols are the major families present in the lipophilic extract of “Dwarf Cavendish”, representing ca. 33–66% and 12–43%, respectively, of the total amount of lipophilic components. Among all the identified compounds, campesterol, stigmasterol, sitosterol and fatty acids, such as palmitic, stearic, linoleic, linolenic, 22-hydroxydocosanoic, 24-hydroxytetracosanoic and 26-hydroxyhexacosanoic acids, were the major components found in all morphological zones. Other families of compounds, such as aromatic compounds, fatty alcohols and alkanes were also identified. The high increase of some components after alkaline hydrolysis, particularly, ferulic and fatty acids, indicates the presence of a considerable fraction of such components in esterified structures.

A synergistic effect of polyoxometalate and laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) has been observed in the aerobic oxidation of a hydrazonaphthalene type colorant. The considerable increase in the decolorization rate of Solophenyl Blue GL dye with the new catalytic system composed by laccase and heptamolybdopentovanadophosphate heteropolyanion, when compared with the treatment with enzyme or heteropolyanion alone, was tentatively explained by the redox mediation action of the heteropolyanion.