M. Sonia Freire

Chestnut shell as heavy metal adsorbent: optimization study of lead, copper and zinc cations removal.

The influence of initial cation concentration, temperature and pH was investigated to optimize Pb(2+), Cu(2+) and Zn(2+) removal from aqueous solutions using acid formaldehyde pre-treated chestnut shell as adsorbent. Experiments were planned according to an incomplete 3(3) factorial experimental design. Under the optimal conditions selected, the metal ion adsorption equilibrium was satisfactorily described by the Langmuir isotherm model. The maximum pre-treated chestnut shell adsorption capacity was obtained for Pb(2+) ions, 8.5 mg g(-1), and the order of cation affinity was Pb(2+)>Cu(2+)>Zn(2+). A model that considered the effect of axial dispersion was successfully used to describe the fixed-bed adsorption behaviour of Pb(2+), Cu(2+) and Zn(2+) ions at the flow rates essayed. Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies showed that the functional groups involved in metal ions binding included carboxyl, hydroxyl, ether, alcoholic and amino groups.

Effect of the Extraction Technique and Operational Conditions on the Recovery of Bioactive Compounds from Chestnut (Castanea sativa) Bur and Shell

The aim of this work was to study the extraction of phenolic compounds from chestnut bur and shell, both waste products of chestnut processing in the food industry. Two extraction techniques were compared—maceration with solvents and microwave-assisted extraction. The influence of the solvent used (water, 50% MeOH or 50% EtOH) and temperature (25-50-75°C) on extraction yield and extract total phenols content and FRAP, DPPH, and ABTS antioxidant activities was studied. In the conventional extraction, the yield was significantly higher for the bur (8.54–19.58%) than for the shell (2.91–13.27%); however, the shell extracts showed substantially greater properties. The best extract properties were achieved at 75°C using 50% MeOH for the bur and water for the shell and phenolic compounds with demonstrated antioxidant properties, as gallic acid esters of glucose and ellagic acid, were identified in these extracts by RP-HPLC-ESI-TOF. In addition, the aqueous extracts showed ability to inhibit the growth of gram positive and negative bacteria but not fungi. The kinetic of the extraction process was well fitted by the Pelegs model. The non-conventional microwave-assisted extraction slightly improved the chestnut bur extraction by reducing the extraction time.

Environmentally friendly wood adhesives based on chestnut (Castanea sativa) shell tannins

The aim of this work was the formulation of adhesives for particleboards based on tannins extracted from industrial lignocellulosic wastes, namely chestnut shell, chestnut bur and eucalyptus bark. The interest was centred on the possibility of completely removing formaldehyde from adhesive formulations. For this, hardener alternatives to formaldehyde were used: tris(hydroxymethyl)nitromethane (TRIS), glyoxal (GLY) and hexametilentetramine (HEX). The influence of the type and concentration of the hardener and pH on adhesive gel time and pot-life were studied. A comparative structural characterization of the adhesives was performed by 13C-NMR spectroscopy. Thermomechanical analyses (TMA) tests were carried out as an indication of the final strength of the adhesive systems. Particleboards type 2 of interior use (EN 312) were manufactured with adhesives based on chestnut shell tannins alone or mixed with chestnut bur/or eucalyptus bark tannins. Free-formaldehyde was determined, and boards were prepared with TRIS, GLY and HEX tannin adhesives were classified as E0.

Recovery of phenolic compounds from Eucalyptus wood wastes using ethanol-salt-based aqueous two-phase systems

In this work the partition behavior of phenols using ethanol-salt-based aqueous two phase systems (ATPS) was evaluated. The aim was the recovery of phenolic compounds with antioxidant capacity from eucalyptus wood industrial wastes. Experiments were planned to study the influence of several parameters on phenols partition, including type of inorganic salt (ammonium sulphate, a mixture of monopotassium phosphate and potassium diphosphate and potassium diphosphate), tie-lie lenght (TLL), volume ratio (Vr), settlement time and temperature. Phenols could be recovered preferently from the top or bottom phases depending on the salt used. It was demostrated that tie-lie lenght, volume ratio and temperature had influence on phenols partition. The highest total phenols yield 5,36 mg gallic acid equivalent (100 mg oven dried wood)-1 and FRAP antioxidant activity, 20 mmol AAE (100 g oven dried wood)-1, was obtained using ATPS formed by 40.6% (w/w) ethanol and 12% (w/w) of ammonium sulphate at 65oC. Analysis of the extract by RP-HPLC-ESI-TOF confirmed the presence of the phenolic compounds with potential antioxidant activity, namely, ellagic acid, myricetin 3-O-rhamnoside and quercetin 3-glucoside.

UV protection effects of phenolic extracts from chestnut fruit and forest industries residues

Extracts from different lignocellulosic sources were applied in the wood veneer dyeing process with the aim of preventing colour changes caused by ultraviolet (UV) degradation. Chestnut (Castanea sativa) fruit shell and bur, and barks from Pinus pinaster, Eucalyptus globulus and Quercus frainetto extracted using water or aqueous solutions of sodium sulphite and/or sodium hydroxide were used. Wood veneers from ash (Fraxinus excelsior), koto (Pterygota bequaertii) and lime (Tilia cordata) were dyed, treated with extracts and subjected to accelerated exposure to UV light for variable lengths of time. The colour degradation was measured and the results were studied using cluster analysis. Pinus pinaster bark extracts were the best protectors for dyed veneers. Chemical changes due to UV exposure were analyzed by X-ray photoelectron spectroscopy. The degraded untreated wood increased its functional groups rich in oxygen, that is, photo-oxidation occurred. Nevertheless chemical bonding of wood treated with extracts hardly underwent changes.

Estudio del mojado y caracterización superficial por microscopía de barrido laser confocal de chapas de madera obtenidas por desenrollo

The aim of this work was to study the surface properties of rotary-peeled veneers of five species ofhardwoods: okume, ayous, poplar, fromager and eucalyptus and to compare the behavior of both sidesof the veneers. The equilibrium contact angles were determined together with the wood surface freeenergy and its polar and disperse components. Additionally, surface roughness was evaluated usingconfocal laser scanning microscopy. Surface free energy ranged from 49-64 mJ/m2 and decreased in theorder okume> fromager> poplar> eucalyptus ~ ayous, indicating a decrease in wettability in that order.Okume wood with the highest value of the surface free energy and the lowest values of the equilibriumcontact angle was confirmed as the species with the best wetting properties, and also presented the highestvalues of surface roughness parameters. In general, there were not significant differences between theproperties of both sides of the veneers, except for roughness. The largest differences were obtained forokume veneers whose interior side showed higher wettability.