Comparative study of wood flour photodegradation of two wood species submitted to artificial weathering

Abstract

In this work Eucalyptus grandis and Dipteryx odorata were submitted to photodegradation by ultraviolet radiation. The effect of ultraviolet radiation irradiation on the color change and chemical composition of each wood flour were evaluated. The samples were submitted to a total of 500h of artificial weathering using condensation stages and ultraviolet radiation B irradiation cycles. The changes in wood flour color were monitored by spectrocolorimetry, while the changes in wood chemical composition were evaluated by Fourier transform infrared spectroscopy. Both species showed changes in color with increased exposure time to artificial weathering. For both wood species the variation in color change was considered very appreciable after 500h. The Eucalyptus grandis specie showed appreciable color change after 120h, while for Dipteryx odorata specie the color change is appreciable only after 240h. The Fourier transform infrared spectroscopy results showed that lignin was strongly degrades by ultraviolet radiation radiation in both species. However, Dipteryx odorata was more resistant to photodegradation than Eucalyptus grandis, probably due to lower lignin content in this wood. The results clearly indicated that for the wood species studied the rate of weathering is influenced by wood species.

Ultrasound Assisted Synthesis of Gadolinium Oxide-Zeolitic Imidazolate Framework-8 Nanocomposites and Their Optimization for Photocatalytic Degradation of Methyl Orange Using Response Surface Methodology

“…The negative values of ∆a and ∆b indicate that the MO solution tended to become less reddish owing to photocatalytic degradation. The total color change, ∆E, indicates the color difference between two colors under UV light irradiation [34,35]. Before the color of the solution was measured by a color spectrophotometer, the solution was centrifuged for 1 min to remove the photocatalyst from the solution.…”

Intemperismo Artificial De Quatro Revestimentos Aplicados Em Madeiras De Duas Espécies Florestais

“…Os compostos de elevado peso molecular e os ácidos orgânicos (vanilina e siringil) são lixiviados provocando alterações na estética da madeira (MATTOS et al, 2014). Já os componentes de baixo peso molecular, tais como os grupamentos carbonila, causam descoloração da madeira ao longo do período de intemperismo (CHANG et al, 2010;YILDIZ et al, 2013;POLETTO, 2017).…”

“…A lignina é o componente químico da parede celular da madeira mais susceptível às intempéries, principalmente a luz UV (QIAN et al, 2017). A lignina é capaz de absorver entre 80 e 95% de radiação solar devido a presença de grupos fenólicos em sua estrutura molecular (LESAR et al, 2011;POLETTO et al, 2017). Simultaneamente ao efeito na aparência, determinadas características físicas e morfológicas podem ser afetadas, tais como molhabilidade e presença de micro rachaduras (CHANG et al, 2010).…”

Liquefaction behaviour of twelve tropical hardwood species in phenol

“…A strong broad band at 3000-3600 cm -1 is related to O-H stretching and a band at 2800-3000 cm -1 is related to asymmetric methyl and methylene stretching groups present in the wood (Poletto 2017). In the fingerprint region, band at 1740 cm -1 is assigned to non-conjugated carbonyl group in hemicellulose and the band at 1510 cm -1 and 1610 cm -1 have their origin in the aromatic ring of lignin.…”