David Tilotta

The effect of torrefaction on the chemistry of fast-pyrolysis bio-oil

Fast pyrolysis was performed on torrefied loblolly pine and the collected bio-oils were analyzed to compare the effect of the torrefaction treatment on their quality. The results of the analyses show that bio-oils produced from torrefied wood have improved oxygen-to-carbon ratios compared to those from the original wood with the penalty of a decrease in bio-oil yield. The extent of this improvement depends on the torrefaction severity. Based on the GC/MS analysis of the pyrolysis bio-oils, bio-oils produced from torrefied biomass show different compositions compared to that from the original wood. Specifically, the former becomes more concentrated in pyrolytic lignin with less water content than the latter. It was considered that torrefaction could be a potential upgrading method to improve the quality of bio-oil, which might be a useful feedstock for phenolic-based chemicals.

Identification of free radicals in pyrolysis oil and their impact on bio-oil stability

The existence of radicals in pyrolysis oil generated from loblolly pine in three different reactor systems was verified with electron paramagnetic resonance (EPR) spectroscopy. Characterization of the bio-oil via its sub-fractions revealed the radicals were preferentially located in the bio-oil lignin fraction, especially in the higher molecular weight lignin. Based on the observed EPR spectra (which lacked hyperfine structure) and low g-factors, the radicals are proposed to be stable, carbon-centered and delocalized in a highly conjugated lignin π system. Furthermore, this study also examined the impact of radicals on bio-oil aging severity using an accelerated aging method and the addition of radical scavengers. Preliminary results support the hypothesis that bio-oil radicals are present in a stable state because radical scavengers showed negligible effects on controlling pyrolytic lignin condensation. Only a mild radical concentration reduction was observed after bio-oil accelerated aging.

Morphological and interfacial properties of chemically-modified tropical hardwood

Chemical modification of wood with acetic anhydride is an environmentally friendly process to sustain and improve wood properties over a longer term than naturally allowed. Such an approach offers many potential and attractive product avenues for the wood industry. In this study, obeche tropical hardwood (Triplochiton scleroxylon) was acetylated with acetic anhydride to improve its mechanical and interfacial properties relative to unmodified wood; specifically, dimensional stability in terms of anti-swelling efficiency (ASE), water repellent efficiency (WRE), and hydrophobicity were the target properties of interest. The chemical modification was carried out at 120 °C with five varying reaction times (1–5 h) to optimize the reaction based on weight percent gain (WPG). It was found that as the reaction time increased, the WGP and hydrophobicity increased, but the percentage of water absorption and volumetric swelling diminished. In total, acetylation provided the hardwood with good dimensional stability. The chemically-modified wood was characterized by Fourier transform-infrared (FT-IR), dynamic contact angle, and an Owens–Wendt surface energy analysis.

Effect of different headspace concentrations of bornyl acetate on fecundity of green peach aphid and balsam woolly adelgid

ABSTRACT Balsam woolly adelgid (Adelges piceae) (Hemiptera: Adelgidae) (BWA) is an exotic pest introduced from Europe to North America in the early 1900s. Subsequent introductions and spread have enabled this pest to infest native Fraser fir stands in the Southern Appalachians and become a troublesome pest for the region’s Christmas tree industry. Means to study its fecundity and control it are consequently of high importance. Headspace solid phase micro-extraction coupled with gas chromatography and mass spectrometry were used to compare chemical differences in stem tissue between a resistant species, Veitch fir (Abies veitchii) and the susceptible Fraser fir (Abies fraseri). Comparisons demonstrated that bornyl acetate (BA), a terpenoid, was qualitatively more abundant in resistant Veitch fir than Fraser fir. Varying headspace concentrations of BA were tested to ascertain any biological impacts on egg eclosion of BWA, as well as fecundity of green peach aphid (Myzus persicae) (GPA), an insect serving as a proxy. Varying concentrations of BA and a known number of adelgid eggs did not indicate any impact of concentration on egg eclosion success. However, defoliated Veitch fir branches in treatment jars produced a significant negative impact on BWA eclosion success. Implications of these findings are discussed.