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Gao Q.,Umea University | Cieplik M.K.,Energy Research Center of the Netherlands | Budarin V.L.,University of York | Gronnow M.,Biorenewables Development Center | Jansson S.,Umea University
Chemosphere | Year: 2016

Isomer distribution patterns of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) were investigated in microwave-assisted pyrolysis (MAP) products of woody biomass. The feedstocks included bark and impregnated wood. The results indicated that isomer distributions in MAP are more selective compared to those reported from wood burning and waste incineration. Favored formation of 4-MoCDF and highly selective chlorine substitution at the 2,4-position observed during MAP suggested a preferred formation pathway of PCDFs involving (chloro)phenol precursors followed by subsequent chlorination. The PCDD distribution was dominated by isomers typically formed from chlorophenol condensation at relatively low temperature. The PCN isomer distributions showed a tendency for sequential chlorination from non-substituted naphthalene at successive positions. The presence of isomers such as 1-MoCDD, 4-MoCDF, 1,2,3-TriCN with low thermodynamic stability indicates that kinetic factors may be important in the MAP process. © 2016 The Authors. Source


Gao Q.,Umea University | Budarin V.L.,University of York | Cieplik M.,Energy Research Center of the Netherlands | Gronnow M.,Biorenewables Development Center | Jansson S.,Umea University
Chemosphere | Year: 2016

Microwave-assisted pyrolysis (MAP) of lignocellulosic biomass is a technique that could potentially be used to produce and upgrade renewable energy carriers. However, there is no available information about the formation of dioxins and other organic pollutants in MAP treatment of woody biomass. In this study, MAP experiments were conducted in lab-scale using virgin softwood, bark, and impregnated wood as feedstocks. The non-condensable gas, liquid (fractionated into aqueous and oil phases), and char fractions generated during pyrolysis were collected and analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs). The concentrations of PCDDs, PCDFs and PCNs in the pyrolysis products ranged from 0.52 to 43.7 ng kg-1. All investigated compound groups were most abundant in the oil fraction, accounting for up to 68% (w/w) of the total concentrations. The highest PCDD, PCDF and PCN concentrations were found from the pyrolysis of bark, which has relatively high contents of chlorine and mineral matter, followed by impregnated wood, which contains organic and metal-based preservatives. The homologue profiles of all three compound groups were dominated by the less chlorinated homologues. The homologue abundance decreased as the degree of chlorination increased. This trend was observed for all three feedstocks. © 2015 The Authors. Source


Budarin V.L.,University of York | Shuttleworth P.S.,CSIC - Institute of Polymer Science and Technology | De Bruyn M.,University of York | Farmer T.J.,University of York | And 4 more authors.
Catalysis Today | Year: 2014

Through a series of case studies it is demonstrated that microwave dielectric heating can be a powerfultool to recover and synthesize valuable molecules from a wide range of biomass types. In addition, undermicrowave irradiation the production of chemicals from biomass proceeds at markedly lower temper-atures (up to 150?C) compared to conventional heating. This has a secondary benefit in that moleculeswith a high degree of functionality are produced while conventional heating tends to produce a greatproportion of lower value gases. Furthermore, the technical set-up of a microwave reactor can easilyaccommodate for an in-situ separation of acids and valuable products therewith improving the shelf lifeof the latter. The benefits of combining hydrothermal conditions with microwave irradiation are alsoillustrated. In addition, a specialized case of selective heating in a biphasic reaction system is discussed,allowing for improved yields and selectivity. © 2013 Elsevier B.V. Source


Bielecka M.,University of York | Bielecka M.,Wroclaw Medical University | Kaminski F.,University of York | Adams I.,University of York | And 7 more authors.
Plant Biotechnology Journal | Year: 2014

Summary: We used expressed sequence tag library and whole genome sequence mining to identify a suite of putative desaturase genes representing the four main activities required for production of polyunsaturated fatty acids in hemp seed oil. Phylogenetic-based classification and developing seed transcriptome analysis informed selection for further analysis of one of seven Δ12 desaturases and one of three Δ15 desaturases that we designate CSFAD2A and CSFAD3A, respectively. Heterologous expression of corresponding cDNAs in Saccharomyces cerevisiae showed CSFAD2A to have Δx+3 activity, while CSFAD3A activity was exclusively at the Δ15 position. TILLING of an ethyl methane sulphonate mutagenized population identified multiple alleles including non-sense mutations in both genes and fatty acid composition of seed oil confirmed these to be the major Δ12 and Δ15 desaturases in developing hemp seed. Following four backcrosses and sibling crosses to achieve homozygosity, csfad2a-1 was grown in the field and found to produce a 70 molar per cent high oleic acid (18:1Δ9) oil at yields similar to wild type. Cold-pressed high oleic oil produced fewer volatiles and had a sevenfold increase in shelf life compared to wild type. Two low abundance octadecadienoic acids, 18:2Δ6,9 and 18:2Δ9,15, were identified in the high oleic oil, and their presence suggests remaining endogenous desaturase activities utilize the increased levels of oleic acid as substrate. Consistent with this, CSFAD3A produces 18:2Δ9,15 from endogenous 18:1Δ9 when expressed in S. cerevisiae. This work lays the foundation for the development of additional novel oil varieties in this multipurpose low input crop. © 2014 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd. Source


Wu C.,University of Hull | Budarin V.L.,University of York | Wang M.,University of Hull | Sharifi V.,University of Sheffield | And 5 more authors.
Applied Energy | Year: 2015

Thermal-chemical processing of biomass is expected to provide renewable and clean energy and fuels in the future. Due to the nature of endothermic reactions, microwave and conventional heating have been applied to this technology. However, more studies need to be carried out to clarify the difference between these two heating technologies. In this work, we investigated two bio-char samples produced from conventional pyrolysis of wood biomass (yield of bio-char: 38.48 and 59.70wt.%, respectively) and one bio-char produced from microwave pyrolysis with a yield of 45.16wt.% from the same biomass sample at different process conditions. Various methodologies have been used to characterise the bio-chars. CO2 gasification of bio-char has also been studied using a thermogravimetric analyser (TGA) and a fixed-bed reaction system. The results show that volatile and carbon contents of the bio-char derived from microwave pyrolysis were between the two conventional bio-chars. However, the microwave bio-char is more reactive for CO2 gasification, as more CO was released during TGA experiments, and the CO release peak was narrower compared with the CO2 gasification of the conventional bio-chars. It is suggested that the conventional bio-char is less reactive due to the presence of more secondary chars which are produced from secondary reactions of volatiles during the conventional biomass pyrolysis. While the microwave pyrolysis generates more uniform bio-chars with less secondary char, and therefore, has advantages of producing bio-char for downstream char gasification. © 2015 Elsevier Ltd. Source

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