Biljana Bujanovic

Bio: Biljana Bujanovic is an academic researcher from State University of New York College of Environmental Science and Forestry. The author has contributed to research in topics: Lignin & Kraft process. The author has an hindex of 12, co-authored 37 publications receiving 463 citations. Previous affiliations of Biljana Bujanovic include University of Wisconsin-Madison & Western Michigan University.

Lignin-Furfural Based Adhesives

Abstract: Lignin recovered from the hot-water extract of sugar maple (Acer saccharum) is used in this study to synthesize adhesive blends to replace phenol-formaldehyde (PF) resin. Untreated lignin is characterized by lignin content and nuclear magnetic resonance (NMR) analysis. The molecular weight distribution of the lignin and the blends are characterized by size exclusion chromatography (SEC). The effect of pH (0.3, 0.65 and 1), ex situ furfural, and curing conditions on the tensile properties of adhesive reinforced glass fibers is determined and compared to the reinforcement level of commercially available PF resin. The adhesive blend prepared at pH = 0.65 with no added furfural exhibits the highest tensile properties and meets 90% of the PF tensile strength.

Commercializing Biorefinery Technology: A Case for the Multi-Product Pathway to a Viable Biorefinery

Abstract: While there may be many reasons why very interesting science ideas never reach commercial practice, one of the more prevalent is that the reaction or process, which is scientifically possible, cannot be made efficient enough to achieve economic viability. One pathway to economic viability for many business sectors is the multi-product portfolio. Research, development, and deployment of viable biorefinery technology must meld sound science with engineering and business economics. It is virtually axiomatic that increased value can be generated by isolating relatively pure substances from heterogeneous raw materials. Woody biomass is a heterogeneous raw material consisting of the major structural components, cellulose, lignin, and hemicelluloses, as well as minor components, such as extractives and ash. Cellulose is a linear homopolymer of D-glucopyrano-units with β-D(1®4) connections and is the wood component most resistant to chemical and biological degradation. Lignin is a macromolecule of phenylpropanoid units, second to cellulose in bio-resistance, and is the key component that is sought for removal from woody biomass in chemical pulping. Hemicelluloses are a collection of heteropolysaccharides, comprised mainly of 5- and 6-carbon sugars. Extractives, some of which have high commercial value, are a collection of low molecular weight organic and inorganic woody materials that can be removed, to some extent, under mild conditions. Applied Biorefinery Sciences, LLC (a private, New York, USA based company) is commercializing a value-optimization pathway (the ABS Process™) for generating a multi-product portfolio by isolating and recovering homogeneous substances from each of the above mentioned major and minor woody biomass components. The ABS Process™ incorporates the patent pending, core biorefinery technology, “hot water extraction”, as developed at the State University of New York College of Environmental Science and Forestry (SUNY-ESF). Hot water extraction in the absence of mineral acids and bases is preferred because of its ability to generate multiple high value output products without chemical input, recovery, or disposal costs. Instead of added chemicals in the cooking phase, the ABS Process™ relies upon an autocatalytic reaction in which acetyl groups, bound through an ester linkage to hemicellulose chains, are hydrolyzed at high temperature in water. The resulting acidic conditions (final pH ~3.5) and temperatures of 160–170 °C permit further solubilization and diffusion of oligomeric 5- and 6-carbon sugars, acetic acid, aromatic substances, monomeric sugars, and other trace compounds into the extract solution. These conditions also avoid extensive degradation of monosaccharides, enabling membrane fractionation and other chemical separation techniques to be used in the following separations. A range of separation techniques are applied on the extract solution to isolate and purify fermentable sugars, acetic acid, lignin, furfural, formic acid, other hemicellulose related compounds, lignin, lignin degradation products, and phenolic extractives for commercial sale. The extracted lignocellulosic biomass, with reduced hemicellulose content and is thus less heterogeneous, carries the value-added advantages of: (1) enhanced product characteristics, and (2) reduced energy and chemical manufacturing costs. Thus, by fractionating woody biomass into more homogeneous substances, the ABS Process™ holds potential as an economically viable pathway for capturing sustainable, renewable value not currently realized from lignocellulosic biomass.

Chemical Composition of Apricot Pit Shells and Effect of Hot-Water Extraction

Abstract: Agricultural residues, such as corn stover, wheat straw, and nut shells show promise as feedstocks for lignocellulosic biorefinery due to their relatively high polysaccharide content and low or no nutritional value for human consumption. Apricot pit shells (APS) were studied in this work to assess their potential for use in a biorefinery. Hot water extraction (HWE; 160 °C, 2 h), proposed to remove easily accessible hemicelluloses, was performed to evaluate the susceptibility of APS to this mild pretreatment process. The chemical composition of APS before and after HWE (EAPS) was analyzed by standard methods and 1H-NMR. A low yield of the remaining HW-extracted APS (~59%) indicated that APS are highly susceptible to this pretreatment method. 1H-NMR analysis of EAPS revealed that ~77% of xylan present in raw APS was removed along with ~24% of lignin. The energy of combustion of APS was measured before and after HWE showing a slight increase due to HWE (1.61% increase). Near infrared radiation spectroscopy (NIRS), proposed as a quick non-invasive method of biomass analysis, was performed. NIRS corroborated results of traditional analysis and 1H-NMR. Determination of antioxidizing activity (AOA) of APS extracts was also undertaken. AOA of organic APS extracts were shown to be more than 20 times higher than that of a synthetic antioxidizing agent.

Polyoxometalates in Oxidative Delignification of Chemical Pulps: Effect on Lignin

Abstract: Chemical pulps are produced by chemical delignification of lignocelluloses such as wood or annual non-woody plants. After pulping (e.g., kraft pulping), the remaining lignin is removed by bleaching to produce a high quality, bright paper. The goal of bleaching is to remove lignin from the pulp without a negative effect on the cellulose; for this reason, delignification should be performed in a highly selective manner. New environmentally-friendly alternatives to conventional chlorine-based bleaching technologies (e.g., oxygen, ozone, or peroxide bleaching) have been suggested or implemented. In an attempt to find inorganic agents that mimic the action of highly selective lignin-degrading enzymes and that can be applicable in industrial conditions, the researchers have focused on polyoxometalates (POMs), used either as regenerable redox reagents (in anaerobic conditions) or as catalysts (in aerobic conditions) of oxidative delignification. The aim of this paper is to review the basic concepts of POM delignification in these two processes.

Nanofibrillated Cellulose (NFC): A High-Value Co-Product that Improves the Economics of Cellulosic Ethanol Production

Abstract: Cellulosic ethanol is a sustainable alternative to petroleum as a transportation fuel, which could be made biologically from agricultural and forestry residues, municipal waste, or herbaceous and woody crops. Instead of putting efforts on steps overcoming the natural resistance of plants to biological breakdown, our study proposes a unique pathway to improve the outcome of the process by co-producing high-value nanofibrillated cellulose (NFC), offering a new economic leverage for cellulosic ethanol to compete with fossil fuels in the near future. In this study, glucose has been produced by commercial enzymes while the residual solids are converted into NFC via sonification. Here, we report the morphology of fibers changed through the process and yield of glucose in the enzymatic hydrolysis step.

Importance of chemical pretreatment for bioconversion of lignocellulosic biomass

Abstract: Lignocelluloses are often a major or sometimes the sole components in different waste streams from various sources such as industries, forestry, agriculture and municipalities. It represents an as-of-yet untapped source of fermentable sugars for significant industrial use. Many physico-chemical, structural and compositional factors hinder the hydrolysis of components present in the biomass to sugars and other organic compounds that can later be converted into fuels. During the past few years, a large number of chemical pretreatment methods including lime, acid, steam explosion, sulfur dioxide explosion, ammonia fiber explosion, ionic liquid and others have been developed for efficient pretreatment of biomass. Many pretreatment methods have shown high sugar yields i.e. more than 90% of the theoretical yield from lignocelluloses. In this review, we discuss various chemical pretreatment processes, feasibility of the processes at industrial scale in terms of the mechanisms involved, advantages, disadvantages and economic assessment. It is not possible to define the best pretreatment method as it depends on many factors such as type of lignocellulosic biomass, process parameters, environmental impact, economical feasibility, etc. However, some of these chemical pretreatments have disadvantages such as formation of inhibitory compounds especially furfural and 5-hydroxyl methyl furfural (HMF).

Fourier transform infrared spectroscopy

Abstract: Fourier Transform Infrared Spectroscopy: Applications to Chemical Systems Vol 1 Edited by J R Ferraro and L J Basile Pp 311 (Academic: New York, San Francisco and London, 1978) $25; £1625

Recent Advances in Characterization of Lignin Polymer by Solution-State Nuclear Magnetic Resonance (NMR) Methodology.

Abstract: The demand for efficient utilization of biomass induces a detailed analysis of the fundamental chemical structures of biomass, especially the complex structures of lignin polymers, which have long been recognized for their negative impact on biorefinery. Traditionally, it has been attempted to reveal the complicated and heterogeneous structure of lignin by a series of chemical analyses, such as thioacidolysis (TA), nitrobenzene oxidation (NBO), and derivatization followed by reductive cleavage (DFRC). Recent advances in nuclear magnetic resonance (NMR) technology undoubtedly have made solution-state NMR become the most widely used technique in structural characterization of lignin due to its versatility in illustrating structural features and structural transformations of lignin polymers. As one of the most promising diagnostic tools, NMR provides unambiguous evidence for specific structures as well as quantitative structural information. The recent advances in two-dimensional solution-state NMR techniques for structural analysis of lignin in isolated and whole cell wall states (insitu), as well as their applications are reviewed.