Research on biomass products and residues presented at PACWest 2017

UBC researchers from the Faculty of Applied Sciences presented their projects related to forest biomass at the PACWest 2017 conference  in Whistler on June 9. Their presentations drew interest and queries from a number of delegates representing pulp, paper and forestry industries.

Hydroxyethyl lignin derivatives for bioplastics

Liyang Liu, L. N. Sathsiksunoh, M. Cho, S. Chowdury and Scott Renneckar, University of British Columbia.
Li-Yang Liu is a PhD student of Wood Science at UBC. His research interests lie in the area of lignin, ranging from the characterization to the valorization of lignin. His research focus is specifically on a green way to convert lignin into homogeneous structure in preparation of bioplastics, such as foams, coating and polyester.
Abstract: Isolated lignins have phenolic hydroxyls, aliphatic hydroxyls including primary and secondary hydroxyls and carboxyl acid groups, which can undergo select modification to limit some of the heterogeneous functionality. This research investigated the use of ethylene carbonate as a reactant in the presence of alkali metal catalysts to create hydroxyethyl lignin derivatives from kraft lignin. Reaction conditions were studied and the conversion of phenolic hydroxyls and COOH groups were measured using quantitative 31P nuclear magnetic resonance spectroscopy. Under modest conditions derivatization decreased the glass transition temperature (Tg) and enhanced the thermal stability of the lignin with nearly 100% substitution of phenolics. At the highest temperature reaction conditions used in the study, 170°C, lignin modification decreased the Tg to room temperature and the material lost solubility across most solvents. With the reaction occurring in “solvent-free” conditions, the methods provide modification of lignin amendable for industrial processes for bioplastics.

Processing of pulp and paper mill waste to obtain hemicellulose and enhance the properties of NBSK pulp

Varun Rangu, Xue Feng Chang, Rodger P. Beatson, Chemical and Environmental Technology, British Columbia Institute of Technology, Burnaby; Heather L. Trajano, Department of Chemical and Biological Engineering, University of British Columbia.
Varun’s research in the Master of Engineering program at the Department of Chemical and Biological Engineering at UBC progresses from a background of operations in oil refineries in India and a bachelor’s in Chemical Engineering. His research interest is biorefining.
Abstract: Non-renewable fossil fuels and an alarming acceleration of climate change have drawn significant research to the forest biorefinery. The pulp and paper industry is positioned to lead the implementation of new technologies from such research. Hemicellulose present in hog fuel and primary sludge—two pulp mill waste streams—can be separated and utilized as a strength additive to improve tensile strength of pulp, and reduce refining energy.  Process conditions required to extract and absorb hemicellulose onto NBSK pulp are being studied.

Compositional analysis has detected as much as 62% and 68% hemicellulose and cellulose derived sugars in hog fuel and primary sludge, respectively.  Hemicellulose oligomer yields greater than 90% were obtained from hog fuel via autohydrolysis under various process conditions. The effect of temperature and residence time on the oligomer yield, pH of hydrolysate and removal of lignin were studied. The results are encouraging and suggest these waste streams have significant potential for the production of a green hemicellulose-based paper strength additive. A similar study was conducted for primary sludge after addition of acid in order to lower the pH. In addition to the results of this study, the absorption of hemicellulose to NBSK pulp will be investigated to identify the ideal conditions for the production of a hemicellulose that is most effective in maximizing the quality improvement of NBSK pulp.

A bio-refinery scheme to fractionate bamboo into high-grade dissolving pulp and ethanol

Zhaoyang Yuan, Department of Chemical and Biological Engineering, University of British Columbia; Yangbing Wen, Tianjin Key Laboratory of Pulp and Paper, Tianjin University of Science and Technology, Tianjin, China; Rodger Beatson, Department of Chemical and Biological Engineering, University of British Columbia; Chemical and Environmental Technology, British Columbia Institute of Technology, Burnaby.
Zhaoyang Yuan was awarded his PhD on March 9, 2017. At the end of his PhD, Zhaoyang already had 6 publications related to developing green and sustainable industrial processes. His research interests relate to utilizing cellulose from bamboo for novel green bio-products through a process which captures carbon-dioxide.
Abstract: Bamboo is a highly abundant source of biomass underutilized despite having a chemical composition and fibre structure similar to wood. The main challenge for the industrial processing of bamboo is its high level of silica, which negatively affects the processing. A cost-competitive and eco-friendly scheme for the production of high purity dissolving-grade pulp from bamboo not only requires a process for silica removal, but also needs to utilize fully all of the materials dissolved in the process that includes lignin, and cellulosic and hemicellulosic sugars as well as the silica. Alkaline pretreatment of bamboo was conducted to extract silica prior to the pulping process. An integrated process which combines dissolving pulp production with excellent sustainable biofuels and biochemical feedstocks recovery is presented. Pretreatment at 95oC with 12% NaOH charge for 150 minutes extracted all the silica and about 30% of the hemicellulose from bamboo. After kraft pulping, xylanase treatment and cold caustic extraction, pulp with hemicellulose content of about 3.5% was obtained. This pulp, after bleaching, provided a cellulose acetate grade dissolving pulp with α-cellulose content higher than 97% and hemicellulose content less than 2%. The amount of silica and lignin that could be recovered from the process corresponded to 95% and 77.86% respectively of the two components in the original chips. Enzymatic hydrolysis and fermentation of the concentrated and detoxified sugars mixture liquor showed that an ethanol recovery of 0.46 g/g sugar was achieved with 93.2% of hydrolyzed sugars being consumed. A mass balance of the overall process showed that 76.59 g solids was recovered from 100 g (o.d.) of green bamboo. This process could alleviate the silica associated challenges and provide feedstocks for bio-based products, thereby allowing the improvement and expansion of bamboo utilization in industrial processes.

The PACWest conference was an excellent venue to promote UBC’s Master of Engineering Leadership program. This one-year program is designed to develop highly qualified personnel with the specialized knowledge and practical experience to assume challenging roles in the rapidly evolving lignocellulosic biomass products sector. Prof. Nuwan Sella Kapu (right) and staff member of the Pulp and Paper Centre, Chitra Arcot, are pictured at the MEL table with PACWest Executive Secretary, Mary Barnes (left).