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Fitchburg, WI, United States

Li X.,Central South University of forestry and Technology | Li X.,U.S. Department of Agriculture | Cai Z.,U.S. Department of Agriculture | Horn E.,Biopulping International, Inc. | Winandy J.E.,University of Minnesota
Holzforschung | Year: 2011

The main objective of this study was to evaluate the effect of oxalic acid (OA) wood chips pretreatment prior to refining, which is done to reduce energy used during the refining process. Selected mechanical and physical performances of medium-density fiberboard (MDF) - internal bonding (IB), modulus of elasticity (MOE), modulus of rupture (MOR), water absorption (WA) and thickness swelling (TS) - made from this OA-pretreated wood were tested and the effect of the OA treatment on carbohydrates investigated. The results showed that the OA treatment significantly reduced refining energy usage, and improved MDF dimensional stability and lightness. However, the OA treatment had a negative effect on the internal bonding strength of MDF panels. The amount of extracted carbohydrates was dramatically increased, up to 24 times, by the OA pretreatment. Carbohydrates extracted from wood chips could be a potential sustainable resource for biofuel or bio-based chemicals. This paper is a contribution to the so-called "value prior to pulping (VPP)" concept. © 2011 by Walter de Gruyter · Berlin · Boston. Source

Luo X.,South China University of Technology | Luo X.,U.S. Department of Agriculture | Luo X.,Capital Normal University | Gleisner R.,U.S. Department of Agriculture | And 7 more authors.
Industrial and Engineering Chemistry Research | Year: 2010

The potentials of deteriorated mountain pine beetle (Dendroctonus ponderosae)-killed lodgepole pine (Pinus contorta) trees for cellulosic ethanol production were evaluated using the sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) process. The trees were harvested from two sites in the United States Arapaho-Roosevelt National Forest, Colorado. The infestation age of the trees varied from zero to about 8 years. Mild (170°C) and harsh (180°C) SPORL pretreatments were conducted. The chemical charges were sulfuric acid of 2.21% and sodium bisulfite of 8% on oven dry wood for the harsh and half of those for the mild pretreatment. The results suggest that beetle-caused mortality enriched glucan content by as much as 3 percentage points (or 7.5%) in wood. The glucan enrichment seems to increase with infestation age. The enriched glucan can be captured after SPORL pretreatment followed by enzymatic hydrolysis. The killed trees are more susceptible to SPORL pretreatment, which enhanced substrate enzymatic digestibility (SED). Enzymatic hydrolysis glucose yields (EHGY) from killed trees were about 5-20% higher than those from their corresponding live trees. Total fermentable sugar productions from dead trees (including a tree laying on the ground) were 4-14% higher than corresponding production from live trees, depending on pretreatment conditions and infestation age. An ethanol yield of 267 L/metric ton of wood or 69% theoretical value was achieved from a tree infested 4 years, 7% higher than the 250 L/metric ton of wood from the corresponding live tree. The results also demonstrated the robustness of SPORL pretreatment for lodgepole pine. © 2010 American Chemical Society. Source

Houtman C.,U.S. Department of Agriculture | Horn E.,Biopulping International, Inc.
Tappi Journal | Year: 2011

Pilot data indicate that wood chip pretreatment with oxalic acid reduced the specific energy required to make thermomechanical pulp. A combined oxalic acid/bisulfite treatment resulted in 21% refiner energy savings and 13% increase in brightness for aspen. A low level of oxalic acid treatment was effective for spruce. Energy savings of 30% was observed with no significant change in strength properties. Adding bisulfite did not significantly increase the brightness of the spruce pulp. For pine, the optimum treatment was a moderate level of oxalic acid, which resulted in 34% energy savings and an increase in strength properties. For all of these treatments 1-3 w/w % carbohydrates were recovered, which can be fermented to produce ethanol. The extract sugar solution contained significant quantities of arabinose. Source

Li X.,Central South University of forestry and Technology | Cai Z.,U.S. Department of Agriculture | Horn E.,Biopulping International, Inc. | Winandy J.E.,University of Minnesota
Tappi Journal | Year: 2011

This study was conducted to evaluate the effect of oxalic acid (OA) pretreatment on carbohydrates released from rice straw particles and wood chips. The results showed that OA treatment accelerated carbohydrates extraction from rice straw particles and wood chips. OA pretreatment dramatically increased the amount of carbohydrates extracted, up to 24 times for wood chips and 2.3 times for rice straw particles. Sugars released from the OA-treated rice straw particles and wood chips increased with increasing treatment temperature and duration. OA treatment also improved the primary physical properties of rice straw particleboard and wooden medium density fiberboard (MDF), except for the mechanical strength of MDF. Carbohydrates extracted from rice straw particles and wood chips could be a potential sustainable resource for biofuel or biobased chemicals. Source

Agency: Department of Agriculture | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 349.91K | Year: 2008

The Medium Density Fiberboard or MDF industry in North America is facing many challenges, largely as a result of the weak housing market. Residential construction is 20 percent below 2006 levels and it is not likely that an improvement will happen before mid 2008. Rising imports of secondary wood products from China and other low costs countries also have a detrimental impact on the North American production of furniture, mouldings, and other secondary wood products. In an environment of fierce international competition, Canadian and other foreign mills exporting to the USA are usually absorbing the exchange losses themselves, rather than losing the sale to a competitor. In addition, the MDF industry has to grapple with expensive and ever stiffer environmental regulations. We expect upward pressure on prices during the next five years, particularly from 2008 onwards, as environmental standards increase the cost of resins and demand escalates. The companies specializing in higher value added products are doing better. Therefore, the North American MDF industry is progressing by way of shifting its production towards higher value-added products. We have developed an innovative process of treating wood chips with a dilute solution of oxalic acid, patent pending, for the production of MDF, which compared to the control is more resistant to water infiltration in 24 hour swelling and water adsorption tests. The process not only produces value added MDF with increased strength, reduced moisture content, reduced energy consumption, etc. with reduced manufacturing cost but also further increases the profitability of this industry by producing a stream of carbohydrate resource that can be converted into cellulosic ethanol and other value added chemicals. The proposed research fits both USDAs crosscutting priorities, Agriculturally related manufacturing technology and alternative and renewable energy. Making ethanol from cellulose dramatically expands the types and amount of available material for ethanol production and would not compete with food supplies. Presently ethanol is made where grain is available. An ethanol manufacturing facility could be co located with a MDF plant. Additional societal impact will be gained if material from overcrowded forests is proven suitable for the process. The rural economic development will be an advantage, but if material thinned from our forests can be used then the health of the forests and help in prevention of forest fires will also be increased. This will enhance our resource base by providing new carbohydrate for fermentation and health of the environment by improving our standing forests. Each new identified source of carbohydrate that can be converted into fuels and chemicals will help to increase our energy independence. Cellulose ethanol production will also provide additional greenhouse gas emissions reductions.

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