Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
  • D21C5/005—Treatment of cellulose-containing material with microorganisms or enzymes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/22—Other features of pulping processes
  • D21C3/222—Use of compounds accelerating the pulping processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
  • D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
  • D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
  • D21C9/144—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 and other bleaching agents in a multistage process

Definitions

• the invention relates generally to the field of pulping and bleaching lignocellulosic materials. More specifically, the present invention is directed to pulping and bleaching of lignocellulosic materials which includes biopulping and/or water extraction processes.
• Pulp is the fibrous slurry that is fed to a paper machine to produce paper.
• Mechanical, chemical and hybrid methods dominate commercial pulping plants. About 25% of worldwide pulp production is mechanical pulp. It is a high-yield process but suffers from high energy costs and damage to the lignocellulosic fibers. This damage produces lower strength paper.
• These disadvantages (cost and quality) limit the number of applications for pulp.
• Chemical pulp is the pulp produced by chemical pulping. The dominant chemical wood pulping process is the kraft process. In this process a digesting solution of sodium hydroxide and sodium sulfide is employed.
• the advantage of chemical pulp is reduced damage to the lignocellulosic fibers insofar as the chemical pulping operation permits a sufficient amount of the lignin constituent in the lignocellulosic materials to be dissolved so that the lignocellulosic fibers separate without significant mechanical action.
• the production of pulp begins with lignocellulosic materials, such as wood chips.
• lignocellulosic materials such as wood chips.
• the lignocellulosic materials are 'digested' with one or more fungi types prior to mechanical or chemical pulping.
• the fungi soften the lignocellulosic materials by degrading or breaking lignin-carbohydrate complexes in the lignocellulosic materials.
• Lignocellulosic materials comprise cellulose, lignin and hemicellulose.
• Conventional pulping operations recover the cellulose values in the form of fibers.
• the value provided by lignin, which is removed in the pulping operation, is recovered as energy, by its combustion. That is, conventional pulping, whether or not including a biopulping step, does not address a major aspect of commercial exploitation of lignocellulosic materials.
• the first is cellulose.
• the pulping operation yields fibers which are substantially the cellulose component.
• a second component is lignin, which is removed in the pulping operation.
• biopulping involves fungal digestion of lignin.
• the third component which is usually utilized for its energy value, along with the lignin, is hemicellulose.
• Hemicellulose is a mixture of sugar and sugar acids, a major component of which are xylans.
• the difficulty in the prior art of isolating the product values of hemicellulose has limited the utility of the hemicellulose component in wood to the marginal energy value of that component.
• An acid pretreatment can be used to depolymerize the xylan to xylose and xylose oligomers. The acid would also catalyzes hydrolysis of acetyl groups (2-4.5% of the weight of the original wood) to acetic acid. If the wood is treated with hot water a low initial rate of acetic acid would be obtained. However, each acetic acid molecule formed would then act as an acid catalyst in a process referred to as autohydrolysis.
• biopulping there are some drawbacks to biopulping, such as a reduction in the brightness and opacity of the resulting fibers. Since the production of higher quality papers is desirable, use of biopulped fibers will require improvements in brightness and opacity. Research is underway to develop strategies to address these drawbacks. Preliminary bleaching studies with hydrogen peroxide and addition of calcium carbonate to improve both brightness and opacity have met with early success.
• the present invention provides a method for producing pulp that addresses the above and other issues.
• the present invention is directed to an omnibus process of pulping lignocellulosic materials, especially wood chips, wherein many of the problems of both mechanical and chemical pulping in terms of pulping efficiency, production of quality paper and recovery of chemical values, is optimized.
• a process of pulping lignocellulosic materials is provided.
• lignocellulosic materials are treated with a fungus mat breaks lignin-carbohydrate complexes.
• the lignocellulosic materials product of this contact is thereupon mechanically, chemically or mechanically-chemically pulped.
• the pulp product of this step is bleached. That bleaching step occurs in the presence of an enzyme which breaks lignin-carbohydrate complexes.
• that enzyme is the crude broth product of the fungus contacting step.
• the lignocellulosic materials product that is not pulped and the pulp which is not bleached is combusted.
• lignocellulosic materials in another aspect of pulping lignocellulosic materials in accordance with the present invention lignocellulosic materials, whether or not contacted with a fungus that breaks lignin-carbohydrate complexes, is contacted with hot water at a temperature in the range of between about 20 0 C and about 200 0 C and a pH in the range of between about 0.5 and about 6.9 for a period in the range of between about 1 minute and about 7 days.
• the product of this extraction is an aqueous extract and extracted lignocellulosic materials.
• the extracted lignocellulosic materials are pulped and subsequently bleached.
• the extracted lignocellulosic materials not subject to pulping is combusted.
• a charge of a lignocellulosic material is contacted with a fungus which breaks lignin-carbohydrate complexes in lignocellulosic materials.
• the lignocellulosic material product of this contact is contacted with water at a temperature in the range of between about 20 0 C and about 200 0 C and a pH in the range of between 0.5 and about 6.9 for a period of time in the range of between about 1 minute and about 7 days wherein an aqueous extract and the extracted lignocellulosic material product is obtained.
• the extracted lignocellulosic material product is pulped wherein individual fibers and fiber bundles are produced.
• the pulp product of this step is bleached.
• the extracted lignocelMosic product not subjected to pulping and bleaching is combusted.
• a charge of lignocellulosic material is pulped wherein individual fibers and fiber bundles are produced.
• the pulped product is thereupon bleached by contacting the pulped product with chlorine dioxide in the presence of an agent selected from the group consisting of oxygen, magnesium hydroxide, another magnesium-containing compound, oxygen and magnesium hydroxide or another magnesium-containing compound, potassium hydroxide and calcium hydroxide.
• the pulp has a specific surface area in the range of between about 5,000 cm 2 /g and about 40,000 cm 2 /g and a specific volume in the range of between about 1.5 cm 3 /g and about 4.0 cm 3 /g.
• FIG 1 illustrates the lignolytic enzyme activity change for the laccase enzyme, where thermomechanical pulping (TMP) is performed over a six hour treatment time on Picea abies (Norway Spruce) wood chips with fungal treatment using P. snbserialis, T. versicolor and C. subvermispora, in accordance with Example 1.
• TMP thermomechanical pulping
• Figure 2 illustrates the lignolytic enzyme activity change for the manganese peroxidase enzyme, for comparison with the results of Fig. 1 in Example 1.
• Figure 3 is a schematic flow diagram of the omnibus pulping process of the present application.
• Figure 4 is a graph demonstrating yield as a function of Kappa number in Example 2.
• Figure 5 is a graph demonstrating viscosity as a function of Kappa number in Example 2
• Figure 6 is a graph showing delignification as a function of kraft cooking times in Example 2;
• Figure 7 is a graph demonstrating void volume of wood chips as a function of the temperatures of hot water extraction in Example 2;
• Figure 8 is an 1 H-NMP spectra recorded at 600 MHz for 5 sugars and the internal standard in Example 3;
• Figure 9 is a graph demonstrating lignin remaining in wood following extraction as fraction of the original wood mass in Example 3;
• Figure 10 is a graph showing glucose present as a function of hot water extraction temperature in Example 3;
• Figure 11 is a graph showing maximum xylan recovery as a function of hot water extraction temperature in Example 3.
• Figure 12 is a plot of xylan solubilization for sugar maple wood meal (i) and wood chips (ii) in Example 5;
• Figure 13 is a plot xylan deacetylation for sugar maple wood meal (i) and wood chips (ii) in Example 5;
• Figure 14 is a plot showing the concentration of acetyl groups in the hydrolyzate with increasing severity in Example 5;
• Figure 15 is a plot showing pH of hydrolyzate as a function of treatment severity in Example 5;
• Figure 16 is a plot showing xylose yield as a function of treatment severity in Example 5.
• Figure 17 is a plot showing the formation of furfural as a function of treatment severity in Example 5.
• the pulping process of the present invention begins with the raw material utilized in the production of pulp and its by-products - lignocellulosic materials.
• the lignocellulosic materials utilized in pulping are woods, grasses and the like.
• the classes of wood within this category include wood chips or tree species especially useful as a biomass fuel, e.g., a shrub willow (Salix dasyclados) and the like. In general, woods not suitable for use as lumber and certain species of grass are most commonly employed as raw materials in pulp and subsequent paper production.
• Lignocellulosic materials in accordance with the omnibus process depicted in Figure 3, is, in one preferred embodiment, subjected to hot water contact 3.
• water at temperature in the range of between about 20 0 C and about 200 0 C and a pH in the range of between about 0.5 and about 6.9 contacts a charge of the lignocellulosic material for a period in the range of between about 1 minute and about 7 days.
• the water is at a temperature is in the range of between about 100 0 C and about 160 0 C
• at a pH is the range of between about 2.0 and about 5.0
• a contact time between the lignocellulosic material charge and the hot water in the range of between about 10 minutes and about 4 days.
• This contacting step which serves as an extraction step, represents a significant advance in the art insofar as this step not only enhances the rate of pulping, which is conducted subsequent to this step, but, in addition, the step that occurs downstream of the pulping step, pulp bleaching, is more successful. That is, the bleaching step of the present invention yields a pulp having greater brightness than the pulp prepared from the same lignocellulosic material not subjected to the hot water extraction of the present process. It is furthermore theorized that the carbohydrate/cellulose of the brighter pulp, resulting from the step, has a higher average degree of polymerization which results in paper and paperboard products having higher strength properties than similar products produced from pulp not subjected to hot water extraction. In regard to the rate of pulping, it is found that the rate of pulping is increased by between about 1.2 and about 12 times than an identical pulping step in which the same lignocellulosic materials are not subjected to this hot water extraction step.
• the hot water contacting step 3 produces an extracted lignocellulosic product and an aqueous extract.
• the extract 13, an aqueous solution is subject to further processing to recover chemical values present in the original lignocellulosic materials charged into the process.
• the aqueous extract 13, in accordance with this aim is passed into a separation unit 14.
• molecular separation is employed to effectuate this result.
• a molecular separation occurs, preferably employing a mono-sized porous membrane, which effects separation of hemicellulose sugars and acetic acid, extracted from the lignocellulosic materials charge, present in the aqueous extract 13.
• Acetic acid is a highly prized commodity chemical.
• Hemicellulose sugars, principally xylans can, in the absence of the separated acetic acid, be fermented to produce ethanol and other valuable fermentation products.
• Xylans can also be polymerized to produce important xylan polymers.
• the aqueous extract 13 is separated by molecular separation 14 into an acetic acid stream, accumulated at 15 and a hemicellulose sugar aqueous solution stream collected at 16.
• the hemicellulose sugar can, in the absence of acetic acid, be fermented to produce ethanol and other commercially valuable fermentation products. Ethanol and other fermentation products are illustrated by reference numeral 17.
• the xylan sugar 16 can be polymerized to product xylan polymers 18.
• the lignocellulosic material after hot water extraction is next subjected to pulping.
• Pulping is effectuated by chemical pulping, mechanical pulping or a combination of mechanical and chemical pulping.
• Mechanical pulping denoted by reference numeral 7, is effectuated by methods known in the art.
• mechanical pulping involves grinding the lignocellulosic materials on a pulpstone refiner, e.g. a rotating disk attrition mill.
• Chemical pulping may be utilized in the pulping step.
• a predominant chemical pulping method is the kraft process.
• an alkaline pulping liquor or digesting solution includes sodium hydroxide and sodium sulfide.
• the two components are present in a weight ratio of about 3:1, sodium hydroxide to sodium sulfide.
• chemical pulping is effectuated by a kraft process modification. That is, the kraft process is modified by the addition of polysulfide which are introduced under alkaline conditions and relatively low temperature, e.g. about 100 0 C to about 12O 0 C.
• Another modification of the kraft process that may utilized in the chemical pulping process is the addition of an anthraquinone.
• an anthraquinone for example, sodium anthraquinone-2-sulfonate
• small amounts of a quinone salt are added to kraft pulping liquors.
• Yet another chemical pulping process within the contemplation of the present invention is soda cooking.
• the lignocellulosic materials are contacted with sodium hydroxide.
• Such a process is advantageously employed when the lignocellulosic material is certain hardwood species or is a nonwood plant.
• a related process that is encompassed by the chemical pulping step of the present invention is the use of the soda cooking method catalyzed by an anthraquinone.
• a further related process favorably utilized in the process of the present invention is soda cooking in the presence of a redox catalyst.
• a preferred redox catalyst utilized in this embodiment is anthraquinone (AQ) or 2-methylanthraquinone (MAQ).
• AQ anthraquinone
• MAQ 2-methylanthraquinone
• Kraft pulping is the dominant process for the conversion of wood chips into pulp fibers in the United States (-85% of all virgin pulps from wood chips).
• the key to the kraft process is the Tomlinson furnace that is quite efficient at recovering the pulping chemicals, NaOH and Na 2 S.
• This H 2 S has to be selectively removed by adsorption onto a solid sorbent or into a solvent.
• the H 2 S would have to be desorbed from the solid sorbent and the surface reconditioned for another sulfidation cycle. If the H 2 S is absorbed into a solvent then desorption into a non-reactive gas followed by re-absorption into NaOH or Na 2 CO 3 would be required. Poor efficiency and selectivity was observed when direct absorption into caustic was attempted at the New Bern mill where pilot scale gasification of kraft BL is being attempted.
• the chemicals in the soda/AQ process would be NaOH or KOH plus 0.05- 0.1% AQ on chips.
• the small amount of residual AQ can be sent to a gasifier since it is composed of carbon, hydrogen and oxygen only.
• Yet another chemical pulping process utilized in the present invention is chemical pulping conducted in the presence of an anion selected from the group consisting of a carbonate, bicarbonate, sulfite, bisulfite and mixtures thereof.
• sodium carbonate is presently used to delignify wood to ⁇ 85% yield in semi- chemical pulping operations, i.e. a hybrid process between chemical and mechanical pulping.
• Chemicals pulps are also produced by sulfite and bisulfite cooking processes and carbonate and bicarbonate anions are used for pH adjustment.
• chemical pulping is conducted in the presence of a base selected from the group consisting of potassium hydroxide, calcium hydroxide and magnesium hydroxide.
• Ca(OH) 2 or Mg(OH) 2 may be able to replace NaOH or KOH for HWP-E chips that are easier to delignify. We have also performed pulping trials with Mg(OH) 2 and oxygen.
• the pulping step in another preferred embodiment, is carried out by a combination of mechanical and chemical pulping.
• This process sometimes referred to as a semichemical process, is essentially a chemical delignification process in which the chemical reaction is stopped at the point where mechanical treatment is necessary to separate fibers from the partially cooked lignocellulosic materials.
• Any of the chemical pulping processes discussed above may be utilized in the chemical pulping phase of the combined mechanical and chemical pulping operation.
• this processing step is denoted in Figure 3 by the same reference numeral employed to designate chemical pulp processing, reference numeral 8.
• the pulp 9, produced in the mechanical pulping step 7 or the pulp 10 produced in the chemical pulping or the combination of mechanical and chemical pulping step 8, is thereupon bleached in a bleaching step 11.
• pulp 9 produced by mechanical pulping 7 is bleached
• bleaching be accomplished by contacting the pulp with a strong oxidizing agent.
• a particularly preferred oxidizing agent employed in this bleaching step is hydrogen peroxide.
• pulp 10 prepared by chemical pulping or by a combination of chemical and mechanical pulping
• bleaching is effectuated by contacting the pulp with an oxidizing agent selected from the group consisting of oxygen, hydrogen peroxide, ozone, peracetic acid, chlorine, chlorine dioxide, a hypochlorite anion and mixtures thereof.
• the pulp 10 is bleached in two oxygen-contacting stages. In that preferred embodiment, it is desirable that there be a washing step between the two oxygen-contacting stages. Alternatively, that preferred embodiment with oxygen and sodium hydroxide between the two oxygen-contacting stages.
• the bleaching of pulp 10 includes contacting pulp 10 with chlorine dioxide in the presence of at least one additional agent.
• the additional agent is oxygen.
• the additional agent is magnesium hydroxide or another magnesium- contacting compound.
• the additional agents are oxygen and magnesium hydroxide or another magnesium containing compound.
• the additional agent is potassium hydroxide or calcium hydroxide.
• the initial step prior to hot water extraction, involves abiopulping step 4 wherein a charge of a lignocellulosic material is contacted with at least one fungus that breaks lignin-carbohydrate complexes (LCC) in lignocellulosic materials.
• fungi which degrade lignin are utilized.
• Particularly preferred fungi of this type are species of Cerioporiopsis, Trametes and Phlebia. These fungi exude a lignin-degrading enzyme which permit their digestion of lignin.
• the fungus Upon contact, the fungus grows on the lignocellulosic material at a relatively slow rate compared to normal processing time scales in the pulp industry.
• the treatment of lignocellulosic material with at least one LCC breaking fungus, preferably a lignin-degrading fungus can take anywhere from two to six weeks or longer depending on the degree of treatment desired. The treatment time can be shortened by using greater concentrations of fungi initially but this comes at higher cost. Previous related work has indicated that the inoculation amounts (5 g/ton of lignocellulosic material) and treatment time of 2 weeks are reasonably feasible from an economic standpoint. Moreover, the use of a biological agent does not cause contamination or health concerns relating to concentrated cultures of microorganisms since the organisms used are all naturally-occurring and limit their attack to lignocellulosic materials.
• the fungus-treated lignocellulosic material is thereafter subjected to the aforementioned hot water treatment.
• the product of the fungus biotreatment 2 an enzyme extract 4 is separated and may or may not be recovered.
• the recovered enzyme is donoted by reference numeral 5. That enzyme extract 5 is obtained as a course broth or as a pressate, obtained by the application of mechanical pressure to the fungus-treated lignocellulosic material. A concentrated broth is thereupon formed by centrifugation. The recovered enzyme broth may be utilized in subsequent steps of the process.
• the biopulped lignocellulosic material is thereupon treated in accordance with the first discussed embodiment of the process of the present invention. That is, the biopulped lignocellulosic material is subjected to the hot water extraction step 3 whereafter the lignocellulosic material is pulped. Again, pulping is effectuated by mechanical pulping, chemical pulping or a combination of mechanical and chemical pulping.
• aqueous extract obtained in the water extraction step 3 is processed in accordance with the method discussed supra to obtain acetic acid and hemicellulose aqueous solutions.
• the pulping processing is, but for one aspect, substantially identical to mechanical pulping in the first preferred embodiment. That aspect is the optional introduction of a LCC breaking enzyme, preferably a lignin-degrading enzyme, into the mechanical pulping operation 7.
• a LCC breaking enzyme preferably a lignin-degrading enzyme
• enzyme is provided by the enzyme- containing crude broth 5 recovered in the biopulping step 2.
• fresh enzyme 6 may be co-introduced, with the pulp, into the mechanical pulping step 7.
• the introduction of enzyme into the mechanical pulping step 7 increases the rate of pulping insofar as the enzymatic removal of lignin reduces the mechanical work necessary to accomplish the same task.
• pulping is performed by chemical pulping or a combination of mechanical and chemical pulping, denoted by reference numeral 8.
• the lignocellulosic materials subjected upstream to hot water processing step 3 are pulped in accordance with the process of chemical pulping discussed in the first aspect of the process described supra.
• the pulp 9, produced in the mechanical pulping step 7, or the pulp 10, produced in the chemical pulping or the combination of mechanical and chemical pulping step 8, is next bleached in bleaching step 11. In this step the pulp is whitened without adversely affecting the strength of the fibers.
• Bleaching step 11 in this second aspect of the present invention is conducted in accordance with the bleaching step within the contemplation of the first aspect of the process of the present invention.
• the additional processing step of introducing an enzyme that breaks LCC bonds into the bleaching reactor is included.
• that enzyme is a lignin-degrading enzyme.
• That enzyme may be obtained from vendors marketing such enzymes or may be the enzyme recovered from the biopulping step, e.g. the biopulping step, e.g. the fungus- lignocellulosic contacting step.
• the process of the second aspect of the process of the present invention includes the step of combusting and recovering the energy values of the charge of the lignocellulosic materials not subjected to pulping and bleaching.
• a third aspect of the process of the present invention involves the steps of pulping and bleaching a charge of lignocellulosic material. In that process a charge of lignocellulosic material is pulped to provide individual fibers and fiber bundles.
• the pulping step in this aspect of the present invention may be accomplished by mechanical pulping, chemical pulping or a combination of mechanical and chemical pulping. The preferred embodiments of these pulping methods, discussed supra, in regard to the first two aspects of the present invention, may be utilized.
• the pulped product, in this third aspect of the present invention is bleached.
• This bleaching step involves contacting the pulped product with chlorine dioxide in the presence of an agent selected from the group consisting of oxygen, magnesium hydroxide, another magnesium-containing compound, oxygen and magnesium hydroxide or another magnesium-containing compound, potassium hydroxide and calcium hydroxide.
• an agent selected from the group consisting of oxygen, magnesium hydroxide, another magnesium-containing compound, oxygen and magnesium hydroxide or another magnesium-containing compound, potassium hydroxide and calcium hydroxide.
• a fourth aspect of the present invention focuses upon another process of pulping and bleaching lignocellulosic materials, hi this fourth aspect a charge of lignocellulosic material is contacted with a fungus that breaks LCC in the lignocellulosic material. This contact yields a biopulped lignocellulosic material and an enzyme product produced by the fungus. The enzyme product is separated and the fungus-contacted lignocellulosic material is pulped. The pulp product of the pulping step is thereupon bleached.
• the fungus-contacted lignocellulosic material not subjected to pulping and the pulp product of the pulping step not subjected to bleaching is combusted to recover the energy value of the charge of lignocellulosic material not utilized in recovering product values.
• the bleaching step include introduction of an enzyme that breaks LCC into the bleaching apparatus, along with the pulp.
• enzyme is provided by the enzyme separated from initial charge of lignocellulosic material contacted by the fungus that breaks LCC.
• a fifth aspect of the present invention is the novel pulp produced by the first and second aspects of the present invention which includes a hot water extraction of the charged lignocellulosic materials.
• That pulp is characterized by a specific surface are in the range of between about 5,000 cm 2 /g and about 40,000 cm 2 /g and a specific volume in the range of between about 1.5 cm 3 /g and about 4.0 cm 3 /g.
• the pulp of the present invention has a specific surface area in the range of between about 15,000 cm 2 /g and about 25,000 cm 2 /g and a specific volume in the range of between about 2.75 cm 3 /g and about 3.75 cm 3 /g.
• Picea abies (Norway spruce), a softwood was utilized in this example.
• different species of woods including hardwoods and/or softwoods, can also be used.
• the invention can be used with virgin wood or waste wood, including, e.g., kiln dried, air-dried and green wood from industrial, residential, sawmill, construction and demolition sources.
• logs from a 79- year old tree were debarked with a 36-cm spoke shave, chipped in a Carthage 10- blade chipper, and air dried to approximately 15% moisture by spreading the chips on a tarp. The chips were then screened in a Williams classifier.
• Test Methods consist of a capital T, followed by a space, then a number (assigned sequentially within several Test Method categories), another space, a two-letter designation of classification, a hyphen, and the last two digits of the year published.
• TAPPI test method T-412 om-94 was followed for moisture content determination.
• a 1500 g OD sample was weighed out for each bioreactor and brought up to 50% moisture content by soaking in distilled water.
• Bioreactors were cleaned and sterilized with a 10% (v/v) commercial Clorox bleach/90% water solution and rinsed with distilled water. Chips were layered in the reactor with 600 g on each layer; the reactor was loosely sealed with an aluminum foil cap covering the vent in the lid and then steamed for 10-minute under atmospheric conditions. The reactor was then cooled for approximately two hours until the temperature was below 30 0 C.
• the moisture content was brought up to 55% moisture by the addition 200 ml water collected during steaming plus additional distilled makeup water.
• the chips can be inoculated with the lignin-degrading fungus by providing a liquid mixture including the fungal inoculum, and applying the liquid mixture to the chips. The inoculated chips were then incubated under conditions favorable to the propagation of the lignin-degrading fungus through the chips.
• the bioreactor was then placed in the incubation chamber at 27 0 C with forced continuous flow of warm humidified air at a rate of 0.028 cubic meters per minute.
• House air was measured by a flow meter and humidification was controlled by passing air through two water filled two-liter glass sidearm flasks (in series) through a fritted ground glass sparger. The sidearm flasks were immersed in a 40 0 C water bath. From the hot water flasks, the warm humidified air passed though a water trap and a final filtering through a 0.2 micron Millipore air filter (for sterilization) before connecting to the individual bioreactors.
• the warm humidified air flow-rate was measured and corrected if needed and the chips were checked for contamination.
• the water trap in the bottom of the incubation locker was emptied and one layer of chips was removed from the reactor placed in a plastic bag, sealed and frozen at -20 0 C until further processing.
• Air-dried and screened Picea abies wood chips (800 g OD) were brought up to 10% moisture content and placed in the sample hopper on the pressurized refiner (Kumagai Riki Kogyo Co. Ltd., Tokyo, Japan, Model BRP45-30055). Low-pressure steam (32 kPa g ) softened the wood chips for three minutes. The TMP produced was sealed in a 40-liter Nalgene® carboy and refrigerated at 4 0 C until use. Culture Supernatant Purification
• Purification involved monitoring laccase and manganese peroxidase activity and harvesting the mycelium from P. subserialis (RLG6074-sp), C. subvermispora (L-14807 SS-3), and T. versicolor (FP-72074) on the first day after peak laccase activity.
• Mycelium was harvested from the liquid culture by centrifuging for 20 min at 10,000 rpm, followed by treating the crude supernatant with 10% (v/v) acetone and refrigerating for one hour at 4 0 C to precipitate any extracellular polysaccharide. The broth was centrifuged again for 20 minutes at 10,000 rpm and filtered through a Whatman glass microfiber GF/A 42.5-mm diameter filter.
• the resulting supernatant was concentrated in a DC-2 ultrafiltration unit (Amicon Corp., Danvers, Mass.) equipped with a 30-kDa molecular weight cutoff hollow fiber filter from an initial volume of 1000 ml to 100 ml. Enzyme activity was monitored at harvest time and after the final concentration.
• Enzyme Treated TMP First-stage coarse thermomechanical pulp was treated with partially purified culture supernatant from P. subserialis, C. subvermispora, and T. versicolor at a dosage determined by normalizing to a manganese peroxidase enzyme activity of 1500 nkatal I "1 .
• Duplicate reaction vessels contained 2.0 g OD coarse refiner mechanical pulp that was suspended in 5% (w/v) 50-mM sodium acetate buffer (pH 4.5). The pulp in each reaction vessel was mixed with concentrated enzyme broth at a normalized enzyme activity of approximately 1.50 nkatal ml "1 manganese peroxidase. Laccase activity was measured and monitored throughout the experiment.
• reaction vessel For each fungus, one reaction vessel was setup in duplicate for analysis at 0, 30, 60, 90, 180 and 360-minute intervals in a constant temperature bath of 3O 0 C. Initial and final laccase and manganese peroxidase enzyme activity were measured for each time interval followed by a complete lignin analysis at each time interval to evaluate the effect of the enzymes on refiner mechanical pulp.
• TAPPI test method T-264 cm 97 details the procedure followed to report chemical analysis on an extractive free basis. Air-dried Wiley milled samples
• the extraction thimbles were removed from the Soxhlet extractors, washed with 100% pure ethanol by placing the thimble in a 100 ml coarse ground glass crucible fitted on a 1000-ml sidearm flask. The thimble was returned to the Soxhlet extractor and extracted for four hours with 100% pure ethanol. The samples were transferred to a Buchner funnel and washed with hot water to remove the ethanol and then allowed to air dry for all subsequent carbohydrate and lignin analyses.
• Picea abies chips were prepared as previously described, inoculated with Phlebia subserialis, Ceriporiopsis subvermispora, and Trametes versicolor", and incubated for 30 days at 27 0 C with forced warm humidified air at a rate of 0.028 cubic meters per minute. The chips were thus incubated under conditions favorable to the propagation of the lignin-degrading fungus through the chips.
• Duplicate 500-g samples were removed from each bioreactor, and double-bagged in 6x9 zip lock bags. One bottom corner of the double bag was cut off with scissors.
• the stainless steel plates on the top and bottom pressing surfaces of the Williams press (Williams Apparatus Co., Watertown, NY) were cleaned first with soap and water and then dried with ethanol.
• the press was blocked up at a 45° angle and secured.
• the zip lock bag containing the sample was placed between the pressing surfaces and a clean 20-dram vial was placed under the cut corner of the bag. Pressure was applied (1500 psi) to the sample and the pressate was captured in the glass vial as a crude broth. Laccase and manganese peroxidase enzyme assays were performed on each vial to determine the enzyme present and enzyme concentration.
• Extracellular lignolytic enzymes secreted into the production and growth media were identified, monitored for peak concentration within the production media, harvested for additional experimentation and finally concentrated ten-fold.
• the broth was centrifuged for 20 minutes at 10,000 rpm and filtered through a Whatman glass microfiber GF/A 42.5-mm diameter filter.
• the resulting supernatant was concentrated in a DC-2 ultrafiltration unit (Amicon Corp., Danvers, Mass.) equipped with a 30-kDa molecular weight cutoff hollow fiber filter from an initial volume of 1000 ml to 100 ml.
• Laboratory analysis of fungal growth established the initial growth conditions and approximate harvesting time for peak production.
• the enzyme concentration was then adjusted to 1.4 nkatal/ml and were used to treat l st -stage TMP as a method to reduce the amount of lignin within the pulp, reducing the electrical refining energy and thereby increasing pulp strength.
• This system can also be used as a first-stage biobleaching of mechanical pulp.
• the enzyme activity levels were monitored, followed by a lignin analysis of the TMP.
• Table 1 lists the laccase and manganese peroxidase enzyme activity levels throughout the pulp treatment. Initial activity was measured from the concentrated production medium before addition to each sample and then the manganese peroxidase enzyme concentration was normalized to approximately 1.50 nkatal ml "1 for the zero-time condition. The laccase and manganese peroxidase activities were measured and monitored for the change in activity over time.
• Table 1 Enzyme activity change over 1he 6-hour treatment time of thermomechanical pulp with partially purified lignolytic enzymes from P. subserialis, T. versicolor and C. subvermispora
• Laccase from P. subse ⁇ alis showed a 22% decrease in activity while T. versicolor and C. subvermispora showed much smaller changes in activity, 3.1 and 1.4%, respectively. This difference may not be significant due to the much lower laccase activity in the enzyme broth from P. subserialis.
• Initial manganese peroxidase activity levels were on the same order of magnitude for all three fungal extract applications. The range in overall manganese peroxidase activity loss was from 15.8% for P. subserialis to 8.9 and 25.7% loss for T. versicolor and C. subvermispora, respectively.
• Figures 1 and 2 chart the enzyme activity throughout the experiment and show the decrease in activity over the life of the experiment.
• Fig. 1 illustrates the lignolytic enzyme activity change for the laccase enzyme, where thermomechanical pulping (TMP) is performed over a six hour treatment time on Picea abies (Norway Spruce) wood chips with fungal treatment using P. subserialis., T. versicolor and C. subvermispora.
• Fig. 2 illustrates the lignolytic enzyme activity change for the manganese peroxidase enzyme, for comparison with the results of Fig. 1.
• the horizontal axis denotes time, in minutes, from 0 to 400 minutes
• the left hand vertical axis denotes T.v.
• Table 2 outlines the results from lignin analysis on the TMP, showing that the lignolytic enzyme treatment from C. subvermispora removed up to 3.66% of the lignin in the sample over a six-hour period, while P. subserialis and T. versicolor reduced the lignin content by similar amounts, 2.35 and 2.67%, respectively.
• P. subserialis showed a significant decrease in lignin content at the 90-minute sample; however, no significant change occurred after that time interval.
• Both T. versicolor and C. subvermispora appeared to continually decrease lignin content throughout the experiment. A longer running experiment is expected to show greater lignin losses with increased treatment time, with the enzyme activity monitored as a theoretical stopping point.
• the zip lock bag containing the sample was placed between the pressing surfaces and a clean 20-dram vial was placed under the cut corner of the bag. Pressure was applied (1500 psi) to the sample and the pressate was captured in the glass vial.
• the ability of P. subserialis to repeatedly produce laccase under biopulping conditions was significant due the inability to repeatedly produce detectable activity in the laboratory under controlled conditions with this organism. There were large variations in detectable enzymes and activity levels under laboratory conditions and the ability to characterize the fungi under non-induced conditions, while growing in a biopretreatment environment, hold significant potential.
• HWP-E hot water pre-extraction
• the pulping parameters were adjusted for the cooking of pin chips since these cooks were done in 250 mL autoclaves.
• the cooking parameters were: AA 24 %, Sulfidity 26%, and L: W 10:1.
• the autoclaves were brought up to 17O 0 C in 90 minutes and held there for 60, 120, and 180 minutes.
• the extracted sugar maple pin chips were done similarly.
• the exploratory cooks were carried out on standard sugar maple chips for yield optimization.
• the HWP-E was not separated from the cooks; that is the chips were left in the M&K digesters after the HWP-E was drained and immediately de- lignified by way of three types, Kraft, Kraft with polysulfide, and Soda AQ.
• the standard controls on the three schemes were done on non-extracted sugar maple chips.
• the control parameters are seen in Table 1.
• the acrynym AA means active alkali (NaOH+Na 2 S on a Na 2 O basis).
• the acrynym EA means effective alkali (NaOH+l/2Na 2 S).
• Chips were HWP-E at 140, 150, and 160 0 C for this study.
• the wood chips were separated into different 1/2 gal "Wiffle” Reactors according to the temperatures at which they were extracted. A portion of un-extracted wood chips was also put into a "Wiffle” Reactor.
• These reactors are made in house and are named such, because of their resemblance to a wiffle ball. That is the reactor is cylindrically shaped with a plurality of openings even spaced on its peripheral. Each reactor was then submerged into a separate 4L plastic beaker containing a weak alkali solution.
• the solution was made up of 0.1 N sodium hydroxide at a 20: 1 L:W ratio. This was an approximate volume of 3.5 L. 10 mL samples were removed periodically over the course of six days. The samples were then analyzed in a UV spectrophotometer at the peak of 205 nm.
• the data shown in Figure 6 measures the concentration of soluble lignin leached out of both control and extracted chips into solution.
• the bottom set of points represent non-extracted sugar maple, and consecutively above them chips extracted at increasing temperatures.
• a mixture of hardwood chips was given a HWP-E treatment and ⁇ 20% of the mass was removed.
• the HWP-E and un-extracted chips were both cooked to -17 kappa number by the kraft process.
• the pulp from the un-extracted chips achieved a brightness of 86.3% while the HWP-E pulp achieved a brightness of 91.6%.
• HWP-E was used to remove 12% of the mass from sugar maple chips. After soda/AQ pulping a kappa number of 16.5 was obtained. After our standard oxygen delignification the kappa number decreased by 61% to 6.5.
• the O 2 delignification results for a wide range of hardwood chemical pulps under the same standard conditions are given in Table 4. The largest decrease in kappa number was 53%.
• Table 2 Decrease in kappa number of Conventional Hardwood Kraft Pulps caused by O 2 delignification.
• a mild HWP-E was used to extract ⁇ 5% of the wood mass. Mild HWP-E is normally conducted for shorter times but with the addition of a small dose of acetic acid. In commercial practice, this acetic acid would be obtained by recycling some of the HWP-E effluent. Soda/AQ pulping was performed in accordance to Table 2 but for 90 instead of 120 minute. A 31 kappa number pulp was obtained but oxygen delignification decreased its kappa number by 72% to 8.8.
• HWP-E The harsher HWP-E does reduce the overall yield of a pulping process. Components removed are predominantly hemicelluloses, which do not add significantly to the final product as far as structural strength. It can be debated that it does act as an adhesive between fibers.
• the milder extractions used to achieve competitive yields to conventional pulping only remove hemicelluloses to the extent of ⁇ 5% based on chip weight. This may be ideal for pulp mills, considering the shorter cooking times, higher yields, and better bleach- ability and the removal of sulfur from the process.
• acetic acid is a higher value commodity as compared to ethanol from fermentation of extracted sugars, which likely requires greater capital than acetic acid separation. If a pulp mill were not to take advantage of the acetic acid market, very little capital would be required to modify an existing process.
• a shorter time in the digester has a positive affect on the degree of polymerization of cellulose and most likely sheet strength. This has not been substantiated yet by making handsheets, but is a strong assumption. Soda AQ may be a good way to cook these extracted sugar maple chips. Eliminating sulfur would greatly simplify the recovery system and likely improve energy efficiency.
• Wood chips arrived in barrels from the SUNY-ESF Genetics Field Station in Tully, New York. The chips were from a single harvest at four years of age of a multi-clone trial. The chips were laid out for two weeks to air dry with a resulting oven-dry (OD) solids content of 92.3%. After air-drying, the chips were well-mixed and then divided and placed into large plastic bags for storage. It was important to bring the chips to a constant and low moisture content to ensure natural degradation did not take place during storage. When chips were needed for treatment, a 1625 gram air-dry (AD) chip sample (1500 g OD) was brought up to a 50% moisture content by soaking overnight in distilled water.
• AD 1625 gram air-dry
• Xylan in wood is fairly resistant to leaching at low temperatures due to the molecular size of the polymer molecule.
• the soaking was done at room temperature to minimize the loss of xylan during this step.
• the chips were then incubated in an aerated static bed-bioreactor consisting of 21 -L polypropylene containers.
• the lid on the containers vented to the atmosphere through an exit tube.
• a 1- cm side opening provided for controlled inlet airflow.
• the clean, empty bioreactors Prior to inoculation, the clean, empty bioreactors were autoclaved for twenty minutes. After the chips were added to the vessel, steam was injected for thirty minutes through latex tubing connection at the bottom of the reactor. The bioreactors' lids were left slightly ajar to prevent over pressurization. After steaming, the bioreactor was drained to remove the excess water that had condensed inside the vessel. The vessel and its contents were then cooled for two hours before inoculation, with the Met and outlet of the vessel covered with aluminum foil to avoid contamination.
• C subvermispora strain L14807 SS-3 (Cs SS-3) was obtained from the USDA Forest Service, Forest Products Laboratory (FPL) in Madison WI. All stock culture slants were incubated at 26 0 C, stored at 4 0 C, and maintained at 2% (w/v) potato dextrose sugar plates. The samples were prepared and maintained as reported in Example 1.
• the air was humidified by flowing through two water-filled 2-L Erlenmeyer flasks through a fritted ground glass sparger.
• the humidified air passed through a water trap, filtered through a 0.2 ⁇ m Millipore filter, and entered the base of the bioreactor.
• the chips were removed from the incubator and frozen to prevent any further fungal growth prior to the analysis or subsequent extraction.
• the chips were kept frozen until 12 hours before they were used for xylan extraction.
• Hot Water Extraction Hot water extraction was carried out in a 4-L capacity M&K digester equipped with indirect heating through heat exchangers with forced liquor recirculation.
• the basket was filled with chips (1500 g OD) from air-dried willow samples for the control.
• the chips were removed from the freezer allowed to thaw for 12 hours.
• the basket was placed in the digester and distilled water was added to achieve a 4: 1 liquor to wood ratio.
• the digester cover was then closed and the circulation pump turned on. The temperature was set (experiments were at
• the pump and heater were turned off and a bottom valve opened slowly to relieve the pressure and to withdraw the extract for analysis.
• the extract was collected through a valve and heat exchanger to cool the sample below the boiling point.
• the chips were washed thoroughly until a clear liquid was observed. The wash water was not collected.
• the chips were then placed in a drying oven at 105 0 C overnight to determine the mass loss of the chips.
• a sample of the extractant was then evaporated in a 105 0 C oven to determine both the solids content and to prepare a sample for the carbohydrate analysis.
• a 100 to 200-ml portion of the extractant was placed in small porcelain crucibles and evaporated at 105 0 C in a drying oven for 3 days or until a stable weight had been achieved.
• the sample was weighed and then ground with a pestle.
• the powdered sample was then placed in a vial for subsequent carbohydrate analysis using the NMR analytical procedure.
• Klason lignin of control and treated samples were determined in accordance with Tappi T-222 om-88, "Acid-insoluble lignin in wood and pulp" (Tappi, 1994). Klason lignin was used to estimate of the extent of delignification in the untreated and fungal-treated chips.
• the Klason lignin method involves the hydrolysis and solubilization of the carbohydrate component of the lignified material, leaving the lignin as a residue, which is determined gravimetrically.
• the acid soluble lignin procedure in wood supplements the determination of acid-insoluble lignin.
• the soluble fraction was determined in accordance with the useful method UM 250, "Acid-soluble lignin in wood and pulp" (Tappi, 1994). The sum of the acid-insoluble lignin and of the acid-soluble lignin represents the total lignin content in a sample.
• the wood in this research project was not pre-extracted to remove extractives as is typically done and recommended. The pre-extraction would have removed a portion of the total mass from both the original wood sample and the final extracted wood samples.
• Rhamnose is a monosaccharide that is not found in appreciable quantities in most wood hydrolyzate, which gives distinct and well resolved signals associated with the respective ⁇ and ⁇ anomeric proton doublets ( ⁇ signal at 5.10 ppm and ⁇ at 4.86 ppm). Prior analysis of willow showed that rhamnose is present only in trace quantities (Kiemle, 2001).
• each sample was dried overnight immediately prior to processing to remove any moisture it may have absorbed between the time it was ground and processed.
• the oven dried solids portion of the evaporated extractant was determined after grinding with a mortar and pestal.
• 0.040 g of dried wood (or extracted solids) was placed in a 15-ml thick-walled pressure tube with a teflon stopper with 0.2 ml of 72% H 2 SO 4 .
• the dried wood dispersion is stirred and allowed to digest at 40° C for 1.5 hours, stirring every 15 minutes. Based on preliminary testing in this study, only 15 minutes was found to be required for the hydrolysis step for the ground and dried solids portion of the extract.
• Figure 9 shows the amount of lignin remaining in the wood following the extraction based on the mass of the original wood.
• Table 1 shows the results for the soluble lignin in the liquid extractant. A small portion of the lignin may have been washed away in the chip washing step following the extraction and is not captured in this analysis.
• the Tappi acid soluble test method mainly estimates the degradation products from lignin.
• the results in Table 1 may be looked at as a relative indication of the lignin content of the extract, but should be interpreted with caution as the very large dilutions necessary (over 900 times) would magnify small sample errors. It should be noted that work by Jaffe (1974) indicated that a similar hot water extraction procedure on birch extracted 5% to 30% by weight of lignin. The results in Table 1 are consistent with those of Jaffe (1974).
• Figure 11 shows that maximum xylan recovery (measured as the monomer sugar xylose) was 60.5% of the original xylose in the wood. This was achieved with fungal pretreatment A at 15O 0 C. The average recovery for all of the pretreatment trials at this temperature was 37.4% with a range from 24.6% to 60.5% based on the original xylose content in wood. AU values were higher than the 23.2% recovery of the control untreated samples at 15O 0 C. At temperatures between 140 and 15O 0 C, the treated wood chips yielded equal or greater extraction amounts compared to control chips at temperatures 5 to 1O 0 C lower. The mass loss in the chip wash following the extraction was 6.4% with the pretreated samples, but only 1.3% with the control. Potentially, additional xylose could be recovered from the wash water, increasing the overall yield of the xylose.
• subvermispora pretreated wood chips allowed for the extraction of more xylan from the wood or the use of a lower extraction temperature than for control chips at a given extraction amount.
• Recovered extracted xylan (measured as xylose) from the pretreated chips at 15O 0 C ranged from 24.6% to 60.5% based on the original xylose content in wood.
• the recovery of the post-extraction chip washing liquor may yield additional xylan recovery from biomass willow chips.
• the lignin remaining with the wood after water extraction was lower for the pretreated samples than for the untreated wood chips. This might well result in savings later in the process when lignin is to be removed or brightened during pulping. More work should be done to ascertain the relative effects of fungal pretreatment and pH on the lignin removal during the water extraction process. The effect of the hemicellulose extraction and the concurrent lignin modification on the subsequent pulping process is yet to be explored.
• the glucose component in the extracted wood chips did not change between pretreated and untreated chips. This indicates that the cellulose content has not been measurably affected by the pretreatment. However, this does not necessarily mean that strength properties of the resulting paper have been preserved and it yet to be determined. Past results have shown biopulping preserved the strength properties of the chips, but this should be explored further for this particular post-biotreatment extraction procedure.
• a typical bleaching sequence for hardwood kraft pulps is ODoEopDj or ODoEOpD 1 P.
• Softwood kraft pulps normally require more chlorine dioxide (ClO 2 ) and a typical sequence is ODoEopD]ED 2 .
• pulps were dispersed in a large plastic vessel at ⁇ 5% consistency.
• the pulp mixture was then treated with 1.12% KHSO 5 (0.25% equiv. H 2 O 2 ) at room temperature overnight. The pH the following morning was ⁇ 4.7.
• the pulp was then treated with 0.2% NasDTPA with Na 2 CO 3 being used to achieve pH ⁇ 6.
• the pulp was dewatered to ⁇ 25% consistency the following day.
• This pulp was the starting material for bleaching under Di stage conditions. It had a kappa number of 8.4, a viscosity of 23.0 cP and a brightness of 62.5% Elrepho.
• the pulp contained 4 ppm Mn, 25 ppm Fe and 7 ppm Cu.
• Acer saccharum (Sugar Maple) wood logs obtained from ESF Forest Properties were debarked and chipped in a Carthage chipper located in the Paper Science and Engineering department at SUNY-ESF to a size normally used in industry (2.5 x 2.0 x 0.5 cm).
• the chips were air dried to moisture content of 10-12 % and stored in a single lot for use in all the experimental work in order to avoid differences in composition.
• One part of these sugar maple chips was ground in a Wiley Mill to a particle size passing a 30-mesh screen.
• the wood meal obtained was stored separately in a single lot to be used in the autohydrolysis experiments on wood meal.
• the time to heat wood chips to the desired temperature in M/K digester was about 25-30 minutes.
• the time to reach the reaction temperature in the reaction bomb was assumed to be 5 minutes. Since a portion of the reaction material may have reacted during the heating period, only data corresponding to the isothermal reaction condition were used in the data analysis. For both wood meal and wood chips, time zero was taken to be the beginning of the isothermal stage. For wood meal the reaction was terminated by quenching the reaction bombs in cold water and for wood chips by switching off the M/K digester and discharging the liquor through a heat exchanger.
• the severity approach was utilized: The severity analysis is based on the assumption that the overall kinetics follow a first-order concentration dependence and the rate constants have the Arrhenius-type dependence on temperature. However, in this approach time and temperature are combined into a single factor called the severity factor (Overend and Chornet, 1987). Due to its simplified form and more general application (on different raw materials) we have interpreted our data using the severity analysis approach.
• the model for hemicellulose hydrolysis as presented by Garrote et ah, 2002 is given by
• C A (l-a)xC AO +ax C AO xexp(-k r xR 0 ) (1)
• T is the absolute temperature while ⁇ is a function of the reference temperature T r and activation energy, E a and is defined as
• the main advantage of severity analysis is that it enables one to compare the severity of the hydrolysis treatment for a wide range of operation conditions (time and temperature) represented by a single reaction ordinate (R 0 ).
• time and temperature represented by a single reaction ordinate (R 0 ).
• R 0 reaction ordinate
• the material balance is important for determining the conversion efficiency of a chemical process and it also provides the appropriateness of the experimental conditions applied in the process.
• the results of the material balances for the selected experiments that cover the range of treatment severity are given in Table 2.

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