Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
The process claimed herein produces dehydrated solid oligosaccharides and
polysaccharides (SOP)
from chemical substances resident within raw wood particles. Any chemical or
semi-chemical
process of wood pulping involving use of alkaline liquor in the digester is
compatible with the SOP
process. As indicated in the DRAWINGS (Fig. 1), the SOP process includes
capability for washing
and bleaching of SOP and recovery of the liquids used in the process. In
addition, once SOP has
been produced by the process, it can be readily transformed into a clear
solution of oligosaccharides
and polysaccharides merely by mixing dehydrated SOP with water.
The novelty of the SOP process goes beyond linking together a series of
existing
technologies in the correct sequence needed to provide large quantities of SOP
for use in various
commercial production streams. The black liquor issuing from the digester
after pulping contains
not only sulfonated lignin derivatives but also sulfonated and otherwise
chemically modified
compounds derived from the hemicellulose fraction of wood (Niemela 1990 - full
references are
given in the Literature Cited section before the Claims). By removing soluble
and/or miscible
oligosaccharides and polysaccharides at the beginning of the pulping process,
a significant fraction
of wood substance is prevented from contributing to the black liquor stream.
SOP, unbleached or bleached, is the deliverable from the SOP process.
Potential end uses of
SOP are multi-faceted but not the subject of this Specification. SOP may well
be found directly
useful for production of novel kinds of paper (e.g., water-soluble paper) and
is expected to find
application as a paper additive (i.e., as a sizing). SOP as an intermediate
product will, upon further
processing, likely find use in applications such as food (digestive fiber),
chewing and other gums,
bulking agent in well-drilling, ethanol, energy production, and many other end
products.
Background and Prior Art. The first writing/drawing paper was made by the
Egyptians from the
lowermost stem parts of papyrus, a sedge that grows up to 5 m in height, using
a semi-pulping
process involving stem slicing, pounding, cross-lapping and drying (Hunter
1947). Thus, the word
"paper" is derived from the Greek and Latin words papuros and papyrus,
respectively. The
production of paper from papyrus exploited the natural ability of cellulose
present in cell walls of all
plant fibrous elements to bond together even when the plant tissue's adjoining
fibres remain intact,
but "true' paper is made from plant tissues that have been reduced to their
individual fibres (i.e.,
fully pulped) and then re-constituted from a fibrous pulp suspension. True
paper was being
produced manually in China as early as the 2nd century BC, by pounding wetted
cloth rags and/or
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bark to pulp, using a screen to lift the pulp out of the pulp vat and produce
a wet layer of pulp,
followed by pressing absorbed moisture out and then hanging and drying that
`sheet' into paper.
Many centuries of paper-making followed (Hunter 1947).
Wood as it occurs in logs is a relatively hard bulky and inflexible material;
therefore, at the
outset of paper-making, wood was likely given no consideration as a material
for manually
pounding into pulp. Use of wood for paper-making evidently was first suggested
in 1719 by Rene
Antoine Ferchault de Reaumur following his observations of papery nests
created by American and
Canadian wood wasps. Nevertheless, it was not until 1765 that Jacob Christian
Schaffer made
papers from pulp of beech, willow, aspen, mulberry, spruce and other woods,
each paper being
produced from wood pulp in admixture with rag fibres. Schaffer also noted that
wood treated with a
lime paste required less time and energy to beat into pulp than untreated
wood, and this evidently
was the first step toward chemical pulping of wood.
The first paper originating entirely from wood pulp appears to have been a
single page made
of elm-wood fibres and produced in 1786 by Leorier Delisle (in a book authored
by Charles Michel
de Villette). In 1798 Nicolas-Louis Robert constructed a moving screen belt
capable of receiving a
continuous flow of pulp suspension and delivering an unbroken sheet of wet
paper to a pair of
squeeze rolls where most of the residual liquid was removed from the adjoining
fibres, and that
innovation set the stage for mass production of paper hence the demand for
larger quantities of pulp
than could be produced manually. In 1800 the Great Seal Patent office, London,
granted Matthias
Koops a patent "...for a method of manufacturing paper from straw, hay,
thistles, waste, and ruse of
hemp and flax, and different kinds of wood and bark." In 1840 Friedrich
Gottlob Keller secured a
German patent for grinding logs against a millstone and, in 1867, ground-wood
pulp was being
produced in Massachusetts in order to make newsprint solely from wood fibres.
Newsprint as produced from chemically untreated ground wood was dull, darkened
quickly
and was not very strong, and the desire to produce stronger, brighter paper
from wood led to
investigations into chemical pulping. The first chemical pulping of wood to
operate on the industrial
scale was the soda process, so-named because it uses sodium hydroxide (NaOH)
as the cooking
agent. The soda process was developed in 1851 by Hugh Burgess and Charles Watt
in England, and
they secured a USA patent for the process in 1854. Alkaline sulfite pulping
was patented in 1867 by
Benjamin Tilghman in the USA, and Kraft pulping was patented in 1884 by Carl
Dahl of Germany.
Many variations on those chemical pulping processes have subsequently been
described, and
innumerable patents exist in relation to their modifications. One variation
presently invoking
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considerable interest is known as ASAM pulping (alkaline sulfite with
anthraquinone and
methanol), described by Patt and Kordsachia (1986). The SOP process is
compatible with digesters
using soda, alkaline sulfite, Kraft or ASAM chemical, semi-chemical or chemi-
mechanical pulping.
All chemical and related pulping processes are concerned with one or more
direct or
ancillary aspects of the treatment of wood particles with harsh chemicals at
high temperature and
pressure for extended periods, the aim being to break the chemical bonds
between lignin,
hemicelluloses and cellulose in order that the individual woody elements,
usually referred to as
`fibres', can exist independently and generate a useable pulp. Because
chemical methods of pulping
require that the wood particles be treated for several hours above atmospheric
pressure at a
temperature above the boiling point (approximately 100 C) of the cooking
liquor, a pressure cooker
known as a`digester' is used and is the starting point of the pulping process.
Under the harsh
conditions associated with cooking wood particles within a digester, not only
lignins but a variety of
compounds collectively but non-specifically referred to as `hemicelluloses'
are hydrolyzed within
the wood cell walls and released into the cooking liquor. In recent years,
wood hemicelluloses have
been identified as an important material for manufacture of ethanol, and
various patents related to
ethanol production from sugars derived from hemicelluloses have been filed.
However, to the best
of my knowledge none of those patents has addressed development of an
industrial process such as
described herein, for obtaining from a relatively mild alkaline solution
applied to wood particles
within a pulp-mill digester oligosaccharides and polysaccharides before those
substances become
part of the waste black liquor stream.
The use of an aliphatic alcohol to coagulate or "precipitate" polysaccharides
in an alkaline
solution gained acceptance as a routine scientific method, of common knowledge
in the public
domain, early in the 20th century (e.g., Norris and Preece 1930; Sands and
Gary 1933; Adams and
Castagne 1951). Following upon that scientific advance, several patents were
nevertheless awarded
specifically in relation to use of an aliphatic alcohol, such as ethanol, to
precipitate "hemicelluloses"
from alkaline extracts of plant tissues. For example, US patent 3935022 for
the manufacture of
viscose products claimed "a process for removing hemicelluloses from
hemicellulose-containing
alkali solution consisting essentially of adding to said alkali solution a
sufficient amount of a solvent
consisting essentially of ethanol to precipitate hemicellulose from said
alkali solution..." Similarly,
US patent 7101996 claimed "a process for the separation of purified
hemicelluloses from insoluble
cellulose and cellulose-hemicellulose complexes in caustic liquor from
solubilizing fiber with alkali
comprising the steps of adding alcohol to the caustic liquor to precipitate
the hemicelluloses..."
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However, the supposed inventions underlying those claims were already in the
public domain.
Moreover, the details of practicable industrial processes were not specified
as such in those patents.
In addition, there has been a tendency in the patent literature for the term
`hemicellulose' to be used
unclearly, although the meaning of the term has been more rigorously
interpreted (Aspinall 1970,
Wilkie 1985). As noted by Wilkie (1985), "Confusion and uncertainty is caused
when terms are
used that are ill-defined or, as in the case of hemicelluloses, when terms
have considerable, and
unrecognized, variability in their defmition."
The Claims made herewith embody a practicable industrial process for obtaining
a mixture
of solid oligosaccharides and polysaccharides (SOP) in major quantity from raw
wood particles
during pulping involving the use of an alkaline solution in the digester. For
brevity, it is referred to
as the 'SOP process'. The embodiments of the SOP process require that a
distinction be made
between the natural hemicelluloses of wood and the oligosaccharides and
polysaccharides obtained
by the SOP process. Aqueous alkaline treatment of cell walls of woody elements
not only
hydrolyzes into smaller molecules those substances referred to as
hemicelluloses but also saponifies
the natural esters (e.g., acetyl or diferulyl groups) which are natural to the
hemicelluloses. In other
words, alkali extraction changes the true or `native' hemicelluloses of wood
into de-esterified
polysaccharides and shorter oligosaccharides differing in both chemical
properties and chain length
from those occurring naturally in wood (Neilson and Richards 1978). One way to
understand the
distinction is to consider the solubility of hemicelluloses vis-a-vis solid
oligosaccharides and
polysaccharides (SOP) obtained by the SOP process. In general native
hemicelluloses will produce
a cloudy suspension rather than a clear solution when mixed with cool or
lukewarm water. SOP, on
the other hand, upon mixing with water at sub-ambient or higher temperature,
quickly provides a
clear solution of oligosaccharides and polysaccharides. In other words, the
colligative properties of
SOP are different from those of native hemicelluloses.
In developing this invention referred to as the SOP process, a variety of
woody plant species
- 39 tree species and 2 additional species (viz., bamboo and cotton) - growing
worldwide was
investigated (Fig. 2). Based on that research, it can be concluded that many,
possibly all, woods will
yield some amount of SOP when subjected to the SOP process. However, as shown
in Figure 2, the
yield clearly varies among species, with Magnoliophyta in general providing
more SOP than
Coniferophyta. Of the species investigated, bamboo stems yielded the most SOP,
raw fibres of the
cotton boll the least (Fig. 2).
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The chemistry of SOP from Betula populifolia wood was investigated in some
depth, by
dialysis followed by sulfuric acid hydrolysis of the SOP followed by barium
carbonate
neutralization, drying, trimethylsilylation and analysis by combined gas
chromatography - mass
spectroscopy (GC/MS). Dialysis through cellulose acetate of different
molecular-weight cutoffs
established that B. populifolia SOP comprises short-chain oligosaccharides as
well as
polysaccharides. GC/MS of hydrolyzed trimethylsilylated SOP revealed that both
the
oligosaccharides and polysaccharides contain equal amounts of D-xylose and a
second equally
abundant monosaccharide the precise identity of which could not be
unequivocally established.
Preliminary investigations indicate that those two compounds characterize
Magnoliophyta SOP in
general; however, considerable research remains to be done on the chemical
properties of SOP.
The SOP process embodies the requirement for sequential, correctly ordered,
precise and
economically efficient use of a number of existing technologies, viz., 1)
conversion of logs into
particles of wood, 2) conveyance of a known weight of those wood particles
into the cooking
chamber of a pulp-mill digester, 3) preparation of a defmed alkaline solution
of known molarity, 4)
conveyance of a known volume of defined alkaline solution of known molarity to
the wood particles
within the cooking chamber, 5) warming of the alkaline solution within the
cooking chamber to a
known temperature and maintaining the digester's cooking chamber at that
temperature for a known
time, 6) removing a known volume of the alkaline solution from the cooking
chamber and
transferring that volume to a tank capable of stirring the alkaline solution
at ambient temperature, 7)
stirring the known volume of alkaline solution in the tank at ambient
temperature and, while stirring,
adding to the volume of alkaline solution an equal volume of an aliphatic
alcohol at ambient
temperature in order to create a suspension of SOP, 8) transferring the SOP
suspension in a
regulated way from the tank to a mechanical device (e.g., a filter-lined
centrifuge, a paper-making
wire, a vacuum-filtration system, or a gravity-feed filtration system) capable
of separating solids
from liquids followed by washing of the solids, 9) repeating steps 3 - 8 a
second time to achieve a
higher SOP yield, 10) if desired, bleaching SOP with hydrogen peroxide in a
defmed solution of
known concentration at known temperature for a known time, 11) whether or not
SOP is bleached as
per step 10, dehydrating SOP using either aliphatic alcohol or air drying, 12)
distilling the liquid
removed from the SOP suspension in order to reuse the aliphatic alcohol and
alkaline solutions, 13)
further processing of the SOP including treatment with a known volume of water
per unit mass of
solid in order to produce clear solutions, 14) packaging and/or sale of the
SOP, 15) pulping the
residue of wood particles remaining in the digester following completion of
step 9.
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List of Figures and Tables.
Figure 1. Sequential steps of the SOP process when using 2.5 M NaOH, ethanol
and a vertical axis
basket continuous centrifuge. Chemical recovery/recycling operations follow
step 8.
Figure 2. Percentage yield of SOP from dry, raw wood particles of 36
Magnoliophyta and 2
Coniferophyta species; bars indicate standard deviations for 3 replicate
investigations.
Figure 3. Percentage yield of SOP from dry, raw wood as a function of
temperature and NaOH
molarity, based on Betula populifolia wood particles.
Table 1. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
dry, raw Betula
populifolia wood particles for different time periods with 1 M NaOH at 25 C;
standard deviations
(s.d.) are for 3 replicate investigations.
Table 2. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
dry, raw Betula
populifolia wood particles for 1 hour at 50 C;, comparing NaOH molarities;
standard deviations
(s.d.) are for 3 replicate investigations.
Table 3. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
different sizes of dry,
raw Betula populifolia wood particles once or twice for different time periods
with 2.5 M NaOH at
50 C; standard deviations (s.d.) are for 3 replicate investigations.
Table 4. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
dry, raw Betula
populifolia wood particles once or twice for different time periods with 2.5 M
NaOH at 50 C;
standard deviations (s.d.) are for 3 replicate investigations.
Table 5. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
dry, raw Betula
populifolia wood particles with 2.5 M NaOH for one hour at 50 C; and adding
an equal volume of
an aliphatic alcohol to generate a SOP suspension; standard deviations (s.d.)
are for 3 replicate
investigations.
Table 6. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
dry, raw Betula
populifolia wood particles with 1.0 M NaOH or 2.5 M NaOH at 50 C and adding
the indicated
volume of ethanol to generate a SOP suspension; standard deviations (s.d.) are
for 3 replicate
investigations.
Table 7. Dehydrated SOP yields (% of dry, raw wood weight) after extracting
dry, raw Betula
populifolia wood particles with four kinds of alkali at 1.0 M or 2.5 M
concentrations for 1 hour at 50
C; standard deviations (s.d.) are based on 3 replicate investigations.
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Table 8. Yields (% of weight of dry, raw Betula populifolia wood particles) of
unbleached and
bleached (3% H202 for 10 minutes at ambient temperature) dehydrated SOP
retained by a cellulosic
filter following centrifugation at 500 X g; standard deviations (s.d.) are for
3 replicate investigations.
Table 9. Weight change of dehydrated SOP (% of the weight of dehydrated Betula
populifolia raw
SOP based on the yield provided using 50% ethanol) in relation to incremental
increases in ethanol
concentration during centrifugation, always in the presence of 2.5 M NaOH;
standard deviations
(s.d.) are for 3 replicate investigations.
Table 10. Bleached (3% H202 for 10 minutes at ambient temperature) and
unbleached dehydrated
SOP yields (% of weight of dry, raw wood particles) from woods of several tree
species; standard
deviations (s.d.) are for 3 replicate investigations.
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An Example of Use Based on Wood of Grey Birch
Figure 1 indicates the stepwise progression of the SOP process using 2.5 M
NaOH at 50 C in the
digester, ethanol in the SOP-forming tank, and a vertical axis basket
industrial centrifuge to
separate, wash and bleach SOP. These conditions were identified as optimal for
Betula populifolia
(grey birch) wood particles, based on data displayed in the DRAWINGS (Fig. 3,
Tables 1-10). The
process shown in Figure 1 is explained as follows:
STEP 1: A pulp-mill batch digester is loaded with clean debarked particles of
raw wood. The
particles may be the size of chips, but a higher yield of SOP will be obtained
from smaller particles
and the highest yield from ground-wood fibres or sawdust (see DRAWINGS: Table
3).
STEP 2: The digester is filled with 2.5 M NaOH (4 litres or more of NaOH
solution per kilogram of
dry wood). The digester's internal temperature is raised to 50 C and held for
one hour, allowing the
extraction of soluble and miscible substances from the wood particles to
proceed under static
conditions. As shown in DRAWINGS (Fig. 3), SOP yield would be higher at
temperatures above
50 C.
STEP 3: The `1-h 50 C extract' arising from STEP 2 is transferred from the
digester into a SOP-
forming tank containing a stiurer and maintained under ambient conditions. It
was determined by
investigation of wood particles tightly packed into a vertical column
(simulating a digester) that,
following STEP 2, transfer of the 1-h 50 C extract from the digester will
proceed by either gravity
flow or upward displacement.
STEP 4: In order to increase the yield of SOP, immediately following the STEP
3 transfer of the 1-
h 50 C extract to the SOP-forming tank, to the wood particle residue
remaining in the digester is
added a second volume of 2.5 M NaOH (see DRAWINGS: Table 4). Four litres of
NaOH solution
per kilogram of dry wood was found to be the optimal ratio. The digester
internal temperature is
raised to 50 C and held for one hour, allowing the extraction of soluble and
miscible substances
from the wood particles to proceed under static conditions.
STEP 5: The `2-h 50 C extract' arising from STEP 4 is transferred from the
digester into either the
same SOP-forming tank containing the 1-h 50 C extract or a second identical
SOP-forming tank. It
was determined by investigation of wood particles tightly packed into a
vertical column (simulating
a digester) that, following STEP 4, transfer of the 2-h 50 C extract from the
digester will proceed by
either gravity flow or upward displacement. Upon completing the transfer of
the 2-h 50 C extract
from the digester to a SOP-forming tank, if the wood particle residue in the
digester constitutes
wood chips, pulping follows by addition of the white liquor normally used in
the chip-pulping
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process. If the wood particles loaded into the digester is ground wood or
sawdust, depending on the
intended end use it may be considered that no additional digester pulping is
needed and that the
fibres can be mechanically separated (not shown in Fig. 1) and processed for
their end purpose.
STEP 6: To the volume of 1-h 50 C extract and/or 2-h 50 C extract in the SOP-
forming tank is
added an equivalent volume of ethanol from the ethanol tank (see DRAWINGS:
Tables 5 and 6).
The stirrer in the SOP-forming tank is activated for one minute to vigorously
mix the ethanol and 1-
h 50 C extract and/or 2-h 50 C extract. The mixture is then permitted to sit
for at least one hour
under ambient, static conditions whereupon solid oligosaccharide and
polysaccharides (SOP)
precipitate. The resulting suspension in the SOP-forming tank is then
continuously stirred, and
while being actively stirred the SOP suspension is transferred from the SOP-
forming tank by either
pumping or gravity flow to an actively spinning continuous vertical axis
basket centrifuge, said
centrifuge basket being fitted with a cellulose-based filter.
STEP 7: At this step, the option exists to generate washed unbleached SOP via
STEP 7A or washed
bleached SOP via STEP 7B. In general, the yield of bleached dehydrated SOP is
lower than that of
unbleached SOP (see DRAWINGS: Table 8, Table 10).
STEP 7A: The angular velocity of the vertical axis basket centrifuge is set
such that the spinning
vertical axis basket provides a centripetal force equivalent to 500 X g. A
higher g force is
acceptable, but 500 X g was determined to be satisfactory. Centrifugation
results in the incoming
SOP from the SOP-forming tank being packed against the vertical axis basket
filter while the
suspension's clear liquid with its solutes is dispelled through the filter and
transferred to a SOP-
liquid receiving tank. When the vertical axis basket centrifuge has
accumulated a full load of SOP,
the feed valve from the SOP-forming tank is closed to stop transfer of any
additional SOP slurry into
the centrifuge basket. With the centrifuge vertical axis basket still spinning
to provide 500 X g (or
more), SOP in the basket is washed briefly by injecting into the spinning
vertical axis basket 50%
aqueous ethanol increasing stepwise over a 5-minute period at 10% increments
to 95% ethanol,
those ethanolic wash solutions being discharged from the vertical axis basket
centrifuge and
transferred to the SOP-liquid receiving tank. This incremental washing results
in SOP weight
reduction due to dehydration (see DRAWINGS: Table 9). After the 95% ethanol
step has been
accomplished, the centrifuge basket is spun at 500 X g (or more) for a further
5 minutes, then
stopped and the lightly coloured (yellow brown), ethanol-dehydrated SOP is
peeled from the walls
of the centrifuge's vertical axis basket.
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STEP 7B: The angular velocity of the vertical axis basket centrifuge is set
such that the spinning
vertical axis basket provides a centripetal force equivalent to or greater
than 500 X g, resulting in the
incoming SOP from the SOP-forming tank being packed against the vertical axis
basket filter and
clear liquid with its solutes being dispelled through the filter and
transferred from the vertical axis
basket centrifuge to a SOP-liquid receiving tank. When the vertical axis
basket centrifuge has
accumulated a full load of SOP, the feed valve from the SOP-forming tank is
closed to stop transfer
of any additional SOP suspension into the centrifuge's vertical axis basket,
and rotation of the
vertical axis basket is stopped. The discharge valve permitting clear liquid
to pass from the vertical
axis basket centrifuge to the SOP-liquid receiving tank is closed, and to the
centrifuge's vertical axis
basket is added a known volume of water and ethanol (1:1 v/v) in admixture
with 3% (w/v)
hydrogen peroxide in order to re-wet and re-suspend the SOP. The vertical axis
basket centrifuge is
activated briefly to provide a low centripetal or agitational force; then, the
vertical axis basket's
rotation is brought to a stop and held static for 15 minutes. Next, the
vertical axis basket centrifuge
is activated to provide a centripetal force of 500 X g (or more), the
centrifuge discharge valve to the
SOP-liquid receiving tank is opened, and SOP in the vertical axis basket is
washed briefly by
injecting into the spinning vertical axis basket 50% aqueous ethanol
increasing stepwise over a 5-
minute period at 10% increments to 95% ethanol, those ethanolic wash solutions
being discharged
from the vertical axis basket centrifuge and transferred to the SOP-liquid
receiving tank. After the
95% ethanol step has been reached, the centrifuge basket is spun to provide
500 X g (or more) for a
further 5 minutes, then stopped and the bleached (white), ethanol-dehydrated
SOP peeled from the
walls of the centrifuge basket. A variation on STEP 7B involves mixing of
ethanol-dehydrated SOP
as provided from STEP 7A with 3% (w/v) hydrogen peroxide at ambient
temperature in order to
produce a clear solution of oligosaccharides and polysaccharides which are
rapidly bleached. Said
clear solution is then combined with an equal volume of ethanol to produce a
SOP suspension. In
the vertical axis basket centrifuge, SOP is separated and dehydrated as
described above.
STEP 8: The dehydrated SOP is peeled from the vertical axis basket and
transferred to a SOP
packaging and storage facility.
In addition to the preceding eight steps of the SOP process, solvent recovery
is part of the
process. The solution in the SOP-liquid receiving tank is transferred to a
unit where ethanol is
distilled. After distillation, a solution of aqueous alkali remains as the
residue. Distilled ethanol is
returned to the ethanol tank, and the aqueous alkali is transferred by either
pumping or gravity flow
to the alkali tank. The solution in the alkali tank is titrated and its NaOH
concentration adjusted for
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use in STEP 2 and/or STEP 4 or for pulping of the residual chips in the
digester after completion of
STEP 5. Following multiple recycling of the alkaline solution in support of
STEP 2 and/or STEP 4,
there accumulates within that solution an increasing content of high-value
wood extractives, such as
xylitol from birch wood, which can be recovered and sold commercially.
Woods from tree species of worldwide distribution were investigated (DRAWINGS:
Figure
2, Table 10), and SOP yields varied by species. Various modifications can be
made to the SOP
process in order to optimize it to the wood without departing from the scope
of the present
invention. The size of wood particle introduced into the batch digester can
vary from large chip to
ground-wood fibre, the latter clearly giving the better yield (see DRAWINGS:
Table 10); the
alkalinity can be changed from 2.5 M NaOH to either higher or lower molarity
(see DRAWINGS:
Figure 3, Tables 2, 6 and 7); KOH or LiOH rather than NaOH solution can be
used for extraction of
oligosaccharides and polysaccharides (see DRAWINGS: Table 7); the extraction
temperature can be
higher or lower than 50 C (see DRAWINGS: Figure 3); the time of extraction
within the batch
digester can be longer or shorter than 1 hour (see DRAWINGS: Tables 1 and 4);
the number of
digester extractions used to obtain oligosaccharides and polysaccharides can
be reduced to only one
or increased to two or more (see DRAWINGS: Table 4); methanol, 2-propanol or n-
butanol rather
than ethanol can be used to yield SOP (see DRAWINGS: Table 5); separation of
SOP from liquid
can be accomplished by means of a moving wire screen as used in the paper-
making process, or by
vacuum or gravity filtration through a cellulose-based filter; the hydrogen
peroxide concentration,
time and temperature used in bleaching can be modified.
Literature cited
Adams, G.A. and Castagne, A.E. 1951. Canadian Journal of Chemistry 29:109.
Aspinall, G. O. 1970. Polysaccharides. Pergamon Press, Oxford.
Hunter, D. 1947. Papermaking. Dover Publications, New York.
Neilson, M.J. and Richards, G. N. 1978. Journal of the Science of Food and
Agriculture 29:513.
Niemela, K. 1990. Annales Academiae Scientiarum Fennicae, Series A, II.
Chemica 229.
Norris, F.W. and Preece, I. A. 1930. Biochemistry Journal 24:59.
Patt, R. and Kordsachia, O. 1986. Das Papier 40 (10A):V1.
Sands, L. and Gary, W. Y. 1933. Journal ofBiological Chemistry 101:573.
Wilkie, K.C.B. 1985. pp 1-37, in Biochemistry of Plant Cell Walls, edited by
C.T. Brett and J. R.
Hillman, Cambridge U. Press.
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