NZ718115B2 - Process for treating cellulose and cellulose treated according to the process - Google Patents
Process for treating cellulose and cellulose treated according to the process Download PDFInfo
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- NZ718115B2 NZ718115B2 NZ718115A NZ71811512A NZ718115B2 NZ 718115 B2 NZ718115 B2 NZ 718115B2 NZ 718115 A NZ718115 A NZ 718115A NZ 71811512 A NZ71811512 A NZ 71811512A NZ 718115 B2 NZ718115 B2 NZ 718115B2
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- New Zealand
- Prior art keywords
- cellulose
- slurry
- liquid
- process according
- electric field
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- 229920002678 cellulose Polymers 0.000 title claims abstract description 98
- 239000001913 cellulose Substances 0.000 title claims abstract description 97
- 238000000034 method Methods 0.000 title claims abstract description 52
- 239000002002 slurry Substances 0.000 claims abstract description 80
- 239000007788 liquid Substances 0.000 claims abstract description 54
- 150000002500 ions Chemical class 0.000 claims abstract description 43
- 150000003839 salts Chemical class 0.000 claims abstract description 25
- 239000011780 sodium chloride Substances 0.000 claims abstract description 25
- 230000005684 electric field Effects 0.000 claims abstract description 24
- 235000000346 sugar Nutrition 0.000 claims abstract description 24
- 238000005406 washing Methods 0.000 claims abstract description 23
- 230000001939 inductive effect Effects 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 45
- 238000005370 electroosmosis Methods 0.000 claims description 11
- 239000000123 paper Substances 0.000 claims description 7
- 239000002250 absorbent Substances 0.000 claims description 6
- 230000002745 absorbent Effects 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 4
- 239000000843 powder Substances 0.000 claims description 4
- 238000000746 purification Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 150000008163 sugars Chemical class 0.000 claims description 3
- 239000004094 surface-active agent Substances 0.000 claims description 3
- 239000002562 thickening agent Substances 0.000 claims description 3
- 230000000996 additive Effects 0.000 claims description 2
- 239000002131 composite material Substances 0.000 claims description 2
- 239000002537 cosmetic Substances 0.000 claims description 2
- 239000002270 dispersing agent Substances 0.000 claims description 2
- 238000005553 drilling Methods 0.000 claims description 2
- 239000000839 emulsion Substances 0.000 claims description 2
- 230000002708 enhancing Effects 0.000 claims description 2
- 239000006260 foam Substances 0.000 claims description 2
- 235000013305 food Nutrition 0.000 claims description 2
- 239000002105 nanoparticle Substances 0.000 claims description 2
- 239000003960 organic solvent Substances 0.000 claims description 2
- 239000006254 rheological additive Substances 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims 3
- 239000008194 pharmaceutical composition Substances 0.000 claims 1
- 239000004034 viscosity adjusting agent Substances 0.000 claims 1
- 235000010980 cellulose Nutrition 0.000 description 75
- 239000000835 fiber Substances 0.000 description 27
- CSCPPACGZOOCGX-UHFFFAOYSA-N acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 10
- 238000001035 drying Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 10
- 239000011575 calcium Substances 0.000 description 8
- 230000001965 increased Effects 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 210000001724 Microfibrils Anatomy 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 229920003043 Cellulose fiber Polymers 0.000 description 4
- 235000019749 Dry matter Nutrition 0.000 description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M NaHCO3 Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000007792 addition Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 239000012065 filter cake Substances 0.000 description 3
- 239000011121 hardwood Substances 0.000 description 3
- -1 ion ion Chemical class 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000006011 modification reaction Methods 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 241000894006 Bacteria Species 0.000 description 2
- NYQDCVLCJXRDSK-UHFFFAOYSA-N Bromofos Chemical compound COP(=S)(OC)OC1=CC(Cl)=C(Br)C=C1Cl NYQDCVLCJXRDSK-UHFFFAOYSA-N 0.000 description 2
- 241000218657 Picea Species 0.000 description 2
- WWYNJERNGUHSAO-XUDSTZEESA-N Previfem Chemical compound O=C1CC[C@@H]2[C@H]3CC[C@](CC)([C@](CC4)(O)C#C)[C@@H]4[C@@H]3CCC2=C1 WWYNJERNGUHSAO-XUDSTZEESA-N 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-L Sulphite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 2
- BSYNRYMUTXBXSQ-UHFFFAOYSA-N aspirin Chemical compound CC(=O)OC1=CC=CC=C1C(O)=O BSYNRYMUTXBXSQ-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 235000014633 carbohydrates Nutrition 0.000 description 2
- 150000001720 carbohydrates Chemical class 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 210000004027 cells Anatomy 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 239000003651 drinking water Substances 0.000 description 2
- 235000020188 drinking water Nutrition 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 238000004108 freeze drying Methods 0.000 description 2
- 230000000813 microbial Effects 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000011122 softwood Substances 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 244000020998 Acacia farnesiana Species 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- PZZYQPZGQPZBDN-UHFFFAOYSA-N Aluminium silicate Chemical compound O=[Al]O[Si](=O)O[Al]=O PZZYQPZGQPZBDN-UHFFFAOYSA-N 0.000 description 1
- 241000132092 Aster Species 0.000 description 1
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 240000003917 Bambusa tulda Species 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 241000219495 Betulaceae Species 0.000 description 1
- 210000003229 CMP Anatomy 0.000 description 1
- 229960003563 Calcium Carbonate Drugs 0.000 description 1
- 210000001736 Capillaries Anatomy 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N Carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 210000002421 Cell Wall Anatomy 0.000 description 1
- 229940106135 Cellulose Drugs 0.000 description 1
- 241000229754 Iva xanthiifolia Species 0.000 description 1
- 229920000168 Microcrystalline cellulose Polymers 0.000 description 1
- 229920001046 Nanocellulose Polymers 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 1
- 241000018646 Pinus brutia Species 0.000 description 1
- 235000011613 Pinus brutia Nutrition 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 240000008529 Triticum aestivum Species 0.000 description 1
- 229920002522 Wood fibre Polymers 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 230000000845 anti-microbial Effects 0.000 description 1
- 235000019568 aromas Nutrition 0.000 description 1
- 244000052616 bacterial pathogens Species 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 238000006065 biodegradation reaction Methods 0.000 description 1
- 235000018185 birch Nutrition 0.000 description 1
- 235000018212 birch Nutrition 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 238000005251 capillar electrophoresis Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000003247 decreasing Effects 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- LYCAIKOWRPUZTN-UHFFFAOYSA-N glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000009114 investigational therapy Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 230000002427 irreversible Effects 0.000 description 1
- KFZMGEQAYNKOFK-UHFFFAOYSA-N iso-propanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 1
- 125000000468 ketone group Chemical group 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 235000019813 microcrystalline cellulose Nutrition 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 239000002159 nanocrystal Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000010893 paper waste Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 239000011388 polymer cement concrete Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000004627 regenerated cellulose Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- KEAYESYHFKHZAL-UHFFFAOYSA-N sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000001187 sodium carbonate Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- CMXPERZAMAQXSF-UHFFFAOYSA-M sodium;1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate;1,8-dihydroxyanthracene-9,10-dione Chemical compound [Na+].O=C1C2=CC=CC(O)=C2C(=O)C2=C1C=CC=C2O.CCCCC(CC)COC(=O)CC(S([O-])(=O)=O)C(=O)OCC(CC)CCCC CMXPERZAMAQXSF-UHFFFAOYSA-M 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- 239000010902 straw Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000002522 swelling Effects 0.000 description 1
- 229920001059 synthetic polymer Polymers 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000009210 therapy by ultrasound Methods 0.000 description 1
- 235000021307 wheat Nutrition 0.000 description 1
- 239000002025 wood fiber Substances 0.000 description 1
Abstract
Process for purifying a slurry comprising cellulose by salt/ion depletion and/or free sugar depletion. The process comprises the following steps of providing a slurry comprising cellulose and liquid, subjecting the slurry to a first application of an electric field inducing the liquid of the slurry to flow, separating the liquid from the cellulose thus obtaining a liquid depleted slurry, adding a washing liquid to the liquid depleted slurry, subjecting the liquid depleted slurry to a second application of an electric field inducing the washing liquid of the slurry to flow and separating the washing liquid from the cellulose, thus obtaining a purified cellulose. to flow, separating the liquid from the cellulose thus obtaining a liquid depleted slurry, adding a washing liquid to the liquid depleted slurry, subjecting the liquid depleted slurry to a second application of an electric field inducing the washing liquid of the slurry to flow and separating the washing liquid from the cellulose, thus obtaining a purified cellulose.
Description
Process for treating cellulose and cellulose treated
according to the process.
Field of invention
The present inven:ion relates to a process for ing,
such as salt/ion deple:ion and/or free sugar depletion,
preferably by using dewatering, a slurry comprising cellulose,
such as micro:fibrillated cellulose, by subjecting the slurry to
an electric field.
Background
Microfibril' ated cellulose (MFC), which also is known as
nanocellulose, is a material_ typically made from wood cellulose
fibers. "t can a:_so be riade from microbial sources, agricultural
fibers, dissolved cellul_ose or CMC etc. "n micrO':ibrillated
cellulose the individua' =ibrils have been partly or totally
detached from each other.
Microfibrillated cellulose has a very high water binding
ty and it is thus very di icu'L to reduce the water
content o_ a slurry comprising microfibriila:ed cellulose and
accordingly it is thus di icu'L so puri fy. {igh water content ol
a slurry comprising microfibri"a:ed cellulose also prevents
usage or MFC in many di "erenL ation where MFC with high
solids would be required.
Today there exist several di""erenL meLhods :0 remove water
from a slurry comprising cellulose, such as microfibrillated
cellulose. "v is "or example possible to use di ereno drying
techniques. ixamp'es o di "erenL drying techniques are; freeze
drying, spray drying and supercritical . These techniques
are however quite energy demanding and thus not so cosL e "icient
to use in large scale processes. Also, ication, or
superhornLfication, 0: the fibrillated cellulose fibers
often tends to occur when water is removed with di "erent drying
techniques. iorni.:ica ,ion is when irreversible bonds between the
Sibers are ‘ormed. When horni:fication has occurred it is not
le jor the jibers to expand and swell in wa':er and :he
origina:_ water bonding capaci VY o. the jibers is :hus lOS' The
horni :l cation may be prevented by addition o: chemicals which
physica:_ly prevent or modi.iy she jibers in such way chat she
"orma ion 0' bonds between ose Sibers are limited or
prevented. CA120863Z_A describes a process to re—disperse dried
micrO':ibril'ated ce' 'ulose by addition o: additives that will
preven the "ibrils :rom bonding to each other and thus also
preven:s horni-=ication o the jibers.
Further there is disclosed by L Jchache et al. in Annals o:
the University o:: Craiova, ilectri C ingineering , No. 32,
2008; ISSN 1842—4805 dewatering o: p le and paper waste sludge.
Mechanica: treatments in order :0 remove water :rom a slurry
comprising cel:_ulose, such as micro: ibrillated cellulose can also
be used. However, they are normally no very success:ul due to
the small fiber size and size distribu':ion 0 the
micrO'=ibri'lated cellulose. Moreover, l tracion O'— a slurry
sing cellulose, such as micrO' ted cellulose is
di "icult due to the dense web formed by the s:_urry. Furthermore,
the bonds between the micro:fibrilla:ed ce' lulose :ibers are also
quite strong and this will also make mechanica:_ dewatering less
e'"icient.
The ine""iciency or 'imitations in drying in e.g.
pressurized dewatering wi'l "ur cher give problems with the
removal of ions of ose constituents. Since a filter cake is formed during ring, a
higher resistance to dewatering is obtained. At the same time, it is more difficult to remove e.g.
ions or other ved species since these might be accumulated in the filter cake. Therefore,
the obtained dewatered filter cake of MFC might in fact contain the initial amount of ions or
even substantial higher amount of ions.
When using a normal drying method, the ions and residual chemicals will remain in the
concentrated fiber suspensions and finally in the dried MFC or cellulose sample.
Object of the Invention
It is an object of the present invention to substantially overcome or at least ameliorate
one or more of the above disadvantages, or to at least provide a useful alternative.
Summary of Invention
According to a first aspect of the present invention, there is provided a process for
purifying by salt/ion depletion and/or free sugar depletion a slurry comprising cellulose, wherein
the process comprises the following steps:
-providing a slurry comprising ose and a liquid,
-subjecting the slurry to an electric field ng the liquid of the slurry to flow,
-separating the liquid from the cellulose thus obtaining a liquid depleted slurry,
-adding a washing liquid to the liquid ed slurry,
-subjecting the liquid depleted slurry to an electric field inducing the g liquid of
the slurry to flow, and
-separating the washing liquid from the cellulose, thus obtaining a purified cellulose.
AH26(11116350_1)
The present invention also es ing to a second aspect, a cellulose purified
according to the first aspect.
The t invention also provides according to a third aspect, cellulose obtained by the
process according to the first aspect.
The present invention also provides according to a fourth aspect, use of the cellulose
according to the second or the third aspect in a strength additive, a thickener, a ity
modifier, a rheology modifier, a cleaning powder, a washing powder, a ent, a foam
composition, a barrier, a film, a food product, a ceutical composition, a cosmetic
product, a paper or board product, a coating, a hygiene/absorbent product, an
emulsion/dispersing agent, a drilling mud, a composite material, in water cation, in a filter,
in a solar cell, in a battery, in an electronic circuit (which may be flexible, printed or coated), or
to enhance the reactivity of cellulose in the manufacture of regenerated cellulose or cellulose
derivatives.
Preferably, the use of an electric field improves purifying such as salt/ion ion
and/or free sugar (carbohydrate) depletion, preferably by using dewatering, of a slurry
comprising cellulose, such as microfibrillated cellulose.
The purifying, such as salt/ion depletion and/or free sugar depletion, may preferably be
done using dewatering by using electro-osmosis (or capillary electrophoresis). This dewatering
may also additionally also involve stimulation of other external sources such as mechanical or
l or magnetic field. One example is an ultrasound treatment. The purifying, may also be
followed by any one or a combination f of the below methods to further dry the material:
AH26(11116350_1)
1) Drying methods by evaporation
2) Freeze drying because of sed solids
3) Adding de-hornification additives can also be used in drying of dewatered material
4) dewatered material may also partially be dried further to obtain material which behaves like
solid particles and thus more easily used in commercial applications while still easily mixed
AH26(11116350_1)
and dispersed to other components (individual fibers are
essentially maintained) or easily used as such.
"t is pre'ferred that an elec ,ric field with a voltage 0: 10-
lOO V is used. Increasing the vol cage ,ypically increases the
wa:er extraction rate. The al val ie is when the current
in censi cy o_ the generated electric field and the voltage
gradien': are at maximum ble levels.
Pressure and/or heat may also be applied to the slurry in
order to further improve the puri fying, such as salt/ion
depletion and/or free sugar deple :ion, o: the slurry, preferably
when using dewatering. The pressure may be d a.:ter she
electric field has been applied and :he dewatering o: the slurry
has been started. This is due to tha it may be preferred to
increase the dry content 0: the s' urry before pressure is
app:_ied. r possibili:y is to have weak dewatering inI_‘4—A
_Eie' d simultaneously as mechanica:_ pressure is applied. However,
it s o: course on the dry content 0: the slurry being
treated.
The pressure applied is pre:ferably a mechanica: pressure,
such as compression by the use 0 "or example a roll nip or
felts.
The dry content 0: the slurry comprising cellulose, such as
ibrillated cellulose, be'fore puri':ying, such as salt/ion
deple:ion and/or free sugar dep:_etion, preferably by using
dewa':ering is preferably about "—10% by weight. After she
trea:ment ing to the process i, is preferred that the dry
content 0. she purified, such as salt/ion depleted and/or free
sugar ted, pre:ferably by using dewatering, slurry comprising
cellulose, such as micro:fibrillated cellulose, is about 5—50% by
weight.
The temperature 0: the slurry during purifying, preferably
involving dewatering, is ably above 30°C and preferably
below 100°C.
The slurry may also comprise nanoparticles (such as
absorbents), salt and/or surfactants which are s:imulated by the
electric field and improves the liquid flow. "n this way the
purifying, salt/ion deple':ion and/or free sugar depletion,
pre ferably involving dewatering, 0: the slurry is increased.
Further, aromas may be ed.
The present invention also relates to ce:_lulose, such as
microfibrillated cellulose, being purified, such as salt/ion
ed and/or free sugar depleted, pre'ferab' y by using
dewatering according to the process bed above. It has been
shown that by purifying, such as salt/ion dep:_etion and/or free
sugar depletion, preferably by using dewatering, a slurry
comprising cellulose, such as micro:fibrillated cellulose by the
aid o:: an e' ectric "le- d no or very d horni-=ication c" the
micrO'fibril' ated ce'lu' osic fibers will OCCUK.
Detailed description of the invention
The present ion relates to a process for purifying,
such as salt/ion depletion and/or free sugar depletion,
pre ferably by using dewatering a slurry comprising cellulose,
such as micro fibril' ated cellulose. Due to the characteristics I)
micro:fibrilla':ed ce' lulose fibers, e.g. its size, size
distribution and fiber bonds, it is normally very di""iculc to
purify, such as salt/ion deplete and/or free sugar deplete, a
slurry comprising mi ri'lated cellulose by using ring.
It is intended throughout the present description that the
expression "cellulos e” embraces any type of ce'lulose, such as
cellu'ose fibres (cellulose material). The ce"u'ose may also be
a microfibrillated ce' 'u'ose (MFC). The ose may be bleached
or unbleached. The ce' _u_ ose may also be crystalline cellulose,
MCC (microcrystallinic cellu' ose; has high purity need due to its
potential use in pharriaceutical compositions or other medical
uses), ENC, NCC (nanocrystal' inic cellulose; may be used in
electrical applications and has magnetica:_ properties), CNC, CMC
(carboxymethylated cellulose) or synthetic polymer fibers and
fibers made from disso' ving pulp. The ce' 'ulose may be present in
she "orm O" a pulp, which may be a' pU' p, mechanical pulp,
:hermomechanical pulp or chemi(thermo)mechanical pulp (CMP or
CTM?). Said chemica' pulp is preferably a sulphite pulp or a
Kraft pulp.
The pulp may consist 0'' pulp from hardwood, softwood or both
types. The pulp may e.g. contain a mixture o:: pine and spruce or
a mixture 0: birch and spruce. The al pulps that may be
used in the present invention include all types 0: chemical wood—
based pulps, such as bleached, ha' f—bleached and unbleached
sulphite, kra ft and soda pulps, and mixtures o: these. The pulp
may be 0: dissolved type. The pulp may also comprise textile
fibers. The pulp may also come from agriculture (e.g. ,
bamboo or ).
It is intended hout the present description that the
expression ":free sugar” embraces not only sugars in monomeric
forms but also smaller polymers. lt embraces also free
carbohydrates.
It has been shown that by subjecting a slurry comprising
cellulose, such as microfibril'ated cellulose fibers to an
electric field the purification such as salt/ion depletion and/or
free sugar depletion, preferab'y by using dewatering can strongly
be improved. One theory 0: why it works so well, is that the
electric field s the liquids o: the slurry to flow and thus
pU' 's the water molecules away from she microfibri"ated
ce' 'ulose fibers instead 0: pushing the microfibri"aced fibers
as a ical treatment will do. Pilling the water molecules
will make it possible to also remove water molecules being
absorbed by the microfibri'lated fibers in a very e "icient way.
It is thus very easy to purify the ose fibers 0" the
slurry.
It has been shown that by purifying, such as salt/ion
depletion and/or free sugar depletion, preferab'y by Jsing
dewatering, a slurry comprising cellulose, such as
microfibrillated cellulose, by subjecting the slurry to an
electric field, no substantial hornification c" the
microfibri"aced fibers will occur. It is thus possible for the
microfibri"ated cellulose obtained ing to the process or
the first aspect to swell when the micro:fibrillated cellulose is
in contact wi':h water again. This is 0" great importance when the
microfibrillated cellulose for example is used as a Strength
ve, a thickener or as a viscosity er. Furthermore,
the g y 0: the dewatered microfibrillated cellulose
is also very good, i.e. no subStantial decrease in bonding
ability is seen.
When it comes to on deple :ion this e "ect may be due
to she fact thaw she voltage gradient induces a migration of the
di""erent i ons wish the filtrate. This leads to a decrease in the
specific conduc civity o_ the product and a decrease in the
conductivity o: the sample.
Preferred embodiments of she first aspect 0: the invention
are apparen , from the dependent claims and the s iject matter
thereo is "urther set out below.
The dewatering is preferably done by the use 0: electro—
osmosis. fl4n ec:ro—osmotic flow is 0 ften abbreviated EOF which is
synonymous with electro—osmosis or electro—endosmosis. FFF is
also one further o—osmosis process. Electro—osmosis is the
motion o: l iquid, such as water, induced by an applied potential
or electric field across a porous material, capillary tube,
membrane, hannel, or any other uid conduit. The voltage
generated by the electric field is pre'ferably between lO—lOO V.
The liquid containing ion/salt and or free sugars of the
slurry are separated from the cel'u' ose, such as microfibrillated
ce"ulose, by removing the liquid. It can ably be done by
di""erent " iitering techniques.
The s;urry comprises cellulose, such as ibrillated
cellulose, and a liquid. The liquid may be water, a solvent and
mixtures 0 di" "erent ts and/or liquids. The solvent may be
an alcohol, such as isopropanol, polyethylene glycol, glycol or
ethanol. It can also be an acid or base. Solvents, such as
isopropano; , can change the surface tension o: the slurry and
this will promote ring. The t may also be a solvent
having at least one ketone group, and this may preferably be
acetone. "t is a' so possible that the liquid is an ionic liquid.
The slurry may a:.80 comprise nanopar':icles, polymers, pigments,
salts and/or surfactants which are s:imulated by the electric
field and will ir1prove the liquid migration and movement, i.e.
she flow, in the electric field and thus also the ring.
According to a further preferred embodiment o: the presen
invention the washing liquid is water and/or an c solven .
The organic solvent is preferably acetone. In case drying is
ble as a follow—up 0: the process according to the firs
aspect as set out earlier, water (most pre:ferred distilled water)
is red as washing liquid in case 0: the cellulose being
MFC, NCC, NFC or other cellulose deriva':ive in a more e "icient
way (solvents should there be avoided) to avoid ication.
The slurry rmay also as set out above se fibers 0'
regular length. It is also possible that the slurry comprises
__I' 'ers, such as nanoclays, polymeric based absorbents, PCC,
Kaolin or calcium carbonate. The amounts 0' microfibrillated
ce' 'ulose in the slurry may be between 20—90% by weight, :he
amount 0 - regular sized fibers such as kra:ft, hardwood and/or
softwood fibers may be lO—80% by weight. larger amounts or
__|' lers and longer fibers are present in the slurry it is
possible to achieve a s:_urry with very high dry content by using
the dewa':ering process according to the invention. A dry content
o: up to 90% by weight is possib:_e to achieve since the present
0 long fibers and/or fillers wi 'l make it easier to r the
slurry.
It is however, red to use a slurry comprising high
amoun VS O micrO'=ibril'ated cellulose. A slurry comprising
microfibrillated cellulose in an amount 0: 80—lOO% by weight, or
80—90% by weight, is often preferred. "n many cases it is
preferred that the slurry comprises 100% O" microfibrillated
cellulose, i.e. no fibers 0" longer size is present. The amount
0' microfibrillated cellulose depends on the end use 0: the
microfibrillated ce'lu'ose.
It may also be advantageous to subject the slurry to
increased pressure in combination with the e'ectric field. "t has
been shown that the combination 0" electric "ield and pressure
will ly improve the purification, preferably by using
dewatering, o: a slurry comprising cellulose, such as
microfibril'ated cellulose. "t is preferred to apply the pressure
after the dewatering with the e'ectric "ie'd has started, i.e
when the solid t ol the s:_urry has sed, rably to
about 4% by weight. the solid content ol the slurry is too low
when the pressure is applied, the microfibrillated cellu:_ose is
pressed through the openings o: the dewatering device together
with the water and no purification (such as salt/ion depletion
and/or free sugar depletion) o: the microfibri'lated cellulose
will occur. When the solid content ol the slurry is sed,
the viscosity is also increased and it is possible to apply
pressure to the slurry and be able to increase the dewatering I)
the slurry.
The pressure is preferab— y a mechanical pressure being
applied in any possible way. It possible to use, for example a
roll nip, belt or "elts "or applying the mechanical pressure to
slurry during dewatering.
It is also possible to combine the
ent with the electric field with other kind ol en tS
in order to se the dewatering. ixamples 0" other treatments
s increasing the pressure are acoustic and vacuum based
systems.
The dry content 0: the slurry comprising ose, such as
microfibrillated cellulose, before purifying, such as salt/ion
ion and/or free sugar depletion, preferably by using
ring, is about l—50% by weight. It may also have about 1—
% by weight or about l—lO% by weight.
After the treatmenc according to the process ol the first
aspect it is preferred that the dry content 0: the dewatered
slurry comprising cellulose, such as ibrillated cellulose,
is about 5—50% by weight, more preferably above 20% by weight. It
is thJS possible to receive a slirry comprising microfibril'ated
cellulose with very high dry content in a very energy e "icient
way. Even though the dry content is increased the properties or
the microfibrillated cellulose after dilution 0" water is
maintained, e.g. the water swelling properties and strength.
The temperature 0: the slurry may be below 30°C before
dewatering and increased during the ring process but Kept
at a temperature below 100°C. However, lower temperatures, for
example room temperatures are also possible. The temperature
should preferably be kept below boiling point. sed
temperature may improve the dewatering. This is due to that that
the viscosity 0: water is decreased.
The present invention also relates to cellulose, such as
microfibrillated cellulose, being ed according so she
process ol the first aspect above. It has been shown chac by
purifying, such as salt/ion deplete and/or free sugar deplete,
preferably by using dewatering, a slurry comprising ce'lu'ose,
such as microfibri'lated cellulose, by the aid 0: an ic
fie'd, no or very limited hornification O" the microfibri'lated
cellu'osic fibers wi 'l OCCUK. It is thus possible to produce a
microfibril'a:ed cellulose with improved properties in a fast and
very energy e "icient way compared to the use 0 "or e
drying techniques.
A microfibri' lated cellulose fiber is normally very thin
(~20 nm) and :he length is o:ften between 100 nm to 10 um.
However, the fibrils may also be longer, for e between
L0—200 um, bu: _lengths even 2000 um can be found d Je to wide
length dis:ribution. Fibers that has been fibri' la:ed and which
have microfibri 's on the surface and ibri' S that are
separated and located in a water phase 0 " a slurry are included
in the definition MFC. Furthermore, whisgers are also included in
the definition MFC.
The microfibrillated cellulose is typically made from wood
ce'lulose fibers, it is possible to use both hardwood and
od fibers. "t can also be made from microbial S,
agricultural fibers, such as wheat straw pulp or other non—wood
fiber sources. It can also be produced by bacteria or made from
CMC.
Using this electric field set out in the first aspect o: the
invention, in addition also reduces the number 0: bacteria as
their cell walls will blow up. The process 0. the first aspect,
as it removes ions, also removes ions and wa':er also from
microbes. This means cha this ion removal and water removal will
kill/antimicrobial e EC
According to a further pre'ferred ment o: the present
invention the process according to the first aspec o. the
invention may be ed by one or more modi:fication steps, such
as a counter—ion change as set out below.
According to a further pre'ferred embodiment o_ she present
invention the cellu:_ose according to the second and the third
aspec may further be processed by using ion exchange e.g. as
disclosed in WOQOO9' 96’06 which disc:_oses a method for modifying
ce"ulose fibers. "t wou:_d be possib:_e to change cellulose to
di "erent counter—ion IOrms to get e.g. CMC adsorbed/absorbed
inco fibres. Thus it wou:_d e.g. be possible to have a sodium
CO inter ion modi:fication to e MFC production. It would also
be possible to e.g. go from Ca—form to m and vice versa.
According to a "urcher preferred embodimenc of the present
invention counter—ion change, which preferably fol'ows after the
process steps 0. the first aspect, may be per:formed h a
process comprising the ing steps:
]J washing ions away from she pu:_p with o s (until
she filtrate conductivi:y is :_ow enough) — optionally
followed by addition 0' liquid, pre':erably distil' ed wafer,
2) washing the “clean” pu:_p with a sodium carbonate such as
NaHCO3 and a basic agent , such as NaOH (to se the pH
to about 9) — preferab' y this may be done by adding NaHCO3
and NaOl into the washing liquid o: the electro—osmosis
apparath
washing the pulp with distilled wa':er in the electro—osmosis
apparatus to remove excess Na—ions.
Changing o: the counter—ions as set out above could be
desirable in several applications;
to make pu:_p more homogenous for chemical reactions,
for enabling di "erent chemical reactions,
- LOI improved vity 0: the pulp,
- LOI improved drying or
improved re—dispergativity 0'' - LOI the one’s dried pulp.
"n r applica':ions, which may be multi—layered, as set
out in the fourth aspecc O_ the presen: invention the use of the
cellulose according to the second and third aspect may be
especially desirable in ing o: electronic equipment, or
when making solar ce' 's or batteries from cellulose, due to
purity.
The purified ce' 'ulose according to the second and third
aspect can be t as low metal pulps. As such they may be
use ul "or low conductivity paper (due to di—electrical
prop rti s), nzym tr atm nts o: pulps or as pulp for chemical
modifications.
The purified cellulose according to the second and third
aspect in the form 0" micro*ibrillated cellulose may be
especially useful in the __O' lowing applications/uses:
— barriers due to ed "ilm "orming properties
— washing powders due to ved Cafi removal (absorbs/adsorps)
or in other similar applications where hard wa':er is a problem
— cleaning drinking water as it is possible to achieve improved
heavy metal removal from drinking waters (this is still a large
problem in some areas 0:: word)
— by oxidation and di "erent ves one can improve metal
absorption properties
— metal absorbents which are biodegradable
Preferred features 0'' each aspect o: the invention are as
for each 0: the other aspects mutatis mutandis. The prior art
documents mentioned herein are incorpora ced to the fullest extent
permitted by law. The invention is further described in :he
following examples, :ogether wich she appended figures, the only
purpose 0: which is :o illustrace she invention and are in no way
intended to limit the scope o. she invention in any way.
Figures
Figure 1 disc:_oses the dewatering setup scheme (left) and
cathode plate with holes.
Figure 2 disc:_oses dependencies of current and mass of
collected water on time at constant applied voltage 20 V.
Figure 3 disc:_oses dewatering of 'ow conductivity MFC.
Figure 4 dis closes time dependencies of the water mass
cted during ring 0:5 low conductivity MFC at di""erent
vo:_tages are ted.
Examples
1.Experimental set-up
For investigation 0: MFC dispersion dewatering an
experimental setup was assembled, scheme 0: which is on Fig. 1.
It consiscs o a plastic pipe with interna' diameter 46 mm,
fitted in:0 a stainless steel funne'. At the lower end 0. she
pipe there is a plate with holes, a:_so made 0:_ ess s:eel,
which serves as the lower electrode, usually e. A paper
__|' ter is placed on the plate, the MFC dispersion is loaded onto
she filter. On top or the MFC column there is one more paper
__|' ter, a fter this the upper electrode (anode) is placed.
The best results were achieved with platinum electrode — no
process changes due to the electrode corrosion or contamination
were observed.
The setup 0; Fig. l constituted a cell with MFC investigated;
DC voltage was applied inco it jrom the current source. The
water, emerging jrom she junnel was assembled into beaker, which
was situated on top of a balance; the mass or the water ex :racted
from MFC was registered during experiments. The experiments
y were carried out in two modes: with a e U constant
or with current i constant.
Dependencies of current and mass of collec:ed water on time
at constant applied voltage 20 V is disclosed in Figure 2. An
increase of re increase both 2
causes an or current and
increment 0' co'lected water.
Surprisingly it was thus found that o—osmosis dewatering
may be used i:'I
- in the beginning (more or less) only electro—osmosis is used
- due to dewatering the ity wi '1 increase enough — that
mechanical pressure may be applied (as reflected in Fig. 2)
Figure 3 discloses dewatering of low conductivity MFC.
Figure 4 disc:_oses time dependencies of the water mass
ted during dewatering of low conductivity MFC at di "erent
voltages are presented. The voltage increase causes an increase
o: dewatering speed (initial slope) and process tion value.
Example 2
Re:ference MFC (initial MFC) — dry t (LR) 1.7%
Sa Lt/Metal contents based on dry matter;
Al 9.5 mg/g
Fe L6 mg/g
Ca L200 mg/kg
Cu 5.5 mg/kg
K 310 mg/kg
g 210 mg/kg
L.l mg/kg
L400 mg/kg
L.6 mg/kg
?b L.l mg/kg
Si 76 mg/kg
Zn 5.9 mg/kg
Dewatering procedure 1 - only removing water;
A paper 1 oer was places on cathode then MFC and then a
second paper 1 oer. A Ler chis the anode was laid on she top 0.
:his. The pressure (o: weigh 0 L anode) was 750 kPa. After shor
time (2 min) an additional weight was added (pressure to 2400
?a). The voltage during dewa':ering was 100V and time 640s.
?rocedure was repeated 3 times and pressure was increased (last
time 4.6* 10A5 Pa).
Dewatered MFC (electro—osmosis MFC)—results are given below:
etal contents based on dry matter 30.5%
Al 8.5 mg/kg
Fe ll mg/kg
Ca 30 mg/kg
Cu 0.69 mg/kg
K 85 mg/kg
g 5.7 mg/kg
n 0.24 mg/kg
Va 12 mg/kg
Vi 0.68 mg/kg
?b <0.4 mg/kg
Si L3 mg/kg
Zn ;.5 mg/kg
Example 3
Reference MFC (initial MFC) — dry content (IR) 1.7%
Salt/Metal contents based on dry matter;
A1 9.5 mg/g
Fe L6 mg/g
Ca L200 mg/kg
Cu 5.5 mg/kg
K 310 mg/kg
g 210 mg/kg
n L.l mg/kg
Va L400 mg/kg
Vi L.6 mg/kg
?b L.l mg/kg
Si 76 mg/kg
Zn 5.9 mg/kg
Dewatering procedure 2 — removing water and washing with acetone
MFC was red 5 min (as in procedure 1 above i.e.
ixample 9). Aster this the current was switched o and acetone
was added (about the same amount as water was removed in previous
step). A:fter this dewatering was started and continued about 10
min.
Dewatered MFC (electro—osmosis MFC with acetone)—results given
below:
Salt/Metal ts based on dry matter 23.5%
Al 4.6 mg/kg
Fe L0 mg/kg
Ca L0 mg/kg
Cu 0.68 mg/kg
K 40 mg/kg
g 7.; mg/kg
n 0.;3 mg/kg
Va 14 mg/kg
Vi 0.50 mg/kg
?b <0.4 mg/kg
Si L3 mg/kg
Zn ;.5 mg/kg
Example 4 — Temperature test
Using the same set up as out above, temperature tests were
performed.
Temperature 90 — 95 °C — dewatering in 60s = about L6 g
water
Temperature 21 °C — dewatering in 60s = about L3.5 g
water
Accordingly it was beneficial to use higher temperature to
improve dewatering. Thus the energy needed for dewatering is much
lower at elevated temperatures.
ixamp'e 5
A further trial was done where even more ions (especially
Ca2+ ions) were removed.
In the start the total amount was 20 g 0: wet MFC.
t ll g 0: water was removed with o—osmosis
a.netal content 0: the water
i. Ca 14 mg/l
ii. K 2.7 mg/l
iii. Na 26 mg/l
iv. Si 1.3 mg/l
2) about "0 g 0" disti"ed water was added
3)abou: "0 g 0: water was removed
a.netal content 0: the water
i. Ca 8 mg/l
ii. K 0.56 mg/l
iii. Na 0.78 mg/l
iv. Si 0.22 mg/l
4)abou: 10 g o" discil'ed water was added
)abou: 9 g 0: water was removed
a” metal contenc o_ the water
i. Ca 7.4 mg/l
ii. K 0.56 mg/l
iii. Na 0 mg/l (below ion limit)
iv. Si 0.076 mg/;
6) distilled water (as reference)
a” metal content 0: the water
i. Ca 0.079 mg/l
ii. K 0(below detection limit)
iii. Na w detection limit)
iv. Si 0(below detection limit)
"n view o: the above detailed description o: the present
invention, Other modifications and variations will become
nt to those skilled in the art. However, it shou;d be
apparent that such other modifications and variations may be
e""ected without departing from the spirit and scope or the
invention.
I
Claims (15)
1. Process for purifying by salt/ion depletion and/or free sugar depletion, a slurry sing cellulose, wherein the process comprises the following steps: -providing a slurry comprising cellulose and liquid, -subjecting the slurry to a first application of an electric field inducing the liquid of the slurry to flow, -separating the liquid from the cellulose thus obtaining a liquid depleted slurry, -adding a washing liquid to the liquid depleted slurry -subjecting the liquid depleted slurry to a second ation of an electric field inducing the washing liquid of the slurry to flow and -separating the washing liquid from the cellulose, thus obtaining a purified ose.
2. The process according to claim 1 wherein the liquid separation is done by electroosmosis.
3. The process according to any one of the preceding claims n the electric field has a voltage of 10-100 V.
4. The process according to any one of the preceding claims n pressure also is applied to separate the liquid from the ose.
5. The process according to claim 4 wherein the re is applied after the electric field has been applied and the liquid separation has started.
6. The process according to any one of claims 4-5 wherein the pressure is a mechanical pressure.
7. The process according to any one of the preceding claims wherein the dry content of the slurry comprising cellulose, before liquid separation, and/or on depletion and/or free sugar depletion, is about 1-50% by weight.
8. The process according to any one of the preceding claims wherein the dry content of the liquid depleted slurry comprising cellulose, is about 5-50% by weight. AH26(13619370_1):KEH
9. The process according to any one of the preceding claims wherein the temperature of the slurry during liquid tion is above 30°C and below 100°C.
10. The process according to any one of the preceding claims n the slurry comprises nanoparticles, absorbents, salt, free sugars and/or surfactants which are stimulated by the electric field.
11. The process according to any one of the preceding claims wherein the washing liquid is water and/or an organic solvent.
12. The process according to any one of the preceding claims, wherein the cellulose is microfibrillated cellulose.
13. The process according to any one of the ing claims further comprising a counterion change and/or one or more further washing steps.
14. Cellulose, obtained by the process according to any one of claims 1-12.
15. Use of a cellulose, ing to claim 14 in a strength additive, a thickener, a viscosity modifier, a rheology modifier, a cleaning powder, a washing , a ent, a foam ition, a barrier, a film, a food product, a pharmaceutical composition, a cosmetic product, a paper or board product, a g, a hygiene/absorbent product, an emulsion/dispersing agent, a drilling mud, a composite material , in water purification, in a filter, in a solar cell, in a battery, in an electronic circuit, or to enhance the reactivity of cellulose in the manufacture of regenerated ose or cellulose derivatives.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE1150436-2 | 2011-05-13 | ||
SE1150436 | 2011-05-13 | ||
NZ61711812 | 2012-05-11 |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ718115A NZ718115A (en) | 2017-10-27 |
NZ718115B2 true NZ718115B2 (en) | 2018-01-30 |
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