EP1397419A1 - A method for preparation of absorbing substances - Google Patents

A method for preparation of absorbing substances

Info

Publication number
EP1397419A1
EP1397419A1 EP02722325A EP02722325A EP1397419A1 EP 1397419 A1 EP1397419 A1 EP 1397419A1 EP 02722325 A EP02722325 A EP 02722325A EP 02722325 A EP02722325 A EP 02722325A EP 1397419 A1 EP1397419 A1 EP 1397419A1
Authority
EP
European Patent Office
Prior art keywords
treatment
monomer
polymerization
water
lignocellulosic material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02722325A
Other languages
German (de)
English (en)
French (fr)
Inventor
Yrjö MÄLKKI
Merja Marjut Toikka
Antti Jussi SIPILÄ
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cerefi Oy
Original Assignee
Suomen Viljava Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Suomen Viljava Oy filed Critical Suomen Viljava Oy
Publication of EP1397419A1 publication Critical patent/EP1397419A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H8/00—Macromolecular compounds derived from lignocellulosic materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
    • C08F251/02—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof on to cellulose or derivatives thereof

Definitions

  • the objective of this invention is a method for preparing absorptive substances from lignocellulosic materials such as straw, peels or hulls of cereal crop, plant leaves, wood chops, bagasse or jute.
  • absorbents are absorbing and release of water, flocculation of colloids, filtering aids, removal and a possible recovery of harmful organic or inorganic compounds, based among others on the ion exchange properties of absorbents, and controlled release of medicines and agrochemicals.
  • the range of applications is wide from hygiene and hospital articles to various purposes in the industry, agriculture and environmental protection.
  • the starch-based products developed initially could have water absorbing capacity of several hundred times that of the weight of the dry absorbent. However, along with the increase of the amount water absorbed, mechanical properties of the gel formed were weakened, and a substantial part of the water was released under pressure. Since hygiene articles have been a major field of application of the organic absorbents, the main part of the demand has been directed to absorbents, which can imbibe and hold water and dilute solutions such as blood and excreta even under mild pressures. A similar quality requirement is valid also for substances used for absorbing and release of water in agricultural and horticultural applications.
  • Fibres can be formed by polymerizing the same monomer or from another synthetic polymer.
  • an absorbing layer can be prepared on the surface of isolated natural polymers such as cellulose or wool fibres.
  • a fibrous absorbing material can be bound to other fibrous materials by weaving or by using non-woven techniques known as such. Advantages of using fibrous materials are an easy separation from the liquid phase, which enables uses similar to filtering materials, or when mixed in large amounts of liquids, a separation merely by sedimentation.
  • a hydrogel forming polymer, 2-methyl hydroxyethyl methacrylate (HEMA) has been grafted on the surface of cellulose fibres, polyethylene, or silicon rubber.
  • initiators used for grafting have been light, ⁇ - irradiation, or chemical initiation. Weaknesses of these methods are, according to Karlsson and Gatenholm (Polymer 38, 4727-4731, 1997), high equipment costs, a weak controllability of the polymerization, and difficulties to avoid homopolymerization.
  • These researchers have used for chemical initiation a treatment with ozone on the surface of moistened cellulose fibres, this treatment forming hydroperoxides on the surface.
  • Polymerization is subsequently formed in methanol solution under nitrogen atmosphere.
  • the duration of the ozone treatment has been 90 minutes. This treatment, however, caused breaking of cellulose molecules thus weakening the mechanical properties of the fibrous material. Grafting started from the pores and crevices of the surface, and for a complete covering of the surface with the hydrophilic layer, an amount of grafting material higher than 100% of the weight of the cellulose treated was needed. Absorbing properties of the material obtained have not been published. Graft polymerization has also been applied on non-isolated natural fibre materials.
  • lignocellulosic material such as straw, peels and hulls are formed. They have been used as absorbents as such or after some simple chemical treatments.
  • the water absorbing capacity of untreated material is weak, being maximally two parts by weight per one part of the dry absorbing material. For this reason, this material as such is economically feasible for absorbing purposes only for absorbing excreta of cattle or poultry.
  • Its water absorbing capacity can be elevated by treatments with alkali or by a combined treatment with alkali and peroxides, as it is presented in the United States patent no. 4,806,475. Fibre preparations obtained by such treatments are marketed as water absorbing food additives. Their water absorbing capacity is 6 to 8 parts per one part of dry matter of the absorbing material. No data exist on their water absorbing capacity under pressure, and these materials are not marketed, for example, for preparation of hygiene articles.
  • lignocellulosic material is treated with alkali to remove a part of its lignin and/or hemicellulose content
  • step (b) after step (a), the material is treated to provide its cellulose content with reactive radicals capable of functioning as polymerization initiators, (c) after step (b), at least one polymerizable monomer and at least one cross-linking agent are added to the material,
  • preparation of an absorbent is performed advantageously by initiating the treatments by water washing of the lignocellulosic material, whereby finely dispersed and water-soluble compounds are removed, and among others, the contents of starch and protein are reduced.
  • the pretreated material is now treated with an alkaline solution and a treatment with hydrogen peroxide, persulfate, or another strongly oxidizing treatment for enabling the fixation of the polymer and for initiating the polymerization.
  • Into a moist material one or several monomers and cross-linking agents, separately or previously mixed, are added, and the polymerization is performed at a temperature below 75°C.
  • Straw, peels, hulls or another lignocellulosic material deriving from an industrial process can contain extraneous material such as soil, and starch and proteins deriving from other materials such as cereal grains. Since these materials can weaken the fixation of the polymer formed and/or inactivate radicals formed for initiating the reaction, it is advantageous to preclean the material for removal of extraneous compounds. A great part of the said impurities can be removed by washing with water. When materials with a waxy surface are used, the wax has to be removed. This can be most efficiently performed by a solvent treatment.
  • the purpose of the alkali treatment is to remove from the lignocellulosic material hemicellulose, lignin and other phenolic compounds, which could at the following stage hamper or disturb the initiation by capturing radicals, and by weakening the fixing of the polymer formed onto the fibres.
  • a substantial cost advantage is however obtained thereby, that according to the invention these materials or components are only partially removed, without an attempt to purify the cellulose completely from other components.
  • alkali treatment and the possibly preceding water washing 30 to 95% advantageously 50 to 80% of the total amount of lignin and hemicellulose can be removed.
  • Preferential starting materials such as cereal straw, peels and hulls, are fibrous or foil-formed in the structure. Additionally, it can be advantageous to separate the fibres in order to increase the reactive surface in relation to the total weight, and to modify physical properties of the material according to the requirements of the end use. In case a chemical defibration would be performed, the costs would be easily high and the yield would remain at about 40% of the initial weight. The material obtained would not be competitive as compared to cellulose from the present large- scale industrial processes. An analogous defibrating effect can however be obtained by treating the material according to the invention with alkali, whereby the main part of hemicellulose and a substantial part of lignin is dissolved and removed.
  • An effective defibrating is achieved especially by treating with a strong alkaline solution at a temperature under 40°C.
  • Economical defibrating treatments are also mechanical wet-millings in water suspensions, and chemo-mechanical wet milling, both of which can be performed at temperatures from 0 to 100°C, or at higher temperatures under pressure using, for example, extrusion techniques.
  • the advantage of chemo-mechanical wet milling as compared to alkaline extraction without milling is a lower consumption of chemicals and a more effective defibrating, the disadvantage is some disruption of the fibres in the process.
  • the initiation treatment whereby reactive radicals are formed is in this invention performed advantageously by using an oxidative chemical, such as hydrogen peroxide or sodium persulfate.
  • an oxidative chemical such as hydrogen peroxide or sodium persulfate.
  • This stage is followed by addition of one or several monomers and cross-linking agents to the moist material, preferentially without any washing or other intermediate stages.
  • Polymerization can be accelerated by heating the reaction mixture, mamtaining the temperature, however, below 75°C.
  • Monomers to be used in this invention can be one or several compounds containing a vinyl group, such as acrylic acid, methacrylic acid, styrene, N-vinyl pyrrolidone, or their derivatives.
  • Choice of the monomers and cross-linking agents depends on the properties desired for the end product, such as ion exchange properties, water binding capacity and the effect of acidity, ionic strength, and pressure on these properties.
  • the properties of the product can also be influenced by down stream treatments following the polymerization.
  • acrylic acid when acrylic acid is used as a monomer, weakly dissociating carboxyl groups which can act as ion exchangers are formed in the polymer layer, and the water absorbing capacity can be elevated by treatments with alkali, whereby a part of these groups are neutralized.
  • Strongly dissociating cation exchanging atomic groups can be obtained by using as one of the monomers vinyl monomers which contain a strongly or intermediately strongly dissociating atomic group such as sulfonic acid group.
  • the product after the polymerization can be subjected to a treatment whereby such groups are formed, for example by treating with chlorosulfonic acid.
  • anion exchange properties can be obtained in the product by using as the monomer or as one of the monomers a vinyl compound containing basic atomic groups, or by performing after the polymerization a treatment whereby such groups are formed or introduced, according to methods known as such.
  • the experimental material used in the investigations on which this invention is based has been oat hulls. Its content of cell walls is as a mean more than 83%, its content of lignin being below 10%, of cellulose 30 to 35%, and of hemicellulose 30 to 35%, respectively (Welch, Journal of the Science of Food and Agriculture 34, 417-426, 1983).
  • Example 2 The mixture of oat hulls and potassium hydroxide obtained in Example 2 was diluted to a twofold volume with distilled water, and one part by weight of 30% hydrogen peroxide was added. Mixing was continued at room temperature for three hours. The solution was removed by decanting. After this treatment, the dry weight of the solids was 84.3% of that taken for the treatment in this example. Its water absorbing capacity, determined as in the example 2, was 7-fold as compared to the dry weight.
  • the solids after decanting in the Example 3 were transferred without any preceding washing into a reaction vessel.
  • 2.38 parts by weight of redistilled acrylic acid and 0.13 parts by weight of redistilled ethyleneglycol dimethacrylate (EDMA) were added. Air was removed by leading argon gas through the reaction mixture for 5 minutes, and 0.04% by weight of sodium persulfate were added.
  • the temperature was elevated to 60°C, and polymerization was continued for 1.5 hours, mamtaining the temperature of the mixture below 75°C.
  • the polymer formed was cooled, washed with a 0.0125 mol/L sodium hydroxide solution, separated from the solution by filtering under vacuum, and dried in vacuum.
  • the water binding capacity, as measured with a 0.9% sodium chloride solution under pressure was 16.5 fold as compared to the dry weight.
  • Example 4 The experiment according to Example 4 was repeated by using fibrous material obtained from a treatment according to Example 2 as starting material.
  • the product obtained had 12.5 fold water binding capacity as compared to the dry matter, when tested under pressure.
  • the experimental scheme according to Examples 2 to 4 was repeated in a modification where under the alkali treatment the temperature was elevated to 40°C for one hour, after which the solution was removed by decanting, and the duration of the hydrogen peroxide treatment was one hour.
  • the product obtained had a 18-fold water binding capacity as compared to the dry matter, when tested under pressure.
  • the examples indicate the operation principles, but do not limit ingredients or their proportions in the implementation. They may be selected depending on the physical form and functional properties desired.
  • the method can be used to treat other lignocellulosic materials, which either are in thin layers or can be brought to thin layers. Examples of other materials are wood chips, bagasse, jute and leaves of plants.
  • the dissolved material obtained at the stages described in Examples 1 and 2 is a byproduct which can be recovered and marketed separately, based on its high content of hemicellulose, for industrial raw materials or for feeds.
EP02722325A 2001-05-16 2002-05-15 A method for preparation of absorbing substances Withdrawn EP1397419A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI20011034 2001-05-16
FI20011034A FI113375B (fi) 2001-05-16 2001-05-16 Menetelmä absorboivien aineiden valmistamiseksi lignoselluloosamateriaalista
PCT/FI2002/000415 WO2002092669A1 (en) 2001-05-16 2002-05-15 A method for preparation of absorbing substances

Publications (1)

Publication Number Publication Date
EP1397419A1 true EP1397419A1 (en) 2004-03-17

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP02722325A Withdrawn EP1397419A1 (en) 2001-05-16 2002-05-15 A method for preparation of absorbing substances

Country Status (5)

Country Link
US (1) US20040231059A1 (un)
EP (1) EP1397419A1 (un)
CA (1) CA2447520A1 (un)
FI (1) FI113375B (un)
WO (1) WO2002092669A1 (un)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI122815B (fi) * 2005-04-18 2012-07-13 Cerefi Oy Menetelmä lignoselluloosamateriaalien ja niistä saatujen jakeiden fraktioimiseksi
FI20096198A0 (fi) * 2009-11-18 2009-11-18 Valtion Teknillinen Hapetettu ligniinipitoinen aine, sen käyttö sekä menetelmä saastuneiden nesteiden puhdistamiseksi
JP6063416B2 (ja) * 2014-06-10 2017-01-18 デクセリアルズ株式会社 水浄化剤、及び水浄化方法
EP3600650B1 (en) * 2017-03-29 2021-10-27 Lappeenrannan-Lahden teknillinen yliopisto LUT Method of using extracted lignocellulosic material as an adsorbent
WO2018236293A1 (en) * 2017-06-20 2018-12-27 Mitr Phol Sugarcane Research Center Co., Ltd. ABSORBENT CELLULOSIC MATERIAL
CN109731435B (zh) * 2019-01-17 2021-10-29 江苏省农业科学院 一种纤维素基甲醛吸附剂在吸附甲醛的应用

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4028290A (en) * 1975-10-23 1977-06-07 Hercules Incorporated Highly absorbent modified polysaccharides
FR2628764A1 (fr) * 1988-03-16 1989-09-22 Du Pin Cellulose Procede de fabrication de produits fibreux a base de cellulose modifiee presentant des proprietes absorbantes ameliorees et produits obtenus

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4036588A (en) * 1976-03-09 1977-07-19 Research Corporation Method of increasing the water absorption of cellulose-containing materials
US4806475A (en) * 1983-12-28 1989-02-21 The United States Of America As Represented By The Secretary Of Agriculture Alkaline peroxide treatment of agricultural byproducts
FR2574826B1 (fr) * 1984-12-14 1987-01-09 Du Pin Cellulose Procede de preparation de cellulose modifiee lui conferant des proprietes absorbantes ameliorees
US4818598A (en) * 1985-06-28 1989-04-04 The Procter & Gamble Company Absorbent structures
US4842877A (en) * 1988-04-05 1989-06-27 Xylan, Inc. Delignification of non-woody biomass

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4028290A (en) * 1975-10-23 1977-06-07 Hercules Incorporated Highly absorbent modified polysaccharides
FR2628764A1 (fr) * 1988-03-16 1989-09-22 Du Pin Cellulose Procede de fabrication de produits fibreux a base de cellulose modifiee presentant des proprietes absorbantes ameliorees et produits obtenus

Also Published As

Publication number Publication date
FI20011034A0 (fi) 2001-05-16
FI20011034A (fi) 2002-11-17
WO2002092669A8 (en) 2003-07-24
FI113375B (fi) 2004-04-15
US20040231059A1 (en) 2004-11-25
CA2447520A1 (en) 2002-11-21
WO2002092669A1 (en) 2002-11-21

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