JP2010221208A - Method of separating/recovering pulp component and inorganic component from paper making sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of separating/recovering a pulp component and an inorganic component from paper making sludge. <P>SOLUTION: There is provided the method of separating/recovering the pulp component and the inorganic component by heating the paper making sludge together with an ion liquid and dissolving the pulp component contained in the paper making sludge. There is provided the method of separating/recovering the pulp component and the inorganic component by recovering the used ion liquid and using the recovered ion liquid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for separating and recovering a pulp component and an inorganic component contained in a papermaking sludge that is an industrial waste.

  Papermaking sludge is mostly waste generated during the paper manufacturing process. The amount of paper sludge incineration is enormous, and the space shortage at the landfill site for ash generated during incineration has become serious. Papermaking sludge contains organic components such as pulp components and synthetic fibers such as polyester fibers, and inorganic components such as silicic acid, alumina, calcium oxide, magnesium oxide, and titanium oxide added as a filler. In recent years, as an attempt to recycle these, research on reusing as a filler (Patent Documents: JP-A-2007-015874, JP-A-2005-329392, JP-A-2004-182538) and zeolitization has been conducted (Patent Documents). : JP 2008-144347, JP 2006-138044).

JP2007-015874A JP-A-2005-329392 JP 2004-182538 A JP2008-144347 JP 2006-138044 A

  These recycle the incinerated ash which incinerated papermaking sludge once at 900 ° C. to eliminate organic components. However, these methods cannot effectively utilize the pulp component. Therefore, in this research, the pulp component is taken out from the papermaking sludge, and the issue is to make effective use of both the inorganic component and the pulp component.

  The present invention that achieves the above object performs separation and recovery of pulp components and inorganic components in papermaking sludge by chemically treating the papermaking sludge with an ionic liquid.

  The ionic liquid has the characteristics of being stable, flame retardant, zero vapor pressure, recoverable and reusable. Further, this ionic liquid has the property of dissolving cellulose, which is an organic component in papermaking sludge, at a temperature of 100 ° C. By utilizing this property, the organic component can be recovered by dissolving the pulp component, which is the main organic component in the papermaking sludge, at a low environmental load of 100 ° C., and then adding ethanol to precipitate it. . Moreover, since an inorganic component does not melt | dissolve in an ionic liquid, the inorganic component which remained after melt | dissolving the pulp component contained in papermaking sludge can be collect | recovered using an ionic liquid.

It is a figure which concerns on the spectrum of the infrared spectrophotometer of the pulp component obtained by this invention. It is a figure which concerns on the X-ray-diffraction figure of the inorganic component obtained by this invention.

  Embodiments of the present invention will be described below. The papermaking sludge described in the present invention refers to precipitates and suspensions generated in the manufacturing process of a paper mill and wastewater from the paper mill. The components of a general papermaking sludge are 20% organic, 20% inorganic, and 60% moisture. The organic component mainly contains a pulp component. Inorganic components vary depending on the paper mill, but talc, kaolin, calcium carbonate, titanium oxide and the like are common. Moreover, depending on a factory, only the pulp component and synthetic fiber which are organic components may be contained.

  The ionic liquid used in the present invention is used to dissolve pulp components, which are organic components contained in papermaking sludge.

  A papermaking sludge placed in a container equipped with a mesh net is fixed to a container containing ionic liquid and heated. By collecting papermaking sludge in a container equipped with a mesh net, it is possible to easily recover the inorganic component after dissolving the pulp component. As heating conditions, heating at 70 ° C. or higher for 1 hour is sufficient for carrying out this study, but a heating temperature of 100 ° C. or higher is preferable.

  As the ionic liquid that can be used in this study, water or ethanol is used as a poor solvent when the pulp is deposited, and therefore, an ionic liquid having water solubility or ethanol solubility can be used. For example, 1-alkyl-3-methylimidazolium salt, 1-allyl-3-alkylimidazolium salt, 1-alkyl-2,3-dimethylimidazolium salt, N-alkylpyridium salt, methyl-N-butylpyridinium Examples include salt. Representative examples include 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-allyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-allyl-3- Examples thereof include ethyl imidazolium bromide, 1-ethyl-2,3-dimethylimidazolium chloride, N-ethylpyridium chloride, and 3-methyl-N-butylpyridinium chloride. In this study, 1-butyl-3-methylimidazolium chloride having a low melting point and water solubility and ethanol solubility is preferable.

  After the papermaking sludge is heated with the ionic liquid, the container provided with the mesh net is taken out. By this operation, inorganic components and synthetic fibers that cannot be dissolved in the ionic liquid can be recovered. The pulp component dissolved in the ionic liquid is recovered by filtration after adding a poor solvent of the pulp component to precipitate it. As a poor solvent to be used, ethanol, water, isopropanol or the like can be used.

  The poor solvent and the ionic liquid used in precipitating the pulp component dissolved in the ionic liquid are each recovered by vacuum distillation using a rotary evaporator, and the ionic liquid and the used poor solvent can be reused. As the poor solvent to be used, ethanol is preferable from the viewpoint of distillation under reduced pressure, ease of reuse and cost.

The outline of the present invention will be described below.
Papermaking sludge was placed in a cylindrical container equipped with a mesh net, and this was installed in a hydrophobic resin container containing an ionic liquid. The hydrophobic resin container was stirred for a certain time while being heated at 100 ° C. by a water bath to dissolve the pulp component in the papermaking sludge. The cylindrical container is taken out and the inorganic component is first recovered. A poor solvent was added to the ionic liquid in which the organic component in the Teflon container was dissolved to precipitate the pulp component. The precipitated pulp component was recovered by filtering with a filter paper which is a hydrophobic resin. The used ionic liquid and poor solvent can be separated and recovered by distillation under reduced pressure using a rotary evaporator and reused.

  Next, the present invention will be specifically described with reference to examples. In light of the common general research knowledge in the field, it is clear that the present invention is not limited to the final conditions of the experimental conditions used in the following examples.

  A description will be given of Embodiment 1 of the present invention. Made of Teflon containing 20 g of 1-butyl-3-methylimidazolium chloride, which is an ionic liquid, into a cylindrical container equipped with a mesh net (opening 70 μm), 20 g of paper-dried sludge (average particle diameter 1 mm) in an absolutely dry state Installed in a container (sampler tech). The Teflon container was stirred while being heated at 100 ° C. by a water bath. After 0.5, 1, 1.5, 2, 3, 4 and 6 hours, the cylindrical container was taken out. Ethanol was added to the ionic liquid in the Teflon container to precipitate the pulp component dissolved in the ionic liquid, and filtered using PTFE filter paper (ADVANTEC PF050 90 mm).

  A description will be given of Embodiment 2 of the present invention. The experiment was performed in the same manner as in Example 1 except that the papermaking sludge particle size was 4.75 mm.

  A description will be given of Embodiment 3 of the present invention. The ionic liquid and ethanol mixture used in Example 1 or 2 were distilled under reduced pressure using a rotary evaporator at a distillation temperature of 40 ° C. and a set pressure of 74 hPa, thereby separating and recovering the ionic liquid and ethanol.

  A description will be given of Embodiment 4 of the present invention. The experiment was performed in the same manner as in Example 1 except that the ionic liquid recovered in Example 3 and the reaction time were 6 hours. Using the recovered ionic liquid, a repeated test was performed four times to obtain a pulp component recovery rate.

Comparative Example 1

  A description will be given of Comparative Example 1. The experiment was performed in the same manner as in Example 1 except that stirring was not performed and the reaction time was 3 hours.

Comparative Example 2

  A description will be given of Comparative Example 2. The experiment was conducted in the same manner as in Example 1 except that the papermaking sludge particle size was 1 mm or less and the reaction time was 4 hours.

  The organic component content and inorganic component content contained in the sludge contained in the absolutely dry paper sludge are obtained by calcining dried paper sludge at 700 ° C. for 30 minutes, the lost weight as the organic component amount, and the remaining weight as the inorganic component. Calculated as a quantity.

[Evaluation of Recovery Rate] The inorganic component (WI ₀ ) remaining in the cylindrical container and the organic component (WO ₀ ) recovered using PTFE filter paper are the residual WI after firing the inorganic component using a muffle furnace (Yamato FM37). ₁ and the residue WO ₁ after organic component baking were obtained. For WI ₀ , WO ₀ , WI ₁ , and WO _1, the weight (g) was measured, and the recovery rates of the pulp component and the inorganic component were calculated by the following formula. The weight of the absolutely dry papermaking sludge used was W _total . The organic component content and inorganic component content of the absolutely dry paper sludge used in this experiment were 38.9% and 61.1%, respectively. 0.389 and 0.611 in the formula indicate the values.
Pulp component recovery rate (%) = [(WO ₀ −WO ₁ ) / W _total × 0.389] × 100
Inorganic component recovery rate (%) = [WI ₁ / W _total × 0.611] × 100
Total recovery rate (%) = [(WO ₀ −WO ₁ ) + WI ₁ ] / W _total × 100

  [Quality of recovered pulp component and inorganic component] The recovered pulp component was qualified using a Fourier transform infrared spectrophotometer (FT-IR6100, JASCO Corporation). The result is shown in FIG. From FIG. 1, a peak derived from cellulose was detected and confirmed to be pulp.

  [Quality of recovered inorganic component] The recovered inorganic component was measured using an X-ray diffractometer (RINT2000, Rigaku Denki Co., Ltd.). The result is shown in FIG. From FIG. 2, a peak derived from papermaking sludge was detected, and the inorganic component could be recovered without changing the crystal structure of the inorganic component in the papermaking sludge.

  Tables 1 and 2 show the recoveries of Examples 1 and 2, respectively.

  From Examples 1 and 2, the pulp component recovery rate improved as the reaction time increased. The inorganic component recovery rate was better when the reaction time was shorter. Thus, when the reaction time was 2 hours or 3 hours, both the pulp component and the inorganic component showed a high recovery rate, and the pulp component and the inorganic component could be separated.

  The recovery rates of the ionic liquid and ethanol recovered in Example 3 were 95.2% and 92.3%, respectively. The ionic liquid and ethanol used with the rotary evaporator could be recovered with high efficiency.

  Table 3 shows the results of Example 4.

  From the results in Table 3, the pulp components contained in the papermaking sludge could be recovered even when the recycled ionic liquid was used. From the results of Examples 3 and 4, it was shown that the ionic liquid can be easily recovered and the pulp component dissolving ability of the ionic liquid is maintained.

  In the case of Comparative Example 1, the pulp component recovery rate was 0%. From this, it was found that stirring is important in the present invention.

  In the case of Comparative Example 2, the pulp component recovery rate at the reaction time of 4 hours was the highest at 83.46%. However, the particle size is small, and the outflow of the inorganic component from the reaction vessel occurs, making it difficult to recover the inorganic component. From this, it was found that the particle size also affects the solubility in ionic liquid and the recovery rate.

  According to the present invention, the pulp component contained in the papermaking sludge can be recovered, and the pulp component that could not be reused conventionally can be effectively used. At that time, since an inorganic component or synthetic fiber that cannot be dissolved in the ionic liquid can be taken out, it is possible to separate and recover the inorganic component, the synthetic fiber, and the pulp component. Further, since the used ionic liquid and the added poor solvent can be recovered and reused by distillation under reduced pressure using a rotary evaporator, paper sludge can be recycled with a low environmental load.

Claims (3)

Method of separating and recovering pulp components and inorganic components contained in paper sludge using ionic liquid The method according to claim 1, wherein the ionic liquid has an affinity for a solvent exhibiting poor solvent properties with respect to a solution in which a pulp component is dissolved. The method according to claim 1, wherein the used ionic liquid is recovered, and the recovered ionic liquid is reused.

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