KR101776572B1 - Method for producing anionic nanocellulose flocculant - Google Patents

Abstract

The present invention relates to a method for producing an anionic nanocellulose coagulant used for wastewater treatment by recycling waste paper such as woodfree paper like copying paper printed by a toner ink. The method for producing an anionic nanocellulose coagulant comprises a dissociation step, a deinking step, an oxidizing step and a homogenization step.

Description

TECHNICAL FIELD The present invention relates to an anionic nanocellulose flocculant,

The present invention relates to a method for producing an anionic nano-cellulose coagulant used for wastewater treatment by recycling waste paper such as a copy paper printed with a toner ink.

Sludge discharged from industrial wastes and municipal wastewater treatment process is high in water content and contains a large amount of organic matter, which causes great environmental damage due to the generation of odor and pest in wastewater treatment process. In recent years, there has been an attempt to reuse organic substances contained in sludge rather than disposal of sludge having a high content of organic matter.

In order to reuse the sludge, it is important to lower the water content of the sludge to a certain level. Flocculant pretreatment method, sludge washing method and heat treatment method are used as effective concentration and dewatering methods of sludge. In consideration of economical aspect, flocculant pretreatment method is most effective.

The flocculant pretreatment method utilizes the principle of electrically neutralizing the surface of the sludge particles by treating the flocculant or enhancing the dehydration property through ion exchange with the ions present in the floc. For example, a cationic flocculant is used in wastewater treatment including sulfide or clay, and an anionic coagulant is mainly used in treating wastewater containing metal hydroxide.

The flocculant is largely composed of an inorganic coagulant including aluminum sulfate (Al 2 O ₃ ), ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum polychloride (PAC) . The polymer flocculant has an advantage that the sludge generated in comparison with the inorganic coagulant is relatively small and the dehydration property is improved.

Polymer flocculants are classified into cationic, anionic, and nonionic. The cationic polymer flocculant is used for sedimentation and floatation separation of a suspension having a negative electron (zeta potential), and specifically, water-soluble aniline resin hydrochloride, polythiourea hydrochloride, polyethylene aminotriazole, polyvinylbenzyltrimethylammonium chloride, chitosan , Polyethyleneamine, vinylpyridine copolymer salt, and the like. The anionic polymer flocculant is used for sedimentation and floatation separation of an inorganic suspension having a cationic charge, and specifically may include sodium alginate, sodium polyacrylate, maleic acid copolymer salt, and polyacrylamide partially hydrolyzate. The nonionic polymer flocculant is used for sedimentation and floatation separation of an inorganic mixed suspension, and may specifically include polyacrylamide, polyethylene oxide, and the like.

Recently, natural plant-based coagulants have also been developed. For example, biopolymers extracted from plants such as Nirmali seeds, M. Oleifera, Tannin, and Cactus have been used as coagulants. In addition, Chemical Engineering Journal 231 (2013) 59-67 ( non-patent document 1) after the oxidation by the hydroxyl groups of the C2 and C3 positions of the cellulose with the periodic acid sodium salt (NaIO ₄₎ converted to an aldehyde group, ah aldehyde group There is a method in which dicarboxylic acid nanocellulose prepared through a two-step oxidation process in which sodium carbonate (NaClO ₂ ) is oxidized to a carboxylic acid group is used as a coagulant for wastewater treatment.

However, as disclosed in the present invention, a method for producing an anionic nano-cellulose flocculant using waste paper as a raw material has not been disclosed in any literature.

Chemical Engineering Journal 231 (2013) 59-67 "Coagulation-flocculation treatment of municipal wastewater based on anionized nanocelluloses &

An object of the present invention is to provide a method for producing an anionic nano-cellulose coagulant used for wastewater treatment by using waste paper as a raw material.

In order to solve the above problems, the present invention provides a method for producing an anionic nano-cellulose flocculant by recycling waste paper,

a) a dissociation step of decomposing the waste paper to obtain a fibrous slurry;

b) deinking step of obtaining a stock from which the ink or filler has been removed from the fibrous slurry;

c) an oxidation step of treating the cellulose contained in the stock with an oxidizing agent to produce oxidized cellulose; And

d) homogenizing the oxidized cellulose to produce an anionic nano-cellulose flocculant; / RTI >

(C) the oxidation step is carried out using a primary oxidation step carried out using an oxidizing agent of an alkali metal iodate (MIO ₄ , where M is an alkali metal element) oxidizing agent and a polyalkylene oxide copolymer represented by the following formula , And sodium hypochlorite (NaClO ₂ ) oxidizing agent.

[Chemical Formula 1]

[EO] _x - [PO] _y

(Wherein EO is ethylene oxide repeating unit, PO is propylene oxide repeating unit, x and y are the number of moles of each repeating unit, and the mole ratio of x: y is in the range of 10 to 40: 60 to 90)

The present invention produces a high value-added flocculant for water treatment from waste paper, and therefore has a favorable effect in terms of environmental friendliness and economy.

Further, in the production method of the present invention, the effect of increasing the content of carboxylic acid groups in the cellulose fibers by using the polyalkylene oxide copolymer represented by the above formula (1) as an oxidizing auxiliary in the oxidation step of converting the hydroxyl groups in the cellulose into carboxylic acid groups .

In addition, the anionic nano-cellulose coagulant prepared in the present invention has properties that are useful for coagulant application because it can be uniformly dispersed in wastewater without agglomeration due to electrostatic repulsion between carboxylic acid groups.

1 is a field emission scanning electron microscope (FE-SEM) photograph of the anionic nanocellulose coagulant prepared in the present invention.
2 is a scanning electron microscope (SEM) photograph of the anionic nanocellulose coagulant prepared in the present invention.
3 is a graph showing the standard potential of the anionic nanocellulose coagulant prepared in the present invention.

The present invention relates to a method for producing anionic nanocellulose coagulant using waste paper as a raw material.

A method for producing an anionic nano-cellulose flocculant according to the present invention comprises:

a) a dissociation step of decomposing the waste paper to obtain a fibrous slurry;

b) deinking step of obtaining a stock from which the ink or filler has been removed from the fibrous slurry;

c) an oxidation step of treating the cellulose contained in the stock with an oxidizing agent to produce oxidized cellulose; And

d) homogenizing the oxidized cellulose to produce an anionic nano-cellulose flocculant; .

The method for producing the anionic nanocellulose coagulant according to the present invention will be described in more detail as follows.

Step a) is a dissociation step of decomposing the waste paper to obtain a fibrous slurry.

The waste paper used as a raw material in the present invention can be a corrugated cardboard box, a waste newspaper, a waste paper, and the like. In the following embodiments, a white ledger such as a copy paper printed with a toner ink is used. Even if similar other waste paper is used, the object of the present invention can be sufficiently achieved.

The dissociation step may be carried out by a conventional method of separating waste paper into a fibrous form by applying a chemical or mechanical shearing force thereto. That is, in the dissociating step, the waste paper is dissociated by a pulper to peel off the ink particles from the surface of the fiber, and the peeled ink particles are broken down to a size (10 to 150 mm) And then aging to prevent adsorption to obtain a fiber slurry.

Specifically, pulp was pulsed with helical pulp at an agitation speed of 200 to 400 rpm under the condition of pH 10 to 12 by adding pulp paper and water having a pulping concentration of 10 to 15% by weight. When pulping is maintained at a temperature of 50 to 70 캜, the dissociation efficiency can be further increased. After pulping, the sample was concentrated to a concentration of 3 to 10 wt%, and aged at a temperature of 40 to 60 ° C for 20 to 60 minutes to obtain a fibrous slurry.

Also, if necessary, deinking agent may be added in the pulping process. When the deinking agent is added to the pulping process, the ink may be trapped together with the bubbles to be more easily removed, or the effect of removing the ink adsorbed on the fibers by the deinking agent may be expected. In general, deinking agents include fatty acids, fatty acid derivatives, fatty acid alcohol derivatives and the like, and since they have different foaming properties, entrapment properties and spreading properties, suitable ones can be selected and used.

In the present invention, an alkoxylated fatty acid alcohol represented by the following general formula (2) can be used as a deinking agent.

(2)

[FA] [EO] _a [PO] _b

(Wherein FA is a fatty acid alcohol having 10 to 20 carbon atoms, EO is an ethylene oxide repeating unit, PO is a propylene oxide repeating unit, a and b are EO obtained by addition-polymerizing a hydroxyl group (OH) The number of moles of PO is an integer of 10 to 30, respectively, wherein the molar ratio of a: b is in the range of 1: 0.8 to 1.2)

The deinking agent represented by the above formula (2) has a strong permeability to ink due to the nature of the fatty acid alcohol, exhibits a strong ink peeling action, and has an advantage that the size of the ink particles is largely peeled off to facilitate the floating treatment. In the case of the deinking agent represented by the above formula (2), by adjusting the HLB (Hydrophile-Lipophile Balance) value by controlling the molar ratio of EO and PO, a more desirable effect is obtained in collecting the ink particles from the fibrous slurry in the deinking process You can expect. Preferably, the deinking agent of Formula 2 has a weight average molecular weight (Mw) in the range of 1,500 to 3,000 and a molar ratio of ethylene oxide (EO) to propylene oxide (PO) added to the fatty acid alcohol (FA) It is preferable to use the one adjusted in the range of 0.8 to 1.2.

The amount of the deinking agent represented by Formula 2 may be 0.1 to 1 part by weight based on 100 parts by weight of waste paper. If the amount of the deinking agent used is too small, the effect of adding the deinking agent can not be expected. On the contrary, when the amount of the deinking agent used exceeds the above range and is used in an excess amount, the ink particles adhere to each other in the fiber slurry state in the deinking process step so that the ink particles do not float over the water surface and are dispersed or precipitated in the slurry form, And the ink particles may adhere to the surface of the deinking apparatus to cause a problem of contamination of the apparatus.

If necessary, enzymes such as cellulase and xylanase may further be added and dissociated in the range of pH 8 to 12.

Step b) is a deinking step of removing ink from the fibrous slurry obtained through the dissociation process.

Deinking is a step of removing the ink separated and dispersed in the fibers through the above-mentioned dissociation process by the flotation process and the cleaning process. The deinking process can be influenced by the amount of introduced bubbles, the size of the bubbles, the size of the ink adhering to the bubbles, and the like.

Specifically, the fibrous slurry obtained through the dissociation process is agitated at a speed of 200 to 400 rpm to agitate the ink particles, which have been peeled off from the fibers, to be uniformly dispersed without re-adsorption on the fibers. Then, an ink removing operation is performed using a flotation type deinking device to remove foreign substances including ink. The float treatment can be carried out at a temperature of 30 to 50 ° C and a pH of 9 to 10.

Step c) is an oxidation step for converting the hydroxyl groups of the cellulose contained in the ground treated by the deinking process into a carboxylic acid group.

In the oxidation step, an anionic cellulose is produced by introducing a carboxylic acid group onto the surface of the cellulose fiber.

Generally, in the oxidation reaction of cellulose, the hydroxyl group (OH) group is preferentially converted to the aldehyde group (COH) as shown in Reaction Scheme 1 below, and when it is further oxidized, it is converted into the carboxylic acid group (COOH).

[Reaction Scheme 1]

Alcohol (-OH) → aldehyde (-COH) → carboxylic acid (-COOH)

In Chemical Engineering Journal Journal 231 (2013) 59-67 (Non-Patent Document 1) exemplified in the above-mentioned conventional invention, the cellulose is oxidized to an aldehyde group by sodium diiodate (NaIO ₄ ), and then the aldehyde group is converted into sodium hypochlorite NaClO ₂ ) to convert it to a carboxylic acid group. However, in the non-patent document 1, virgin cellulose is used as the raw material, but the present invention differs from the above in that the recycle cellulose obtained through the dissociation and deinking process of the waste paper is used as a raw material. Therefore, when the two-step oxidation process proposed in the non-patent document 1 is applied to the oxidation process of the recycle cellulose of the present invention, the carboxylic acid substitution ratio is very low as about 1.07 mmol / g in relation to the cellulosic weight. [Refer to Comparative Example 1 of Table 1]

Accordingly, in the present invention, as a method for improving the substitution ratio of carboxylic acid, a method of further adding a polyalkylene oxide copolymer represented by the following formula (1) as an oxidation auxiliary agent in a primary oxidation step using an oxidizing agent of an alkali metal periodate is newly developed Respectively.

[Chemical Formula 1]

[EO] _x - [PO] _y

(Wherein EO is ethylene oxide repeating unit, PO is propylene oxide repeating unit, x and y are the number of moles of each repeating unit, and the mole ratio of x: y is in the range of 10 to 40: 60 to 90)

The oxidation auxiliary agent represented by the formula (1) is a polymer material prepared by copolymerizing 10 to 40 mol% of ethylene oxide and 60 to 90 mol% of propylene oxide, and has a weight average molecular weight of 2,000 to 3,000 g / mol. In the oxidation auxiliary agent represented by the general formula (1), a higher molar ratio of propylene oxide (PO) to ethylene oxide (EO) is more advantageous in the oxidation reaction. This is because the molecular weight of propylene oxide (PO) in the oxidation auxiliary agent represented by the above formula (1) is increased and the surface of the cellulose is modified to be hydrophobic, so that the reactivity with the oxidizing agent of the periodic acid metal salt can be further improved. The molar ratio of EO: PO constituting the copolymer is preferably controlled to 10 to 40: 60 to 90 mol%, more preferably the molar ratio of EO: PO is controlled to 10 to 20 : 80 to 90 mol%.

The oxidation auxiliary agent represented by the above formula (1) may be used in an amount of 1 to 5 parts by weight based on 100 parts by weight (solid content) of the ground. If the amount of the above-mentioned oxidizing auxiliary agent is too small, the effect of accelerating the oxidation of the alkali metal periodate can not be expected. On the other hand, if the amount of the above-mentioned oxidizing auxiliary agent used exceeds the above range and is used in an excess amount, the oxidation promoting effect can not be expected further, so that the economical efficiency may be lowered.

The oxidation process of the paper stock according to the present invention will be described in more detail as follows.

The oxidation of the paper stock of the present invention may be carried out by a primary oxidation process using an oxidizing agent of an alkali metal iodate oxidant and a polyalkylene oxide copolymer represented by the general formula (1); And a secondary oxidation process using sodium hypochlorite (NaClO ₂ ) oxidizing agent; Lt; / RTI >

Specifically, 100 to 200 parts by weight of an oxidizing agent of an alkali metal iodate and 1 to 5 parts by weight of an oxidizing auxiliary represented by the general formula (1) are used based on 100 parts by weight (solids content) of the ground. The primary oxidation process can be carried out at a temperature of 30 to 70 ° C, preferably at a temperature of 40 to 60 ° C. The primary oxidation process time may be 1 to 8 hours, preferably 1 to 5 hours. The oxidized cellulosic fibers obtained through the first oxidation step may be washed with distilled water until the pH is about 6-8.

The oxidized cellulosic fibers after the primary oxidation process have a carboxylic acid group content of about 1.0 to 1.21 mmol / g based on the fiber weight. In addition, the oxidized cellulose fibers are not oxidized by carboxylic acid groups and remain aldehyde groups. Therefore, a secondary oxidation process is performed to convert residual aldehyde groups into carboxylic acid groups after the first oxidation process.

Specifically, in the secondary oxidation step, 150 to 200 parts by weight of sodium hypochlorite (NaClO ₂ ) oxidizing agent is used based on 100 parts by weight (solid content) of the primary oxidized cellulose fiber, Can be performed. The secondary oxidation process may proceed at a temperature of 20 to 60 ° C, preferably at a temperature of 20 to 30 ° C. The second oxidation process time may be 30 to 60 hours, preferably 40 to 50 hours. When the secondary oxidation process is completed, residual impurities can be removed through filtration. The oxidized cellulose fibers obtained through the secondary oxidation step may be washed with distilled water until the pH is about 6 to 7.

The cellulose fibers after the second oxidation process have a carboxylic acid group content of about 1.3 to 1.5 mmol / g in terms of fiber weight, and thus can be usefully used as an anionic nano-cellulose coagulant.

Step d) is a step of homogenizing the oxidized cellulose to prepare an anionic nano-cellulose flocculant.

The homogenization can be performed by subjecting a suspension containing oxidized cellulose to a physical impact on the cellulose fibers using a homogenizer such as a high pressure homogenizer. The pressure applied to the oxidized cellulose in the homogenization process is about 300 to 1000 bar, and it is possible to obtain nanofiberized cellulose fibers by circulating 1 to 5 times.

The suspension containing nanofibrated cellulose fibers obtained after the homogenization process can be used directly as a coagulant for wastewater treatment.

Considering the convenience of storage and distribution, it may be commercially advantageous to convert the suspension containing nanofibrated cellulosic fibers into a solid form through a conventional dehydration process. The dehydration of the suspension containing the nano-sized cellulosic fibers can be carried out using a conventional dehydration method such as an electric dryer, a vacuum dryer, a hot air drier or a freeze dryer.

The nanocellulose fiber obtained through the above-mentioned production method is an anionic nanocellulose fiber having a carboxylic acid group introduced on its surface, and can be used as an anionic coagulant for wastewater treatment.

The present invention will now be described in more detail with reference to the following examples, but the present invention is not limited thereto.

[Examples] Preparation of anionic nano-cellulose coagulant

Example 1.

a) dissociation step

200 g of waste paper and an amount of 65 DEG C in an amount corresponding to 13% by weight of a pulping concentration were added to a helico type pulpper, and then an alkoxylated fatty acid alcohol of the formula (2) 1 g of an oleic alcohol having a weight average molecular weight of 2200 and a molar EO: PO molar ratio of 1: 1) was added thereto, and then sodium hydroxide (NaOH) was added thereto to adjust the pH to about 10 to 11. The mixture was stirred at 300 rpm for 30 minutes / RTI > After pulping, 170 g of pulp slurry (solid content) was sampled and diluted to a concentration of 5% by weight, and then aged in a constant temperature water bath at 50 캜 for 30 minutes. After aging, the mixture was diluted to a concentration of 1% by weight with water at 45 캜, and the ink particles peeled off from the fibers were stirred for 3 minutes to prevent re-adsorption to the fibers and uniform dispersion. The fibrous slurry obtained here was used as a raw material in the following deinking step.

b) Deinking step

A deinking device of a floating flotation type was used to remove ink and debris for 5 minutes at a pH of 9.5 and a temperature of 40 DEG C to obtain a flour having a solid concentration of about 1% by weight. The obtained paper stock was used as a raw material in the following oxidation step.

c) oxidation step

c-1) primary oxidation

0.005 g of diethylenetriaminepentaacetic acid pentasodium (DTPA 5Na) as a chelating agent was added to 1 kg of solid matter (solid content: 10 g) having a solid content concentration of 1% by weight, and the mixture was stirred at room temperature for 30 minutes. 10 g of sodium periodate sodium salt and 10 g of a polyalkylene oxide copolymer (PE-61 product of Hannon Chemical Co., Ltd., weight average molecular weight 2000 to 2500, EO: PO molar ratio 10: 90). The reaction was conducted at 50 캜 for 3 hours using a silicone oil bath. The oxidized cellulose fibers were separated by filtration using a wire net (150 mu m), and the filtration was repeated until the oxidized cellulose fibers were not filtered. The obtained oxidized cellulose fibers were repeatedly washed several times with distilled water using a filter paper (whatman filter papers 541, 11 cm in diameter) to obtain a final pH of 7. The oxidized cellulosic fibers prepared through the above-mentioned primary oxidation process were stored in a refrigerator at 4 ° C.

c-2) secondary oxidation

Using 0.5 M sodium acetate buffer (pH 4.5 adjusted with acetic acid), the oxidized cellulose fibers prepared through the primary oxidation process were diluted to a solids concentration of 1 wt%. 18 g of sodium chlorite (NaClO ₂ ) was added to 1 kg of the oxidized cellulose fiber having a solid content concentration of 1 wt% (10 g in terms of solid content), and then the mixture was stirred at room temperature for 48 hours at a speed of 500 rpm. The solid fibers were filtered using a filter paper (whatman filter papers 541, diameter 11 cm) and washed several times with distilled water to give a final pH of 7.

The oxidized cellulose obtained by performing the above primary and secondary oxidation processes exhibited a yield of about 60% relative to the weight of the waste paper, and the concentration of the suspension was adjusted to about 0.3% to be applied to the homogenization step.

d) homogenization step

The suspension containing oxidized cellulose in an amount of 0.3% based on the solid content was made into a nanofiber using a high-pressure homogenizer (EMAX TECH MiniDebee). At this time, the inner pressure of the high pressure homogenizer was adjusted to 500 bar, and the nanofiber was formed by circulating it three times. The homogenized nanocellulose fibers were dewatered by a freeze dryer to obtain a solid anionic nanocellulose flocculant.

Example 2.

An anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that 0.3 g of the polyalkylene oxide copolymer as the oxidation aid in the c) primary oxidation step of Example 1 was added.

Example 3.

An anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that 0.4 g of a polyalkylene oxide copolymer as an oxidizing auxiliary in the c) primary oxidation step of Example 1 was added.

Example 4.

The anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that the reaction time was shortened to 1 hour in the c) primary oxidation step of Example 1 above.

Example 5.

The anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that the reaction time was extended to 5 hours in the c) primary oxidation step of Example 1 above.

Comparative Example 1

An anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that the polyalkylene oxide copolymer represented by Chemical Formula 1 was not added as an oxidizing auxiliary in the c) primary oxidation step of Example 1 above .

Comparative Example 2

An anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that the polyalkylene oxide copolymer represented by Chemical Formula 1 was not added as an oxidizing auxiliary in the c) primary oxidation step of Example 1 above , And 15 g of sodium periodate iodide were added.

Comparative Example 3

An anionic nano-cellulose flocculant was prepared from the waste paper by the method of Example 1, except that the polyalkylene oxide copolymer represented by Chemical Formula 1 was not added as an oxidizing auxiliary in the c) primary oxidation step of Example 1 above , And 20 g of sodium periodate.

Photographs of the anionic nano-cellulose coagulant prepared in Example 2 by field emission scanning electron microscopy (FE-SEM) and scanning electron microscope (SEM) were attached to FIGS. 1 and 2, respectively. The shape of the nanofibers can be observed through the field emission scanning electron microscope (FE-SEM) image of FIG. 1, and the size of the coagulant particles can be confirmed through a scanning electron microscope (SEM) photograph of FIG. The anionic nanocellulose coagulant prepared in the present invention has a width of about 5 to 30 nm and a length of about 1 to 10 μm.

[Experimental Example]

Experimental Example 1. Measurement of carboxylic acid group content

The content of carboxyl groups in the cellulose fibers was measured for the cellulose obtained through the primary oxidation process and the secondary oxidation process according to Examples 1 to 5 and Comparative Examples 1 to 3 by the following measurement method. The results are shown in Table 1 below.

≪ Measurement of carboxylic acid group content >

To 50 mL of distilled water was added 0.5 g (weight) of oxidized cellulose fiber to prepare a suspension. The suspension was lyophilized in a vacuum state at -70 캜 or lower for 48 hours using a freeze dryer. 0.2 to 0.3 g of a lyophilized sample was added to 60 mL of distilled water, adjusted to a pH of 3.0 or less with a 0.1 M hydrochloric acid aqueous solution, and then 0.04 M NaOH aqueous solution was added dropwise to adjust the pH to 11 and then the electrical conductivity was measured. Then, the carboxylic acid group content was calculated based on the following formula (1).

[Equation 1]

division  Carboxylic acid group content in cellulose fiber after oxidation (mmol / g) Primary oxidation Secondary oxidation room
city
Yes One 1.13 1.33 2 1.20 1.43 3 1.21 1.42 4 1.10 1.30 5 1.15 1.34 ratio
School
Yes One 0.54 1.07 2 0.62 1.10 3 0.68 1.13

According to the above Table 1, the anionic nano-cellulose flocculant prepared in Examples 1 to 5 has a carboxylic acid group content of not less than 1.3 mmol / g, although waste paper is used as a raw material.

On the contrary, the anionic nano-cellulose flocculants of Comparative Examples 1 to 3, which were prepared without using the polyalkylene oxide copolymer oxidation auxiliary agent, show that the carboxylic acid group content is very low.

According to the results of Table 1, it can be seen that the use of the polyalkylene oxide copolymer auxiliary agent in the primary oxidation step is effective in the process of producing the anionic nanocellulose coagulant using waste paper as a raw material.

Experimental Example 2. Measurement of Standard Potential of Anionic Nanocellulose

The solid anionic nanocellulose prepared in Example 2 was suspended in water at a concentration of 0.1%. 0.010, 0.025, 0.035, 0.040 g of p-diallyldimethylammonium chloride (p-DADMAC; specific gravity 1.085) was added as a cationic coagulant based on 0.1 L of the suspension, and the magnet was stirred directly for 10 minutes. After sufficient agitation, the supernatant was separated by centrifugation (4,000 G) for 5 minutes. The toluidine blue indicator was added to the supernatant and titrated with 0.001 N anionic polyvinylsulfate potassium salt (PVSK).

Then, a positive charge demand was calculated based on the following equation (2).

&Quot; (2) "

The positive charge demand (meq / g) = [(CPA x CPC) - (APU x APC)] / SW

CPQ is the concentration of the cationic coagulant (p-DADMAC) (meq / L), APU is the titration of the anionic PVSK APC is the concentration of anionic PVSK (meq / L), and SW is the usage (g) of the sample)

The positive charge demand amount calculated based on Equation (2) is shown in FIG.

Experimental Example 3. Measurement of Coagulation Effect of Wastewater

Coagulation experiments were carried out using white water (pH 10) from wastewater recycling plant in wastewater.

Before the agglomeration experiment, pH of white water was adjusted to 6.5 ~ 7.5 using acid and base. At this time, the zeta potential is 40 (-mV), the turbidity is 250 NTU, and the COD is about 175 ppm.

The zeta potential was measured with a Zeta-meter (ZM3 + 412, USA), turbidity was measured with a turbidity meter (2100 AN) from Hach, and COD was calculated by the following equation (3).

&Quot; (3) "

COD (mg / L) = (b-a) x f (1,000 / V) x 0.2

(In the equation 3, a is a control appropriate amount (mL) of 0.025N solution of KMnO _4, b is the sample an appropriate amount (mL) of 0.025N solution of KMnO _4, f is 0.025N-KMnO ₄ Factor of the solution and V is the volume (mL) of the sample)

Test solution 1) Anionic nanocellulose 50 ppm suspension

200 mL of white water and 50 ppm of aluminum sulfate (Al ₂ (SO ₄ ) ₃ 18H ₂ O) were added to a beaker, and the mixture was stirred at room temperature for 5 minutes at 200 rpm at a magnetic bar. Subsequently, 50 ppm of the anionic nanocellulose suspension prepared in Example 2 was added, and the mixture was stirred at 50 rpm for 20 minutes. After sufficient stirring, the mixture was allowed to stand for 1 hour to precipitate the contents. The supernatant was taken to measure turbidity and COD.

Test solution 2) Anionic nanocellulose 30 ppm suspension

A test solution was prepared in the same manner as in the preparation of Test Solution 1 except that 30 ppm of anionic nanocellulose suspension was added.

Test solution 3) Anionic nanocellulose 10 ppm suspension

A test solution was prepared in the same manner as in the preparation of Test Solution 1 except that 10 ppm of anionic nanocellulose suspension was added.

Comparative Test 1) 100 ppm aluminum sulfate suspension

A test solution was prepared in the same manner as in the preparation of Test Solution 1 except that no anionic nanocellulose suspension was added and instead, only 100 ppm of aluminum sulfate was added.

Comparative Test 2) A suspension of 50 ppm of aluminum sulfate and 50 ppm of PAM

A test solution was prepared in the same manner as in the preparation of Test Solution 1 except that 50 ppm of aluminum sulfate and 50 ppm of commercial cationic polymer flocculent polyacrylamide (PAM) were added instead of the anionic nanocellulose suspension.

Comparative test solution 3) A suspension of 50 ppm of aluminum sulfate and 30 ppm of PAM

A test solution was prepared in the same manner as in the preparation of Test Solution 1 except that 50 ppm of aluminum sulfate and 30 ppm of commercial cationic polymer flocculant polyacrylamide (PAM) were added instead of the anionic nanocellulose suspension.

Comparative Test 4) A suspension of 50 ppm of aluminum sulfate and 10 ppm of PAM

A test solution was prepared in the same manner as in the preparation of Test Solution 1 except that 50 ppm of aluminum sulfate and 10 ppm of commercial cationic polymer flocculent polyacrylamide (PAM) were added instead of the anionic nanocellulose suspension.

In Table 2, turbidity and COD of the suspensions prepared in Test Solutions 1 to 3 and Comparative Test Solutions 1 to 4 are summarized.

division Turbidity  COD NTU Removal rate (%) ppm Removal rate (%) Sample (white water) 250 0 175 0
Test solution One 100 60 85.8 51 2 118 53 96.3 45 3 130 48 99.8 43
compare
Test solution One 213 15 166.3 5 2 90 64 136.5 22 3 85 66 120.8 31 4 55 78 89.3 49

According to the results shown in Table 2, the anionic nanocellulose coagulant prepared in the present invention was produced by recycling the waste paper, but it is confirmed that the turbidity and the COD value are at the level of the commercial coagulant.

Claims (8)

a) a dissociation step of decomposing the waste paper to obtain a fibrous slurry;
b) deinking step of obtaining a stock from which the ink or filler has been removed from the fibrous slurry;
c) an oxidation step of treating the cellulose contained in the stock with an oxidizing agent to produce oxidized cellulose; And
d) homogenizing the oxidized cellulose to produce an anionic nano-cellulose flocculant; / RTI >
The dissociation step a) is carried out using a deinking agent of an alkoxylated fatty acid alcohol represented by the following formula 2,
(C) the oxidation step is carried out using a primary oxidation step carried out using an oxidizing agent of an alkali metal iodate (MIO ₄ , where M is an alkali metal element) oxidizing agent and a polyalkylene oxide copolymer represented by the following formula , Sodium hypochlorite (NaClO ₂ ), and the like. The method for producing an anionic nano-cellulose flocculant according to claim 1,
[Chemical Formula 1]
[EO] _x - [PO] _y
(Wherein EO is ethylene oxide repeating unit, PO is propylene oxide repeating unit, x and y are the number of moles of each repeating unit, and the mole ratio of x: y is in the range of 10 to 40: 60 to 90)
(2)
[FA] [EO] _a [PO] _b
(Wherein FA is a fatty acid alcohol having 10 to 20 carbon atoms, EO is an ethylene oxide repeating unit, PO is a propylene oxide repeating unit, a and b are EO obtained by addition-polymerizing a hydroxyl group (OH) The number of moles of PO is an integer of 10 to 30, respectively, wherein the molar ratio of a: b is in the range of 1: 0.8 to 1.2)
delete The method according to claim 1,
Wherein an enzyme selected from the group consisting of cellulase and xylanase is further added in the dissociation step a).
The method according to claim 1,
Wherein the oxidized cellulosic fibers produced in the step (c) are bonded with the carboxylic acid groups in an amount of 1.3 to 1.5 mmol / g based on the weight of the fibers.
The method according to claim 1,
Wherein the c) oxidation step is carried out at a temperature of 30 to 70 ° C.
The method according to claim 1,
(C) 100 to 200 parts by weight of an oxidizing agent of an alkali metal iodate based on 100 parts by weight (solids content) of the ground material in the primary oxidation step of the oxidation step, and the oxidizing auxiliary of the polyalkylene oxide copolymer 1 to 5 parts by weight of anionic nano-cellulose.
7. The method according to claim 1 or 6,
Wherein the weight average molecular weight of the polyalkylene oxide copolymer represented by Formula 1 is in the range of 2,000 to 3,000 g / mol. ≪ RTI ID = 0.0 > 1. < / RTI >
The method according to claim 1,
Wherein the step c) is performed at a pH of from 4 to 6, and the second oxidation step of the oxidation step is carried out at a pH of from 4 to 6. The method for producing an anionic nano-

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