KR20220099859A - Absorbent using rice husk and method for manufacturing the same - Google Patents

Abstract

The present invention discloses an adsorbent using rice husk, which has excellent anion adsorbability and anion adsorption selectivity through a graft copolymerization reaction and an amination reaction, and a preparation method thereof. The preparation method of an adsorbent according to the present invention comprises the step of: (a) pre-treating rice husk; (b) mixing the pretreated rice husk with an initiator, a crosslinking agent, an acrylic monomer, and an organic solvent to be graft copolymerized; and (c) adding an amine-based compound to the graft-polymerized polymer to be amineized.

Description

Absorbent using rice husk and manufacturing method thereof

The present invention relates to an adsorbent using rice hull and a method for manufacturing the same.

Ions such as phosphate, nitrate, and arsenic are major nutrients needed for the growth of living things.

However, as the concentration of these ions increases, eutrophication of surface water and groundwater occurs, and water pollution such as green algae and red algae increases.

For example, arsenic is a carcinogen and exists mainly in the form of inorganic anions in natural and drinking water. Many techniques have been developed to remove arsenic from water, such as ion exchange membranes, coagulation, precipitation, and adsorption.

Among them, the adsorption technique is known to be the most effective for removing anions such as arsenic.

An adsorbent used in adsorption technology is a solid material that accepts adsorption, a phenomenon in which molecules of a gas or solution stick to a solid surface. Such an adsorbent is an excellent adsorbent that has a large surface area adsorbed per unit volume, that is, a large reaction area.

Polymer-based adsorbents are mainly used as adsorbents, but there is a limit to adsorbing anions.

An object of the present invention is to provide a method for producing an adsorbent having excellent anion adsorption properties.

Another object of the present invention is to provide a method for preparing an adsorbent having excellent adsorption selectivity for anions.

Another object of the present invention is to provide an adsorbent having excellent anion adsorption properties.

Another object of the present invention is to provide an adsorbent having excellent adsorption selectivity for anions.

The objects of the present invention are not limited to the objects mentioned above, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the appended claims.

The method for producing an adsorbent according to the present invention comprises the steps of (a) pre-treating rice husk; (b) mixing the pretreated rice hull with an initiator, a crosslinking agent, an acrylic monomer and an organic solvent to perform graft copolymerization; and (c) adding an amine-based compound to the graft copolymerized polymer for amination.

The acrylic monomer includes glycidyl methacrylate (GMA), and the amine-based compound is one of diethylenetriamine (DETA), ethylenediamine (EDA), dimethylamine (DMA), and trimethylamine (TMA). may include more than one.

Step (c) may be performed at 40 to 100° C. for 1 to 8 hours.

After the step (c), the method may further include washing and drying the amination product after filtering.

The method for preparing an adsorbent according to the present invention can prepare an adsorbent having excellent anion adsorption property and excellent adsorption selectivity for anion through a graft copolymerization reaction and an amination reaction.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is a cross-sectional view of a grafting reactor used in the method for preparing an adsorbent of the present invention.
Figure 2 shows the reaction temperature of the amine-type rice hull adsorbent (RH- g -GMA-Am) prepared under the conditions of fixing the amination reaction time to 4 hours and changing the reaction temperature in the range of 40 ~ 100 ℃ NO ₃ ^- ions The graph shows the adsorption amount of
3 is a graph showing the adsorption amount of NO ₃ ^- ions by reaction time of RH- g -GMA-Am prepared under the condition that the amination reaction temperature is fixed at 80° C. and the reaction time is changed from 1 to 8 hours.
Figure 4 is a graph showing the NO ₃ ^- adsorption amount of RH- g -GMA-Am activated with hydrochloric acid, brine and caustic soda solution.
5 is a graph comparing the differences in the NO ₃ ^- and PO ₄ ^3- adsorption removal rates of rice hulls, pre-treated rice husks, graft polymers RH- g -GMA, and aminated RH- g -GMA-Am.
6 shows a comparison of FT-IR spectra.
7 is a mechanism showing the process of graft polymerization and amination and chemical structural change.
8 is a SEM photograph of rice husk and amination of RH- g -GMA-Am.
9 is a graph showing the measured values of the surface potential for each pH of rice husk, graft-polymerized RH- g -GMA, and aminated RH- g -GMA-Am.
10 is an evaluation of the adsorption capacity for NO ₃ and PO ₄ of the rice hull adsorbent (RH-g-GAM-Am) aminated using DETA, EDA, DMA and TMA.
FIG. 11 shows that 0.2 g of RH- g -GMA-Am adsorbent was administered to 100 mL of a test solution mixed so that the initial concentration of ions was 0.5 mmol/L, respectively, and adsorbed for 2 hours, then the adsorption amount of each ion, and strong basicity A graph showing the adsorption selectivity of (SAR) and weakly basic (WAR) anion exchange resins.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

When it is described that a component is “connected”, “coupled” or “connected” to another component, the components may be directly connected or connected to each other, but the other component is “interposed” between each component. Alternatively, it will be understood that each component may be “connected”, “coupled” or “connected” through another component.

Hereinafter, an adsorbent using rice hull and a method for manufacturing the same according to some embodiments of the present invention will be described.

The method for producing an adsorbent according to the present invention comprises the steps of (a) pre-treating rice husk; (b) mixing the pretreated rice hull with an initiator, a crosslinking agent, an acrylic monomer and an organic solvent to perform graft copolymerization; and (c) adding an amine-based compound to the graft copolymerized polymer for amination.

The acrylic monomer includes glycidyl methacrylate (GMA), and the amine-based compound is one of diethylenetriamine (DETA), ethylenediamine (EDA), dimethylamine (DMA), and trimethylamine (TMA). may include more than one.

Step (c) may be performed at 40 to 100° C. for 1 to 8 hours.

After step (c), the method may further include washing and drying the aminated product after filtering.

As described above, a detailed example of the adsorbent using rice husk and a method for manufacturing the same will be described as follows.

1. Preparation of adsorbent

1) Preparation of experimental materials and reagents

The rice husks (rice husks) were collected at a local mill. The collected rice hulls were washed several times with distilled water to remove impurities attached to the surface, and then dried at 80°C until constant weight. The dried rice husks were pulverized using a disk mill, sieved, and the particle size was adjusted to 0.3-0.6 mm, and then stored in a desiccator.

Caustic soda (NaOH) was used as a reagent for pretreatment of rice hulls.

-methylene-bis-acrylamide(MBA, Aldrich)를, 반응용매로는 cyclohexane을 각각 사용하였다. 아민화를 위한 시약으로는 diethylenetriamine(DETA, 97%, Daejung), ethylenediamine(EDA, 97%, Deajung), dimethylamine(DMA, 40% in H₂O, Aldrich), trimethylamine(TMA, 30% in H₂O, Yakuri)를 사용하였다. A monomer for introducing an epoxy group is glycidyl methacrylate (GMA, 98%, Junsei), an oxidation-reduction initiator for inducing graft polymerization is potassium peroxydisulphate (K ₂ S ₂ O ₈ ), and a crosslinking agent is

-methylene-bis-acrylamide (MBA, Aldrich) was used, and cyclohexane was used as a reaction solvent, respectively. Reagents for amination include diethylenetriamine (DETA, 97%, Daejung), ethylenediamine (EDA, 97%, Deajung), dimethylamine (DMA, 40% in H ₂ O, Aldrich), trimethylamine (TMA, 30% in H ₂ ). O, Yakuri) was used.

Artificial wastewater for evaluation of rice hull adsorption capacity was prepared by dissolving appropriate amounts of NaF, NaNO ₃ , NaH ₂ PO ₄ , Na ₂ SO ₄ in distilled water or an acetic acid buffer solution. An acetic acid buffer solution was prepared using CH ₂ COOH and CH ₃ COONa. As comparative adsorbents, Samyang's strongly basic anion exchange resin (TRILITE SAR10, -N ⁺ (CH ₃ ) ₃ Cl ^- ) and weakly basic anion exchange resin (DIAION WA30, -(CH ₂ ) _n N ⁺ (CH ₃ ) ₂ ) was used.

2) Preparation of adsorbent using rice husk

In order to remove the soluble components and phenolic compounds in the rice husk, it was pre-treated with a caustic soda solution. 10 g of rice husk was added to 100 mL of 5% caustic soda solution, stirred at 50° C. for 2 hours (120 rpm), and then filtered using GF-C filter paper. The solids on the filter paper were washed with distilled water until the pH of the washing solution reached 6.0, and then completely dried at 80°C.

100 mL of distilled water, 10 g of pretreated rice husk, 1 g of K ₂ S ₂ O ₈ and 0.5 g of MBA were added to a 500 mL three-necked flask-type reactor, and stirred for 5 minutes using a mechanical stirrer to mix (FIG. 1). A monomer solution of 15 mL of GMA and 15 mL of cyclohexane was added to this mixture, and a graft copolymerization reaction of rice husk and GMA was induced while stirring (150 rpm) at 70° C. for 4 hours. After the reaction was completed, the rice hulls were separated through filtration, washed with distilled water 2-3 times, and completely dried at 60°C.

For the amination reaction, put 5 g of GMA graft copolymerized rice hull (RH- g -GMA) and 50 mL of amine reagents in a 100 mL glass bottle, seal completely with a lid, and leave at 40 to 100°C for 1 to 8 hours while standing for 30 It was carried out by shaking and redispersing at intervals of minutes.

After the reaction was completed, the rice hulls were separated by filtration, washed sufficiently with distilled water to completely remove unreacted amines, and then completely dried at 60° C. and stored in a desiccator. In order to confirm the effect of activation on the adsorption capacity, a part of the washed rice husk was treated with 0.2 M hydrochloric acid solution (HCl), 0.2 M brine (NaCl) and 0.2 M caustic soda solution (NaOH) at room temperature for 2 hours, after which the pH It was washed with distilled water until neutral and dried.

3) Characteristics evaluation of adsorbent

Scanning electron microscope (SEM: Shimadzu S-3000N) observation, FT-IR (Magna IR) to examine the surface characteristics and chemical structure change of rice hull (RH- g -GMA-Am) in which GMA is graft copolymerized and amine group is introduced Spectrometer 550) analysis and surface potential analysis were performed.

Surface potential analysis was carried out by dispersing 0.4 g of the sample in 200 mL of 0.01M NaCl solution, adding 0.1M HCl and 0.1M NaOH, and titrating to pH 3 to 11.

(C/cm²)는 산 및 염기의 첨가량과 측정된 평형 pH를 바탕으로 계산하였다.surface dislocation density

(C/cm ² ) was calculated based on the amount of acid and base added and the measured equilibrium pH.

(1)

(One)

where F is the Faraday constant (96,500 C/mol), W is the dose of rice husk (g/L), C _A and C _B are the concentrations of acid and base (mol/L), [H ⁺ ] and [OH ^- ] is the equilibrium concentration of H ⁺ and OH ^- ions, and A is the specific surface area of the rice husk (cm ² /g).

The evaluation of adsorption characteristics was carried out based on a batch type adsorption experiment in which 0.2 g of rice hull adsorbent was administered to 100 mL of artificial wastewater of known ionic species and concentration, and then stirred at 25° C. at 150 rpm using a constant temperature stirrer.

After the adsorption was completed, it was filtered using a 0.45 μm thin-film filter paper, and the concentration of anions remaining in the filtrate was analyzed using a UV spectrometer (Shimadzu UV 2401-PC) or LC (Waters LC system). The adsorption amount, q (mg/g), was calculated based on the anion mass balance between the stock solution and the filtrate after the adsorption reaction.

(2)

(2)

Here, C _o and C are the cation concentrations (mg/L) of the filtrate after the initial and adsorption experiments, respectively, V is the volume of the experimental solution (L), and W is the dose (g) of rice husk.

2. Physical property evaluation result

One) In 100 mL of distilled water, 10 g of rice husk as a substrate polymer, 1 g of K ₂ S ₂ O ₈ as an oxidation-reduction initiator, 15 mL of GMA as a monomer, 0.5 g of MBA as a crosslinking agent, and 15 mL of cyclohexane as a solvent are added and mixed. As a result of inducing a polymerization reaction for 4 hours, rice hull-GMA polymer (RH- g -GMA) grafted with 110 to 130% of GMA was obtained.

Amination conditions were studied using this polymer as a matrix polymer. In order to examine the conditions for the amination of RH- g -GMA, DETA was first used as an amination reagent, and the amination efficiency according to the reaction temperature and reaction time was evaluated based on the NO ₃ ^- adsorption capacity.

Figure 2 shows the reaction temperature of the amine-type rice hull adsorbent (RH- g -GMA-Am) prepared under the conditions of fixing the amination reaction time to 4 hours and changing the reaction temperature in the range of 40 ~ 100 ℃ NO ₃ ^- ions shows the amount of adsorption.

As shown in FIG. 2, the adsorption amount of NO ₃ ^- ions increased by about 27% from 23.30±0.26 mg/g to 29.53±0.59 mg/g when the reaction temperature was raised from 40°C to 60°C, but at 80°C and 100°C. At ℃, the adsorption amount was 30.20±0.88 mg/g and 31.10±1.65 mg/g, respectively, which increased only 3~7% compared to the 60℃ condition, so the effect of temperature increase on the adsorption amount was small.

Figure 3 shows the adsorption amount of NO ₃ ^- ions by reaction time of RH- g -GMA-Am prepared under the condition that the amination reaction temperature is fixed at 80 ° C and the reaction time is changed from 1 to 8 hours. The adsorption amount increased to 18.20±1.90 mg/g, 28.09±0.89 mg/g, and 30.20±0.88 mg/g as the time was increased to 1 hour, 2 hours, and 4 hours. showed a trend.

From the above results, it can be seen that amination of RH- g -GMA is sufficiently achieved when the reaction temperature is 60° C. or more and the reaction time is 4 hours or more.

In general, after the amination reaction, treatment with dilute hydrochloric acid to activate the amine group is widely used.

Accordingly, in this study, to confirm the effect of amine group activation on the adsorption amount, RH- g -GMA-Am was mixed with 0.2M hydrochloric acid solution (HCl), brine (NaCl) and caustic soda solution (NaOH) at room temperature for 2 After activation by treatment for a period of time, the adsorption capacity of each was compared with that without activation.

The evaluation of the adsorption capacity according to the activation was carried out at a constant pH (4.7) condition using an acetic acid buffer in order to minimize the effect of pH on the adsorption capacity.

As a result, as shown in FIG. 4, the NO ₃ -adsorption amount of RH ^- g -GMA-Am activated with hydrochloric acid, brine and caustic soda solution was 26.50±1.21 mg/g, 26.17±2.02 mg/g, and 25.63±1.98, respectively. It showed a slight increase compared to RH- g -GMA-Am (25.33±1.96 mg/g) not activated at mg/g, but the difference was less than 5%. it can be seen that

Therefore, the activation process was omitted in subsequent experiments.

Figure 5 shows the difference in the NO ₃ ^- and PO ₄ ^3- adsorption removal rate of rice hull, pre-treated rice husk, graft polymer RH- g -GMA and aminated RH- g -GMA-Am. In the case of NO ₃ ^- , at an initial concentration of 1 mmol/L and an adsorbent dose of 2 g/L, rice hull was 0.8%, pre-treated rice hull was 3.6%, and RH- g -GMA was 6.3%, showing a very low adsorption removal rate. Minified RH- g -GMA-Am showed an adsorption removal rate of 85.6%, which was more than 100 times higher than that of untreated rice husk. In the case of PO ₄ ^3- , 11.6% of rice hull, 15.0% of pre-treated rice hull, and 16.0% of RH- g -GMA were adsorbed and removed under the same adsorption test conditions. It increased more than 8 times compared to untreated rice husk.

The above results support that an amine group was introduced to the surface of the rice hull through GMA graft polymerization and amination reaction, and the introduced amine group functions as an anion adsorption functional group.

2) Chemical structure and surface properties of adsorbent

In order to check the chemical structure and surface properties change of rice hull by pretreatment, graft polymerization, and amination reaction, rice husk, pre-treated rice husk, graft polymer RH- g -GMA and aminated RH- g -GMA-Am FT-IR analysis, surface potential analysis and SEM observation were performed.

6 is a comparison of FT-IR spectra, in the case of untreated and pre-treated rice husks, peaks due to CO stretching of cellulose at 1030 cm ^-1 and 1440 cm ^-1 , 1650 cm ^-1 and 3300 cm ^-1 CH, CC in the vicinity And while it is characterized by peaks due to OH, in the case of rice hulls in which GMA is graft polymerized, peaks due to C = O and CH stretching are newly detected in the vicinity of 1720 cm ^-1 and 2930 cm ^-1 It was confirmed that GMA was introduced on the surface of the rice husk.

On the other hand, in the case of aminized rice hull, peaks of -CH ₂ -NHR ₂ type nitrogen and aliphatic CN group were characteristically detected in the vicinity of 1480 cm ^-1 and 2840 cm ^-1 , confirming the presence of an amine group.

The graft polymerization and amination process and chemical structural change estimated based on this are shown in FIG. 7 .

Figure 8 shows the contrast of SEM images of rice husk and amination RH- g -GMA-Am. Although the surface of the rice hull consists of an outer side made of numerous projections and a flat and smooth inner side (Fig. 8b) It shows well that GMA is graft-polymerized in the form of a polymer on the surface of the rice hull.

9 is a comparison of the surface potentials by pH for rice hull, graft-polymerized RH- g -GMA and amination RH- g -GMA-Am, and the surface potential of rice husk and RH- g -GMA is pH _pzc showed a difference of 6.2 and 7.2, respectively, but showed similar characteristics without significant change except in the strongly acidic and strongly alkaline areas.

On the other hand, the surface potential of RH- g -GMA-Am showed a characteristic of changing into a large positive value and a negative value depending on the pH based on pH _pzc 6.4. This means that at pH 6.4 or less, the surface becomes strongly positively charged, so that the adsorption of negatively charged ionic species can be made more easily.

3) Adsorption and adsorption selectivity for each amine reagent

The amination reaction is a process of introducing a functional group of positive potential by chemically bonding an amine (-NH ₂ ) to an epoxy group (-COC-) of GMA graft-polymerized on the surface of rice husk as shown in FIG. Anion adsorption functionality is influenced by the amine group.

There are three types of amines: primary, secondary, and tertiary amines depending on the number of hydrogens substituted with an alkyl derivative of ammonia. Primary amine (R-NH ₂ ) is most widely used in the amination reaction for introducing anion adsorption functional group, but secondary amine (2R-NH) and tertiary amine (3R-N) are sometimes used.

In this study, the primary amine EDA (H ₂ N(CH ₂ ) ₂ NH ₂ ) and the secondary amine DMA((CH ₃ ) ₂ NH ) and _TMA (( _{CH 3} ) _{3 N} ) _, which is _a tertiary amine _, were additionally selected to Minification reaction was carried out, and the adsorption capacity and adsorption selectivity of each product (RH- g -GMA-Am) for anions were comparatively evaluated.

10 is an evaluation of the adsorption capacity for NO ₃ and PO ₄ of the rice hull adsorbent (RH-g-GAM-Am) aminated using DETA, EDA, DMA and TMA. Commercial strong basicity evaluated under the same conditions The adsorption capacity of (SAR) and weakly basic (WAR) anion exchange resins are compared.

The adsorption experiment was conducted by administering 0.2 g of an adsorbent to 100 mL of a test solution containing 1.0 mmol/L of NO ₃ or PO ₄ ions as a single ion species and adsorbing them for 2 hours. As the blank solution, an acetic acid buffer solution (pH 4.7) with a total concentration of 0.01 M was used to maintain a constant pH condition.

The adsorption capacity of RH- g -GMA-Am was generally high in the order of DETA≥EDA>DMA>TMA, showing a tendency to decrease as the primary amine was highest, followed by secondary and tertiary amines.

_In addition, the adsorption capacity for each ion is PO ₄ >NO ₃ in the case of DETA and EDA and NO ₃ >PO ₄ in the case of DMA and TMA _. showed higher characteristics.

Since the bond between the epoxy group and the amine group of GMA is formed in a form in which the methylene group (-CH ₂ ) of the epoxy group replaces the hydrogen of the amine together with the ring-opening reaction of the epoxy group (FIG. 7), the primary amine In the case of secondary amines, secondary amines, tertiary amines, and tertiary amines, considering that they must be combined in the form of quaternary ammonium salts, the difference in adsorption capacity for each amine type is due to the ease of bonding (reaction) between the epoxy group and the amine and the molecule of the bound amine group. This is thought to be due to the different structures.

All of the anion exchange resins used as comparative adsorbents had adsorption functional groups in the form of tertiary amines, and their adsorption capacity was NO ₃ >PO ₄ .

In the case of amination using TMA, the lowest adsorption capacity is considered to be because TMA must be converted to a quaternary ammonium salt, so there may be differences in the molecular structure of the amine group, but binding to GMA was not relatively easy.

Liu et al have suggested that hydrochloric acid (HCl) can be used as a catalyst in the amination reaction of an epoxy group using TMA, so it is necessary to review this later.

F, NO ₃ , PO ₄ , SO ₄ were selected as anions to examine the adsorption selectivity of rice hull adsorbent (RH- g -GMA-Am) for anions, and the adsorption capacity for each ion was compared when these ions coexist. evaluated.

In order to evaluate the adsorption competition between ions in the same pH environment, based on a total concentration of 0.01M acetic acid buffer (pH 4.7), add RH- g - After administration of 0.2 g of GMA-Am adsorbent and adsorption for 2 hours, the adsorption amount of each ion was calculated and shown in FIG. 11 .

In addition, in order to compare the adsorption selectivity of the RH- g -GMA-Am adsorbent with the currently commercially available anion exchange resins, the adsorption selectivity of strong basic (SAR) and weakly basic (WAR) anion exchange resins was evaluated under the same adsorption experimental conditions. is shown in comparison with FIG. 11 .

The adsorption selectivity of RH- g -GMA-Am was also dependent on the amine type used for amination. That is, when DETA and EDA are used as amination reagents, the adsorption selectivity for anions is SO ₄ >PO ₄ >NO ₃ >F, whereas when DMA is used, SO ₄ >NO ₃ >PO ₄ >F. , and NO ₃ showed higher selectivity compared to PO ₄ like commercial anion exchange resins.

TMA showed adsorption selectivity similar to that of DMA, but the adsorption capacity of all ionic species except SO ₄ was very low, so its effectiveness as an amination reagent was questionable.

The difference in adsorption selectivity is -1 valence (NO ₃ ^- , H ₂ PO ₄ ^- , F ^- ) except for SO ₄ ^2- ions, where each anionic species is -2 in the adsorption experimental condition (pH 4.7) of this study. Considering the point, it can be seen that the difference in the molecular structure of the amine group, which is the anion adsorption functional group, is reflected along with the difference in oxidation number.

The total anion adsorption amount of RH- g -GMA-Am adsorbent (Am=DETA, EDA, DMA, TMA) and commercial anion exchange resin (SAR, WAR) was highest in the order of DETA≥EDA>SAR>WAR>DMA>TMA. .

From the above results, it can be seen that the RH- g -GMA-Am adsorbent aminated using DETA or EDA can be used as a PO ₄ -P selective adsorbent having an adsorption capacity equal to or higher than that of a commercial anion exchange resin.

4) Conclusion

In order to prepare a biosorbent capable of removing anions in an aqueous solution using rice hull, an agricultural by-product, a method of introducing an anion adsorption functional amine group to the surface of the rice hull through graft polymerization and amination reaction was reviewed. could come to a conclusion.

1. By chemically bonding GMA through a graft polymerization reaction using K ₂ S ₂ O ₈ as an oxidation-reduction initiator, and then reacting it with an amine. Could.

Through this, it was possible to improve the adsorption capacity of rice hulls by more than 100 times for NO ₃ -N and more than 8 times for PO ₄ -P.

2. The introduction of an amine group, a functional group with an anion adsorption function, was made through an amination reaction in which the epoxy group of GMA graft-polymerized on the surface of the rice hull and an amine were combined. It was over 4 hours.

3. The anion adsorption capacity and adsorption selectivity of amination rice hull (RH- g -GMA-Am) were different depending on the type of amine used in the amination reaction.

That is, the adsorption capacity was high in the order of DETA≥EDA>DMA>TMA, showing the highest primary amine, secondary amine and tertiary amine decreasing in the order, showing characteristics inversely proportional to the amine order.

The adsorption selectivity of DETA and EDA was in the order of SO ₄ >PO ₄ >NO ₃ >F, whereas DMA and TMA showed the highest in the order of SO ₄ >NO ₃ >PO ₄ >F.

Primary amine had higher adsorption capacity for PO ₄ , and secondary and tertiary amines exhibited higher adsorption capacity for NO ₃ .

4. Total anion adsorption amount is RH- g -GMA-DETA≥RH- g -GMA-EDA>Strongly basic anion exchange resin>Weakly basic anion exchange resin>RH- g -GMA-DMA>RH- g -GMA-TMA appeared higher in the order of It was found that the rice hull adsorbent obtained by graft polymerization of GMA and amination using DETA or EDA can be used as a PO ₄ -P selective adsorbent having an adsorption capacity equivalent to or higher than that of a commercial anion exchange resin.

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in the present specification. It is obvious that variations can be made. In addition, although the effects according to the configuration of the present invention have not been explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Claims (4)

(a) pre-treating the rice hull;
(b) mixing the pretreated rice hull with an initiator, a crosslinking agent, an acrylic monomer and an organic solvent to perform graft copolymerization; and
(c) adding an amine-based compound to the graft copolymerized polymer for amination;
According to claim 1,
The acrylic monomer includes glycidyl methacrylate (GMA),
The amine-based compound is a method for producing an adsorbent comprising at least one of diethylenetriamine (DETA), ethylenediamine (EDA), dimethylamine (DMA), and trimethylamine (TMA).
According to claim 1,
The step (c) is a method for producing an adsorbent that is carried out at 40 ~ 100 ℃ for 1 ~ 8 hours.
According to claim 1,
After step (c), the method for producing an adsorbent further comprising the step of washing and drying the amination product after filtration.

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