KR20160125810A - Draw solution for forward osmosis using salt of polyvalent carboxylic acid and use thereof - Google Patents

Abstract

According to the present invention, provided are: a forward osmosis draw solution containing, as a forward osmosis draw solute, a polyvalent carboxylate which has a number average molecular weight of 2,000 or smaller and has at least three carboxylic groups, preferably at least four carboxylic groups; a method for manufacturing a refined fluid by using the forward osmosis draw solution; and a refinement apparatus. According to the present invention, the forward osmosis draw solution uses, as a draw solute, a polyvalent carboxylate which has at least three carboxylic groups, preferably at least four carboxylic groups. Accordingly, excellent forward osmosis efficiency is secured, and the draw solute can be easily recovered. Therefore, a water treatment apparatus and a method therefor using the forward osmosis draw solution can reduce energy consumption in the separation and recovery of a draw solute, and have an excellent water treatment effect.

Description

[0001] The present invention relates to an induction solution for polyunsaturated carboxylic acid,

The present invention relates to an induction solution for positive osmosis using a polyvalent carboxylic acid salt and its use.

Due to excessive energy consumption, the reverse osmosis membrane process is being used as a distillation method for seawater desalination. However, the reverse osmosis membrane process also has high energy consumption due to the high pressure, and the osmosis membrane process has been studied to solve this problem. The reverse osmosis membrane process operates at a pressure higher than osmotic pressure of seawater, but the osmosis membrane process removes salts through semipermeable membrane due to osmotic pressure difference without applying pressure.

Currently, the purified osmosis membrane is used in commercial use, but the reason why the osmosis membrane process is not activated is that induction solute that can induce osmotic pressure is not developed. Induced solute should not only be able to induce high osmotic pressure, but should be easy to recover, have high solubility in water and be harmless to human body.

The various inducing solutes that have been studied so far have problems in that most of the recovered solutes are harmful to the human body when the osmotic pressure is high. The solutes used in the osmotic pressure induction solution include ammonium hydrogencarbonate, aluminum sulfate, sulfur dioxide, aliphatic alcohol, glucose, nano iron compounds, and polyvalent organic acids. However, it has not yet overcome the problem of recall.

It is an object of the present invention to provide an induction solution for cleansing osmosis which is superior in osmotic pressure while solving the problems in the conventional osmosis process such as difficulty in recovery and reuse of induction solution and reverse osmosis process, .

A first aspect of the present invention provides a derivatized solute for osmosis containing a polyvalent carboxylic acid salt represented by the following general formula (1), (2) or (3).

[Chemical Formula 1]

(2)

(3)

In this formula,

M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,

p, m and n are each independently an integer of 0 to 5;

A second aspect of the present invention provides an induction solution for positive osmosis containing the induction solute for positive osmosis according to the first aspect of the present invention.

A third aspect of the present invention is a method for preparing a compound represented by the formula (5), comprising: a first step of reacting diethyl malonate with a compound represented by the following formula (4) And a second step of hydrolyzing the compound represented by the formula (5) with an alkali metal hydroxide or an alkaline earth metal hydroxide to produce a compound represented by the following formula (1).

[Chemical Formula 1]

[Chemical Formula 4]

[Chemical Formula 5]

In this formula,

M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,

R is vinyl or X- (CH _{2) m} -, and

X is a leaving group,

R < ₁ > is _C1-5 alkyl,

p, m and n are each independently an integer of 0 to 5;

A fourth aspect of the present invention is a method for producing a purified fluid by osmotic pressure of an induction solution for positive osmosis containing an induction solute for positive osmosis comprising the steps of: Permeable to the induction solution for normal osmosis by osmotic pressure; And optionally a second step of permeating the fluid permeated through the first membrane through a second membrane through which the induction solute for osmosis is not passed, Which is an osmotic solution for osmosis.

In a fifth aspect of the present invention, there is provided an apparatus for purifying a fluid from a stock solution by osmotic pressure of an induction solution for positive osmosis containing an induction solute for positive osmosis, comprising: an induction solution for positive osmosis according to the second aspect; And a first membrane for separating the stock solution from the induction solution for positive osmosis.

Hereinafter, the present invention will be described in detail.

Osmotic pressure means that a semi-permeable membrane that does not allow the passage of solute through the solvent is fixed, and a solution and a pure solvent are separately placed on both sides of the semi-permeable membrane, a certain amount of solvent penetrates into the solution to reach equilibrium. At this time, It is a pressure difference that has the same temperature but a difference in pressure. Such a substance that causes osmotic pressure is called a draw solute.

In the present invention, the number average molecular weight refers to an average molecular weight obtained by averaging the molecular weights of component molecular species of a general compound or a polymer compound having a molecular weight distribution by several fractions or mole fractions, have.

The present invention is characterized in that a polyvalent carboxylic acid salt represented by the following formula (1), (2) or (3) is used as an induction solute for osmosis, preferably having a number average molecular weight of 2,000 or less.

[Chemical Formula 1]

(2)

(3)

In this formula,

M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,

p, m and n are each independently an integer of 0 to 5;

The polyvalent carboxylic acid salt as the inducing solute is a compound or polymer having a larger molecular weight than conventional inorganic salts and furthermore, it forms three or more, preferably four or more salt forms (i.e., -COO ^- M ⁺ ) in one molecule Since it exhibits a high negative charge, the osmosis efficiency is excellent, and it is easy to recover even by simple membrane filtration or centrifugation.

Preferably, in Formula 1, Formula 2 or Formula 3, M may be a monovalent alkali metal ion, and more preferably, M may be Li ⁺ , Na ^+, or K ⁺ .

Preferably, p in the general formulas (1) and (2) may be an integer of 0 to 2.

Preferably, in Formula 3, p may be an integer of 2 to 5.

In the present invention, the polyvalent carboxylic acid salt used as the induction solute for positive osmosis may be a compound represented by the following formula (6) or (7), but is not limited thereto.

[Chemical Formula 6]

(7)

In this formula,

And M is a monovalent or divalent alkali metal ion or alkaline earth metal ion.

Preferably, in Formula 6 or Formula 7, M may be a monovalent alkali metal ion, and more preferably, M may be Li ⁺ , Na ^+, or K ⁺ .

The more organic acid groups (carboxyl groups in the present invention) in one molecule of the organic acid, the more the one or more organic acid salts in a molecule can be produced, and the osmotic pressure can be further increased under the same conditions. The induction solute for cleansing osmosis of the present invention has three or more, preferably four or more carboxylic acid groups, and has an advantage of exerting excellent osmotic pressure.

Further, when such organic acid salts having three, preferably four, carboxyl groups are applied to the positive osmosis process, excellent osmotic pressure can be provided, and recovery of the inducing solute and solution can be easily performed, and reuse thereof is possible.

When the fluid such as water is purified from the fluid source by the osmotic pressure of the induction solution for normal osmosis containing the induction solute for normal osmosis, the larger the molecular weight of the inducing solute, the smaller the osmotic pressure is. However, in the present invention, the polyhydric carboxylate represented by the formula (1), (2) or (3), which is an organic acid salt having a large molecular weight as the induction solute of the same concentration (% by weight), is compared with NaCl having a small molecular weight. As a result, The polyvalent carboxylic acid salt represented by the general formula (1), (2) or (3) can show a permeation flow rate comparable to NaCl having a small molecular weight, and it is confirmed that the back diffusion of the solute is remarkably reduced unlike NaCl One).

Furthermore, in the present invention, the polyvalent carboxylic acid salt represented by the general formula (1), (2) or (3), that is, the purified osmotic solute of the present invention is more excellent in the osmotic pressure inducing ability than the triosodium citrate having three carboxyl groups, It was confirmed that the flow rate was high and the recovery rate of the induced solute was even better (Table 2 and Table 3).

In the present invention, the content of the polyvalent carboxylic acid salt represented by the above formula (1), (2) or (3) as an induction solute in the induction solution may be 3 to 30% by weight.

The present invention can provide a method for producing the induction solute for cleansing osmosis according to the present invention.

As a preferred embodiment, the present invention can provide a process for producing an induction solute for positive osmosis as shown in the following reaction formula (1).

[Reaction Scheme 1]

Preferably, the process for preparing the purified osmosis solute of the present invention may comprise the following steps:

A first step of reacting diethyl malonate with a compound represented by the following formula (4) to prepare a compound represented by the following formula (5); And

A step of hydrolyzing a compound represented by the formula (5) with an alkali metal hydroxide or an alkaline earth metal hydroxide to prepare a compound represented by the following formula (1).

[Chemical Formula 1]

[Chemical Formula 4]

[Chemical Formula 5]

In this formula,

M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,

R is vinyl or X- (CH _{2) m} -, and

X is a leaving group,

R < ₁ > is _C1-5 alkyl,

p, m and n are each independently an integer of 0 to 5;

Preferably, X is a leaving group, such as, but not limited to, a halogen such as Cl, Br, or I, or a tosyl group or a mesyl group.

The first step is a step of reacting diethyl malonate with the compound represented by Formula 4 to prepare the compound represented by Formula 5 having at least four carboxylate groups.

In the present invention, the compound represented by Formula 4 may be ethyl acrylate, ethyl chloroformate or ethyl chloroacetate, but is not limited thereto.

In the present invention, the first step can be carried out in the presence of a Lewis acid and an organic base. Preferably, the first step can be carried out in the presence of lithium perchlorate as a Lewis acid and triethylamine as an organic base, but is not limited thereto.

In the present invention, the reaction temperature in the first step may be room temperature, preferably 10 to 50 ° C. If the reaction temperature is lower than 10 ° C, the reaction rate becomes slow and the reaction time may become longer. If the reaction temperature is higher than 50 ° C, impurities may be generated and the yield may be lowered.

In the present invention, the reaction time of the first step may preferably be 12 to 24 hours. If the reaction time is shorter than 12 hours, the reaction may not be completed and the starting material may remain. Normally, the reaction time is completed within 24 hours, so that a reaction time of more than 24 hours is not necessary.

In the second step, the compound represented by Chemical Formula 5 is hydrolyzed with an alkali metal hydroxide or alkaline earth metal hydroxide to convert the carboxylate ester group present in the compound represented by Chemical Formula 5 into a carboxylic acid salt of an alkali metal or alkaline earth metal .

The term "alkali metal" used in the present invention is a chemical element other than hydrogen among the group 1 of the periodic table, and includes lithium (Li), sodium (Na), potassium (K), rubidium (Cs), and francium (Fr). The term "alkaline earth metal" used in the present invention is a Group II chemical element of the periodic table and includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) ), And radium (Ra).

The term "alkali metal hydroxide " used in the present invention may mean a compound formed by ionic bonding of an alkali metal cation and an anhydrous anion (OH ^- )." Alkali metal hydroxide ""May mean a compound formed by ionic bonding of an alkaline earth metal cation and an anion (OH ^- ).

In the present invention, but are the alkali metal hydroxide or alkaline earth metal hydroxide may be made to preferably LiOH, NaOH, KOH, Ca ( OH) 2, Mg (OH) 2, Ba (OH) 2 or mixtures thereof, limited to no.

In the present invention, the second step may be carried out in water, C _{1 -6} alcohol or mixtures thereof.

In the present invention, the second step may be carried out at 5 to 40 占 폚, preferably at 5 to 25 占 폚.

In the present invention, the second step may be performed for 12 to 48 hours, preferably 20 to 28 hours.

As a specific embodiment, the present invention can provide a method for producing an induction solute for positive osmosis as shown in the following Reaction Scheme 1-1.

[Reaction Scheme 1-1]

That is, as shown in Reaction Scheme 1-1, ethyl acrylate is reacted twice with 1 equivalent of ethyl acetate as a compound represented by Chemical Formula 4 in which R is a vinyl group, and then hydrolyzed with KOH to give p = 1 and m = n = 2 Potassium pentane-1,3,3,5-tetracarboxylate can be prepared.

As another specific embodiment, the present invention can provide a method for producing an induction solute for positive osmosis as shown in the following reaction formulas 1-2.

[Reaction Scheme 1-2]

That is, ethyl chloroacetate as a compound represented by the general formula (4) wherein R is Cl-CH ₂ - and ethyl acrylate as a compound represented by the general formula (4) in which R is a vinyl group, And subsequently hydrolyzed with KOH to prepare potassium butane-1,2,2,4-tetracarboxylate having p = m = 1 and n = 2 as an inducing solute.

As another specific embodiment, the present invention can provide a method for producing an induction solute for positive osmosis as shown in the following reaction formulas 1-3.

[Reaction 1 - 3]

That is, as shown in Scheme 1-3, diethyl malonate is first mono-halogenated and then reacted with diethyl malonate to obtain tetraethyl ethane-1, 1, 2, After 2-tetracarboxylate was prepared, ethyl acrylate was reacted as a compound represented by the formula (4) in which R was a vinyl group in an amount of 2 equivalents and then hydrolyzed with KOH to obtain p = m = n = 2 Potassium hexane-1,3,3,4,4,6-hexacarboxylate can be prepared. Further, the above obtained tetraethyl ethane-1,1,2,2-tetracarboxylate, which is a compound in which two diethyl malonates are bonded, is re-halogenated and then reacted with diethyl malonate to obtain diethyl malonate after the manufacture the three-bonded forms of the compounds of ethyl hexahydro -1,1,2,2,3,3- hexafluoro propane carboxylate, R is Cl-CH ₂ - ethyl of the compound represented by the formula (4) Reacted with chloroacetate and then hydrolyzed with KOH to prepare potassium pentane-1,2,2,3,3,4,4,5-octacarboxylate with p = 3, m = n = 1 as the derivatized solute .

By using the halogenation reaction as described above, it is possible to prepare an inducible solute having a large number of carboxylate salts by increasing the diethyl malonate unit, and the unit increase reaction can also be achieved by oxidative coupling and a number of other known methods. The halogenation reaction may be chlorination, bromination or iodination.

As another specific embodiment, the present invention can provide a process for producing an induction solute for positive osmosis as shown in the following reaction formula (1-4).

[Reaction Scheme 1-4]

That is, a compound which is represented by R Cl- the formula (4) as shown in Reaction Scheme 1 to 4 is reacted with ethyl chloroformate (ethyl chloroformate), and then, R is Cl- (CH _{2) m} - is of the formula (4) Compounds are successively reacted and then hydrolyzed with KOH to prepare a compound of formula (1) wherein p = 1, n = 0, and m = 0 to 5 as an induced solute.

As another preferred embodiment, the present invention can provide a process for producing an induction solute for positive osmosis as shown in Reaction Scheme 2 below.

[Reaction Scheme 2]

Preferably, the process for preparing the purified osmosis solute of the present invention may comprise the following steps:

A step 2-1 of producing a compound represented by the following formula (2) by hydrolyzing a compound represented by the following formula (8) with an alkali metal hydroxide or an alkaline earth metal hydroxide.

(2)

[Chemical Formula 8]

In this formula,

M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,

R < ₁ > is _C1-5 alkyl,

p, m and n are each independently an integer of 0 to 5;

In the step 2-1, the compound represented by the formula (8) is hydrolyzed with an alkali metal hydroxide or an alkaline earth metal hydroxide to convert the carboxylate ester group present in the compound represented by the formula (8) into a carboxylic acid salt of an alkali metal or an alkaline earth metal .

In step 2-1, the alkali metal hydroxide, the alkaline earth metal hydroxide, and the operating conditions are the same as those described in the second step.

As another preferred embodiment of the present invention, the present invention can provide a method for producing an induction solute for positive osmosis as shown in Reaction Scheme 3 below.

[Reaction Scheme 3]

Preferably, the process for preparing the purified osmosis solute of the present invention may comprise the following steps:

A step 2-2 of reacting a compound represented by the following formula (9) with an alkali metal hydroxide or an alkaline earth metal hydroxide to prepare a compound represented by the following formula (3).

(3)

[Chemical Formula 9]

In this formula,

M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,

p, m and n are each independently an integer of 0 to 5;

In the step 2-2, the carboxylic acid compound represented by the formula (9) is neutralized with an alkali metal hydroxide or an alkaline earth metal hydroxide to convert a carboxyl group present in the compound represented by the formula (9) into a carboxylic acid salt of an alkali metal or an alkaline earth metal .

The compound represented by the above formula (9) is commercially available or can be directly prepared by a known method. For example, a maleic anhydride oligomer can be prepared by radical polymerization of maleic anhydride (MA) using benzoyl peroxide (BPO) as a polymerization initiator. Hydrolysis of the maleic anhydride oligomer can easily yield the compound of formula (9) ( Molecules , 2011, 16, 1981-1986).

Specifically, examples of the compound represented by the above formula (9) include 1,2,3,4-butanetetracarboxylic acid and the like, but are not limited thereto.

In the step 2-2, the alkali metal hydroxide, the alkaline earth metal hydroxide, and the operating conditions are the same as those described in the second step.

According to a fourth aspect of the present invention, there is provided a method for producing a purified fluid by osmotic pressure of a solution for induction of osmosis according to the fourth aspect of the present invention comprises the steps of: passing fluid in a stock solution through a first membrane to an induction solution for osmosis through osmotic pressure; And optionally a second step of permeating the fluid permeated through the first membrane through a second membrane through which the induction solute for osmosis is not passed, using the induction solution for positive osmosis according to the first aspect . At this time, the second step may be omitted.

On the other hand, an apparatus for purifying a fluid from an undiluted solution by osmotic pressure of an induction solution for positive osmosis containing the induction solute for positive osmosis according to the fifth aspect of the present invention is characterized in that the induction solution for positive osmosis according to the first aspect; And a first membrane for separating the undiluted solution from the induction solution for positive osmosis.

The fluid may be water or potable water, but is not limited thereto.

The induction solution for normal osmosis can control the molecular weight and the concentration of a suitable polyvalent carboxylic acid salt in order to realize a desired net osmosis permeation flow rate.

Preferably, the first membrane is a semi-permeable membrane for impermeability that is impermeable to a substance other than a fluid to be permeated, and is preferably a semipermeable membrane that is water permeable when the fluid is water.

In addition, the second membrane is made such that the fluid that has permeated through the first membrane is permeated, while the induction solute for osmosis is not passed. Non-limiting examples of the second membrane include an ultrafiltration membrane (UF), a nano filtration membrane (NF), and a reverse osmotic membrane (RO). Preferably, the membrane includes a nanofiltration membrane filtration membrane. Furthermore, the second membrane may be a nanofiltration membrane having a molecular weight cutoff of 200 to 2000. If the fraction molecular weight is less than 200, the derivatized solute can not be easily recovered, and if the fraction molecular weight exceeds 2000, the recovery rate of the induced solute may be significantly lowered.

Since the carboxylic acid salt has a negative charge, it is preferable that the second membrane carries a negative charge so that the carboxylic acid salt does not pass through the second membrane due to the electrostatic force.

In the present invention, the second step may be a step of separating and recovering the induction solute for osmosis from the induction solution for positive osmosis through membrane filtration through the second membrane. At this time, the collected induction solute for osmosis can be used by reintroducing into the induction solution for osmosis.

Membranes such as an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane may be used for recovery of the induced solute for the osmosis from the induction solution for positive osmosis, but it may also be possible through a centrifugal separator.

FIG. 1 shows a purification apparatus for water treatment by osmotic pressure of an induction solution for positive osmosis containing an induction solute for positive osmosis according to an embodiment of the present invention. Referring to FIG. 1, one embodiment of the present invention is explained do.

The operation mechanism of the reflux osmotic purification apparatus moves the water in the stock solution to be treated in the forward osmosis system 1 through the first membrane 11 with an induction solution for high osmosis using a high osmotic pressure, The induction solution for pure osmosis containing water is transferred to the recovery system 2 to separate the induced solute, and the remainder is discharged as a purified fluid. The separated induction solute can be reused by reintroducing the undiluted solution to be treated into the induction solution for normal osmosis contacted with the first membrane (11) therebetween.

As described above, the polyvalent carboxylic acid salt of the present invention, which is the inducing solute, has a large molecular weight and has three or more, preferably four or more, salts And the like. That is, since it has a large particle size and charge, it can be separated from the easily purified fluid by filtration through the second membrane 21. For example, since the polyvalent carboxylic acid salt represented by the formula (1), (2) or (3) can be separated and separated by filtration through a nanofiltration membrane having a cutoff molecular weight of 200 to 2000, the recovery system (2) And at the same time, easy filtration is possible. Furthermore, since the organic acid salt has a negative charge, it may be preferable that the second membrane 21 has the same negative charge so that the organic acid salt does not pass through the second membrane 21 due to the electrostatic force.

The organic acid salt, which is the separated and recovered derivatized solute, can be added to the osmotic induction solution, which is in contact with the undiluted solution, and reused by the connection means (3).

The connection means 3 may include a conduit through which the separated and recovered induced solute can flow, an electrical conductivity meter on the conduit, a flow meter, and the like in order to maintain a constant concentration of the induction solution for positive osmosis, no. It is possible to monitor the satisfaction of the reference value concentration and the flow rate of the induced solute separated and recovered through the electric conductivity meter and the flow meter.

The means (4) for discharging the remainder of the induction solute separated by the recovery system as a purified fluid may include a pipe through which the purified fluid can be discharged, an electric conductivity meter installed on the pipe, and a flow meter. It is not. Through the electric conductivity meter and the flow meter, it is possible to monitor whether or not the impurity exceeds the reference value and the flow rate according to the purpose.

The undiluted solution may be sea water, brackish water, ground water, waste water, and the like. For example, the purified osmosis purification apparatus may be used to purify seawater to obtain a purified water as drinking water.

In addition, since the fluid, which is the solvent of the undiluted solution, passes through the first membrane 11 and moves to the induction solution for positive osmosis, the solvent can be removed from the undiluted solution, thereby concentrating the undiluted solution It is possible.

INDUSTRIAL APPLICABILITY The induction solution for cleansing osmosis of the present invention can provide an excellent osmotic pressure and can easily recover an inducing solute by using a polyvalent carboxylic acid salt having three or more, preferably four or more, carboxylic acid groups as an induction solute. Therefore, the water treatment apparatus and the water treatment method using the same can reduce the energy for the separation and recovery of the induction solute, and the water treatment effect is excellent.

1 is a schematic diagram of a purified osmosis purification apparatus according to one embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

Example  One: Induced solute  Produce

According to the following reaction formula, potassium pentane-1,3,3,5-tetracarboxylate was synthesized as the derivatized solute of the present invention.

Ethyl acrylate (150 ml) was added dropwise at room temperature for 2 hours to a mixed solution of diethyl malonate (100.0 g), lithium perchlorate (3.0 g) and triethylamine (1.0 ml), and the mixture was stirred at room temperature for 20 hours . The reaction mixture was dissolved in dichloromethane (500 ml), washed with water (50 ml x 2 times) and saturated brine (50 ml), dried over sodium sulfate, and concentrated under reduced pressure to obtain a yellow liquid (608 g) . The obtained compound was purified by vacuum distillation to obtain tetraethylpentane-1,3,3,5-tetracarboxylate (223 g) as a colorless transparent liquid (yield: 87.7%).

Boiling point: 174-175 DEG C / 670 mTorr; ^{1 H NMR (500 MHz, CDCl} 3) δ 1.26 (m, 12H, 4CH 3), 2.21 (m, 4H, 2CH 2), 2.31 (m, 4H, 2CH 2), 4.13 (q, J = 7.1 Hz, _{4H, 2OCH 2), 4.18 (} q, J = 7.1 Hz, 4H, 2OCH 2).

25% KOH (520 g) was added to a mixture of tetraethylpentane-1,3,3,5-tetracarboxylate (180 g) obtained above and ethanol (100 ml) Stir for 24 hours. The reaction mixture was concentrated under reduced pressure, washed with methanol (500 ml, 200 ml) and dried to give potassium pentane-1,3,3,5-tetracarboxylate (188.1 g) as a white solid (Yield: 94 %).

¹ H NMR (500 MHz, D ₂ O)? 1.84 (m, 4H, 2CH ₂ ), 1.91 (m, 4H, 2CH ₂ ); ^{13 C NMR (125 MHz, D} 2 O) δ 29.7, 33.6, 61.0, 181.2, 183.6.

Example  2: Induced solute  Produce

According to the following reaction formula, sodium butane-1,2,3,4-tetracarboxylate was synthesized as the derivatized solute of the present invention.

120 g of 1,2,3,4-butanetetracarboxylic acid (BTCA, TCI, 98%) was slowly added to 567 g of 15% aqueous NaOH solution for 30 minutes and then stirred at room temperature for 20 hours. The reaction mixture was concentrated under reduced pressure, washed with methanol (500 ml, 200 ml) and dried to obtain 159 g of sodium butane-1,2,3,4-tetracarboxylate as a white solid (yield: 98%).

^{1 H NMR (500 MHz, D} 2 O) δ 2.17 (dd, J = 15.0, 5.0 Hz, 2H, 2C H H), 2.35 (m, 2H, 2CH H), 2.45 (m, 2H, 2CH)

Example  3: Induced solute  Produce

According to the following reaction formula, potassium butane-1,2,3,4-tetracarboxylate was synthesized as the derivatized solute of the present invention.

120 g of 1,2,3,4-butanetetracarboxylic acid (BTCA, TCI, 98%) was slowly added to 610 g of 20% KOH aqueous solution for 30 minutes and then stirred at room temperature for 20 hours. The reaction mixture was concentrated under reduced pressure, washed with methanol (300 ml, 200 ml) and dried to obtain 185 g of potassium butane-1,2,3,4-tetracarboxylate as a white solid (yield: 97%).

^{1 H NMR (500 MHz, D} 2 O) δ 2.17 (dd, J = 15.0, 5.0 Hz, 2H, 2C H H), 2.35 (m, 2H, 2CH H), 2.47 (m, 2H, 2CH)

Comparative Example  One: As an induction solute Tri-potassium Citrate  Produce

According to the following reaction formula, trivalent citrate was synthesized as a comparative inductive solute.

180 g of citric acid was slowly added to 680 g of 25% aqueous KOH solution for 1 hour and then stirred at room temperature for 20 hours. The reaction mixture was concentrated under reduced pressure, washed with methanol (500 ml, 200 ml) and dried to obtain 296 g of triptassium citrate (yield: 98%).

^{1 H NMR (500 MHz, D} 2 O) δ 2.44 (d, J = 15.0, 2H, 2C H H), 2.56 (d, J = 15.1, 2H, 2CH H)

Example  4: Preparation and Characterization of Induction Solution

The potassium pentane-1,3,3,5-tetracarboxylate prepared in Example 1 was used as an induction solution in an aqueous 5 wt% solution. As a positive osmosis membrane, permeability and despreading were evaluated by using a positive osmosis membrane of HTI (USA). Pure water was used as the feed solution.

The conductivity of the induction solution was contacted with the pure water (conductivity 6-7 μS / cm) in the cell, and the weight change of the induction solution was measured by circulating the feed and the inducing solution. The amount of back diffusion of the material to pure water was measured using a conductivity meter. The results are shown in Table 1 below.

Induced solute Example 1 NaCl Transmission flow rate (L / m ² hr) 8 12 Despreading (uS / cm) 6 32

From the above Table 1, it was confirmed that the induced solute of the present invention had a slightly lower permeate flow rate but a significantly smaller reverse diffusion amount as compared with NaCl.

Example  5: Preparation and characterization of induction solution

An induction solution was prepared in the same manner as in Example 4, except that sodium butane-1,2,3,4-tetracarboxylate prepared in Example 2 was used instead of the induction solute of Example 1 as the induction solute The permeability and despreading were evaluated.

As a result, it was confirmed that the permeate flow rate was 2.5 L / m ² hr and the despreading was 5.5 uS / cm. The permeate flow rate was very low as compared with Example 2, but the despreading was similar.

Example  6: Preparation and properties of induction solutions

An induction solution was prepared in the same manner as in Example 4 except that potassium butane-1,2,3,4-tetracarboxylate prepared in Example 3 was used instead of the induction solute of Example 1 as the induction solute The permeability and despreading were evaluated.

As a result, it was confirmed that the permeate flow rate was 1.8 L / m ² hr and the despreading was 6.3 uS / cm. The permeate flow rate was very low as compared with Example 4, but the despreading was similar.

Comparative Example  2: Tree sodium Citrate With induction solute  Preparation and Characterization of Induction Solution Used

An induction solution was prepared in the same manner as in Example 2 except that trisodium citrate was used as the induction solute, and the permeability and the despreading were evaluated.

As a result, it was confirmed that the permeate flow rate was 2.9 L / m ² hr and the despreading was 5.9 uS / cm. The permeate flow rate was very low as compared with Example 2, but the despreading was similar.

Comparative Example  3: Tri-potassium Citrate With induction solute  Preparation and Characterization of Induction Solution Used

An induction solution was prepared in the same manner as in Example 4 except that the inducible solute used in Example 1 was replaced by the trivalent citrate prepared in Comparative Example 1, and the permeability and despreading were evaluated.

As a result, it was confirmed that the permeate flow rate was 4.3 L / m ² hr and the despreading was 6.1 uS / cm. The permeate flow rate was lower than that of Example 2 and the despreading was similar.

Example  7: Using nanofiltration Induced solute  collection

Using the inductive solution used in Examples 4 to 6 and Comparative Examples 2 to 3, the pressure was fixed to 5 kgf / cm ² using a nanofiltration membrane (NE-90) manufactured by Woongjin Chemical and permeation flow rate and removal rate were measured . The results are shown in Table 2 below.

Example 4 Example 5 Example 6 Comparative Example 2 Comparative Example 3 Permeate flow (L / m²h) 27 5.8 6.9 11.3 18 Removal rate (%) 99.6 99.6 99.1 99.3 99.5

From the above Table 2, it can be seen that when the induction solution of the present invention is used, the permeation flow rate is also excellent with a removal rate similar to that of the induction solutions of Comparative Examples 2 to 3.

Example  8: Using nanofiltration Induced solute  collection

The permeate flow rate and the removal rate were measured in the same manner as in Example 7, except that NE-40 was used instead of NE-90 as the nanofiltration membrane. The results are shown in Table 3 below.

Example 4 Example 5 Example 6 Comparative Example 2 Comparative Example 3 Permeate flow (L / m²h) 36 9.1 10.3 15.0 29.3 Removal rate (%) 99.1 98.9 97.6 97.5 98.5

From the above Table 3, it can be seen that when the induction solution of the present invention is used, the permeate flow rate is also excellent with a removal rate similar to that of the induction solutions of Comparative Examples 2 and 3.

Description of the main parts of the drawings
1: Positive Osmosis System
2: Recovery system
3: Induction solute input connection means
4: Purified fluid discharge means
11: first membrane
21: Second membrane

Claims (17)

A purified osmotic solute containing a polyvalent carboxylic acid salt represented by the following general formula (1), (2) or (3)
[Chemical Formula 1]

(2)

(3)

In this formula,
M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,
p, m and n are each independently an integer of 0 to 5;
The induction solute according to claim 1, wherein the polyvalent carboxylic acid salt represented by Formula 1, Formula 2 or Formula 3 has a number average molecular weight of 2,000 or less.
An induction solution for normal osmosis containing the induction solute for clearing osmosis according to any one of claims 1 to 2.
4. The induction solution for normal osmosis as claimed in claim 3, wherein the content of the induction solute in the induction solution is 3 to 30% by weight.
A method for producing an induction solute for normal osmosis comprising the steps of:
A first step of reacting diethyl malonate with a compound represented by the following formula (4) to prepare a compound represented by the following formula (5); And
A step of hydrolyzing a compound represented by the formula (5) with an alkali metal hydroxide or an alkaline earth metal hydroxide to prepare a compound represented by the following formula (1).
[Chemical Formula 1]

[Chemical Formula 4]

[Chemical Formula 5]

In this formula,
M is a monovalent or divalent alkali metal ion or alkaline earth metal ion,
R is vinyl or X- (CH _{2) m} -, and
X is a leaving group,
R < ₁ > is _C1-5 alkyl,
p, m and n are each independently an integer of 0 to 5;
1. A method for producing a purified fluid by osmotic pressure of an induction solution for positive osmosis containing an induction solute for positive osmosis,
Permeating the fluid in the fluid source through the first membrane to the induction solution for osmosis by osmotic pressure; And
Optionally, a second step of permeating the fluid permeated through the first membrane through a second membrane through which the induction solute for osmosis is not passed,
Wherein the induction solution for normal osmosis is the induction solution for cleansing osmosis according to any one of claims 3 to 4.
[7] The method of claim 6, wherein the second step comprises separating and recovering the induction solute for osmosis from the induction solution for osmosis by membrane filtration through the second membrane.
8. The method of claim 7, further comprising the step of reintroducing the purified osmosis solute recovered in the second step into the induction solution for osmosis.
7. The method of claim 6, wherein the second membrane carries a negative charge.
The method of claim 6, wherein the second membrane is a nano filtration membrane (NF).
7. The method of claim 6, wherein the second membrane is a nanofiltration membrane having a molecular weight cutoff of 200 to 2000.
7. The method according to claim 6, wherein the fluid is water or drinking water.
An apparatus for purifying a fluid from an undiluted solution by osmotic pressure of an induction solution for positive osmosis containing an induction solute for positive osmosis,
An induction solution for cleansing osmosis according to any one of claims 3 to 4; And
And a first membrane for separating the stock solution from the induction solution for positive osmosis.
14. The purification device according to claim 13, further comprising a second membrane for passing the fluid mainly without passing the induction solute for positive osmosis.
15. The purification apparatus according to claim 14, further comprising means for reintroducing the induction solute for clearing osmosis, which is separated and recovered from the induction solution for normal osmosis through the second membrane, into the induction solution for cleansing osmosis.
15. The purification apparatus of claim 14, wherein the second membrane carries (-) charge.
15. The purification apparatus of claim 14, wherein the second membrane is a nanofiltration membrane.

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