KR102301288B1 - Method for producing Poly aluminum magnesium sulfate based flocculant for water treatment and aqueous solution for Poly aluminum magnesium sulfate based flocculant - Google Patents

Abstract

The present invention relates to a method for producing a polyaluminum sulfate-magnesium coagulant and an aqueous solution for the polyaluminum sulfate-magnesium coagulant, and more specifically, to a method for producing the coagulant for water treatment and the aqueous solution for aluminum sulfate-magnesium coagulant prepared thereby, which exhibit improved effects than conventional aluminum sulfate-based coagulant, therefore, floc formation and a sedimentation rate of the formed flocs are excellent.

Description

Method for producing poly aluminum sulfate-magnesium coagulant and aqueous solution for poly aluminum sulfate-magnesium coagulant

The present invention relates to a method for producing a polyaluminum sulfate-magnesium coagulant and an aqueous solution for a polyaluminum sulfate-magnesium coagulant. The present invention relates to a method for producing a coagulant for water treatment having an excellent floe settling rate, and an aqueous solution for an aluminum sulfate-magnesium coagulant prepared thereby.

A coagulant for water treatment is used as a water treatment means for purifying water and sewage and sewage. The coagulant for water treatment contains a positively charged inorganic metal component, thereby causing a coagulation phenomenon in which flocs are formed through charge neutralization with negatively charged suspended substances and colloidal particles present in water and sewage and sewage, and agglomeration phenomenon in which they coarsen and settle. . Therefore, water treatment using a coagulant for water treatment exhibits the effect of improving water purification and turbidity through floc formation and sedimentation in water and sewage and sewage.

Conventionally used coagulants for water treatment have been mainly used as coagulants containing polyaluminum chloride (PAC, Poly Aluminum Chloride) or aluminum sulfate (Alum, Aluminum Sulfate) as an inorganic metal component.

The polyaluminum chloride-based flocculant, which is estimated to be in the form of a polymer or multinuclear complex, has a basicity of 36 to 60%, which means the percentage of the equivalent of the ^{hydroxyl group (OH -) relative to the equivalent of the positively charged inorganic metal component in the coagulant.} As aluminum oxide (Al2O3), a product containing 10 to 17% is generally used, and the pH range for forming flocs is wide, so the stability of the water treatment operation is high, and the flocculation rate and sedimentation rate are fast.

However, polyaluminum chloride-based coagulants having a high basicity of 36 to 60% of basicity have a problem in that storage stability is low because precipitation and precipitation phenomena occur on their own due to an increase in the molecular weight of the coagulant according to the increase in basicity. Accordingly, Korean Patent No. 10-1159236 (published on June 25, 2012) discloses a method for producing a low-basic polyaluminum chloride-based coagulant in which basicity is reduced to a level of 10 to 20% by adding hydrochloric acid (HCl). However, the coagulant manufacturing method has a problem in that the process of adding hydrochloric acid to reduce the basicity of polyaluminum chloride reverses the increase and decrease of the basicity, thereby reducing the manufacturing efficiency.

On the other hand, the aluminum sulfate-based coagulant for water treatment (alumina sulfate, Alum) containing _{monomolecular form of aluminum sulfate (Al 2} (SO ₄ ) ₃ .6H _{2 O) is generally 8.0% as liquid (Al2O3),} Since aluminum sulfate raw materials are inexpensive and easy to handle, they have been mainly used with polyaluminum chloride-based coagulants. However, these aluminum sulfate-based coagulants for water treatment have a narrower pH range than polyaluminum chloride-based coagulants and form flocs. , there is a problem that the effect of aggregating the formed flocs is small, so the specific gravity used is decreasing.

In addition, the crystallization point of the liquid aluminum sulfate is as low as -14°C when 8.3%, and when the concentration is increased, the crystallization temperature increases rapidly and crystals are precipitated even at room temperature. This is the maximum concentration and due to storage and storageability, so far, there has been no liquid aluminum sulfate product of 8.0% or more as an aluminum oxide standard.

In this regard, Korean Patent Registration No. 10-1131372 (published on April 4, 2012) discloses a method for preparing an aluminum salt solution containing aluminum sulfate, It is technically characterized to add a quaternary ammonium salt to reduce the occurrence. However, the aluminum sulfate solution prepared from the above patent document does not disclose a configuration to increase the floc formation and sedimentation efficiency, which is the original function of the coagulant, so the technical solution for increasing the use of the aluminum sulfate-based coagulant is not presented. have.

In the aluminum sulfate-based coagulant _{, the higher the content of aluminum oxide (Al 2} O ₃ ) in the solid content, the greater the floc formation and sedimentation efficiency, but the crystallization point when the aluminum oxide content is 8.3% is -14 ℃ Therefore, there is a problem in terms of storage stability in which crystals are precipitated at room temperature. Currently, the aluminum oxide content of 8.0% or more of aluminum sulfate-based coagulant for water treatment is not commercially available.

In addition, development of a coagulant capable of forming flocs with a large diameter and high density of floc particles formed after water treatment to speed up sedimentation when a large amount of polluted water due to floods such as the rainy season needs to be quickly treated is also very urgently needed. Therefore, there is a need for research and development of an aluminum sulfate-based coagulant for water treatment that can solve these technical problems.

Korean Patent Registration No. 10-1159236 (2012.06.25. Announcement) Korean Patent Registration No. 10-1131372 (2012.04.04. Announcement)

In order to solve the above problems, the present invention can improve the water treatment work efficiency and improve the turbidity improvement performance and the present invention is superior to the conventional aluminum sulfate-based coagulant or polyaluminum chloride-based coagulant, the formation of flocs and the sedimentation rate of the formed flocs are excellent. An object of the present invention is to provide an aqueous solution for a novel poly aluminum sulfate-magnesium-based coagulant for water treatment by exhibiting an improved effect of improving storage stability.

In addition, another object of the present invention is to provide a novel method for manufacturing the poly aluminum sulfate-magnesium-based coagulant for water treatment.

In order to achieve the above object, the present invention comprises the steps of (a) mixing aluminum hydroxide, water and sulfuric acid, followed by heating to prepare an aluminum sulfate-based aqueous solution; and (b) mixing a component containing magnesium with the aluminum sulfate-based aqueous solution prepared in step (a) to prepare a poly aluminum sulfate-magnesium-based coagulant; A method for producing a coagulant-based agent is provided.

As an embodiment, in step (a), the total weight of the aluminum sulfate-based aqueous solution is 100, and 5 to 35% by weight of aluminum hydroxide, 10 to 80% by weight of water, and 10 to 60% by weight of sulfuric acid (based on 95%) are mixed. and can be heated.

As an embodiment, the heating in step (a) may be made in a temperature range of 80 to 180 ℃.

As an embodiment, in step (b), the component containing magnesium may include one or a mixture thereof selected from magnesium hydroxide, magnesium sulfate, and magnesium chloride, and preferably, the component containing magnesium is It may be an aqueous solution of magnesium hydroxide obtained by reacting magnesium oxide in an aqueous solution.

As an embodiment, the content of the component containing magnesium, which is mixed with the aluminum sulfate-based aqueous solution in step (b), is a coagulant aqueous solution component obtained by mixing the component containing magnesium with the aluminum sulfate-based aqueous solution in step (b). With a total volume of 100 ml, the reaction may be carried out by mixing to have a range of 1 to 7 g as the content of magnesium oxide (MgO).

As an embodiment, the step (b) may further include a step of heating at 80 to 180° C. after mixing the component including magnesium in the aluminum sulfate-based aqueous solution.

_{In addition, in the present invention, the concentration of aluminum based on aluminum oxide (Al 2} O ₃ ) is 5 to 11 g, and the concentration of magnesium based on magnesium oxide (MgO) is 100 ml with the total volume in the component of the aqueous coagulant solution being 100 ml It provides an aqueous solution for a poly aluminum sulfate-magnesium coagulant, characterized in that 0.5 to 5 g, and a pH (based on 2.0% (w/v)) of 2.7 to 5.

As an embodiment, the basicity of the aqueous solution for the poly aluminum sulfate-magnesium coagulant may be in the range of 8 to 12%.

In one embodiment, the concentration of aluminum in the aqueous solution for the poly aluminum sulfate-magnesium-based coagulant may be in the range of 6.5 to 10.5 g based on _{aluminum oxide (Al 2} O _{3 ) with the total volume of the aqueous coagulant solution component being 100 ml.} .

The aqueous solution for poly aluminum sulfate-magnesium coagulant according to the present invention can provide an aluminum sulfate-magnesium coagulant having two metal components by mixing a component containing magnesium in the aluminum sulfate-based aqueous solution, which is a conventional water treatment method. As a coagulant, the low basicity in aluminum sulfate (AS), a monomolecular flocculant, dramatically increased the basicity from 0 to 1%, greatly increasing the floc formation and sedimentation efficiency, and also aluminum oxide (Al2O3) in aluminum sulfate. In the present invention, the 8.0% content as a standard, the aluminum content was stably increased to 8 to 11%, and the storage property was very high, and compared to the conventional aluminum sulfate-based coagulants and polyaluminum chloride-based coagulants, the formation of flocs and the sedimentation rate of the formed flocs It is possible to provide a coagulant for water treatment that exhibits an improved effect of improving water treatment operation efficiency and improving turbidity improvement performance and storage stability by being excellent.

In addition, the poly aluminum sulfate-magnesium coagulant can easily produce a high-functional coagulant from aluminum sulfate, a low-cost raw material, thereby reducing the cost of producing the coagulant and adequate water treatment efficiency even with a small amount of the coagulant. Even if the load of suspended substances flowing into the water treatment plant increases, it can effectively respond due to the excellent coagulation effect and sedimentation performance.

In addition, the poly aluminum sulfate-magnesium coagulant according to the present invention has the largest diameter and high density of the formed flock particles compared to the aluminum sulfate-based coagulant or the polyaluminum chloride-based coagulant according to the prior art, showing that the sedimentation rate is the best. , it shows an excellent effect for more efficient water treatment when a large amount of water in the flood or monsoon season needs to be treated quickly.

1 is a diagram showing the change in turbidity of wastewater according to the input of the coagulant in Examples and Comparative Examples of the present invention.
2 is a diagram showing the total organic carbon (TOC, Total Organic Carbon) results according to the input of the coagulant in Examples and Comparative Examples of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is those well known and commonly used in the art.

As used herein, terms such as “comprises,” “comprises,” or “has” refer to the presence of, and refer to, a feature, number, step, operation, component, part, or combination thereof described in the specification. It does not exclude the possibility that other features, figures, steps, acts, components, parts, or combinations thereof may exist or may be added, unless otherwise noted.

In the manufacturing method of the coagulant for water treatment according to the present invention, in the manufacturing process of the aluminum sulfate-based coagulant used as a coagulant in the prior art, the aluminum sulfate-based aqueous solution is prepared from aluminum hydroxide, water and sulfuric acid, and then added to the aluminum sulfate-based aqueous solution. By mixing the components containing magnesium, it is possible to provide a novel poly aluminum sulfate-magnesium coagulant containing aluminum and magnesium as cationic metal components and sulfate as anionic components.

According to the prior art, the aluminum sulfate-based flocculant used as a coagulant for water treatment is _{a monomolecular flocculant comprising aluminum sulfate (Al 2} (SO ₄ ) ₃ ) as a component, wherein the aluminum sulfate is a cation of aluminum ion (Al ^{3 ). +} ) and an anion, sulfate (SO ₄ ^2- ). At this time, the positively charged aluminum ions dissolved in the water to be treated environment form negatively charged suspended solids and colloidal particles and flocs, which improve turbidity and form flocs and A water purification effect according to sedimentation may be exhibited.

On the other hand, as a coagulant similar to the aluminum sulfate-based coagulant, the polyaluminum chloride-based coagulant contains a chlorine ion (Cl ⁻ ) as an anion, and an aluminum atom and a chlorine atom as a cation or an aluminum atom and an aluminum atom are connected to each other to form a bonded polymer of polyaluminum ions, the pH range for forming flocs is wide, and it is easy to coarsen the formed flocs, and due to the advantages of improved sedimentation efficiency, the proportion of use is gradually increasing despite the high price. The excellent polok formation and sedimentation performance of these polyaluminum chloride-based coagulants is an advantage due to the long-chain coagulant structure between aluminum atoms, but as its molecular weight increases, it causes precipitation and precipitation on its own. There may be a problem that the efficiency of work decreases, so the need for improvement is required.

Accordingly, the inventors of the present invention, in the manufacturing process of the conventional aluminum sulfate-based coagulant, by mixing a component containing magnesium in the aluminum sulfate-based aqueous solution after preparing an aluminum sulfate-based aqueous solution from aluminum hydroxide, water and sulfuric acid, a novel poly A method for producing an aluminum sulfate-magnesium sulfate-based coagulant was focused on, and the aluminum sulfate-magnesium sulfate-based coagulant prepared by the method significantly improved floc formation and sedimentation performance compared to aluminum sulfate and polyaluminum chloride-based coagulants, as well as stable storage characteristics. It was found to have a , and led to the completion of the present invention.

More specifically, the method for producing a coagulant for water treatment according to the present invention comprises the steps of: (a) mixing aluminum hydroxide, water and sulfuric acid, followed by heating to prepare an aluminum sulfate-based aqueous solution; and (b) mixing a component containing magnesium with the aluminum sulfate-based aqueous solution prepared in step (a) to prepare a poly aluminum sulfate-magnesium-based coagulant; It will be described in detail.

The step (a) in the method for producing a coagulant for water treatment according to the present invention is a step of preparing an aluminum sulfate-based aqueous solution by mixing aluminum hydroxide, water and sulfuric acid, and then heating it, which is an aluminum sulfate-based coagulant in the prior art. The manufacturing process and reaction are the same.

More specifically, in step (a), the total weight of the aluminum sulfate-based aqueous solution is 100, and 5 to 35% by weight of aluminum hydroxide, 10 to 80% by weight of water, and 10 to 60% by weight of sulfuric acid (based on 95%) are mixed. It may be heated, preferably in the range of 15 to 30% by weight of aluminum hydroxide, 15 to 70% by weight of water and 15 to 55% by weight of sulfuric acid (based on 95%).

In the case of aluminum hydroxide used at this time, aluminum hydroxide hydrate (Aluminum hydroxide hydrate, Al(OH) ₃ .xH2O) containing hydrated water or aluminum hydroxide anhydride that does not contain hydrated water (Aluminum hydroxide, Al ( OH) ₃ ) may be used, and in the present invention, the relative content range is calculated based on the anhydride content of the aluminum hydroxide.

In addition, in the case of the sulfuric acid used in the present invention, it can be used without being limited in concentration, and preferably sulfuric acid having a concentration range of 20% to 98%, more preferably 40% to 96%. and, more preferably, sulfuric acid having a concentration range of 50% to 96% may be used.

At this time, in step (a), the heating conditions after mixing are made in a temperature range of 80 to 180 °C, preferably in a temperature range of 105 to 160 °C, more preferably in a temperature range of 110 to 145 °C. If the temperature in the mixing and heating is less than 80 ℃, there is a problem that unreacted aluminum hydroxide may be generated when low concentration sulfuric acid is used (85% or less), and at a temperature exceeding 180 ℃, side reactions may occur or the reaction conditions may be too severe Therefore, the above range is preferable.

In addition, after mixing aluminum hydroxide, water and sulfuric acid according to step (a) in the present invention, and heating to prepare an aluminum sulfate-based aqueous solution, a component containing magnesium in step (b), which is a subsequent process In order to proceed with the reaction more efficiently, water is added to the aluminum sulfate-based aqueous solution obtained in step a) to make the total volume in the aqueous solution component 100 ml, and the amount of aluminum based on _{aluminum oxide (Al 2} O _{3 ) is} The concentration may be adjusted within the range of 5 to 11 g, and the amount of additionally added water may be in the range of 700 to 2,000 parts by weight, preferably 1,000 to 2,000 parts by weight, with the content of water initially used according to step (a) being 100. 1,500 parts by weight.

Meanwhile, step (b) in the present invention corresponds to a step of preparing a poly aluminum sulfate-magnesium-based coagulant by mixing a component containing magnesium with the aluminum sulfate-based aqueous solution prepared in step (a), and an aqueous aluminum sulfate solution By mixing and reacting the component containing magnesium in the above, magnesium cation may be included as a cation component in the coagulant together with the aluminum cation component, and the poly aluminum sulfate-magnesium-based flocculant in this case has a structure in the form of a polymer or multinuclear complex ion. As an example, aluminum atoms are chemically bonded to other aluminum atoms, or magnesium atoms are bonded to the aluminum atoms, or are located around aluminum atoms in the form of polymers or polynuclear complex ions, and the aluminum atoms and / Alternatively, it is estimated that at least some of the magnesium atoms may be bonded to a hydroxyl group, thereby increasing basicity.

In this case, in order to ensure uniformity of the mixing and reaction of the aluminum sulfate-based aqueous solution and the component containing magnesium, the component containing magnesium in step (b) is a magnesium component (a component containing magnesium ions as a cation) is an aqueous solution It may be mixed in a state dissolved in or mixed in a slurry state in an aqueous solution, and the concentration of the magnesium component in the aqueous solution or the content of the magnesium component in the aqueous solution (based on the conversion of magnesium oxide (MgO)) is determined in order to dissolve the magnesium component. When the content of added water is 100 ml, or when the content of water added to the aqueous solution for mixing in a slurry state is 100 ml, 5 to 50 g, preferably 10 to 45 g, more preferably 15 to 30 g may have a range.

In addition, the component containing magnesium in step (b) may include one or a mixture thereof preferably selected from magnesium hydroxide, magnesium sulfate and magnesium chloride, and more preferably include magnesium hydroxide. and more preferably an aqueous solution containing magnesium hydroxide, and more preferably an aqueous magnesium hydroxide solution obtained by reacting magnesium oxide (MgO) in an aqueous solution.

When the magnesium hydroxide aqueous solution is used in the present invention, magnesium oxide having an average particle diameter in the range of 0.5 to 300 μm, preferably 1 to 100 μm is added to the aqueous solution, and at 50 to 90° C. for 10 minutes. It is most preferable to use an aqueous solution of magnesium hydroxide obtained by reacting for from 30 minutes to 120 minutes, preferably for 30 minutes to 120 minutes. It may be in the range of 5 to 50 g, preferably 10 to 45 g, more preferably 15 to 30 g based on 100 ml.

In addition, the step (b) in the present invention may further include a step of heating the mixed component at 80 to 180 degrees after mixing the component containing magnesium in the aluminum sulfate-based aqueous solution, preferably It may include a step of heating at 90 to 150 ℃, more preferably 100 to 125 ℃, wherein the heating time is 5 minutes to 12 hours, preferably 30 minutes to 2 hours, more preferably 60 minutes to 90 minutes It can be in the range of minutes. Here, if the temperature in the heating process is less than 80 ℃, there _{is a problem that unreacted Mg(OH) 2} may remain, and if it exceeds 180 ℃, side reactions may occur or the reaction conditions may be too severe This range is preferred.

In addition, the content of the component containing magnesium, which is mixed with the aluminum sulfate-based aqueous solution in step (b) according to the present invention, is an aqueous coagulant solution obtained by mixing the component containing magnesium with the aluminum sulfate-based aqueous solution in step (b). The total volume in the component is 100 ml, and the content of magnesium oxide (MgO) may be mixed to have a range of 1 to 7 g, and the reaction may be carried out, preferably from 1.2 to 6 g, more preferably from 1.5 to The reaction may be carried out by mixing to have a range of 5 g.

That is, in the step (b), the content of the magnesium-containing component added for the reaction between the aluminum sulfate and the magnesium-containing component in the aluminum sulfate-based aqueous solution is the end of the reaction between the aluminum sulfate and the magnesium-containing component. As the content of magnesium oxide (MgO) in the poly aluminum sulfate-magnesium-based coagulant aqueous solution obtained according to Depending on the conditions, poly aluminum sulfate-magnesium-based flocculants may be prepared.

Here, when the content of the component containing magnesium is added so that the content of the component containing magnesium is lower than 1 g when the total volume of the obtained coagulant aqueous solution component is 100 ml, magnesium in the obtained coagulant Since the content of the component is small, it is difficult to express a differentiated effect compared to the existing aluminum sulfate coagulant. It may not be made uniformly or a phenomenon in which polyaluminum sulfate-magnesium-based coagulant is precipitated by unreacted magnesium hydroxide may occur.

In addition, the present invention provides an aluminum component (aluminum oxide (Al _{2 )} O ₃ ) finally adjusting the concentration of the reference); may additionally include.

This is to strengthen the long-term storage stability of the polyaluminum sulfate-magnesium coagulant that is finally prepared, suppress side reactions during storage, and perform the reaction of step (b) to have an optimal concentration to prevent precipitation, etc. After completion, by appropriately adding water as necessary, it is possible to finally control the magnesium content and the aluminum content in the poly aluminum sulfate-magnesium coagulant.

That is, in the step (b) in the present invention, the content of the magnesium component (based on the content of magnesium oxide (MgO)) input for the reaction between the aluminum sulfate and the component containing magnesium in the aluminum sulfate-based aqueous solution is determined by the reaction As the content of magnesium oxide (MgO) in the poly aluminum sulfate-magnesium-based coagulant aqueous solution obtained according to the termination, when the total volume of the obtained flocculant aqueous solution component is 100 ml, it is optimized to have a range of 1 to 7 g. The poly aluminum sulfate-magnesium coagulant may be prepared according to the reaction conditions, and the resulting poly aluminum sulfate-magnesium coagulant aqueous solution may be used as it is without being diluted by mixing additional water, or may be used for a longer period according to the user's request. When stability is required, the content of magnesium oxide (MgO) in the polyaluminum sulfate-magnesium-based coagulant solution finally obtained is originally adjusted by performing a process of adding and mixing additional water as step (c) after step (b). Lower than step (b) of step (b), when the total volume in the coagulant aqueous solution component is 100 ml, the concentration of magnesium based on magnesium oxide (MgO) is 0.5 to 5 g, preferably 0.8 to 4.5 g, more preferably can provide an aqueous flocculant solution having a range of 1.5 to 3.5 g, more preferably 1.5 to 2.5 g.

At this time, as the polyaluminum sulfate-magnesium coagulant aqueous solution obtained in step (b), the preferred range of the concentration required to be diluted with water is when the total volume of the aqueous coagulant solution component is 100 ml, magnesium oxide in the poly aluminum sulfate-magnesium coagulant solution solution. In the case of an aqueous flocculant solution having a content of (MgO) in the range of 2 to 7 g, more preferably 2.5 to 7 g, a lower concentration of 0.5 g to 5 g, preferably 0.8 to 4.5 g by adding water thereto , more preferably in the range of 1.5 to 3.5 g, more preferably in the range of 1.5 to 2.5 g.

Here, when the content of the magnesium component as the content of magnesium oxide (MgO) has a range lower than 0.5 g, the content of magnesium in the obtained coagulant is small, so it is difficult to express a differentiated effect compared to the conventional aluminum sulfate coagulant, and the magnesium component If the content has a range higher than 5 g, long-term storage stability may be lowered, so it is preferable to have the above range.

On the other hand, the poly aluminum sulfate-magnesium coagulant prepared according to the present invention is a multi-metal component-based coagulant containing positively charged polyaluminum ions and magnesium ions and negatively charged sulfate ions, and the basicity in the finally obtained coagulant is 3 to 50, Preferably, it may appear in the range of 4 to 45, more preferably 5 to 40, more preferably 6 to 35, and still more preferably 7 to 25%.

_{More specifically, in the present invention, the concentration of aluminum based on aluminum oxide (Al 2} O ₃ ) is in the range of 5 to 11 g, and the concentration of aluminum based on magnesium oxide (MgO) is 100 ml in the total volume of the coagulant aqueous solution component. It provides an aqueous solution for a poly aluminum sulfate-magnesium coagulant, characterized in that the magnesium concentration is in the range of 0.5 to 5 g, and the pH (based on 2.0% dilution (w/v) compared to the stock solution) is in the range of 2.7 to 5.

At this time, as a more preferable feature of the poly aluminum sulfate-magnesium-based aqueous coagulant solution, _{the concentration of aluminum based on aluminum oxide (Al 2} O ₃ ) is in the range of 6.5 to 10.5 g with the total volume of the coagulant aqueous solution component being 100 ml. and the concentration of magnesium based on magnesium oxide (MgO) is 1.5 to 3.5 g , more preferably 1.5 to 2.5 g , and may have a pH (based on a 2.0% dilution (w/v) of the stock solution) of 2.8 to 4.8, more preferably 3.5 to 4.5.

Here, the basicity of the aqueous solution for the poly aluminum sulfate-magnesium coagulant may be controlled to preferably 7 to 25%, more preferably 8 to 12%, more preferably 8.5 to 11.5%, and the poly aluminum sulfate - The concentration of aluminum in the aqueous solution for the magnesium-based coagulant is preferably 6.5 to 10.5 g, more preferably 8 to 9.5 g, based on _{aluminum oxide (Al 2} O _{3 ).}

That is, as described above, the aqueous solution for polyaluminum sulfate-magnesium coagulant obtained through the method for producing polyaluminum sulfate-magnesium coagulant according to the present invention contains a component containing magnesium as a basicity increasing agent with respect to the conventional aluminum sulfate solution. By mixing, it shows very good floc formation and sedimentation efficiency as a coagulant for water treatment, and when it has an appropriate concentration range of magnesium component, storage stability is excellently improved, so long-term storage, transport and storage easiness can be remarkably improved. It is possible to provide a novel coagulant for water treatment that has a very high application potential in the field of water treatment.

here. As a performance indicator of the coagulant for water treatment, the basicity refers to the percentage of the number of moles of ^{hydroxyl groups (OH − ) relative to the number of moles of cationic components in the coagulant (refer to Equation 1 below).}

[Equation 1]

Basicity (%) = ( ^{number of moles of hydroxyl groups (OH -} ) per unit molecule of coagulant) / (3 * number of moles of positively charged inorganic metal component (eg, Al ³⁺ ) per unit molecule of flocculant) * 100

The basicity is an indicator determined by the composition and structure of the coagulant, and it is known that the higher the basicity, the higher the floc formation and storage stability of the coagulant. The low formation and aggregation effect is presumed to be due to the molecular structure of the monomolecular form constituting the flocculant and the low basicity of the flocculant itself.

For example, the polyaluminum chloride-based coagulant includes polyaluminum chloride (eg, Al ₁₃ (OH) ₃₂ ⁷⁺ ) in the form of a polymer or polynuclear complex ion, and the polyaluminum chloride cation represents the structure of the polymer, and also basicity In addition, it has a high +7 charge, so as a monomolecular flocculant, it has a low basicity, and has a structure that is advantageous for crosslinking between flocs compared to _{aluminum sulfate (Al 2} O _{3 )-based flocculants having a +3 charge.} Therefore, it is estimated that the aggregation effect is excellent.

On the other hand, the finally obtained poly aluminum sulfate-magnesium flocculent obtained according to the present invention has a basicity of 3 to 50, preferably 4 to 45, more preferably 5 to 40, still more preferably 6 to 35, still more preferably It can be controlled in a high range of 7 to 25%, and as a multi-metal component system, it has a structure advantageous for cross-linking between flocs, so it has better efficiency than aluminum sulfate-based flocculants, and at the same time, precipitation and precipitation phenomena occur on their own. Therefore, it is possible to solve the problem of polyaluminum chloride-based coagulant, which has a low limit of storage stability, showing high application potential in the water treatment field.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not to be construed as being limited by these examples.

<Example 1>

1 kg of aluminum hydroxide (anhydrous basis), 1 kg of water, and 1.882 kg of sulfuric acid (95%) are mixed, heated at a temperature of 130 ° C for 1 hour, and then water is added so that the total volume becomes 5 L, and aluminum sulfate-based aqueous solution is added. was prepared.

12.5 mL of magnesium hydroxide aqueous solution was mixed with 165 mL of the prepared aluminum sulfate-based aqueous solution at a temperature of 115° C. and reacted for 65 minutes to prepare a poly aluminum sulfate-magnesium-based coagulant solution. The aqueous magnesium hydroxide solution is obtained by reacting 20 w/v% (20 g of MgO in 100 ml of water) magnesium oxide in an aqueous solution at a temperature ranging from 70 to 80° C. for 60 minutes.

Finally, water is additionally added so that the total volume of the poly aluminum sulfate-magnesium coagulant aqueous solution becomes 250 mL, the total volume of the coagulant aqueous solution component is 100 ml, and the magnesium oxide (MgO) is 1.0 g (hereinafter, magnesium Concentration is referred to as 1 wt%), and the concentration of each metal is adjusted to 8.18 g (hereinafter referred to as aluminum concentration 8.18 wt%) as _{aluminum oxide (Al 2} O _{3 ).} did.

<Examples 2 to 5>

In the poly aluminum sulfate-magnesium-based coagulant manufacturing method of Example 1, the volume of the magnesium hydroxide aqueous solution mixed in the aluminum sulfate-based aqueous solution was 25 mL (Example 2), 40 mL (Example 3), 50 instead of 12.5 mL mL (Example 4) and 60 mL (Example 5) were carried out in the same manner as in Example 1, except that a poly aluminum sulfate-magnesium-based coagulant aqueous solution was prepared.

The poly aluminum sulfate-magnesium-based coagulant is 2.0 g by weight as magnesium oxide (MgO) (Example 2, with a total volume of 100 ml in the coagulant aqueous solution component, 2.0 g as magnesium oxide (MgO), a magnesium concentration of 2 wt%, Hereinafter, the same expression is used), 3.2 wt% (Example 3), 4.0 wt% (Example 4), and 4.8 wt% (Example 5) are poly aluminum sulfate-magnesium-based coagulants adjusted in concentration.

<Examples 6, 11, 16 and 21>

In the poly aluminum sulfate-magnesium-based coagulant manufacturing method of Example 1, the volume of the prepared aluminum sulfate-based aqueous solution was 175 mL (Example 6), 185 mL (Example 11), 195 mL (Example) instead of 165 mL. 16), and 205 mL (Example 21) was carried out in the same manner as in Example 1, except that a poly aluminum sulfate-magnesium-based coagulant solution was prepared.

<Examples 7 to 10, 12 to 15, 17 to 20>

For each of the poly aluminum sulfate-magnesium-based coagulant manufacturing methods of Examples 6, 11, 16 and 21, the volume of the magnesium hydroxide aqueous solution mixed with the aluminum sulfate-based aqueous solution was 25 mL instead of 12.5 mL (Examples 7, 12, 17), 40 mL (Examples 8, 13, 18), 50 mL (Examples 9, 14, 19), 60 mL (Examples 10, 15, 19) Examples 6, 11 except for mixing , 16 and 21 were carried out in the same manner as in each of the poly aluminum sulfate-magnesium-based coagulant aqueous solution was prepared.

<Comparative Example 1>

1 kg of aluminum hydroxide (anhydrous basis), 1 kg of water, and 1.882 kg of sulfuric acid (95%) are mixed, heated at a temperature of 130 ° C for 1 hour, and then water is added so that the total volume becomes 5 L, and aluminum sulfate-based aqueous solution is added. was prepared.

The aluminum sulfate-based coagulant whose concentration was adjusted to 8.18 wt% as _{aluminum oxide (Al 2} O ₃ ) was prepared by adding water so that the total volume became 250 mL without adding magnesium hydroxide to 165 mL of the prepared aluminum sulfate-based aqueous solution. .

<Comparative Examples 2 to 5>

In the method for preparing the aluminum sulfate-based coagulant of Comparative Example 1, the volume of the aluminum sulfate-based aqueous solution was 175 mL (Comparative Example 2), 185 mL (Comparative Example 3), 195 mL (Comparative Example 4), 205 mL instead of 165 mL An aluminum sulfate-based coagulant was prepared in the same manner as in Comparative Example 1 except for mixing (Comparative Example 5).

<Comparative Examples 6 to 7> (PAC preparation)

As the content of aluminum oxide (Al ₂ O ₃ ), 11 wt% (Comparative Example 6, 11 g with the total volume in the aqueous coagulant solution component being 100 ml) or 17 wt% (Comparative Example 7, the total volume in the coagulant aqueous solution component was 100 ml (17 g) of poly aluminum chloride-based (PAC) coagulant was prepared.

<Measurement of basicity>

The basicity of a part of the aqueous flocculant solution obtained according to the above example was measured and shown in Table 1 below.

Example basicity Example basicity Example basicity Comparative Example 1 0 Example 5 42.28 Example 12 10.38 Example 1 6.8 Example 6 6.1 Example 13 20.4 Example 2 10.53 Example 7 10.49 Example 16 4.6 Example 3 23.27 Example 8 21.05 Example 17 6.23 Example 4 30.1 Example 11 5.5 Example 18 13.5

<Evaluation Example 1 - Storage stability evaluation>

Storage stability of the flocculants of Examples 1 to 25 and Comparative Examples 1 to 5 was evaluated. When the coagulants of Examples and Comparative Examples were left for 1 to 12 weeks at 25 ° C. at room temperature, the storage stability results based on the amount of precipitation are shown in Tables 2 to 6 below, and storage in Tables 2 to 6 below. The notational description of stability can be expressed as ○: good (no precipitation), △: trace precipitation, and ×: precipitation (many precipitation).

division Al ₂ O ₃
content
(g/100ml) MgO
content
(g/100 ml) undiluted pH 2.0%w/v pH importance storage stability 1 week 2 weeks 3 weeks 4 weeks 8 weeks 12 weeks Example 1 8.18
% 1.0% 2.28 3.67 1.279 ○ ○ ○ ○ ○ ○ Example 2 2.0% 2.94 3.91 1.284 ○ ○ ○ ○ ○ ○ Example 3 3.2% 2.98 3.95 1.302 ○ ○ ○ ○ ○ ○ Example 4 4.0% 3.04 4.06 1.326 ○ ○ ○ ○ ○ ○ Example 5 4.8% 3.08 4.15 1.345 ○ ○ ○ ○ ○ △ Comparative Example 1 0 % 2.15 3.4 1.275 ○ ○ ○ ○ ○ ○

division Al ₂ O ₃
content
(g/100 ml) MgO
content
(g/100 ml) undiluted pH 2.0%w/v pH importance storage stability 1 week 2 weeks 3 weeks 4 weeks 8 weeks 12 weeks Example 6 8.68
% 1.0% 2.35 3.32 1.301 ○ ○ ○ ○ ○ ○ Example 7 2.0% 2.85 3.92 1.306 ○ ○ ○ ○ ○ ○ Example 8 3.2% 2.89 3.94 1.323 ○ ○ ○ ○ ○ ○ Example 9 4.0% 2.96 3.99 1.344 ○ ○ ○ ○ ○ △ Example 10 4.8% 3.05 4.12 1.361 ○ ○ ○ ○ △ △ Comparative Example 2 0 % 2.12 3.1 1.285 ○ ○ △ △ × ×

division Al ₂ O ₃
content
(g/100 ml) MgO
content
(g/100 ml) undiluted pH 2.0%w/v pH importance storage stability 1 week 2 weeks 3 weeks 4 weeks 8 weeks 12 weeks Example
11 9.18
% 1.0% 2.33 2.92 1.306 ○ ○ ○ ○ ○ ○ Example
12 2.0% 2.82 3.90 1.312 ○ ○ ○ ○ ○ ○ Example
13 3.2% 2.87 3.91 1.336 ○ ○ ○ ○ ○ ○ Example
14 4.0% 2.93 3.96 1.352 ○ ○ ○ ○ △ △ Example
15 4.8% 3.04 4.05 1.365 ○ ○ ○ △ △ △ Comparative Example 3 0 % 2.08 2.89 1.29 △ △ △ × × ×

division Al ₂ O ₃
content
(g/100 ml) MgO
content
(g/100 ml) undiluted pH 2.0%w/v pH importance storage stability 1 week 2 weeks 3 weeks 4 weeks 8 weeks 12 weeks Example
16 9.67
% 1.0% 2.31 2.91 1.316 ○ ○ ○ ○ ○ ○ Example
17 2.0% 2.78 3.88 1.324 ○ ○ ○ ○ ○ ○ Example
18 3.2% 2.86 3.92 1.34 ○ ○ ○ ○ ○ △ Example
19 4.0% 2.91 3.94 1.357 ○ ○ ○ ○ △ △ Example
20 4.8% 3.01 4.02 1.368 ○ ○ ○ △ △ × Comparative Example 4 0 % 2.03 2.85 1.3 △ × × × × ×

division Al ₂ O ₃
content
(g/100 ml) MgO
content
(g/100 ml) undiluted pH 2.0%w/v pH importance storage stability 1 week 2 weeks 3 weeks 4 weeks 8 weeks 12 weeks Example
21 10.17
% 1.0% 2.09 2.9 1.342 ○ ○ ○ ○ ○ △ Example
22 2.0% 2.72 3.81 1.348 ○ ○ ○ ○ ○ ○ Example
23 3.2% 2.85 3.88 1.362 ○ ○ ○ ○ ○ △ Example
24 4.0% 2.88 3.91 1.364 ○ ○ ○ △ △ △ Example
25 4.8% 2.96 3.95 1.37 ○ ○ ○ △ △ × Comparative Example 5 0 % 1.98 2.81 1.33 × × × × × ×

Referring to Tables 2 to 6, the poly aluminum sulfate-magnesium-based coagulant of the embodiment according to the present invention can be stably stored for at least 8 weeks, and in most cases can be stably stored for up to 12 weeks in the long term. Applicability is high, and it also shows that it has excellent storage stability compared to the aluminum sulfate-based coagulant presented in the comparative examples. In particular, the poly aluminum sulfate-magnesium coagulant of Examples 2, 7, 12, 17 and 22 having a content of 2.0 wt % as magnesium oxide (Mg) shows better long-term storage stability than other examples.

<Experimental Example 2 - Evaluation of agglomeration properties and turbidity improvement ability>

In order to evaluate the cohesive properties in wastewater and water treatment, an experiment was performed to evaluate the cohesive properties through a Jar test. The ruler test is an experimental method for evaluating the cohesive properties and turbidity improvement ability of the coagulant by comparing the size and turbidity values of the flocs formed when the coagulant is added to a container containing wastewater.

As the subject of the aggregation characteristic evaluation experiment, in common, the content as magnesium oxide (MgO) is 2.0 wt%, and the content as aluminum oxide (Al ₂ O ₃ ) is 8.18 wt%, 9.18 wt%, or 10.17 wt%, respectively. The polyaluminum-magnesium-based coagulant of Examples 2, 12 and 22, the aluminum sulfate-based coagulant of Comparative Example 1, and the polyaluminum chloride-based coagulant of Comparative Examples 6 and 7 were used.

The characteristics of wastewater to be treated in the magnetic test are shown in Table 7 below.

pH Turbidity (NTU) TOC (mg/L) raw wastewater 4.8 1.23 143.7 Aggregation pH 7.0 corrector NaOH 25.0% -soln" polymer 0.1% Anion Polymer aqueous solution (3ppm)

Table 8 and Figure 1 below show the change in turbidity of wastewater according to the addition of the coagulant of the Examples and Comparative Examples, the sedimentation rate and the size of the formed flocs are shown in Table 9, and the total organic carbon (TOC) results are shown in Table 10 and Fig. 2 is shown.

division Aluminum oxide (Al ₂ O ₃ ) content Turbidity (NTU) as a function of coagulant dose (ppm) 0 300 500 1000 Example 2 Al ₂ O _3: (8.18 %) + MgO content 2.0% 1.23 0.78 0.41 0.13 Example 12 Al ₂ O _3: (9.18 %) + MgO content 2.0% 1.23 0.65 0.36 0.08 Example 22 Al ₂ O _3: (10.17 %) + MgO content 2.0% 1.23 0.62 0.34 0.07 Comparative Example 1 ALUM (Al ₂ O _3: 8.18%) 1.23 0.98 0.75 0.38 Comparative Example 6 PAC (Al ₂ O _3: 11.0%) 1.23 0.95 0.67 0.28 Comparative Example 7 PAC (Al ₂ O _3: 17.0%) 1.23 0.82 0.42 0.17

Referring to Table 8, the poly aluminum sulfate-magnesium-based coagulant of Examples according to the present invention exhibits significantly superior turbidity improvement ability compared to the aluminum sulfate-based flocculant of Comparative Example 1, and Comparative Example known to have excellent turbidity improvement ability When it is assumed that the aluminum content is the same compared to the polyaluminum chloride-based coagulant of 6 and 7, it shows the ability to improve turbidity of equal or greater degree. In particular, the coagulants of Example 12 having an aluminum content of 9.18% and Example 22 having an aluminum content of 10.17% are polyaluminum chloride-based coagulants and show superior performance than Comparative Example 7 having an aluminum content of 17%. can be known

Example 2 Example 12 Example 22 Comparative Example 1 Comparative Example 6 Comparative Example 7 Floc particle diameter ^* D3~D4 D1-D2 D1-D2 Floc particle density highest commonly commonly Settling rate (Vs) fastest commonly commonly * Based on floc particle diameter
D1: 0.1~1 mm, D2: 1-2 mm, D3: 2-3 mm, D4: 3 mm or more

Referring to Table 9, the poly aluminum sulfate-magnesium-based coagulant of Examples according to the present invention has the largest diameter of the floc particles formed in comparison with the agglomeration experiments of Comparative Examples, and the highest density shows that the sedimentation rate is the best, It shows an excellent effect of more efficiently water treatment when a large amount of water in the flood or rainy season needs to be treated quickly.

division Aluminum oxide (Al ₂ O ₃ ) content
(weight%) Total organic carbon (mg/L) by coagulant dose (ppm) 0 300 500 1000 Example 2 Al ₂ O _3: (8.18%) + MgO content 2.0% 143.7 84.6 46.8 13.4 Example 12 Al ₂ O _3: (9.18%) + MgO content 2.0% 143.7 74.2 40.9 12.2 Example 22 Al ₂ O _3: (10.17%) + MgO content 2.0% 143.7 72.1 36.5 11.7 Comparative Example 1 ALUM (Al ₂ O _3: 8.18%) 143.7 104.2 64.5 24.2 Comparative Example 6 PAC (Al ₂ O _3: 11.0%) 143.7 97.2 55.4 20.5 Comparative Example 7 PAC (Al ₂ O _3: 17.0%) 143.7 62.4 34.1 12.2

Referring to Table 10, the poly aluminum sulfate-magnesium-based coagulant of Examples according to the present invention is significantly reduced compared to the aluminum sulfate-based coagulant of Comparative Example 1, indicating excellent ability to remove suspended solids including organic carbon. It shows the ability to improve turbidity equal to or greater than the polyaluminum chloride-based coagulant of Comparative Examples 6 and 7, which is known to have excellent ability to remove suspended solids through formation. In particular, _{as aluminum oxide (Al 2} O ₃ ), the coagulant of Example 12 having an aluminum content of 9.18% and Example 22 having an aluminum content of 10.17% was a polyaluminum chloride-based coagulant compared to Comparative Example 7 having an aluminum content of 17% Therefore, despite the low aluminum content, some are excellent and some are showing a slightly inferior ability to remove suspended solids.

Overall, the polyaluminum sulfate-magnesium-based coagulant of Examples according to the present invention exhibited superior storage stability and cohesive properties indicating floc formation and sedimentation efficiency compared to the conventional aluminum sulfate-based coagulant, and compared to the existing polyaluminum chloride-based coagulant. It shows equivalent or higher flocculation and turbidity improvement properties, showing very high applicability as a coagulant for water treatment.

Claims (10)

Assuming that the total volume in the aqueous coagulant solution component is 100 ml, the _{concentration of aluminum based on aluminum oxide (Al 2} O ₃ ) is 5 to 11 g, and the concentration of magnesium based on magnesium oxide (MgO) is 1.5 to 3.5 g, and , pH (based on 2.0% (w / v)) of 2.7 to 5 poly aluminum sulfate-magnesium-based coagulant aqueous solution.
According to claim 1,
The aqueous solution for poly aluminum sulfate-magnesium coagulant, characterized in that the basicity of the aqueous solution for the poly aluminum sulfate-magnesium coagulant is 8 to 12%.
According to claim 1,
The concentration of aluminum in the poly aluminum sulfate-magnesium-based coagulant aqueous solution _{is 6.5 to 10.5 g based on aluminum oxide (Al 2} O ₃ ) with the total volume of the coagulant aqueous solution component being 100 ml. Poly aluminum sulfate-magnesium sulfate, characterized in that Aqueous solution for coagulant system.
(a) mixing aluminum hydroxide, water and sulfuric acid, followed by heating to prepare an aluminum sulfate-based aqueous solution; and
(b) mixing a component containing magnesium with the aluminum sulfate-based aqueous solution prepared in step (a) to prepare a poly aluminum sulfate-magnesium-based aqueous coagulant solution;
The concentration of magnesium in the finally obtained aqueous solution for polyaluminum sulfate-magnesium coagulant is in the range of 1.5 to 3.5 g based on magnesium oxide (MgO), with the total volume in the aqueous coagulant solution being 100 ml. A method for preparing an aqueous solution comprising:
The content of the component containing magnesium to be mixed with the aluminum sulfate-based aqueous solution in step (b) is 100, the total volume of the coagulant aqueous solution obtained by mixing the magnesium-containing component with the aluminum sulfate-based aqueous solution in step (b). ml, and the content of magnesium oxide (MgO) is mixed so as to have a range of 1 to 7 g, and the reaction is performed.
5. The method of claim 4,
In step (a), the total weight of the aluminum sulfate-based aqueous solution is 100, and 5 to 35% by weight of aluminum hydroxide, 10 to 80% by weight of water, and 10 to 60% by weight of sulfuric acid (based on 95%) are mixed and heated. A method for preparing an aqueous solution for poly aluminum sulfate-magnesium coagulant.
5. The method of claim 4,
Poly aluminum sulfate-magnesium-based aqueous solution preparation method for a coagulant, characterized in that the heating in step (a) is made in a temperature range of 80 to 180 ℃.
5. The method of claim 4,
In step (b), the magnesium-containing component comprises one or a mixture thereof selected from magnesium hydroxide, magnesium sulfate, and magnesium chloride.
5. The method of claim 4,
The step (b) comprises mixing the magnesium-containing component with the aluminum sulfate-based aqueous solution and then heating at 80 to 180 ° C.
5. The method of claim 4,
In the step (b), the magnesium-containing component is an aqueous solution of magnesium hydroxide obtained by reacting magnesium oxide in an aqueous solution. delete

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