JP2021050131A - Basic aqueous aluminum silicate solution - Google Patents

Abstract

To provide an inorganic flocculant which is more superior in turbidity removal power than the most general waterworks PAC (Poly Aluminum Chloride) of 50% basicity in a water treatment method using an inorganic flocculant and an anionic or nonionic polymer flocculant.SOLUTION: A basic aqueous aluminum silicate solution which is characterized in that the concentration of Al2O3 is 0.05 mass% or higher and lower than 8 mass%; the molar ratio of SiO2/Al2O3 and the basicity (%) of the basic aqueous aluminum silicate solution are within the region bounded by the equations 1 to 6 (Equation 1: X≥0.01, Equation 2: X≤1.50, Equation 3: Y≥3, Equation 4: Y≤83, Equation 5: Y≥44X-5.8 in the range of 0.2≤X≤1.2, Equation 6: Y≥76.667X-45 in the range of 1.2≤X≤1.5, where X is SiO2/Al2O3 (molar ratio) and Y is basicity (%)); the haze rate of the solution is 25% or lower; and the difference in turbidity when subjected to the floc strength test is 50 degrees or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a basic aluminum silicate aqueous solution suitable for water treatment applications.

In water treatment using wastewater such as domestic wastewater, factory wastewater, and human waste wastewater as water to be treated, a water treatment method in which an inorganic flocculant and an anionic or nonionic polymer flocculant are used in combination is widely adopted. This is because, in general, the water treatment method using the inorganic flocculant in combination with the anionic or nonionic polymer flocculant coarsens the flocs and causes them to settle quickly, as compared with the water treatment method using the inorganic flocculant alone. This is because the processing time can be shortened. In addition, in water treatment using raw water for tap water such as river water, lake water, groundwater, etc. as the treated water, the treated water may become highly turbid due to the influence of weather changes and environmental changes. Assuming that it will be difficult to deal with water to be treated by the conventional water treatment method using only an inorganic coagulant, a practical study of a water treatment method using a combination of an inorganic coagulant and a polymer coagulant has been conducted. ing.

The expected role of inorganic flocculants is to aggregate turbidity and form fine flocs. This basic mechanism is to agglomerate turbid substances that do not repel each other and aggregate because they are negatively charged by charging and neutralizing them with a positively charged inorganic flocculant by hydrolysis or the like to form fine flocs. It is a thing. Further, the expected role of the polymer flocculant is to form coarse flocs from the fine flocs. The formed coarse flocs can be clarified by separating them by natural sedimentation or pressure flotation.

There are various types of inorganic flocculants and polymer flocculants used in water treatment, and therefore there are various combinations of inorganic flocculants and polymer flocculants.

Typical examples of inorganic flocculants are aluminum sulfate, basic aluminum chloride, aluminum chloride, etc. for aluminum-based flocculants, and ferric chloride, ferric sulfate, ferric sulfate, polysulfate for iron-based flocculants. Ferric etc.

Typical examples of anionic or nonionic polymer flocculants are polyacrylamide, a partial hydrolyzate of polyacrylamide, sodium polyacrylate, and a copolymer of acrylamide and sodium acrylate. There are numerous brands of polymer flocculants due to differences in the types of constituent monomers, molecular weight, and the like. Further, the anionic polymer flocculant can be classified into weak anionic, medium anionic and strong anionic.

Here, the basic aluminum chloride is also referred to as polyaluminum chloride (PAC), and various types are known depending on the range of basicity, the presence or absence of sulfate root, and the like. The Japanese Industrial Standards stipulate the standard for "polyaluminum chloride for water supply (basic aluminum chloride for water supply)" in K1475 (1996), and the _{concentration of aluminum oxide (Al 2} O ₃ ) is 10.0 to 11.0% by mass. It is specified in the range. Similarly, the Japan Water Works Association (JWWA) standard K154: 2016 regarding "polyaluminum chloride for water supply" also _{stipulates the concentration of aluminum oxide (Al 2} O ₃ ) in the range of 10.0 to 11.0% by mass. .. Hereinafter, the above-mentioned "polyaluminum chloride for water supply" will be referred to as "PAC for water supply". As can be understood from the above description of the basic mechanism of aggregation of the inorganic flocculant, since the metal component of the inorganic flocculant acts as an active ingredient in the aggregation, the _{concentration of aluminum oxide (Al 2} O ₃ ) is high. The regulations have an important position.

Patent Document 1 discloses highly basic aluminum chloride containing silicic acid in the range of 0.001 to 0.1 as a molar ratio of _{SiO 2} / Al ₂ O ₃ as one kind of basic aluminum chloride. The highly basic aluminum chloride of Patent Document 1 is intended to be applicable to water treatment, so that the Al ₂ O ₃ concentration in Example 1 is 10.3%, which is within the standard of PAC for water supply. There is.

Non-Patent Document 1 describes a technique relating to polyaluminum silicate chloride (PASC). The method for producing PASC is that after adding polysilic acid and water to an aluminum chloride solution, NaOH is added dropwise.

Japanese Patent No. 6186545

Baoyu Gao et al., Chemosphere 46 (2002) p.809-813, “The chemical species distribution and transformation of polyaluminum silicate chloride coagulant”

PASC described in Non-Patent Document 1 has _{high transparency because polymerized silicic acid is easily dissolved when SiO 2} / Al ₂ O ₃ (molar ratio) is low, but aggregation performance is obtained due to low silicic acid concentration. Tends to be inadequate. On the other hand, if SiO ₂ / Al ₂ O ₃ (molar ratio) is high, a gel-like substance of silicic acid with poor handleability is formed even if the aggregation performance tends to be obtained due to the high concentration of silicic acid. It is not suitable for industrial production because it is easy to form and precipitates such as insoluble matter of polymerized silicic acid and precipitate of aluminum silicate are likely to occur.

The present invention uses the most general water supply PAC with a basicity of 50% (hereinafter referred to as "B50 water supply PAC") in a water treatment method in which an inorganic flocculant and an anionic or nonionic polymer flocculant are used in combination. The challenge is to develop an inorganic flocculant that has better turbidity than if it had been present. Here, excellent turbidity means that the degree of removal of turbidity is high and the formation is high after the inorganic flocculant is added to the water to be treated and then the anionic or nonionic polymer flocculant is added. It means that the oversized flocs that are made are hard to collapse.

As a result of diligent studies on the development of a new inorganic flocculant in order to solve the above problems, the present inventors surprisingly found that among the basic salts containing aluminum, silicate and chlorine as constituents, they were effective. _{The concentration of Al 2} O ₃ which is a component is lower than the standard of PAC for water supply, and the SiO ₂ / Al ₂ O ₃ (molar ratio) and basicity are set in an appropriate range, and the specified transparency. It was found that those having the above are suitable for industrial production and have superior turbidity than the B50 water supply PAC, and the present invention was completed based on such findings. Furthermore, it should be noted that excellent turbidity can be obtained with a _{smaller amount of Al 2} O _{3 injection than the B50 water supply PAC.}

The present invention is as follows.
[1] A basic aqueous aluminum silicate solution having the compositions specified in (composition 1) and (composition 2) below and having the properties specified in (characteristic 1) and (characteristic 2) below.
(Composition 1) The Al ₂ O ₃ concentration of the basic aqueous aluminum silicate solution is 0.05% by mass or more and less than 8% by mass.
(Composition 2) SiO ₂ / Al ₂ O ₃ (molar ratio) and basicity (%) of the basic _{aqueous aluminum silicate solution are X, SiO 2} / Al ₂ O ₃ (molar ratio) is X, and basicity (%). ) Is Y, and it is one of the values in the area surrounded by the following equations 1 to 6.
Equation 1: X ≧ 0.01
Equation 2: X ≤ 1.5
Equation 3: Y ≧ 3
Equation 4: Y ≤ 83
Equation 5: Y ≧ 44 X-5.8 (range of 0.2 ≦ X ≦ 1.2)
Equation 6: Y ≧ 76.667 X-45 (range of 1.2 ≦ X ≦ 1.5)
(Characteristic 1) The Haze rate of the basic aqueous aluminum silicate solution is 25% or less.
(Characteristic 2) The difference in turbidity when the basic aqueous aluminum silicate solution was subjected to the following floc strength test was 50 degrees or less.
[Flock strength test]
1000 mL of simulated water to be treated (simulated water to be treated is distilled water with 5.0 g of paste fertilizer "Takipaste No. 14" manufactured by Taki Chemical Co., Ltd.) contained in a 1 L flat-bottomed glass beaker (inner diameter 10.5 ± 0.5 cm). A flat paddle (two-sheet type) was injected as a basic aluminum silicate aqueous solution so that the injection amount was 10 mg as _{Al 2} O _{3 (} prepared by adding so as to have a concentration of L). The size of one paddle is 25 mm in length x 24 mm in width. The lower end of the paddle is set at a position 5 mm vertically upward from the inner bottom surface of the flat-bottomed glass beaker), and after stirring at 115 rpm for 1 minute, it is weakly anionic. Inject 1.0 mL of a 1.0 mg / mL aqueous solution of "Takiflock A-122A" (trade name of Taki Chemical Co., Ltd.), which is a polyacrylamide-based polymer flocculant, and further stir at 115 rpm for 1 minute, and then at 45 rpm 5 Stir for minutes. Next, after standing for 10 minutes, 100 mL of the supernatant is collected by decantation, and the turbidity is measured and used as turbidity A.
Flat paddle (2 sheets type. The size of one paddle is 25 mm in length x 24 mm in width. The lower end of the paddle is 5 mm vertically upward from the inner bottom surface of the flat bottom glass beaker. After stirring at 200 rpm for 5 minutes using (set to position), let stand for 10 minutes, collect 100 mL of the supernatant by decantation, measure the turbidity, and use it as turbidity B.
The turbidity difference is calculated by the formula: turbidity difference = turbidity B-turbidity A.
[2] A water treatment method in which an aqueous solution of basic aluminum silicate according to the above [1] and an anionic or nonionic polymer flocculant are added to water to be treated to perform agglomeration treatment.
[3] An aqueous solution of basic aluminum silicate according to the above [1], an inorganic flocculant other than the basic aqueous solution of aluminum silicate, and an anionic or nonionic polymer flocculant are added to the water to be treated. A water treatment method for coagulation treatment.
[4] The method for producing a basic aluminum silicate aqueous solution according to [1] above, which comprises the following steps (i) or (ii).
(i) A step of mixing aluminum chloride and / or basic aluminum chloride and sodium aluminosilicate in the presence of water.
(ii) A step of mixing aluminum chloride and / or basic aluminum chloride, sodium aluminosilicate, and a basicity regulator in the presence of water.
[5] A powder obtained by drying the basic aluminum silicate aqueous solution according to the above [1].

The basic aluminum silicate aqueous solution of the present invention exhibits excellent turbidity, especially when used in combination with an anionic or nonionic polymer flocculant, and is therefore suitable for use as a coagulant for water treatment. It is a thing.

In the composition of the basic aqueous aluminum silicate solution of the present invention, when SiO ₂ / Al ₂ O ₃ (molar ratio) is X (horizontal axis) and basicity (%) is Y (vertical axis), Equation 1 : X ≧ 0.01, formula 2: X ≦ 1.5, formula 3: Y ≧ 3, formula 4: Y ≦ 83, formula 5: Y ≧ 44 X-5.8 (range of 0.2 ≦ X ≦ 1.2), and formula 6: Y ≧ It is the figure which showed the area surrounded by 76.667X-45 (the range of 1.2 ≤ X ≤ 1.5). It is a schematic diagram of a flat paddle (with a stirring shaft) used for a flock strength test.

Hereinafter, the present invention will be described in detail based on preferred embodiments, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims.
In the present invention, the notation "numerical value 1 to numerical value 2" regarding the numerical value range means a numerical value range including the numerical values 1 and 2 at both ends, with the numerical value 1 as the lower limit value and the numerical value 2 as the upper limit value. It is synonymous with "numerical value 1 or more and numerical value 2 or less".

The basic aluminum silicate aqueous solution of the present invention (hereinafter referred to as "the aqueous solution of the present invention") has the composition defined by the following (composition 1) and (composition 2), and has the following (characteristic 1) and (characteristic 1). It has the characteristics specified in the characteristic 2).
_{(Composition 1) The Al 2} O ₃ concentration of the aqueous solution of the present invention is 0.05% by mass or more and less than 8% by mass.
_{(Composition 2) SiO 2} / Al ₂ O ₃ (molar ratio) and basicity (%) of the aqueous solution of the present invention are set _{to X for SiO 2} / Al ₂ O ₃ (molar ratio) and Y for basicity (%). Then, it is one of the values in the area surrounded by the following equations 1 to 6.
Equation 1: X ≧ 0.01
Equation 2: X ≤ 1.5
Equation 3: Y ≧ 3
Equation 4: Y ≤ 83
Equation 5: Y ≧ 44 X-5.8 (range of 0.2 ≦ X ≦ 1.2)
Equation 6: Y ≧ 76.667 X-45 (range of 1.2 ≦ X ≦ 1.5)
(Characteristic 1) The Haze rate of the aqueous solution of the present invention is 25% or less.
(Characteristic 2) The difference in turbidity when the aqueous solution of the present invention is subjected to the floc strength test described later is 50 degrees or less.

FIG. 1 is a graph when SiO ₂ / Al ₂ O ₃ (molar ratio) is taken on the X-axis and basicity (%) is taken on the Y-axis. It shows the area that has been removed.

_{The upper limit of the Al 2} O ₃ concentration in the aqueous solution of the present invention is less than 8% by mass as described above. Good handleability and turbidity improving effect tend to be exhibited more as _{the Al 2} O _{3 concentration decreases.} The upper limit of the Al ₂ O ₃ concentration is preferably 7.5% by mass or less, more preferably 7% by mass or less, still more preferably 6.5% by mass or less, still more preferably 6% by mass or less, and particularly. It is preferably 5.5% by mass or less, and more preferably 5% by mass or less. The lower limit of the Al ₂ O ₃ concentration may be a low value because a predetermined turbidity can be obtained by increasing the injection amount, but it is 0.05% by mass from an economical point of view. The lower limit of the Al ₂ O ₃ concentration is preferably 0.1% by mass, more preferably 0.5% by mass, still more preferably 1% by mass, particularly preferably 1.2% by mass, and particularly more preferably 1.5% by mass. It is mass%. The preferred range of Al ₂ O ₃ concentration is 0.05 to 7.5% by mass, 0.05 to 7% by mass, 0.05 to 6.5% by mass, 0.05 to 6% by mass, 0.05 to 5.5% by mass, 0.05 to 5% by mass, 0.1% by mass or more. And less than 8% by mass, 0.1 to 7.5% by mass, 0.1 to 7% by mass, 0.1 to 6.5% by mass, 0.1 to 6% by mass, 0.1 to 5.5% by mass, 0.1 to 5% by mass, 0.5% by mass or more and 8% by mass Less than, 0.5 to 7.5% by mass, 0.5 to 7% by mass, 0.5 to 6.5% by mass, 0.5 to 6% by mass, 0.5 to 5.5% by mass, 0.5 to 5% by mass, 1% by mass or more and less than 8% by mass, 1 to 7.5% by mass, 1 to 7% by mass, 1 to 6.5% by mass, 1 to 6% by mass, 1 to 5.5% by mass, 1 to 5% by mass, 1.2% by mass or more and less than 8% by mass, 1.2 to 7.5% by mass, 1.2 to 7% by mass, 1.2 to 6.5% by mass, 1.2 to 6% by mass, 1.2 to 5.5% by mass, 1.2 to 5% by mass, 1.5% by mass or more and less than 8% by mass, 1.5 to 7.5% by mass, 1.5 to 7% by mass %, 1.5 to 6.5% by mass, 1.5 to 6% by mass, 1.5 to 5.5% by mass, 1.5 to 5% by mass and the like can be exemplified.

_{By the way, regarding the Al 2} O ₃ concentration acting as an active ingredient in aggregation, the range of 0.05% by mass or more and less than 8% by mass of the aqueous solution of the present invention is the range of the Al ₂ O ₃ concentration standard 10.0 to 11.0% by mass of the water supply PAC. It is a low concentration range compared to. It is considered that the reason why the aqueous solution of the present invention can exhibit excellent turbidity is that the existence form of aluminum is different from that of PAC for water supply due to this low concentration range. As a method for analyzing the existence form of aluminum, for example, the ferron method is known. The ferron method is a method for fractionating aluminum species using a chelate reaction between ferron and aluminum. Analysis by the ferron method revealed that the aqueous solution of the present invention contained more colloidal aluminum than the B50 water supply PAC. It is considered that this is because aluminum was polynuclearized by the action of silicic acid. It is presumed that this colloidal form of aluminum contributes to the exertion of the turbidity of the aqueous solution of the present invention.

The aqueous solution of the present invention can be used for various types of water to be treated such as wastewater and raw water for tap water. Depending on the type of water to be treated, it may contain a large amount of aggregation-inhibiting substances such as phosphate ions and proteins. Not limited to the B50 water supply PAC, in general, when the water supply PAC is used in water to be treated containing the above-mentioned aggregation inhibitor, the aggregation ability may be reduced by the aggregation inhibitor. At this time, it is necessary to add more than the usual amount.
On the other hand, it is unclear whether the aqueous solution of the present invention is due to the presence of colloidal aluminum, but the findings obtained from the water treatment test using the aqueous solution of the present invention suggest that it is not easily affected by the aggregation inhibitor. It was a thing. Therefore, the aqueous solution of the present invention exhibits excellent turbidity with respect to the water to be treated containing the above-mentioned aggregation inhibitor, even if the injection amount of _{Al 2} O ₃ which is an active ingredient is smaller than that of the B50 water supply PAC. Can be done.

In addition, the sludge volume increases as the amount of the inorganic flocculant used increases, but the aqueous solution of the present invention, which can obtain excellent turbidity with a _{smaller Al 2} O _{3 injection amount, also helps to reduce the volume of sludge.} It is something that can be done.

In the present invention, the basicity of the basic aqueous aluminum silicate solution is calculated by the following formula 1.

ここで、X_iはi番目のアニオンの濃度、Y_iはi番目のアニオンの価数、Z_iはi番目のアニオンの分子量であり、アニオンの種類iは1〜m個である。また、x_jはj番目のカチオン（ただしアルミニウムを除く。以下同じ）の濃度、y_jはj番目のカチオンの価数、z_jはj番目のカチオンの分子量であり、カチオンの種類jは1〜n個である。なお、数式１において、SiO₂は塩基度計算の対象外とする。

Here, X _i is the concentration of the i-th anion, Y _i is the valence of the i-th anion, Z _i is the molecular weight of the i-th anion, and the types of anions i are 1 to m. In addition, x _j is the concentration of the j-th cation (excluding aluminum; the same applies hereinafter), y _j is the valence of the j-th cation, z _j is the molecular weight of the j-th cation, and the cation type j is 1. ~ N pieces. In Equation 1, SiO ₂ is excluded from the basicity calculation.

From Equations 1 and 2, the amount of silicic acid contained in the aqueous solution of the present invention is in the range of 0.01 to 1.5 as _{SiO 2} / Al ₂ O _{3 (molar ratio).} When SiO ₂ / Al ₂ O ₃ (molar ratio) is less than 0.01, it becomes difficult to obtain the effect of improving the turbidity due to the inclusion of silicic acid. On the other hand, when the above SiO ₂ / Al ₂ O ₃ (molar ratio) exceeds 1.5, good handleability may not be obtained. Equation 1 preferably has X ≧ 0.05, more preferably X ≧ 0.1, even more preferably X ≧ 0.15, and even more preferably X ≧ 0.2. Equation 2 preferably has X ≦ 1.4, more preferably X ≦ 1.3, and even more preferably X ≦ 1.2.

The range of basicity of the aqueous solution of the present invention is 3 to 83% from Formulas 3 and 4. When the basicity is less than 3% or more than 83%, it becomes difficult to obtain good handleability and performance as a flocculant. Equation 3 preferably has Y ≧ 5, more preferably Y ≧ 10, even more preferably Y ≧ 15, even more preferably Y ≧ 20, and particularly preferably Y ≧ 25. More preferably, Y ≧ 30. Equation 4 is preferably Y ≦ 80, more preferably Y ≦ 75, even more preferably Y ≦ 70, even more preferably Y ≦ 65, and particularly preferably Y ≦ 60.

Equation 5 (Y ≧ 44X-5.8) is valid in the range 0.2 ≦ X ≦ 1.2, and the values of (X, Y) at both ends of the range of X are (0.20, 3.00) and (1.20, 47.00). Is. In the range of 0.2 ≦ X ≦ 1.2, it is difficult to obtain good handleability in the portion of Y <44X-5.8.

Equation 6 (Y ≧ 76.667X-45) is valid in the range 1.2 ≦ X ≦ 1.5, and the values of (X, Y) at both ends of the range of X are (1.20, 47.00) and (1.50, 70.00). ). In the range of 1.2 ≤ X ≤ 1.5, it is difficult to obtain good handleability in the portion of Y <76.667X-45. In particular, it is preferable to appropriately round, round off, or round up the values calculated from formulas 5 and 6 so that the region surrounded by formulas 1 to 6 becomes a closed region. For example, it is preferable to process the third digit after the decimal point, but the number of digits other than that may be used.

The amount of chlorine contained in the aqueous solution of the present invention is preferably in the range of 1 to 12 as _{Cl / Al 2} O _{3 (molar ratio).} The lower limit of the range of Cl / Al ₂ O ₃ (molar ratio) is preferably 2, and more preferably 3. The upper limit of the range of Cl / Al ₂ O ₃ (molar ratio) is preferably 11 and more preferably 10.

The aqueous solution of the present invention can be referred to as a dispersion because the Tyndall phenomenon is generally observed, but it is referred to as an "aqueous solution" for convenience because it uses water as a solvent. It should be noted that the observation of the Tyndall phenomenon is not a necessary condition for satisfying the constituent requirements of the present invention.

A preferred form of the aqueous solution of the present invention has good handleability, and a good example is one with low viscosity. For this purpose, it is preferable that precipitation and gelation do not occur immediately after production, and that they do not occur even after storage at 20 ° C. for one week. Aqueous solution of the present invention exhibits a tendency of concentration of Al ₂ O ₃ is increased as the handling property is low, it is preferably 5 wt% or less the upper limit of the concentration of Al ₂ O ₃ from the viewpoint of handling properties. From the viewpoint of higher handling, _{it is preferable to set SiO 2} / Al ₂ O ₃ (molar ratio) and basicity in a specific range _{, especially when the Al 2} O ₃ concentration is in the range of 4 to 5% by mass. As such a specific range, within the region surrounded by equations 1 to 6, the range of SiO ₂ / Al ₂ O ₃ (molar ratio) of 0.05 to 1 and the basicity of 30 to 80%. It can be exemplified.

The aqueous solution of the present invention contains aluminum, silicate and chlorine as essential components, but other components may be contained as optional components as long as the constituent requirements of the aqueous solution of the present invention are satisfied. As other components, alkali metals, alkaline earth metals, sulfate ions and the like can be exemplified. Regarding the content ratio of other components, for example, for alkali metals and alkaline earth metals, when the alkali metal and / or alkaline earth metal is M, M / Al ₂ O ₃ (molar ratio) = 0 to It is preferably in the range of 5. Here, the number of moles of M is obtained by the number of moles of alkali metal + (number of moles of alkaline earth metal × 2). The upper limit of the range of M / Al ₂ O ₃ (molar ratio) is more preferably 4 and even more preferably 3. When it contains an alkali metal and / or an alkaline earth metal, _{it is preferably in the range of M / Al 2} O ₃ (molar ratio) = 0.13 to 4, for example. The sulfate ion _{is preferably in the range of SO 4} / Al ₂ O ₃ (molar ratio) = 0 to 0.35. The upper limit of the SO ₄ / Al ₂ O ₃ (molar ratio) range is more preferably 0.32 and even more preferably 0.25. When sulfate ions are contained, for example, _{it is preferable that SO 4} / Al ₂ O ₃ (molar ratio) = 0.01 to 0.35.
In a preferred embodiment, M is only an alkali metal (does not contain alkaline earth metals). Moreover, in another preferable form, it does not contain sulfate ion. In yet another preferred embodiment, M is only an alkali metal (does not contain alkaline earth metals) and does not contain sulfate ions.

The aqueous solution of the present invention is highly transparent. When the Haze rate, which is an index of the degree of turbidity, is used as a method for evaluating transparency, the aqueous solution of the present invention shows a Haze rate of 25% or less. If the Haze rate exceeds 25%, the handleability has deteriorated due to gelation or precipitation. _{Here, the Al 2} O ₃ concentration of the aqueous solution of the present invention in the Haze rate measurement is 0.5% by mass. The Al ₂ O ₃ concentration can be adjusted by diluting with water, ultrafiltration, or concentrating using an evaporator. Put this in a glass cell with an optical path length of 10 mm, and measure the Haze rate with the chromaticity / turbidity measuring device COH400 manufactured by Nippon Denshoku Kogyo Co., Ltd. As the measuring instrument, an instrument having the same performance as the above may be used. The Haze rate is preferably 20% or less, more preferably 15% or less, and particularly preferably 10% or less. The lower limit of the Haze rate is not particularly limited, but is preferably 0%.

The turbidity of the aqueous solution of the present invention can be evaluated by the floc strength test shown below. In the flock strength test, the flock breaking operation was performed on the degree of removal of turbidity after the addition of the aqueous solution of the present invention and the weak anionic polyacrylamide polymer flocculant, and the coagulation-precipitated coarse flocs formed thereby. This is to evaluate the difficulty of disintegration of coarse flocs when a mechanical load (shearing force) of stirring with a flat paddle is applied.

[Flock strength test]
The simulated water to be treated is prepared by adding a paste fertilizer "Takipaste No. 14" manufactured by Taki Chemical Co., Ltd. to distilled water so as to have a concentration of 5.0 g / L. The pH of the simulated water to be treated is about 8.2. The turbidity of the simulated water to be treated is about 480 degrees.
_{A basic aluminum silicate aqueous solution was injected as Al 2} O ₃ into 1000 mL of simulated water to be treated contained in a 1 L flat-bottomed glass beaker (inner diameter 10.5 ± 0.5 cm) so that the injection volume was 10 mg. , Flat paddle (2 sheets type. The size of one paddle is 25 mm in length × 24 mm in width. The lower end of the paddle is set at a position 5 mm vertically upward from the inner bottom surface of the flat bottom glass beaker) 1 at 115 rpm After stirring for 1 minute, 1.0 mL of 1.0 mg / mL aqueous solution of "Takiflock A-122A" (trade name of Taki Chemical Co., Ltd.), which is a weak anionic polyacrylamide-based polymer flocculant, is injected, and then at 115 rpm for 1 minute. Stir, then stir at 45 rpm for 5 minutes (flock growth operation). Next, after standing for 10 minutes, 100 mL of the supernatant is collected by decantation, and the turbidity is measured and used as turbidity A.
Flat paddle (2 sheets type. The size of one paddle is 25 mm in length x 24 mm in width. The lower end of the paddle is 5 mm vertically upward from the inner bottom surface of the flat bottom glass beaker. Stir at 200 rpm for 5 minutes (flock destruction operation) using (set to position), leave for 10 minutes, collect 100 mL of supernatant by decantation, measure the turbidity, and use it as turbidity B. ..
The turbidity difference is calculated by the formula: turbidity difference = turbidity B-turbidity A.

The supplements and other precautions in the above flock strength test are as follows.
・ "Takipaste No. 14" has the registration number "Raw No. 102719", the type of fertilizer "Liquid compound fertilizer", and the name of the fertilizer " Taki Urea Organic Liquid Complex Fertilizer No. 14 Kai ”, Guaranteed Ingredients: Total Nitrogen 14.0% (Ammonia Nitrogen 1.2%), Soluble Phosphorus 10.0% (Water Soluble Phosphorus 7.2%), Water Soluble Kari 10.0 %, Soluble soil 1.0%, Raw materials that guarantee or contain the total amount of nitrogen (in descending order of content): urea, formaldehyde-processed urea fertilizer, and dried bacterial cell fertilizer. As described above, "Takipaste No. 14" contains phosphate ion and protein (derived from dry cell fertilizer) as aggregation inhibitors. When "Takipaste No. 14" is used for the floc strength test, it is preferable to stir well in advance.
-Injecting a basic aluminum silicate aqueous solution as it is means injecting the basic aluminum silicate aqueous solution to be tested as a stock solution without diluting or concentrating it in advance.
-It is preferable to use the simulated water to be treated, the basic aluminum silicate aqueous solution and the weak anionic polyacrylamide polymer flocculant used for the above injection at a liquid temperature of 15 ± 5 ° C. In addition, it is preferable that the temperature of the simulated water to be treated is maintained at 15 ± 5 ° C. even during the test.
-The shape of the flat paddle is the schematic diagram shown in FIG. 2, and two flat paddles 15 are joined to the stirring shaft 12. The thickness of the flat paddle is not particularly limited. Further, the material is not particularly limited. For example, an example of the thickness when polyvinyl chloride is used as the material is 2 mm.
・ Use a 1L flat-bottomed glass beaker with an inner diameter of 10.5 ± 0.5cm. For example, AGC Techno Glass IWAKI 1L flat-bottomed glass beakers were preferable, and the inner diameters of the six flat-bottomed glass beakers were measured to be 10.3 to 10.5 cm, with an average value of 10.43 cm. It is preferable to set the stirring shaft of the flat paddle to be located approximately at the center of the bottom surface of the flat-bottomed glass beaker.
-For the measurement of turbidity, it is preferable to use the water quality meter WA1 (cell: 2 cm cell) manufactured by Nippon Denshoku Co., Ltd.
-As a comparative test, when an aluminum-based flocculant other than the basic aluminum silicate aqueous solution is used as the test target, the "basic aluminum silicate aqueous solution" is the applicable aluminum-based flocculant in the above test. Should be replaced with.

Here, the turbidity A, the turbidity B, and the turbidity difference in the flock strength test will be described.

Turbidity A is an index for observing the degree of coagulation and precipitation with respect to the simulated water to be treated. The series of operations from the injection of the basic aqueous aluminum silicate solution to the injection of the weak anionic polyacrylamide polymer flocculant and the subsequent stirring is a floc growth operation, which produces coarse flocs. If so, it precipitates by the next standing, and the turbidity A shows a low value.

The degree of turbidity removal is calculated by the formula: turbidity = (turbidity of simulated water to be treated-turbidity A) ÷ turbidity of simulated water to be treated x 100 using turbidity A. Can be evaluated by. The turbidity when the aqueous solution of the present invention is tested is preferably 75% or more. If the turbidity is 75% or more, it can be evaluated as having an excellent turbidity removing ability. The turbidity is more preferably 80% or more, and even more preferably 85% or more.

Turbidity B is an index for observing the degree of collapse of coarse flocs when a mechanical load (shearing force) of stirring with a flat paddle is applied to the coarse flocs that have coagulated and settled.

The turbidity difference evaluates the difficulty of disintegration of coarse flocs. If the coarse flocs are hard to collapse, the turbidity difference is low. If the turbidity difference is 50 degrees or less, it can be judged that a strong coarse floc having a strength that does not easily collapse is obtained. The turbidity difference is more preferably 30 degrees or less, even more preferably 20 degrees or less, particularly preferably 10 degrees or less, and particularly more preferably 5 degrees or less. In a particularly preferred embodiment, the turbidity difference is a negative value.

As described above, by using the aqueous solution of the present invention, strong coarse flocs can be obtained. That is, it can be said that the aqueous solution of the present invention acts as a so-called floc strengthening agent. If the coarse flocs become strong, the durability against shearing force becomes high, so that the flocs are hard to break, and the effect of preventing leakage of turbidity can be expected.

The mechanism of how the aqueous solution of the present invention acts as a floc strengthening agent is not clear, but the following is presumed.
For water supply PAC, the turbidity is charged and neutralized by being added to the water to be treated, and the aluminum hydrolyzate binds the turbidity to each other mainly by adsorption action and is involved in the formation of fine flocs. Is believed to be.
On the other hand, in the aqueous solution of the present invention, when the bond due to the above-mentioned adsorption action is strengthened by silicic acid and coarse flocs are formed by this strengthened adsorption action by an anionic or nonionic polymer flocculant. In addition, it is presumed that it contributes to the strengthening of coarse flocs.

From the viewpoint of allowing the aqueous solution of the present invention to act as a floc strengthening agent, _{the upper limit of the Al 2} O ₃ concentration of the aqueous solution of the present invention is preferably 5% by mass or less. From the viewpoint of acting as a stronger floc strengthening agent _{, SiO 2} / Al ₂ O ₃ (molar ratio) and basicity are set in a specific range _{, especially when the Al 2} O ₃ concentration is in the range of 4 to 5% by mass. _{In such a specific range, the SiO 2} / Al ₂ O ₃ (molar ratio) is 0.1 to 0.6 and the basicity is 30 to 70 within the region surrounded by the formulas 1 to 6. The range of% can be exemplified.

A preferred form (first form) of the water treatment method using the aqueous solution of the present invention is that the aqueous solution of the present invention and an anionic or nonionic polymer flocculant are added to the water to be treated for coagulation treatment. Is. In the coagulation treatment, it is preferable to perform operations such as stirring as appropriate. A preferred order of addition is first the aqueous solution of the invention, then the anionic or nonionic polymeric flocculant. This order of addition is convenient for agglomerating turbid substances with the aqueous solution of the present invention to form fine flocs and then forming coarse flocs from the fine flocs with the polymer flocculant.

Examples of anionic or nonionic polymer flocculants include polyacrylamide, a partial hydrolyzate of polyacrylamide, sodium polyacrylate, and a copolymer of acrylamide and sodium acrylate, but are limited thereto. It's not something. The weight average molecular weight range of the polymer flocculant is preferably about 2 million to 20 million. The range of anionic polymer flocculants includes weak anionic, medium anionic, and strong anionic.

As the anionic or nonionic polymer flocculant, various commercially available products can be used. Here, for example, by the trade name of Taki Chemical Co., Ltd., "Takiflock N-100T", "Takiflock N-131" (above, nonionic polyacrylamide polymer flocculant), "Takiflock A-102", "Takiflock A-102T", "Takiflock A-112T", "Takiflock A-122A", "Takiflock A-132" (above, weak anionic polyacrylamide polymer flocculant), "Takiflock A-103", "Takiflock A-103" Takiflock A-103E, Takiflock A-103T, Takiflock A-103TE, Takiflock A-113T, Takiflock A-133, Takiflock A-104, Takiflock A-104T, Takiflock "A-105T", "Takiflock A-106T", "Takiflock AL-50", "Takiflock AL-65" (above, medium anionic polyacrylamide polymer flocculant), "Takiflock A-177T" (strong anionic) Polyacrylamide-based polymer flocculant), "Takiflock A-108T" (strong anionic polyacrylate-based polymer flocculant), "Takiflock A-122T" (nonionic modified polyacrylamide-based polymer flocculant), " Examples thereof include "Takiflock A-142" and "Takiflock A-162" (above, medium anionic modified polyacrylamide-based polymer flocculants). As polymer flocculants for tap water, MT Aqua Polymer Co., Ltd.'s "A-95PWG-S" (weak anionic polyacrylamide polymer flocculant), "A-110PWG-S", "A" -125PWG-S ”(above, medium anionic polyacrylamide polymer flocculant) and the like can be mentioned.

The amount of the aqueous solution of the present invention and the anionic or nonionic polymer flocculant added is preferably set appropriately depending on the water to be treated. For example, the aqueous solution of the present invention is set as _{Al 2} O _{3 with respect to the water to be treated.} It is 1 to 1,000 ppm, and the anionic or nonionic polymer flocculant is 0.5 to 100 ppm with respect to the water to be treated.

Further, another suitable form (second form) of the water treatment method using the aqueous solution of the present invention is, in the above first form, as an inorganic flocculant, in addition to the aqueous solution of the present invention, other than the aqueous solution of the present invention. Inorganic coagulant (hereinafter referred to as "inorganic coagulant A") is used. That is, the aqueous solution of the present invention, the inorganic flocculant A, and the anionic or nonionic polymer flocculant are added to the water to be treated for coagulation treatment. Examples of the inorganic flocculant A include aluminum sulfate, basic aluminum chloride, aluminum chloride and the like for aluminum-based flocculants, and ferric chloride, ferric sulfate, ferric sulfate, polysulfate for iron-based flocculants. Ferric iron and the like can be mentioned. The preferred order of addition is first the aqueous solution of the present invention and the inorganic flocculant A, then the anionic or nonionic polymeric flocculant. Further, regarding the order of addition of the aqueous solution of the present invention and the inorganic flocculant A, either of them may be added first, or both may be added at the same time. In the second form, it is possible to reduce the amount of the inorganic coagulant added as compared with the case where only the inorganic coagulant A is added as the inorganic coagulant, and it is also possible to reduce the volume of sludge. ..

The addition ratio of the aqueous solution of the present invention and the inorganic flocculant A is preferably set appropriately according to the type of water to be treated and the treatment conditions. _{As a setting example, the molar ratio of the inorganic flocculant A to Al 2} O _{3 in} terms of metal oxide of the aqueous solution of the present invention can be in the range of 0.1 to 1000 times. For example, when the inorganic flocculant A is an aluminum-based flocculant and the amount of the aqueous solution of the present invention added is _{1 mg / L for Al 2} O ₃ , the range of the amount of the aluminum-based flocculant added corresponds to the above-mentioned molar ratio range. Is 0.1 to 1000 mg / L as _{Al 2} O _3. Similarly, when the inorganic flocculant A is a ferric flocculant, the range of the amount of the ferric flocculant added is 0.16 to 1566 mg / L as _{Fe 2} O _3. The molar ratio range is preferably 1 to 1000 times, more preferably 1 to 100 times.

(Production method)
The method for producing an aqueous solution of the present invention includes (i) mixing aluminum chloride and / or basic aluminum chloride and sodium aluminosilicate in the presence of water, or (ii) aluminum chloride and / or basic. It includes a step of mixing aluminum chloride, sodium aluminosilicate, and a basicity adjusting agent in the presence of water. Since both (i) and (ii) are steps performed in the presence of water, when all the raw materials are solid, an appropriate amount of water is added. Further, the mixing ratio of the raw materials is appropriately designed so as to satisfy the composition of the aqueous solution of the present invention defined in the above (composition 1) and (composition 2).

Aluminum chloride (AlCl ₃ ) may be either solid or liquid. The solid aluminum chloride is, for example, aluminum chloride hexahydrate. An example of a method for producing liquid aluminum chloride is to dissolve an aluminum compound such as aluminum hydroxide with hydrochloric acid. In the above melting, it is preferable to melt by heating. The pressure condition at the time of heating may be either normal pressure or high pressure.

Basic aluminum chloride may be either solid or liquid. Liquid basic aluminum chloride can be produced by a conventional method, and an example of the production method is that an aluminum compound such as aluminum hydroxide and hydrochloric acid are placed in an autoclave and hydrothermally treated. By drying this, solid basic aluminum chloride can be obtained. Examples of the drying method include spray drying, aeration drying, vacuum drying, freeze drying and the like. A good example of the composition of basic aluminum chloride is that of basicity in the range of 40-50%, ie Cl / Al ₂ O ₃ (molar ratio) = 3.0-3.6.

Sodium aluminosilicate is, for example, a solid substance obtained by mixing a silicic acid-containing aqueous solution and an aluminum-containing aqueous solution under alkaline conditions and heating them as necessary. Alkaline agents such as sodium hydroxide may be used to create alkaline conditions. Examples of the silicic acid-containing aqueous solution include water glass No. 3, an aqueous solution of sodium metasilicate, and an aqueous solution of sodium orthosilicate. Examples of the aluminum-containing aqueous solution include an aqueous solution of sodium aluminate, an aqueous solution of aluminum chloride, and an aqueous solution of aluminum sulfate. Further, as an easily available sodium aluminosilicate, type A zeolite can be exemplified. The composition of sodium aluminosilicate is in the dry powder dried at 40 ° C., for example, in the range of 10 to 40% by mass _{for Al 2} O _{3, 15 to 45% by mass for SiO 2} , and 10 to 20% by mass for Na. is there.
A suitable method for analyzing the composition of sodium aluminosilicate is to appropriately dilute the aqueous solution obtained by dissolving sodium aluminosilicate in a mineral acid such as dilute nitric acid, and Al ₂ O _{3 is converted to SiO 2} by chelate titration. Na is a method of analysis by ICP-AES.

Examples of the basicity adjusting agent include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, alkali metal hydrogen carbonates, and alkaline earth metals. Hydrogen carbonate, sodium aluminate, potassium aluminate, hydrochloric acid, sulfuric acid, aluminum sulfate, alumina gel slurry and the like. Specific examples of alkali metal and alkaline earth metal hydroxides, carbonates, and bicarbonates include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, calcium hydroxide, and water. Magnesium oxide, calcium carbonate, magnesium carbonate, calcium hydrogen carbonate, magnesium hydrogen carbonate and the like. The alumina gel slurry contains Al, Cl, and Na as essential components and SO ₄ as an optional component, and has an Al ₂ O ₃ concentration of 3 to 15% by mass and Cl / Al ₂ O ₃ (mol). Ratio) is 1 to 4, Na / Al ₂ O ₃ (molar ratio) is 0.5 to 3, SO ₄ / Al ₂ O ₃ (molar ratio) is 0 to 2, and basicity is in the range of 70 to 100%. It is a good example, and more preferably Al ₂ O ₃ concentration is 8 to 12% by mass, Cl / Al ₂ O ₃ (molar ratio) is 1.5 to 3.5, Na / Al ₂ O ₃ (molar ratio) is 1 to 3, SO. ₄ / Al ₂ O ₃ (molar ratio) is in the range of 0 to 1.5 and basicity is in the range of 80 to 100%. The alumina gel slurry is preferably easily soluble in an acidic aqueous aluminum solution. For the evaluation of the solubility, for example, a basic aluminum chloride aqueous solution (Al ₂ O ₃ = 14.2% by mass, Cl = 16.8% by mass, basicity = 43%), distilled water and the alumina gel slurry are used as Al ₂ O. _The residue ratio calculated by dividing the wet weight of the undissolved residue after mixing to 3 = 10.2% by mass and 50% basicity and heating at 50 ° C for 1 hour by the total amount charged is 0.2 weight. If it is less than%, it can be evaluated as easily soluble. The alumina gel slurry can be produced, for example, by the method described in Japanese Patent No. 5986448.

In the step (i) or (ii), the mixing order of each raw material is not particularly limited, and for example, all the raw materials may be added and mixed at the same time. Further, for example, they may be added in order and mixed, or premixed at this time. In addition, water may be added as appropriate for adjusting the concentration and the like. When the dissolution by mixing alone (however, the dissolution here is a state in which the raw material is recognized as dissolved by the naked eye and the Tyndall phenomenon may be observed) is insufficient, (i) or (ii). ) May be followed by a heating step. The heating may be carried out under conditions suitable for melting, for example, at 30 to 100 ° C. for 5 minutes to 6 hours. Further, as a method for producing an aqueous solution of the present invention, there is a method of diluting a basic aluminum silicate aqueous solution produced by the above steps (i) or (ii) with water so as to _{have a predetermined Al 2} O _{3 concentration.} included.

The aqueous solution of the present invention can be made into a powder (hereinafter referred to as "powder A") by drying it. Examples of the drying method include spray drying, aeration drying, vacuum drying, freeze drying and the like, and among these, spray drying is preferable from the viewpoint of industrial production. By mixing the powder A with a predetermined amount of water, a basic aluminum silicate aqueous solution suitable for water treatment can be obtained. _{The Al 2} O ₃ concentration in the basic aluminum silicate aqueous solution prepared from powder A is preferably less than 8% by mass, more preferably 7.5% by mass or less, still more preferably 7% by mass or less. Yes, more preferably 6.5% by mass or less, particularly preferably 6% by mass or less, particularly more preferably 5.5% by mass or less, and particularly even more preferably 5% by mass or less.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

In each Example and Comparative Example, in the charged composition shown in Tables 1 to 5, a basic aluminum silicate aqueous solution was prepared by the following procedure.

(procedure)
Distilled water is added to the aluminum chloride aqueous solution, then 21% by mass of sodium carbonate aqueous solution or 35% hydrochloric acid is added, and then the mixture is stirred until the liquid becomes transparent, and then type A zeolite (Fujifilm Wako Pure Chemical Industries, Ltd.) A 20% by mass slurry of "synthetic zeolite A-4, powder, passing through 75 μm (200 mesh)") was added and sufficiently stirred to prepare a basic aqueous aluminum silicate solution.
Here, as an example, when the compounding ratio of each raw material in Example 59 is introduced, an aqueous solution of aluminum chloride (Al ₂ O ₃ = 11.17% by mass, Cl = 23.65% by mass): 30.39 g, distilled water: 43.80 g, 21% by mass. Aqueous solution of sodium carbonate: 18.40 g, 20% by mass slurry of A-type zeolite: 9.01 g.
_{The design Al 2} O ₃ concentration of the basic aluminum silicate aqueous solution was 1% by mass or less, and the type A zeolite was difficult to dissolve (Examples 1, 2, 7, 13, 14, 18, 19). , 20, 25, 26, 27, 31, 36, 40 and 44), _{basic aluminum silicate prepared at higher Al 2} O ₃ concentrations (eg Al ₂ O ₃ = 4-6% by weight). It was prepared by diluting the aqueous solution with water.
The basic aluminum silicate aqueous solutions of Examples 1 to 103 did not cause precipitation or gelation immediately after production, and did not occur even after storage at 20 ° C. for 1 week.
Among the basic aluminum silicate aqueous solutions of Comparative Examples 7 to 62, those having a basicity of 90% tended to be incompletely dissolved in the A-type zeolite, and the other ones were once dissolved in the A-type zeolite. However, it was inferior in handleability due to gelation.

(Measurement of Haze rate)
The Haze rate is determined by placing a basic aluminum silicate aqueous solution with an Al ₂ O ₃ concentration adjusted to 0.5% by mass in a glass cell with an optical path length of 10 mm, and using a chromaticity / turbidity measuring instrument manufactured by Nippon Denshoku Kogyo Co., Ltd. Measured with COH400. Distilled water was used for dilution in adjusting the concentration of Al ₂ O _3. In addition, _{among Examples 1 to 7 in which the Al 2} O ₃ concentration is less than 0.5% by mass, Examples 1, 2 and 7 are distilled water of a basic aluminum silicate aqueous solution prepared at a _{higher Al 2} O _{3 concentration.} The concentration was adjusted by diluting with, and the other concentrations were adjusted by concentrating using an evaporator.

The Haze rate of the basic aqueous aluminum silicate solutions of Examples 1 to 103 was 5% or less. The Haze rate of the basic aqueous aluminum silicate solutions of Comparative Examples 1 to 6 was also 5% or less.

In the following floc strength test, each basic aluminum silicate aqueous solution obtained in Examples 1 to 103 and Comparative Examples 1 to 6 was used.

(Flock strength test)
As the simulated water to be treated, a paste fertilizer "Takipaste No. 14" manufactured by Taki Chemical Co., Ltd. was added to distilled water to a concentration of 5.0 g / L and mixed.
A basic aluminum silicate aqueous solution was added to 1000 mL of simulated water to be treated contained in a flat-bottomed glass beaker (inner diameter: 10.5 cm) of IWAKI 1L manufactured by AGC Techno Glass Co., Ltd. so that the injection amount was 10 mg as _{Al 2} O _3. Inject it as it is, and insert a flat paddle (2 sheets type. The size of one paddle is 25 mm in length × 24 mm in width. The lower end of the paddle is set at a position 5 mm vertically upward from the inner bottom surface of the above flat bottom glass beaker). After stirring at 115 rpm for 1 minute, 1.0 mL of 1.0 mg / mL aqueous solution of "Takiflock A-122A" (trade name of Taki Chemical Co., Ltd.), which is a weak anionic polyacrylamide-based polymer flocculant, was injected. The mixture was further stirred at 115 rpm for 1 minute and then at 45 rpm for 5 minutes (flock growth operation). Next, after standing for 10 minutes, 100 mL of the supernatant was collected by decantation, and the pH (denoted as "treated water pH" in Tables 1 to 5) and turbidity were measured. The turbidity was measured with a water quality meter WA1 (cell: 2 cm cell) manufactured by Nippon Denshoku Co., Ltd., and was designated as turbidity A.
The residual liquid after collecting the supernatant is stirred at 200 rpm for 5 minutes (flock destruction operation) using the flat paddle (the paddle position is the same as above), and then allowed to stand for 10 minutes, and then decanted. 100 mL of the supernatant was collected, and the turbidity was measured in the same manner as above to give turbidity B.
The turbidity rate was calculated from the formula: turbidity rate = (turbidity of simulated water to be treated-turbidity A) ÷ turbidity of simulated water to be treated x 100.
The turbidity difference was calculated from the formula of turbidity difference = turbidity B-turbidity A.
In the above test, the liquid temperatures of the simulated water to be treated, the basic aluminum silicate aqueous solution and the weak anionic polyacrylamide polymer flocculant used for the injection were around 15 ° C.

The results of the flock strength test are shown in the "Flock strength test" column of Tables 1-5. In Examples 1 to 103, the turbidity rate was 80% or more, the turbidity difference was 10 degrees or less, and most of them were less than 0 degrees. From this, the basic aluminum silicate aqueous solutions obtained in Examples 1 to 103 had excellent turbidity, that is, they had high turbidity removing power and effectively functioned as a floc strengthening agent. It can be judged that it was a thing.

On the other hand, Comparative Examples 1 to 6 could be evaluated as having turbidity removing ability because the turbidity rate was about 70 to 85%, but were formed because the turbidity difference was 200 degrees or more. It can be judged that the coarse flocs were soft.

From the above, it was found that the basic aluminum silicate aqueous solutions obtained in Examples 1 to 103 are suitable for use as a coagulant for water treatment.

[Flock strength test with dry powder solution]
Each basic aluminum silicate aqueous solution obtained in Example 54 and Example 63 was freeze-dried to obtain a dry powder. _{Regarding the Al 2} O ₃ concentration of the dry powder, Example 54 was 20.9% by mass, and Example 63 was 22.3% by mass.
0.5 g of dry powder was dissolved in 4.5 g of water, and this solution was subjected to a floc strength test. The results are shown in Table 6.

From Table 6, the turbidity rate was 90% or more, and the turbidity difference was less than 0 degrees. The turbidity difference and the turbidity difference were the same as the values before drying (see Table 2). From this, it was found that even a dry powder solution has excellent turbidity and is suitable for use as a coagulant for water treatment.

[Comparative Example 63 (B50 water supply PAC equivalent product)]
B50 water supply PAC equivalent products correspond to B50 water supply PAC. Hereinafter referred to as "B50PAC".
B50PAC was produced as follows, with Al ₂ O ₃ concentration: 10.2% by mass, SO ₄ concentration: 2.8% by mass, and basicity of 50% as target compositions.
(Raw material: Preparation of basic aluminum chloride A)
By reacting aluminum hydroxide and hydrochloric acid under hydrothermal treatment conditions using an autoclave _{, basic aluminum chloride A having an Al 2} O ₃ concentration: 14.2% by mass, a Cl concentration: 16.8% by mass, and a basicity of 43% was obtained. It was.
(Raw material: Preparation of alumina gel slurry A)
While stirring 1055 g of distilled water in a 5 L beaker, 1243 g of basic aluminum chloride A and _{702 g of an aqueous sodium aluminate solution (Al 2} O ₃ concentration: 17.6% by mass, Na concentration: 13.5% by mass) were simultaneously applied for 30 minutes with a perista pump. Alumina gel slurry A having an Al ₂ O ₃ concentration of 10.0% by mass, a Cl concentration of 7.0% by mass, and a Na concentration of 3.2% by mass was obtained in an amount of 3000 g.
(Manufacturing)
After putting 96 g of basic aluminum chloride A in a 500 mL four-necked flask equipped with a stirrer and a thermometer, an aqueous aluminum sulfate aqueous solution (Al ₂ O ₃ concentration: 8.0% by mass, SO ₄ concentration: 23.0 mass) is stirred. %) 24 g, Alumina Gel Slurry A 48 g and Distilled Water 32 g were added in this order and mixed. Next, the mixed solution was heated at 50 ° C. for 1.0 hour, and then suction-filtered with No. 5C filter paper to produce B50PAC.

B50PAC was subjected to the flock strength test in the same manner as above.
In the floc strength test, the following two steps were set as the injection amount of B50PAC.
・ Setting 1: _{10 mg as Al 2} O ₃ (same injection amount as the above floc strength test)
・ Setting 2: _{50 mg as Al 2} O ₃ (5 times the injection amount of the above floc strength test)
The results are shown in Table 8.

As is clear from a comparison between Tables 1 and 2, when the _{injection amount of Al 2} O ₃ is 10 mg, the turbidity rate is significantly higher in Examples 1 to 103 than in Setting 1, and the turbidity is high. There was a clear difference when it came to the difference. When the Al ₂ O ₃ injection amount of B50PAC was 50 mg (setting 2), the turbidity rate was almost the same level as in Examples 1 to 103, but there was still a clear difference in the turbidity difference. there were.

From the above, the aqueous solution of the present invention _{can obtain excellent turbidity with a smaller injection amount of Al 2} O ₃ than the B50 water supply PAC, and is particularly suitable for water treatment applications due to its strong floc forming ability. It was confirmed that it was a thing.

[Flock strength test in combination with B50PAC]
As the basic aluminum silicate aqueous solution, the basic aluminum silicate aqueous solution of Example 33 was used. In addition, B50PAC was used as the inorganic flocculant A.
The flock strength test was carried out in the same manner as the flock strength test in the examples, but instead of "injecting a basic aluminum silicate aqueous solution as a form so that the injection amount was 10 mg as _{Al 2} O _3". , "Injected the inorganic flocculant as it was so that the injection amount of _{Al 2} O ₃ shown in Test Groups 1-1 to 3-4 in Table 8 was obtained." In addition, instead of "injecting 1.0 mL of 1.0 mg / mL aqueous solution of" Takiflock A-122A "(trade name of Taki Chemical Co., Ltd.), which is a weak anionic polyacrylamide polymer flocculant," weak anion A 1.0 mg / mL aqueous solution of "Takiflock A-132" (trade name of Taki Chemical Co., Ltd.), which is a sex polyacrylamide-based polymer flocculant, was injected in 1.0 mL. In Test Groups 2-1 to 3-4, B50PAC and the basic aluminum silicate aqueous solution of Example 33 were injected at the same time.

From the results of the floc strength test in Table 8, as compared with Test Groups 1-1 to 1-4 of B50PAC alone, B50PAC and Basic Aluminum Chloride Chloride of Example 33 as shown in Test Groups 2-1 to 3-4. It was found that the turbidity rate was improved by using the aqueous solution together. For example, Test Group 2-1 showed a higher turbidity rate than Test Group 1-2, and Test Group 3-1 showed a high turbidity rate comparable to Test Group 1-4. In addition, test groups 2-3, 2-4, 3-2 to 3-4 showed higher turbidity rates than test groups 1-1 to 1-4 of B50PAC alone. Regarding the turbidity difference, the test plots 2-1 to 3-4 were 5 degrees or less, and most of them were less than 0 degrees, indicating that strong coarse flocs that were hard to collapse were obtained. ..

[Flock strength test in combination with ferric polysulfate]
Beverage factory wastewater (pH 8.4, turbidity 88.2 degrees) was used as the simulated water to be treated, and commercially available ferric sulfate (Fe ₂ O ₃ : 16.7% by mass) was used instead of B50PAC. The flock strength test was carried out in accordance with the "flock strength test in combination with B50PAC". Table 9 shows the injection amount of the inorganic flocculant. In Test Groups 5-1 and 5-2, ferric polysulfate and the basic aqueous aluminum silicate solution of Example 33 were injected at the same time.

When comparing the turbidity rate and turbidity difference with the same Fe ₂ O ₃ injection amount, that is, when comparing test plot 4-1 and test plot 5-1 and test plot 4-2 and test plot 5-2, Regarding the turbidity, it was found that the test plots 4-2 and 5-2 were similar in turbidity, but other than that, the test plots 5-1 and 5-2 gave better results.

[Comparative Examples 64-66 (PASC of Non-Patent Document 1)]
As the PASC described in Non-Patent Document 1, PASCs of Comparative Examples 64 to 66 were produced. The manufacturing procedure is as follows: using the raw materials listed in the raw material column of Table 10, polysilicic acid and water are added to the aluminum chloride solution, then NaOH is added dropwise, and finally the Al ₂ O ₃ concentration becomes 0.5% by mass. Diluted with water.

The flock strength test of PASCs of Comparative Examples 64 to 66 was carried out by the same method as in Examples 1 to 103 and Comparative Examples 1 to 6. From Table 10, the PASCs of Comparative Examples 64 and 65 showed a low Haze rate, but the difference in turbidity was far greater than 50 degrees, so the formed coarse flocs were soft. I can judge. The PASC of Comparative Example 66 had a turbidity difference of less than 0 degrees, but a Haze rate of more than 25%. In the PASC of Comparative Example 66, insoluble matter was formed during the production, and precipitation was observed immediately after the production. By the way, the PASC of Comparative Example 66 gelled unless the aluminum chloride solution and the polysilicic acid were mixed very quickly and in a proper manner at the time of its production. Even if gelation could be prevented, precipitation would occur as described above, so it was not suitable for practical use.

[Comparative Examples 67 and 68 (silicic acid source: silica sol)]
Aqueous solutions of basic aluminum silicate of Comparative Examples 67 and 68 using silica sol as a silicic acid source were produced. The charged composition is shown in Table 11.
The manufacturing procedure is to put basic aluminum chloride A in a 500 mL four-necked flask equipped with a stirrer and a thermometer, and then add hydrochloric acid and distilled water in order while stirring to mix Al ₂ O ₃ Basic aluminum chloride having = 10.9 to 11.1% by mass, Cl = 15.8 to 16.1% by mass, and basicity of 31% was obtained. Next, silica sol is added to this basic aluminum chloride having a basicity of 31%, reacted at room temperature for 0.5 hours, diluted with water, and then suction-filtered with No. 5C filter paper to obtain transparent basic silicic chloride. An aqueous aluminum solution was prepared. As the silica sol, "Adelite AT-20Q" (SiO ₂ = 20.0% by mass) manufactured by ADEKA Corporation was used in Comparative Example 67, and "Snowtex OUP" (SiO _{2) manufactured by Nissan Chemical Industries, Ltd. in Comparative Example 68.} = 15.3% by mass) was used.

The floc strength test of the basic aluminum silicate aqueous solutions of Comparative Examples 67 and 68 was carried out by the same method as in Examples 1 to 103 and Comparative Examples 1 to 6. From Table 11, since the turbidity difference between the basic aluminum silicate aqueous solutions of Comparative Examples 67 and 68 was much larger than 50 degrees, it can be judged that the formed coarse flocs were soft.

12 stirring shaft, 15 flat paddle

Claims (5)

It has the composition specified in (Composition 1) and (Composition 2) below.
Moreover, it has the characteristics specified in (Characteristic 1) and (Characteristic 2) below.
Aqueous solution of basic aluminum silicate.
(Composition 1) The Al ₂ O ₃ concentration of the basic aqueous aluminum silicate solution is 0.05% by mass or more and less than 8% by mass.
(Composition 2) SiO ₂ / Al ₂ O ₃ (molar ratio) and basicity (%) of the basic _{aqueous aluminum silicate solution are X, SiO 2} / Al ₂ O ₃ (molar ratio) is X, and basicity (%). ) Is Y, and it is one of the values in the area surrounded by the following equations 1 to 6.
Equation 1: X ≧ 0.01
Equation 2: X ≤ 1.5
Equation 3: Y ≧ 3
Equation 4: Y ≤ 83
Equation 5: Y ≧ 44 X-5.8 (range of 0.2 ≦ X ≦ 1.2)
Equation 6: Y ≧ 76.667 X-45 (range of 1.2 ≦ X ≦ 1.5)
(Characteristic 1) The Haze rate of the basic aqueous aluminum silicate solution is 25% or less.
(Characteristic 2) The difference in turbidity when the basic aqueous aluminum silicate solution was subjected to the following floc strength test was 50 degrees or less.
[Flock strength test]
1000 mL of simulated water to be treated (simulated water to be treated is distilled water with 5.0 g of paste fertilizer "Takipaste No. 14" manufactured by Taki Chemical Co., Ltd.) contained in a 1 L flat-bottomed glass beaker (inner diameter 10.5 ± 0.5 cm). A flat paddle (two-sheet type) was injected as a basic aluminum silicate aqueous solution so that the injection amount was 10 mg as _{Al 2} O _{3 (} prepared by adding so as to have a concentration of L). The size of one paddle is 25 mm in length x 24 mm in width. The lower end of the paddle is set at a position 5 mm vertically upward from the inner bottom surface of the flat-bottomed glass beaker), and after stirring at 115 rpm for 1 minute, it is weakly anionic. Inject 1.0 mL of a 1.0 mg / mL aqueous solution of "Takiflock A-122A" (trade name of Taki Chemical Co., Ltd.), which is a polyacrylamide-based polymer flocculant, and further stir at 115 rpm for 1 minute, and then at 45 rpm 5 Stir for minutes. Next, after standing for 10 minutes, 100 mL of the supernatant is collected by decantation, and the turbidity is measured and used as turbidity A.
Flat paddle (2 sheets type. The size of one paddle is 25 mm in length x 24 mm in width. The lower end of the paddle is 5 mm vertically upward from the inner bottom surface of the flat bottom glass beaker. After stirring at 200 rpm for 5 minutes using (set to position), let stand for 10 minutes, collect 100 mL of the supernatant by decantation, measure the turbidity, and use it as turbidity B.
The turbidity difference is calculated by the formula: turbidity difference = turbidity B-turbidity A. A water treatment method in which an aqueous solution of basic aluminum silicate according to claim 1 and an anionic or nonionic polymer flocculant are added to water to be treated to perform agglomeration treatment. The basic aluminum silicate aqueous solution according to claim 1, an inorganic flocculant other than the basic aluminum silicate aqueous solution, and an anionic or nonionic polymer flocculant are added to the water to be treated for coagulation treatment. Water treatment method. The method for producing a basic aluminum silicate aqueous solution according to claim 1, which comprises the following steps (i) or (ii).
(i) A step of mixing aluminum chloride and / or basic aluminum chloride and sodium aluminosilicate in the presence of water.
(ii) A step of mixing aluminum chloride and / or basic aluminum chloride, sodium aluminosilicate, and a basicity regulator in the presence of water. A powder obtained by drying the basic aluminum silicate aqueous solution according to claim 1.

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