KR102578887B1 - Method of producing PloyAluminumFerricSulfate aqueous solution - Google Patents

Abstract

Ferric oxide; aluminum hydroxide; and waste sulfuric acid; mixing; and stirring the mixture. A method for producing an aqueous polyaluminum iron sulfate solution is provided.

Description

Method of producing PloyAluminumFerricSulfate aqueous solution}

It relates to a method for producing an aqueous solution of polyaluminum iron sulfate.

Currently, the most widely used inorganic coagulant is polyaluminium chloride (PAC: Poly Aluminum Chloride). PAC is polymerized and given basicity through the reaction of hydrochloric acid and aluminum hydroxide, and shows excellent performance in many aspects such as phosphorus removal, fluorine removal, turbidity and suspended solids removal, etc.

However, PAC is expensive, the supply of hydrochloric acid as a raw material is unstable, and after water treatment, residual chlorine is left behind, which can cause equipment corrosion or air pollution when recycling or incinerating the sludge generated from it, and chlorine ions and chlorine ions are also present in the treated water. It has the disadvantage of increasing the salinity in the treated water because it contains significant amounts of salts such as calcium and magnesium.

Meanwhile, as industries that use semiconductors, such as smartphones, AI, and autonomous driving, grow rapidly, the production of semiconductors is increasing quantitatively, and the amount of waste sulfuric acid emitted is also increasing.

The present invention provides a method for producing an aqueous polyaluminum iron sulfate solution, which is an excellent water treatment agent at a low price, using waste sulfuric acid.

According to one aspect,

Ferric oxide; aluminum hydroxide; and waste sulfuric acid; mixing; and

Stirring the mixture; comprising

A method for producing an aqueous polyaluminum iron sulfate solution is provided.

According to the method for producing an aqueous polyaluminum sulfate solution according to an embodiment, an aqueous polyaluminum sulfate solution that is environmentally friendly and has excellent water treatment ability can be prepared by using waste sulfuric acid.

In addition, recycling waste sulfuric acid discharged in large quantities from the semiconductor process is of great help in environmental and economic terms, and has water treatment performance comparable to that of the widely used PAC (Poly Aluminum Chloride), while maintaining a low chemical price. It is an eco-friendly manufacturing method that has many advantages, such as removing bad odors during water treatment, facilitating recycling and incineration of sludge generated by reducing residual salts (especially chlorine) after water treatment, and improving corrosiveness of facilities.

Figure 1 shows photographs of Comparative Example 1 (Sample A) and Example 1 (Sample B) immediately after manufacturing.
Figure 2 shows photographs of Comparative Example 1 (Sample A) and Example 1 (Sample B) one month after production.
Figure 3 shows a photograph of Comparative Example 2 (Sample C) immediately after manufacturing.
Figure 4 shows a photograph of Comparative Example 2 (Sample C) one month after production.
Figure 5 shows a photograph of Example 2 (Sample D) immediately after preparation.
Figure 6 shows a photograph of Example 2 (Sample D) one month after preparation.
Figure 7 shows a photograph of Comparative Example 3 (Sample E) immediately after manufacturing.
Figure 8 shows a photograph of Comparative Example 3 (Sample E) one month after production.
Figure 9 shows a photograph of the bottom portion of Comparative Example 3 (Sample E) one month after production.

Aluminum polysulfate is a water treatment agent that is equivalent to or superior to PAC, which is currently the most widely used water treatment agent, but has not been commercialized much due to stability problems such as white turbidity or precipitation due to hydrolysis during the storage process after production. If a manufacturing method for polyaluminum sulfate with stable content and basicity is established, it will be greatly advantageous to PAC in terms of price and procurement (recently, the supply of hydrochloric acid, the raw material for PAC, is unstable), so we believe that a sufficient market will be created, so we conducted research on this. This method has been completed.

Waste sulfuric acid discharged in large quantities from the semiconductor industry is mostly sold to water treatment plants as a pH-adjusting agent after removing small amounts of hydrogen peroxide to adjust its concentration, or is recycled as a raw material for cement by neutralizing it with lime, etc. to make gypsum.

Recently, as the production of semiconductors has increased due to the emergence and growth of smartphones, electric vehicles, self-driving cars, and data centers, which consume large amounts of semiconductors, the waste sulfuric acid discharged has increased proportionally, making disposal of waste sulfuric acid a social issue. It can be said that it is meaningful to develop a new water treatment agent using recycled waste sulfuric acid whenever possible.

Aluminum sulfate, commonly called alum, has also been widely used as a water treatment agent, but it has the disadvantages of poor water treatment performance at low temperatures, a large pH drop during water treatment, large alkali consumption, and soluble aluminum, which poses a significant risk to health, may remain. Polyaluminum sulfate that has been polymerized and given basic properties has been attempted. Aluminum polysulfate overcomes these disadvantages of aluminum sulfate and is comparable to PAC in terms of cohesion performance, but it is unstable, producing white turbidity or precipitates due to hydrolysis during storage after manufacture, so not many products have been commercialized so far.

In the traditional manufacturing method, starting from aluminum sulfate, lime, caustic soda, soda ash, aqueous ammonia and other alkaline sources with hydroxyl groups are added to add basicity, and pH is 3.5 to 4.3, usually 3.8 (aluminum hydroxide does not precipitate below pH 3.8). In order to provide stability, phosphate, hydrochloride, sodium heptonate, citric acid, sorbitol, sodium citrate, sodium tartrate, sodium gluconate, etc. are added to partially replace sulfate ions.

In the prior art, basic polyaluminium sulfate was obtained through neutralization of aluminum sulfate (Al ₂ (SO ₄ ) ₃ ) with caustic soda, but a large amount of sodium sulfate was generated as a by-product during the manufacturing process (8 moles when obtaining 4 moles of aluminum polysulfate). moles of sodium sulfate). Meanwhile, when sodium aluminate (NaAlO ₂ ) is neutralized with sulfuric acid to obtain gel-like Al(OH) ₃ and then reacted with aluminum sulfate to produce polyaluminum sulfate, 4 moles of sodium sulfate as a by-product are added to 4 moles of polyaluminum sulfate. shows what is happening. Caustic soda, sodium aluminate, soda ash, calcium carbonate, aqueous ammonia, etc., which are added to provide basicity, generate by-products, so it is not easy to filter and remove them.

As another prior art, there is a method of producing polyaluminum sulfate represented by the formula below by adding sodium aluminate (NaAlO ₂ ) to an aqueous solution of aluminum sulfate and reacting it with high shear mixing. There is no mention of stability.

[Al _A (OH) _B (SO ₄ ) _C (H ₂ O) _E ] _n

where n is a positive integer, A is 1.0, B is 0.75 - 2.0, and C is 0.5 - 1.12.

As another prior art, calcium carbonate was used as a basicity imparting agent to aluminum sulfate and phosphoric acid was used as a stabilizer to produce polyaluminium sulfate stabilized with phosphoric acid (e.g. Al(OH) _1.59 (SO ₄ ) _0.65 (H ₂ PO ₄ ) _0.11 ) Let’s say the manufacturing method is known. However, the problem with this manufacturing method is that gypsum, a by-product, must be removed by filtration, and recently, an atmosphere that is reluctant to use phosphoric acid has been created due to eutrophication of water quality.

As another prior art, there is a known manufacturing method of producing aluminum polysulfate using waste sulfuric acid discharged from the semiconductor process. This method produces aluminum sulfate by additionally adding a separate industrial 95% pure sulfuric acid in addition to waste sulfuric acid. Afterwards, the resulting aluminum sulfate solution is mixed with sodium aluminate and sodium carbonate through a high-speed emulsifier and aged in a low-temperature thermal polymerization tank to obtain basicity.

The above conventional technologies all start from aluminum sulfate, or after production, chemicals that provide basicity and chemicals that provide stability are added, and expensive high-speed emulsifiers (homogenizers) are used to produce polyaluminium sulfate.

The production method according to one embodiment of the present invention can replace PAC at a lower cost and produce an aqueous polyaluminum sulfate solution with no or little change over time.

The purpose of the present invention is to manufacture polyaluminum ferric sulfate (PAFS: PloyAluminumFerricSulfate), which can replace PAC, the most widely used water treatment agent, using waste sulfuric acid discharged in large quantities from the semiconductor production process.

The lack of commercialization of PAS, which is on par with PAC in terms of overall water treatment performance, is due to the formation of white turbidity or sediment due to hydrolysis during storage. Therefore, in order to commercialize PAS, it must be manufactured under conditions that do not cause white turbidity or precipitation due to hydrolysis during storage. To achieve this, a manufacturing method that satisfies a narrow range of Al ₂ O ₃ content and basicity must be found, or a suitable stabilizer must be used. must be added or both must be satisfied simultaneously.

Usually, in order to obtain basicity, alkaline chemicals such as soda ash, caustic soda, slaked lime, calcium carbonate, and aqueous ammonia must be added, but in the present invention, in order to simplify the process and reduce manufacturing costs, an excess amount of aluminum hydroxide is added and reaction is performed at a high temperature. It was designed to achieve basicity. In addition, ferric oxide was added to improve stability during long-term storage.

A method for producing an aqueous polyaluminum iron sulfate solution according to one aspect is

Ferric oxide; aluminum hydroxide; and waste sulfuric acid; mixing; and

It may include the step of stirring the mixture.

The method for producing an aqueous polyaluminum iron sulfate solution according to an embodiment of the present invention uses only waste sulfuric acid without adding separate genuine sulfuric acid, but additionally adds an inexpensive iron component to provide stability.

According to one embodiment, the content of the aluminum hydroxide may be 1.2 to 2.0 times (equivalent) the content of the spent sulfuric acid.

Rather than adding a separate chemical to give basicity to the result, we responded by adding an excess amount of aluminum hydroxide of about 1.2 to 2 times (equivalent) compared to waste sulfuric acid.

There is no need to adopt a high-speed emulsifier as there is no risk of hydrolysis due to local concentration variation as a separate alkaline agent is not added. In addition, when a step of filtering unreacted aluminum hydroxide is added, the aluminum hydroxide remaining after filtration can be reused, so by-products are not generated, making it environmentally friendly and economical.

The ferric oxide is to provide stability.

delete

When using ferric oxide, ferric oxide (Fe ₂ O ₃ ) theoretically reacts with waste sulfuric acid to form ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), so enough waste sulfuric acid to become ferric sulfate is needed. The reaction can also proceed by additionally adding .

Ferric oxide is added to the reactor, aluminum hydroxide is added, and waste sulfuric acid is added while stirring the mixture to react. When the reaction is completed, an appropriate amount of water is added to adjust the concentration and filtered to produce the product. .

During the reaction, a stable polyaluminum iron sulfate aqueous solution can be obtained through several hours of reaction near the boiling point of the mixture.

According to one embodiment, the stirring step may be performed at above 100°C to 200°C. The stirring time can be from 1 hour to 12 hours. At the stirring temperature and time within the above range, an aqueous polyaluminum iron sulfate solution having the desired basicity and stability can be obtained.

Meanwhile, the boiling temperature (the highest temperature achievable at normal pressure) is determined by the molal concentration of the water-soluble substances present in the mixed solution and increases by 0.52°C for each molal concentration. The temperature rises rapidly due to the dilution heat of sulfuric acid and the heat of reaction at the beginning of the reaction, and then gradually. It converges to the boiling temperature determined by molal concentration, and by heating with an appropriate heating device, the temperature can be maintained near the boiling point until the reaction is completed. The stirring step may be a reflux stirring step that allows the reaction to continue at a desired temperature.

At the end of the reaction, water is added to adjust the desired concentration of Al and Fe, and the final product is completed through additional stirring.

According to one embodiment, the basicity of the polyaluminum iron sulfate aqueous solution obtained by the above production method may be 10 to 25%.

If the basicity is less than 10%, the prepared polyaluminium iron sulfate aqueous solution may become cloudy due to hydrolysis over time. If the basicity exceeds 25%, the amount of aluminum hydroxide added is too high and stirring may be difficult, reaction time may take a long time, and filtration may become difficult.

When aluminum oxide is excessively added to about 1.2 to 2.0 times (equivalent) the content of waste sulfuric acid, the target basicity can be achieved.

The basicity is a value obtained based on the basicity analysis method of KS M 1510.

According to one embodiment, the chemical composition of the polyaluminum iron sulfate aqueous solution obtained by the above production method can be expressed as follows:

[Al ₂ (SO ₄ ) _3-x/2 (OH) _x (aq) + Fe ₂ (SO ₄ ) _3-y/2 (OH) _y (aq)]

The expression (aq) means hydrated, and "+" means hydrated Al ₂ (SO ₄ ) _3-x/2 (OH) _x and Fe ₂ (SO ₄ ) _3-y/2 (OH) _y. means that coexist.

According to one embodiment, in the polyaluminum iron sulfate aqueous solution obtained by the above production method, the ratio of Al:Fe may be 3 to 8:1. Here, the ratio of Al:Fe represents the ratio of the Al component of the aqueous solution converted to Al ₂ O ₃ and the content of the Fe component of the aqueous solution converted to Fe ₂ O ₃ . Considering the stability and basicity of the aqueous solution, the above range may be the optimal ratio of Al:Fe.

Considering the above ratio of Al:Fe, the input amount of ferric oxide can be determined in relation to aluminum hydroxide.

According to one embodiment, in the polyaluminum iron sulfate aqueous solution obtained by the above production method, the total content of the Al component and the Fe component may be 9% or less:

Here, the total content of the Al component and the Fe component represents the sum of the Al component of the aqueous solution converted to Al ₂ O ₃ and the Fe component of the aqueous solution converted to Fe ₂ O ₃ .

If the total content of Al and Fe components exceeds 9%, there may be a problem with the stability of the polyaluminum iron sulfate aqueous solution during long-term storage.

According to one embodiment, after stirring the mixture, the step of filtering the mixture to remove remaining aluminum hydroxide may be further included. The mixture is filtered, the filtrate is used as a product, and the filtered solid, aluminum hydroxide, can be reused by adding it to the mixing step.

The polyaluminum iron sulfate aqueous solution according to another aspect may be prepared by the above production method.

For the polyaluminum iron sulfate aqueous solution, refer to the above-mentioned information.

The method for producing an aqueous polyaluminium sulfate solution according to an embodiment of the present invention will be described in detail sequentially as follows.

Ferric oxide; aluminum hydroxide; And the step of mixing waste sulfuric acid may be, for example, adding ferric oxide and aluminum hydroxide to the reactor and adding waste sulfuric acid.

The amount of aluminum hydroxide is 1.2 to 2.0 times the equivalent of waste sulfuric acid, and ferric oxide is added so that the ratio of Al:Fe (as Al ₂ O ₃ :Fe ₂ O ₃ ) is in the range of 3 to 8:1. . When ferric oxide is used, waste sulfuric acid corresponding to the reaction equivalent of reacting with sulfuric acid to form ferric sulfate can be additionally added.

The mixture can be stirred for 3 to 5 hours. At this time, the reaction temperature is determined by the molal concentration of the solute in the reaction solution. Due to the dilution heat of the waste sulfuric acid added at the beginning of the reaction, the decomposition heat of the fruit water in the waste sulfuric acid contained in a small amount, and the heat of reaction between aluminum hydroxide and waste sulfuric acid, the temperature is lowered to near the boiling point. It rises slowly, and as the water evaporates, the molality rises and the temperature rises further.

When the reaction temperature reaches the level of 105 ~ 115 ℃, the reactor must be closed to prevent water vapor from escaping to the outside, and the temperature must be maintained throughout the reaction time. A heating device must be provided to heat when necessary.

When using ferric oxide, aluminum hydroxide and iron oxide are added, and then waste sulfuric acid is slowly added, and when stirring is possible, the stirrer can be operated.

After the reaction is completed, when the temperature of the reaction solution is below 100°C, water can be added so that the concentration of Al and Fe is below 9% based on Al ₂ O ₃ + Fe ₂ O ₃ . If it exceeds 9%, problems may arise with long-term stability.

The reaction product is filtered, the filtrate is used as a product, and the filtered solid can be reused in the first mixing step as aluminum hydroxide.

Basicity is determined by the input equivalent ratio of aluminum hydroxide and waste sulfuric acid, reaction temperature and reaction time, and stable polyaluminum iron sulfate with a basicity of 15 to 25% can be obtained by manufacturing under the conditions suggested above.

Example

The chemicals used were waste sulfuric acid discharged from the semiconductor process of domestic company H, aluminum hydroxide was a general industrial product (99% purity or higher), and iron oxide was a general industrial product (98% purity).

The experimental device was a three-neck flask with a capacity of 1 liter placed on a heating mantle, a stirrer was installed in the middle branch, a thermometer was installed on one of the left and right branches, and a cooling water condenser for vapor condensation was installed on the other side.

After adding aluminum hydroxide and ferric oxide, waste sulfuric acid was slowly added. During the reactant input and initial reaction, the condenser area is opened to input the reactant, and the vapor at the beginning of the reaction is discharged. When the temperature reaches the desired temperature within 105 ~ 115 ℃, the condenser starts to operate and the evaporated vapor is condensed and refluxed into the reactor. And this kept the molality constant. When necessary, the heating intensity of the heating mantle was adjusted to ensure that the reaction could proceed at a constant temperature.

Example 1 and Comparative Example 1

Each reactant was added as shown in Table 1 below, and the reaction proceeded.

division Comparative Example 1 Example 1 aluminum hydroxide 60.6g
(1.1 equivalent of sulfuric acid) 82.6g
(1.5 equivalents of sulfuric acid) Waste sulfuric acid 223.7g (207.5g + 16.2g) 223.7 g (207.5 g + 16.2 g) ¹⁾ Ferric oxide 6.7g 6.7g reaction time 4 hours 4 hours reaction temperature 107℃~110℃ 107℃~110℃ dilution water 250g 300g

1) In the input amount of spent sulfuric acid ‘207.5g + 16.2g’, 207.5g is the amount considering the reaction with aluminum oxide, and 16.2g is the amount considering the reaction with ferric oxide.

The results of Example 1 and Comparative Example 1 are shown in Table 2 and Figures 1 and 2 below.

division Comparative Example 1 Example 1 product quantity 484.1g 537.0g filtration time 1 minute 30 seconds 2 minutes Al ₂ O ₃ +Fe ₂ O ₃ content (%) 8.5%
(Al ₂ O ₃ 7.3%, Fe ₂ O ₃ 1.2%) 8.1%
(Al ₂ O ₃ 7.1%, Fe ₂ O ₃ 1.0%) basicity(%) 9.5% 17.5%

The content of Al ₂ O ₃ was calculated based on the Korean Industrial Standard KSM 1411 and converted to Al ₂ O ₃ .

The content of Fe ₂ O ₃ is calculated from the content of Fe ³⁺ analyzed based on _the free acid and trivalent iron analysis method of ferric sulfate in _the 'Standards, Specifications and Labeling Standards for Water Treatment Agents' notified by the Ministry of Environment. It was converted to .

Basicity is a value obtained by the basicity analysis method of KS M 1510.

The filtration time is measured by attaching ADVANTECH Filter Paper 5A 70 mm to the filter and measuring the time taken until the liquid on the filter paper becomes invisible to the naked eye through vacuum filtration using an aspirator.

Figure 1 shows photographs of Comparative Example 1 (Sample A) and Example 1 (Sample B) immediately after manufacturing.

Figure 2 shows photographs of Comparative Example 1 (Sample A) and Example 1 (Sample B) one month after production.

Referring to Table 2 and Figures 1 and 2, in the case of Comparative Example 1 in which 1.1 times the equivalent of aluminum hydroxide compared to waste sulfuric acid was added and the basicity was 9.5%, white turbidity occurred due to hydrolysis even before one day had elapsed after production ( (see sample A in Figure 2), it can be seen that in the case of Example 1 where 1.5 times the equivalent of aluminum hydroxide compared to waste sulfuric acid was added, the basicity was 17.5%, there was no change over time even after more than a month (sample in Figure 2) see B).

Example 2 and Comparative Examples 2 and 3

Each reactant was added as shown in Table 3 below, and the reaction proceeded.

division Comparative Example 2 Example 2 Comparative Example 3 aluminum hydroxide 82.6g
(1.5 equivalents of sulfuric acid) 77.1g
(1.4 equivalents of sulfuric acid) 82.6g
(1.5 equivalents of sulfuric acid) Waste sulfuric acid ¹⁾ 207.5g 207.5g + 16.2g 207.5g + 16.2g Ferric oxide 0g 6.7g 6.7g reaction time 4 hours 4 hours 4 hours reaction temperature 107℃~110℃ 107℃~110℃ 107℃~110℃ dilution water 250g 300g 200g

1) Content of spent sulfuric acid - 50%

The results of Example 2 and Comparative Examples 2 and 3 are shown in Table 4 and Figures 3 to 9 below.

division Comparative Example 2 Example 2 Comparative Example 3 product quantity 460.1g 526.8g 445.0g filtration time 7 minutes 2 minutes 5 seconds 1 minute 45 seconds Al ₂ O ₃ + Fe ₂ O content (%) 7.3%
(Al ₂ O ₃ 7.3%) 8.0%
(Al ₂ O ₃ 7.1%,
Fe ₂ O ₃ 0.9%) 9.7%
(Al ₂ O ₃ 8.2%,
Fe ₂ O ₃ 1.5%) basicity(%) 17.3% 16.9% 17.5%

Figure 3 shows a photograph of Comparative Example 2 (Sample C) immediately after manufacturing.

Figure 4 shows a photograph of Comparative Example 2 (Sample C) one month after production.

Figure 5 shows a photograph of Example 2 (Sample D) immediately after preparation.

Figure 6 shows a photograph of Example 2 (Sample D) one month after preparation.

Figure 7 shows a photograph of Comparative Example 3 (Sample E) immediately after manufacturing.

Figure 8 shows a photograph of Comparative Example 3 (Sample E) one month after production.

Figure 9 shows a photograph of the bottom portion of Comparative Example 3 (Sample E) one month after production.

In the case of Comparative Example 2, referring to Table 4 and Figures 3 and 4, when only aluminum hydroxide was used without using ferric oxide, it was unstable and appeared cloudy due to hydrolysis after about 1 month even at 7.3% based on Al ₂ O ₃ . You can see that this has been created.

In the case of Example 2, referring to Table 4 and Figures 5 and 6, it can be seen that the total concentration of Al ₂ O ₃ + Fe ₂ O ₃ is 8.0%, and it maintains a stable state without cloudiness or sediment even after long-term storage.

In the case of Comparative Example 3, referring to Table 4 and Figures 7 to 9, when the total content of Al ₂ O ₃ + Fe ₂ O ₃ is 9.7%, the color of the liquid does not change in appearance after about 1 month (see Figure 8). , by tilting and observing the bottom, sediment, which was a hydrolysis product, could be confirmed (see Figure 9).

Referring to the above examples and comparative examples, the basicity is 15 to 25%, the ratio of Al ₂ O ₃ : Fe ₂ O ₃ is 3 to 8: 1, and the total content of Al ₂ O ₃ + Fe ₂ O ₃ is 9% or less. It was found that this was an area with long-term stability. If the basicity is 25% or more, there is no problem with stability, but the reaction time takes a long time and filtration may be difficult.

Water treatment capacity assessment

The water treatment test method was to use a JAR-Tester (Daehan Science Co., Ltd. JT - M6C), measure and add 1 L of raw water to each 1000 mL beaker, stir at 60 rpm, add chemicals, and stir at high speed at 120 rpm (about 1 minute). ), after performing gentle stirring at 20 rpm (20 minutes), stirring is terminated and the floc is allowed to settle for about 20 minutes. When the floc precipitated, the supernatant was filtered and the filtrate was analyzed.

The chemicals used for water treatment were PAC, ferric sulfate, polyaluminum iron sulfate aqueous solution of Example 2, aluminum sulfate (liquid), etc., and the manufacturers and main specifications are shown in Table 5 below.

Injection medicine density basicity manufacture company PAC Al ₂ O ₃ 15.9% 39.8% S company Ferric sulfate Fe 11.0% - Taewon Co., Ltd. PAFS Al ₂ O ₃ + Fe ₂ O ₃ 8.0% 16.9% Example 2 Aluminum sulfate (liquid) Al ₂ O ₃ 7.8% - SJ company

Example 3 and Comparative Examples 4 to 6

For sewage collected from a certain sewage treatment plant in Cheonan City (see Table 6 for main characteristics), each chemical was added as shown in Table 7 below, a JAR TEST was performed using the method described above, and the supernatant was filtered and analyzed. The results are shown in Table 8.

enemy pH T-P Chromaticity Turbidity 6.87 0.141 ppm 8.1 0.899

division Comparative Example 4 Comparative Example 5 Example 3 Comparative Example 6 Injection medicine PAC Ferric sulfate Example 2
Polyaluminum iron sulfate aqueous solution Aluminum sulfate (liquid) Input amount ¹⁾ 30ppm 47.5ppm 59.7 ppm 61.2ppm

1) The amount of metal components (Al and Fe) added was the same.

division Comparative Example 4 Comparative Example 5 Example 3 Comparative Example 6 Injection medicine PAC Ferric sulfate Example 2
Polyaluminum iron sulfate aqueous solution Aluminum sulfate (liquid) Chromaticity (degree) 1.8 4.6 1.7 2.2 Turbidity (NTU) 0.141 0.395 0.122 0.160 pH after injection 6.2 6.0 6.2 6.1 T-P(ppm) 0.04 0.06 0.05 0.07

Referring to Table 8, it can be seen that the results of Example 3 are equivalent to Comparative Example 4 (PAC) and are superior to Comparative Examples 5 and 6.

Meanwhile, the measuring instrument/analyzer and analysis method for each item used to analyze the treated water are shown in Table 9 below.

Analysis items Equipment/Method manufacturing company Model Chromaticity colorimeter KRK CR-30 Turbidity Turbidimeter HACH TL2300 pH pH meter SUNTEX TS-100 person UV-VIS
Spectrometer
(Based on water pollution process test method) Shimadzu UV mini 1240

Example 4 and Comparative Examples 7 to 9

For the final phosphorus treatment facility influent from a water reclamation center in Seoul (see Table 10 for main characteristics), each chemical was added as shown in Table 11 below, a JAR TEST was performed using the method described above, and the supernatant was filtered and analyzed. did. The results are shown in Table 12.

enemy pH T-P Chromaticity Turbidity 6.50 0.323 ppm 22.1 0.868

division Comparative Example 7 Comparative Example 8 Example 4 Comparative Example 9 Injection medicine PAC Ferric sulfate Example 2
Polyaluminum iron sulfate aqueous solution Aluminum sulfate (liquid) input 30ppm 47.5ppm 59.7ppm 61.2ppm

division Comparative Example 7 Comparative Example 8 Example 4 Comparative Example 9 Injection medicine PAC Ferric sulfate Example 2
Polyaluminum iron sulfate aqueous solution Aluminum sulfate (liquid) Chromaticity (degree) 10.4 17.0 9.3 11.0 Turbidity (NTU) 0.260 0.920 0.248 0.451 pH after injection 6.30 6.29 6.31 6.28 T-P(ppm) 0.040 0.091 0.042 0.045

Referring to Table 12, it can be seen that the results of Example 4 are equivalent to Comparative Example 7 (PAC) and are superior to Comparative Examples 8 and 9.

Evaluation of fluoride removal ability from fluoride-containing wastewater

Fluorine removal ability was evaluated in the following manner.

1. Prepare wastewater containing fluorine.

2. Inject each wastewater into a tester (manufacturer: Daehan Science Co., Ltd., model: JT-M6C) and stir. Add each fluoride treatment chemical and add sulfuric acid or slaked lime to adjust the pH to 7 (for evaluation under the same pH conditions)

3. Add an anionic polymer coagulant (manufacturer: Hansol Chemical, model: HA-711, 2 ml of 0.5% dilution), stir at 120 rpm for 1 minute, stir at 20 rpm for 20 minutes, and allow precipitation for 20 minutes.

4. The supernatant was filtered through a 0.45um glass filter, and the fluorine concentration was measured by IC (manufacturer: ThermoFisher Scientific, model: Dionex ICS-1100).

Example 5 and Comparative Examples 10 and 11

The BOE waste liquid generated in the semiconductor process was neutralized and detoxified, the solid sludge was filtered, and a small amount of slaked lime was added to 1000 g of the remaining waste water (fluorine: 180 ppm, Si 27 ppm, ammonium sulfate 30%) to adjust the pH to 9. The reason for adjusting the pH to 9 is to decompose fluorine since most fluorine is in the form of silicofluoric acid (SiF6-) and cannot be removed.

Afterwards, each fluorine treatment chemical was added, the pH was adjusted to 7 with sulfuric acid, and the fluorine concentration was measured through processes 3 and 4 described in the experimental method above. Because the concentration of fluoride was high at the start, the treatment was divided into two stages (first and second).

As shown in Tables 13 and 14 below, PAC, the polyaluminum iron sulfate aqueous solution of Example 2, and aluminum sulfate (liquid) were added in the indicated amounts, and the treatment results are shown.

Medication used input flocculation pH residual fluoride removal rate Comparative Example 10 PAC 6000 ppm 9.0
-->
7.0 28.5ppm 84.2% Example 5 Aqueous polyaluminium sulfate solution of Example 2 14000ppm 21.0 ppm 88.3% Comparative Example 11 Aluminum sulfate (liquid) 12000 ppm 21.1ppm 88.2%

Table 13 relates to the fluorine removal test for each primary water treatment agent, and was added at the ratio of Al moles: F moles = 1:2.

Initial F concentration input flocculation pH residual fluoride removal rate Comparative Example 10 28.5ppm 700ppm 9.0
-->
7.0 11.5 ppm 59.6% Example 5 21.0ppm 1600ppm 9.4ppm 55.2% Comparative Example 11 21.1ppm 1400ppm 10.7ppm 49.2%

Table 14 relates to the fluorine removal test for each secondary water treatment agent, and the number of moles of Al: moles of F = 1:2.

Example 6 and Comparative Examples 12 and 13

This time, a reagent (ammonium fluoride, manufacturer: Junsei, Japan) was added to distilled water to prepare fluorine wastewater containing 132 ppm of fluorine, and as shown in Tables 15 and 16 below, PAC, polyaluminium iron sulfate aqueous solution of Example 2, Aluminum sulfate (liquid) was added in the indicated amounts, flocculated using the method described above, and the fluorine concentration in each supernatant was measured, and the results are shown in Tables 15 and 16.

Medication used input flocculation pH residual fluoride removal rate Comparative Example 12 PAC 4500ppm 7.0 13.7ppm 89.6% Example 6 Aqueous polyaluminium sulfate solution of Example 2 10000ppm 12.5ppm 90.5% Comparative Example 13 Aluminum sulfate (liquid) 9000ppm 12.9 ppm 90.2%

Table 15 relates to the fluorine removal test for each primary water treatment agent, and was added at the ratio of Al moles: F moles = 1:2.

Initial F concentration input flocculation pH residual fluoride removal rate Comparative Example 12 13.7ppm 500ppm 7.0 4.1 ppm 70.0% Example 6 12.5ppm 1200 ppm 4.1 ppm 67.2% Comparative Example 13 12.9ppm 1000ppm 5.0ppm 61.2%

Table 16 relates to the fluorine removal test for each secondary water treatment agent, and the number of moles of Al: number of moles of F = 1:2 was used.

From Examples 5 and 6 and Comparative Examples 10 to 13, PAC, the polyaluminum iron sulfate aqueous solution according to one embodiment of the present invention, and aluminum sulfate (liquid) all have fluorine treatment ability in waste liquid containing a high concentration of salt or in distilled water. It can be seen that it is almost equivalent to artificial wastewater produced by adding ammonium.

The primary and secondary total fluoride removal rates were 93.6% to 94.8% in waste fluid containing a high concentration of salt, and the primary and secondary total fluoride removal rates were 96.6% to 97% in artificial waste fluid prepared with distilled water with little salt.

By recycling waste sulfuric acid discharged in large quantities from the semiconductor process, it has a flocculation performance comparable to that of the most widely used PAC, while maintaining a low chemical price, eliminating odor during water treatment, and reducing the amount of sludge generated by reducing residual salts (especially chlorine) after water treatment. It was shown that polyaluminum iron sulfate, an eco-friendly water treatment agent, can be manufactured with advantages such as easy recycling and incineration and improved corrosion of facilities.

Although the present invention has been described using the above embodiments as examples, these are merely illustrative examples, and those skilled in the art will understand that various modifications and other equivalent implementations are possible. Therefore, the scope of protection of the present invention should be determined by the appended patent claims.

Claims (9)

ferric oxide; aluminum hydroxide; and waste sulfuric acid; mixing; and
Stirring the mixture; comprising
Method for producing polyaluminum iron sulfate aqueous solution. According to paragraph 1,
A method for producing an aqueous polyaluminum iron sulfate solution, wherein the content of the aluminum hydroxide is 1.2 to 2.0 times (equivalent) the content of the waste sulfuric acid. delete According to paragraph 1,
A method for producing an aqueous polyaluminium iron sulfate solution, wherein the stirring step is performed at 105°C to 115°C. According to paragraph 1,
A method for producing an aqueous polyaluminum sulfate solution, wherein the basicity of the aqueous polyaluminum iron sulfate solution obtained by the above production method is 10 to 25%. According to paragraph 1,
In the polyaluminium iron sulfate aqueous solution obtained by the above production method, the Al:Fe ratio is 3 to 8:1. Method for producing a polyaluminum iron sulfate aqueous solution:
Here, the ratio of Al:Fe represents the ratio of the Al component of the aqueous solution converted to Al ₂ O ₃ and the content of the Fe component of the aqueous solution converted to Fe ₂ O ₃ . According to paragraph 1,
Method for producing an aqueous polyaluminium iron sulfate solution in which the total content of Al component and Fe component is 9% or less in the aqueous polyaluminum iron sulfate solution obtained by the above production method:
Here, the total content of the Al component and the Fe component represents the sum of the Al component of the aqueous solution converted to Al ₂ O ₃ and the Fe component of the aqueous solution converted to Fe ₂ O ₃ . According to paragraph 1,
After stirring the mixture, the method for producing an aqueous polyaluminum iron sulfate solution further includes filtering the mixture to remove remaining aluminum hydroxide. An aqueous polyaluminum sulfate solution prepared by the production method of claim 1.