KR101336824B1 - Calcium alumino sulfate for Heavy metal treating agent - Google Patents

Abstract

The present invention relates to a heavy metal treatment agent comprising calcium aluminum sulfate that can be removed by adsorption or replacement of heavy metal dissolved in water as an active ingredient, and more particularly calcium aluminum sulfate obtained by hydrothermal synthesis from aluminum sulfate and calcium salt. Is applied as a heavy metal treatment agent. Heavy metal treatment agent according to the present invention is excellent in the adsorption power with cations, not only high removal rate of heavy metals, but also can be produced at low cost requires low water treatment costs, industrial leaching wastewater contaminated with heavy metals because the leaching amount of the adsorbed heavy metals is extremely small It can be usefully applied to water treatment such as domestic sewage.

Description

Calcium alumino sulfate for Heavy metal treating agent

The present invention relates to a heavy metal treatment agent comprising calcium aluminum sulfate as an active ingredient that can be removed by adsorption or substitution of heavy metal dissolved in water.

Recently, industrial wastewater and household sewage caused by the change of industrial structure and population density have caused serious problems. In particular, industrial wastewater discharged from industrial complex contains a considerable amount of heavy metals, and these wastewater flows into groundwater or surface water. It becomes the cause of water pollution.

There are many reasons for the pollution of the environment, but pollution by heavy metals may have attracted much attention so far. Among the various pollutants, heavy metals are particularly concerned with us, even if they are trace amounts, but they are not excreted and have long-term side effects by biological accumulation. Heavy metals released into the environment circulate the biosphere without being degraded or self-cleaning. This is because the food chain can cause acute or chronic disability in the body by rapidly moving to humans, which can have fatal effects on the human body. Therefore, the best efforts should be made not to include heavy metals that are fatal to humans in water, and if heavy metals are contaminated, high efficiency heavy metal treatment agents are needed to reliably remove heavy metals to protect the aquatic ecosystem.

Current treatment methods mainly used to remove these heavy metal ions include chemical flocculation precipitation method, evaporation method, reverse osmosis membrane method, liquid membrane method, oxidation / reduction method, activated carbon adsorption, ion exchange resin method, and electrolysis method. It is possible to recover heavy metals and used industrially to some extent, but it is economically and technically limited.

The chemical flocculation precipitation method is to precipitate heavy metals by hydroxides or emulsions, and it is suitable to be applied in the case of high concentrations of heavy metals in the waste water, and it is easy to install and has a relatively low maintenance cost. However, there is a problem in that the heavy metal removal rate is low and a large amount of chemical coagulant is used to deal with a large amount of sediment sludge generated. The evaporation method is expensive in energy and has a problem of increasing concentration of nonvolatile materials. The technology using thin films such as reverse osmosis membrane and electrodialysis is too expensive to install and operate, is not selective for metal ions, fouling and membrane destruction. There is a problem.

The ion exchange resin method has the advantage of relatively clean, low concentration contaminated heavy metal ions can be selectively removed, but it is difficult to adsorb and remove heavy metal ions of complex or high concentration, and the ion exchange resin as a polymer As a result, waste disposal costs are high when disposing of the final ion exchange capacity due to the loss of the final ion exchange capacity, and since the ion exchange resin itself is generally expensive, it has a problem in that it is economically inferior as a treatment agent for treating a large amount of heavy metals. . Accordingly, many studies have been conducted to develop a heavy metal treatment agent that minimizes environmental pollution, has high economic efficiency and ion exchange rate, and prevents ion exchanged heavy metals from eluting under adverse conditions in water.

In Korean Patent Laid-Open Publication No. 2004-0007861, polystyrene having sulfonic acid as a functional group and polystyrene having ammonium hydroxide as a functional group are used as ion-exchange resins mixed in a volume ratio of 1.5: 1, thereby arsenic and cadmium, which are harmful heavy metals contained in natural water. , Chromium, mercury, lead, etc., significantly lower the content, while inorganic salts such as copper, manganese, zinc, etc., the elements of the minerals not only maintain the amount, but also can retain a large amount of organic germanium, which has recently been recognized pharmacologically. Heavy metal momentary separator. The above technique has the advantage of maintaining the mineral elements beneficial to the human body while removing heavy metals harmful to the human body, but it is not easy to remove heavy metals in an underwater environment where the medium of the water is complex, such as wastewater, which is not a relatively clean natural water. In addition, the adsorption rate of heavy metals is very low, and the disposal of the resin that has lost the ion exchange capacity has the disadvantage that it can accelerate the environmental pollution.

Korean Patent Laid-Open Publication No. 2003-0091246 combines high density filler beads and ion exchange fibers to improve the disadvantages of lower column packing density of fibrous ion exchanger and lower adsorption performance due to high process pressure loss of bead type ion exchanger. A method for producing an ion exchange adsorption filter is proposed. Unlike the spherical filling beads, the technology uses a high-density composite filter to remove heavy metals from liquid waste and recover valuable metals with high efficiency, as well as to filter the column in a relatively inexpensive and simple manner. The advantage is that you can. However, as in the technique disclosed in Korean Patent Laid-Open Publication No. 2004-0007861, not only is it difficult to remove heavy metals in an underwater environment such as wastewater, but also the adsorption rate of heavy metals is very low, and the ion exchange filter is disposed of. It has the disadvantage of accelerating environmental pollution.

Korean Patent Laid-Open Publication No. 2002-0023378 discloses copper using ion exchange resins to prevent contamination of water environment from toxic chemicals in copper chloride (CuCl ₂ ) wastes generated during the manufacturing process of a printed circuit board (PCB). We propose a treatment method for wastewater containing water, but likewise, it is much less economical to treat heavy metals than heavy metals by hydroxyprecipitation and sulfide sedimentation and cannot overcome the problems caused by the use of polymer-based ion exchange resins. Have

Korean Patent Laid-Open Publication No. 2001-0094573 proposes a method of preparing a crab shell biosorbent for removing heavy metals in water to remove heavy metals in water, sewage, and wastewater by using inexpensive and discarded crab shells. According to this, the adsorbent made from crab shells can be used to effectively remove heavy metals present in water, sewage and wastewater treatment processes, and other waters. Not only is it low cost, but it is also effective in recycling waste. However, although the heavy metal adsorption capacity of the natural polymer chitosan has been reported, there is a problem that the adsorption capacity of the heavy metal may be extremely low in the case of crab shell before preparing chitosan.

Accordingly, the present inventors have conducted studies to improve the conventional method for treating heavy metals by ion exchange resins. As a result, rapid heating by microwaves using a water-soluble organic solvent in the hydrothermal synthesis of calcium aluminum sulfate, and drying the same Using the method, the specific surface area of calcium aluminum sulphate was maximized, so that it was found to exhibit excellent heavy metal adsorption and substitution ability, thereby completing the present invention. Accordingly, an object of the present invention is to provide a new heavy metal treatment agent that can replace the existing ion exchange resin.

The present invention

Dissolving aluminum sulfate in water to prepare an aluminum sulfate solution;

Preparing a slurry by mixing calcium salt, water-soluble organic solvent and water;

Preparing a mixed solution by mixing the aluminum sulfate solution and the slurry;

Hydrothermally synthesizing calcium aluminum sulfate by heating the mixed solution to 30 to 150 ° C; And

Heating the calcium aluminum sulphate by microwave to dry it;

It is characterized by a heavy metal treatment agent using calcium aluminum sulfate prepared as an active ingredient.

The heavy metal treatment agent of the present invention not only has a higher removal rate of heavy metals than other calcium aluminum sulfate-based heavy metal treatment agents, but also has a relatively low price of starting materials for preparing the same, so that the cost competitiveness is superior to conventional ion exchange resins. This low, adsorbed or substituted heavy metal does not elute under adverse conditions in water, thereby minimizing environmental pollution after heavy metal treatment.

Hereinafter, the present invention will be described in more detail.

The present invention not only has a high removal rate of heavy metals, but also has high water treatment efficiency, and is an environmentally friendly heavy metal treatment agent that can protect the underwater ecosystem by preventing the heavy metals from leaching back into the water due to the excellent binding strength with the adsorbed and substituted heavy metals. It is about.

Heavy metal treatment agent of the present invention can be prepared by the following method.

First, aluminum sulfate is dissolved in water to prepare an aluminum sulfate solution. Aluminum sulfate can be used either in a powder type for reagents or in an aqueous type used as an inorganic coagulant. In addition, it is preferable to use distilled water having good purity, but ground water, industrial water, etc. may be used as long as it does not contain environmentally harmful substances such as heavy metals. Although the aluminum sulfate concentration in the said aluminum sulfate solution is not specifically limited, 1.0-20 weight% is preferable. If the aluminum sulfate concentration is low, there is a problem in that the stirring is smooth as the solid content is low, but the yield of calcium aluminum sulfate produced by hydrothermal synthesis with the calcium salt may be lowered. It is preferable to select the above concentration because it is difficult to produce a calcium aluminum sulfate in a uniform state through stirring with a rise.

Next, the step of preparing a slurry by mixing calcium salt, water-soluble organic solvent and water. The calcium salt may be used at least one selected from calcium oxide (CaO), calcium hydroxide (Ca (OH) ₂ ), calcium carbonate (CaCO ₃ ) and calcium sulfate (CaSO ₄ ). Since the calcium salt is insoluble, it is highly desirable to maintain fluidity including water rather than powder for a normal reaction with aluminum sulfate. The calcium salt is used in a slurry in which water is mixed with water. In addition, a water-soluble organic solvent is used as an additive to maximize the specific surface area of the resulting calcium aluminum sulfate to increase the adsorption rate of heavy metals. As the water-soluble organic solvent that can be used, one or more selected from 2-butoxyethanol, 2-ethoxyethanol, acetone, benzyl alcohol, cetyl alcohol, diethylene glycol, ethyl alcohol, ethylene glycol and glycerol may be used. In order to maximize the heavy metal adsorption efficiency, it is advantageous to use 2-butoxyethanol, 2-ethoxyethanol, benzyl alcohol, cetyl alcohol, diethylene glycol, ethylene glycol, glycerol, etc., which have a higher boiling point than water. Such a water-soluble organic solvent is preferably included 5 parts by weight or less based on 100 parts by weight of calcium salt.

Thereafter, the prepared aluminum sulfate solution and the slurry are mixed to prepare a mixed solution. At this time, the molar ratio of aluminum sulfate and calcium salt on the mixed solution is preferably mixed so as to be 1: 4 to 8, more preferably 1: 4.5 to 7.5, most preferably 1: 5 to 7. . When the calcium salt is too small compared to aluminum sulfate, the excess aluminum sulfate remaining in the powder is contained in the powdered calcium aluminum sulfate, and the contained aluminum sulfate makes the pH of the water acidic when treated with calcium aluminum sulfate as a heavy metal treatment agent. It can be undesirable. In addition, when too much calcium salt is supplied, the production rate of calcium aluminum sulphate may be lowered, and the unreacted calcium salt present in the powder lowers the treatment efficiency of heavy metals by providing the hydrogen ion concentration in the water as alkali during the water treatment process. There may be a problem.

Thereafter, the mixed solution is heated in a temperature range of 30 to 150 ° C. to perform hydrothermal synthesis of calcium aluminum sulfate. If the reaction temperature is less than 30 ℃ calcium aluminum sulfate is not produced and unreacted material may exist independently, if the reaction temperature exceeds 150 ℃ calcium aluminum sulfate can be provided completely, but high temperature, high pressure It requires a lot of equipment and maintenance costs due to the need for an autoclave that can withstand it, and not only can increase the risk of workers during the reaction process, but also increase the energy consumption, thereby reducing economic efficiency. It is preferable to heat to the proposed reaction temperature.

Calcium aluminum sulfate, an inorganic heavy metal treatment agent obtained by hydrothermal synthesis, is prepared in the form of a white precipitate, which is filtered through filtration, and then recovered through a drying and pulverizing step to a powder form which is convenient for use as a heavy metal treatment agent.

The drying step not only removes water in the white precipitate, which is calcium aluminum sulfate obtained by the present invention, but also provides an important role in providing physical properties of calcium aluminum sulfate to increase the adsorption rate of heavy metals in water. Drying methods include room temperature drying, hot air heating by oven, rapid heating by microwave (aka: microwave oven), etc. In the present invention, in order to increase the specific surface area of the heavy metal treatment agent to maximize heavy metal adsorption rate, Rapid heating method is used. In the microwave heating method, when a microwave of about 2,450 MHz is added to a sample in which water or a high boiling water soluble organic solvent coexists, polar water molecules or organic solvents coexisting with water increase the temperature due to vibration heat as much as microwaves. By doing so, the water molecules and the water-soluble organic solvent rapidly exit the calcium aluminum sulfate at a very high rate, and the drying rate is fast, as well as the specific surface area of the sample is greatly increased to prepare a heavy metal treatment agent having a high adsorption rate of heavy metals.

The pulverizing step is not limited to the method of processing the calcium aluminum sulfate in the form of agglomerates obtained through drying in the form of fine particles, and has a particle form, thereby increasing the surface area to obtain better heavy metal adsorption and substitution effects. .

Calcium aluminum sulfate prepared by the addition of a water-soluble organic solvent and drying by microwaves has a very good heavy metal removal effect by adsorbing heavy metal ions contained in water or by replacing calcium or aluminum with heavy metal ions in water. Removable heavy metals include, but are not limited to, chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), copper (Cu), and the like. Heavy metals adsorbed or substituted by calcium aluminum sulfate are hardly eluted into water again, and calcium aluminum sulfate, in which heavy metals are adsorbed and substituted, is present as a precipitate and can be removed from wastewater through filtration. In addition, calcium aluminum sulphate in which heavy metals removed from waste water are adsorbed and substituted has the ability to kill microorganisms and viruses, and thus the heavy metal treatment agent of the present invention can be recycled using inorganic antibacterial agents to reduce environmental pollution problems. have.

Hereinafter, the heavy metal adsorption capacity or the substitution capacity of the calcium aluminum sulfate prepared by the above method as a heavy metal treatment agent will be described based on Examples, but the present invention is not limited by the following Examples.

[ Example ]

Example 1

Aluminum sulfate 6-8 hydrate of Samjeon Pure Chemical Co., Ltd. is regarded as aluminum sulfate hexahydrate, and weighed in an amount of 0.1 mol and placed in a 2 L beaker, 1 L of distilled water is added, and then using a stirrer. The aluminum sulfate solution was prepared by completely dissolving aluminum sulfate. Another 500 mL beaker was supplied with 2.5% of glycerol corresponding to 0.6 mol of calcium hydroxide and calcium hydroxide, 250 mL of distilled water was added thereto, and a slurry was prepared by stirring.

After the slurry was added to the aluminum sulfate solution to prepare a mixed solution, the mixture was heated at 95 ° C. for 3 hours while stirring with a stirrer. Then, after cooling the mixed solution, the precipitate was filtered and washed five times, and then rapidly heated and dried using a commercial microwave oven (Lassell, TMW-1100EK) and ground to prepare calcium aluminum sulfate.

6 beakers of 250 mL to confirm the adsorption amount of chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As) and copper (Cu) elements of the prepared calcium aluminum sulfate After preparation of potassium dichromate (K ₂ Cr ₂ O ₇ ) 2.8286 g, cadmium nitrate (Cd (NO ₃ ) ₂ ) 2.1032 g, lead nitrate (Pb (NO ₃ ) ₂ ) 1.5985 g, mercury nitrate (Hg (NO ₃ ) ₂ ) Accurately measure 1.6182 g, arsenic chloride (AsCl ₃ ) 2.4196 g, and 3.9280 g of copper sulfate pentahydrate (CuSO ₄ · 5H ₂ O), respectively, add each to a beaker, supply 100 mL of distilled water, and stir each heavy metal. A stock solution in which 1 g of element was dissolved was prepared.

The calcium aluminum sulfate powder prepared above was precisely weighed by 1 g, and added to each beaker, and stirred for 10 minutes to adsorb heavy metal elements to calcium aluminum sulfate, followed by filtration and washing, followed by drying.

Example 2

In the same manner as in Example 1, but instead of glycerol was used cetyl alcohol.

Example 3

In the same manner as in Example 1, ethylene glycol was used instead of glycerol.

Comparative Example 1

The same procedure as in Example 1 was carried out, except that glycerol was not added to the slurry, and a room temperature drying method was used as a drying method.

Comparative Example 2

The same procedure as in Example 1, except that glycerol was not added to the slurry, a hot air heating method using a dry oven (100 ° C.) was used as a drying method.

Comparative Example 3

Instead of calcium aluminum sulfate, heavy metal adsorption experiments were carried out in the same manner as in Example 1, targeting 4A-zeolite manufactured by ZeoBuilder Corporation.

Comparative Example 4

Instead of calcium aluminum sulfate, heavy metal adsorption experiments were carried out in the same manner as in Example 1 with respect to cation exchange resin (TRILITE SCR-B) of Yilong Chemical Co., Ltd.

Comparative Example 5

A heavy metal adsorption experiment was carried out in the same manner as in Example 1 with respect to Illite (Dongchang Illite Co., Ltd.) reported to have a cation substitution capacity instead of calcium aluminum sulfate.

Heavy Metal Adsorption Rate and Specific Surface Area Evaluation

Accurately weigh 0.1 g of the heavy metal adsorbed in Examples 1 to 3 and Comparative Examples 1 to 5 accurately into a 100 mL beaker to the fourth decimal place, and then digest with nitric acid. After transferring to a 100 mL volumetric flask (volumetric flask), the lid was closed and vigorously shaken up and down to dilute to a uniform concentration, it was used as a sample for heavy metal analysis of the sample of the Examples and Comparative Examples. Cr, Cd, Pb and Cu were analyzed by Jobin Yvon Ultima-C Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and Hg and As were analyzed by Atomic Absorption Spectrometer (Perkin-). Elmer 2380) and Mercury / Hydride systems. Analysis results of heavy metal adsorption rate and specific surface area (Micrometrics, ASAP 2010) are shown in Table 1 below.

division  Heavy Metal Adsorption Rate Specific surface area
(m ² / g) Cr (%) CD(%) Pb (%) Hg (%) As (%) Cu (%) Example 1 19.7 23.6 31.2 18.4 21.2 35.4 94 Example 2 22.4 26.2 34.4 21.4 22.8 38.8 102 Example 3 19.4 23.8 32.0 18.7 21.8 35.5 96 Comparative Example 1 12.4 15.8 20.8 10.9 12.4 19.6 42 Comparative Example 2 13.8 16.8 22.2 12.6 14.6 24.6 45 Comparative Example 3 0.48 0.57 1.24 0.236 0.244 0.842 - Comparative Example 4 3.46 2.18 6.27 0.88 1.06 4.52 - Comparative Example 5 0.01 or less 0.01 or less 0.01 or less 0.01 or less 0.01 or less 0.01 or less -

As shown in Table 1, in Comparative Examples 1 to 2, the adsorption rate of heavy metals was not used by using a water-soluble organic solvent having a high boiling point and using a hot air drying method using a normal drying method or a dry oven, which is a common drying method. It was generally low, and the specific surface area was also low.

In addition, in the case of illite reported to have excellent cation substitution capacity of Comparative Example 5, it was confirmed that there is almost no possibility of removing heavy metal contaminated in water due to the lack of cation exchange capacity, and 4A-zeolites of Comparative Examples 3 to 4 and As a result of confirming the adsorption rate of heavy metals using cation exchange resins, the adsorption rate of heavy metals is somewhat different depending on the type of heavy metals, but the adsorption rate of heavy metals is 0.24 ~ 1.24% for 4A-zeolite, and 0.88 ~ 6.27% which is slightly higher than zeolite for cation exchange resins. The heavy metal adsorption rate of is shown.

On the other hand, as shown in Examples 1 to 3, a water-soluble organic solvent having a high boiling point is selected and supplied as an additive of the heavy metal treatment agent of the calcium aluminum sulphate of the present invention, and synthesized, and the specific surface area is rapidly dried by microwaves. At the same time, it was confirmed that the adsorption rate of heavy metals was greatly improved. As the boiling point was increased, the adsorption rate and specific surface area of heavy metals were proportional to each other.

Heavy Metal Elution Analysis

When the heavy metal ions are adsorbed to calcium aluminum sulfate, the heavy metal adsorbed calcium obtained in Examples 1 to 3 and Comparative Examples 1 to 2 may be used to confirm the possibility of adverse effects on the water environment and the possibility of leaching of the adsorbed heavy metals. 0.5 g of aluminum sulfate powder was accurately measured to the fourth decimal place, and then, 100 mL of distilled water was supplied, stirred with a magnetic stirrer for 10 hours, filtered, and the filtrate was analyzed by ICP-AES. Is shown in Table 2.

division Heavy Metal Elution Cr (ppm) Cd (ppm) Pb (ppm) Hg (ppb) As (ppb) Cu (ppm) Example 1 0.016 0.042 N.D. N.D. 10 N.D. Example 2 0.010 0.028 N.D. N.D. 8.2 N.D. Example 3 0.016 0.038 N.D. N.D. 9.4 N.D. Comparative Example 1 0.022 0.12 N.D. 1.4 16 N.D. Comparative Example 2 0.018 0.088 N.D. 0.96 14 N.D. ND: non-detectable
Detection limits are Pb, Cu is 0.01 ppm, Hg is 1 ppb.

As shown in Table 2, the dissolution test was carried out for 10 hours using the calcium aluminum sulfate heavy metal adsorbent adsorbed to the heavy metal, and most of the calcium aluminum sulfate heavy metal treating agent was not detected or was not detected at a very low concentration. It has been confirmed that there is no possibility of contamination of the water environment, especially when adding a water-soluble organic solvent having a high boiling point during the manufacturing process of calcium aluminum sulfate as in the present invention, and using a rapid heating method by microwave during the drying process, no heavy metal leaching amount It was confirmed that it would play an important role in water treatment as an environmentally friendly heavy metal treatment agent in the future.

After all, the heavy metal treatment agent using calcium aluminum sulfate as an active ingredient produced by the present invention is superior to the ion exchange resin used in the heavy metal adsorption rate, it can be applied to the waste water with a high concentration of heavy metals, Since it hardly elutes in water, it can be confirmed that it can cope with secondary environmental pollution problem.

Claims (6)

delete Dissolving aluminum sulfate in water to prepare an aluminum sulfate solution;
Preparing a slurry by mixing at least one calcium salt selected from calcium oxide, calcium hydroxide, calcium carbonate and calcium sulfate, a water-soluble organic solvent and water;
Preparing a mixed solution by mixing the aluminum sulfate solution and the slurry;
Hydrothermally synthesizing calcium aluminum sulfate by heating the mixed solution to 30 to 150 ° C; And
Heating the calcium aluminum sulphate by microwave to dry it;
Method for producing a heavy metal treatment agent containing calcium aluminum sulfate as an adsorption or substitution component of heavy metal, including
The method of claim 2, wherein the water-soluble organic solvent is at least one selected from 2-butoxyethanol, 2-ethoxyethanol, acetone, benzyl alcohol, cetyl alcohol, diethylene glycol, ethyl alcohol, ethylene glycol and glycerol Method for producing a heavy metal treatment agent.
The method of claim 2, wherein the molar ratio of the aluminum sulfate and the calcium salt is 1: 4-8.
The method of claim 2, wherein the water-soluble organic solvent is contained in 5 parts by weight or less based on 100 parts by weight of calcium salt.
The method of claim 2, wherein the heavy metal is at least one selected from chromium, cadmium, lead, mercury, arsenic, and copper.