KR100432185B1 - Activated carbon for water purification - Google Patents

Abstract

The present invention relates to activated carbon for water purification, in which an inorganic coagulant is supported on activated carbon in the range of 0.05 to 10.0 wt% based on the metal component in the inorganic coagulant for water treatment.

The activated carbon for water purification of the present invention not only effectively removes organic matter and suspended solids contained in raw water, but also has good effect of precipitation. In particular, when activated carbon containing an inorganic coagulant containing copper component was used as a water treatment agent of raw water containing algae organic matter, the algae organic matter removal effect was excellent.

Description

Activated carbon for water purification

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to activated carbon for water purification, which is useful for removing organic substances, suspended suspended solids, and the like, which are water pollution sources, in a water treatment process for purifying water, sewage, or plant wastewater. Specifically, the present invention relates to activated carbon for water purification, in which an inorganic coagulant is supported on activated carbon.

Currently, inorganic flocculants and activated carbon are used as water treatment agents for removing suspended suspended matter and organic matter in raw water.

The chemical added to coagulate the particles in the colloidal solution is called coagulant. Suspended Substances in raw water exist in the form of colloidal particles. When a small amount of flocculant, an electrolyte, is added to the colloidal particles, the suspended solids are condensed by neutralizing the charges of the colloidal particles. Sedimentation material is separated to obtain blue water. For this reason, flocculants are used as water treatment agents.

Activated carbon has a large specific surface area due to internal pores, carboxyl group (-COOH), hydroxyl group (-OH), lactone group (-COO-), carbonyl group (-COCO-), It has functional groups, such as a carboxylic acid anhydride (-COOCO-), and has the activity to adsorb | suck an organic substance and a metal.

Organic matter in raw water is a source of biological oxygen demand (BOD), bad smell and color.

The range of water treatment application of activated carbon is very wide. Activated carbon for water treatment is also used for water treatment, wastewater treatment, and sewage and manure treatment. Activated carbon used for water treatment was Granular Activated Carbon (GAC) and Powdered Activated Carbon (PAC), but was recently developed to recover air cleaners and organic solvents in the gas phase. Activated Carbon Fiber (hereinafter referred to as ACF) has been applied to water treatment. Powdered activated carbon is usually used for pretreatment in water treatment, and granular activated carbon is used as a filter material for forming the activated carbon filter layer. According to the American Water Association's water treatment regulations, powder activated carbon and granular activated carbon are used, and domestic water treatment regulations are allowed to use powder or granular activated carbon.

The surface chemical function (characteristic functional group) of activated carbon varies depending on the raw material, manufacturing method, or use, and all activated carbon does not have the same function but has various functions depending on the manufacturer. The ability is different.

Until now, activated carbon for water treatment uses activated carbon produced by the manufacturer without any treatment, which has a problem in that the adsorption capacity of organic materials is reduced.

Recently, in order to improve the adsorptive properties of activated carbon for the purpose of adsorbing basic materials such as hydrogen sulfide or ammonia, or acid gases, non-volatile inorganic caustic sodium (NaOH), sodium carbonate (Na ₂ CO ₃ ) or non-volatile inorganic acid sulfuric acid Activated carbon immersed in (H ₂ SO ₄ ) or phosphoric acid (H ₃ PO ₄ ) is applied. This is essentially to improve the adsorption effect by van der Waals forces since the surface of the activated carbon is nonpolar. In the case of gas phase adsorption, when an acidic or basic substance is immersed, it is not desorbed. However, in liquid adsorption, the immersed substance can be desorbed and dissolved.

The aluminum-based inorganic coagulants include aluminum sulfate (Al ₂ (SO ₄ ) ₂ ), polyaluminum chloride (PACl), polyaluminum silicate (PACS), polysilicate aluminum silicate (PASS), and aluminum chloride (AlCl ₃ ). In the Fe-based inorganic coagulant, ferrous sulfate or ferric sulfate, ferrous chloride or ferric iron, polyferric sulfate (PFS, poly ferric sulfate), and iron chloride (PFC, poly ferric chloride) are used. These inorganic coagulants can remove inorganic and organic substances in water by forming various complex compounds and adsorption through the hydration reaction in water. Activated charcoal has superior surface adsorption properties than inorganic materials, and the adsorption power of soluble organic matters is excellent while inorganic adsorption effects are very low.

Activated carbon is used for pretreatment to treat algae, and copper sulfate is used as algae remover if necessary. In the world, copper sulfate, ethanolamine copper compound and triethanolamine copper compound are used as algae organic remover. They are designated water treatment agents of the National Sanitary Federation (hereinafter referred to as NSF) and the American Waterworks Association. In Korea, only copper sulfate is designated as a water treatment agent. However, due to the fact that copper is harmful to the human body, it is excellent in terms of effectiveness but is reluctant to use it in water treatment.

In general, the water treatment process removes water-soluble organics and suspended substances, which are the main causes of BOD in raw water. Activated carbon is useful for removing water-soluble organics, but it has poor sedimentation and adsorption capacity to acidic substances in water. The inorganic flocculant is useful for removing suspended solids, but it can be used only when it is dispersed uniformly to increase the efficiency of use. On the other hand, the inorganic flocculant has low dispersion capacity, no adsorption capacity, and low organic matter removal effect.

It is an object of the present invention to provide activated carbon for water purification, which can remove both organic matter and suspension contained in purified water.

The present inventors use the large specific surface area of activated carbon to impregnate inorganic coagulants with activated carbon and use them for water purification, which has a synergistic effect on their dispersion, flocculation and adsorption functions, effectively removing organic matter and suspended solids from raw water. After confirming that the present invention was completed.

Conventional activated carbon is added only for the purpose of removing soluble organics, so the effect of removing inorganic matters could not be expected. However, when the inorganic coagulant based on aluminum or the inorganic coagulant based on iron (Fe) based on activated carbon is used, the organic matter removal effect increases. In addition to being able to remove inorganic substances, it is not only convenient to use, but also a significant reduction in the cost of water treatment chemicals due to the reduction in the amount of use. In addition, the activated carbon itself is light, so that the specific gravity is increased as the metal component is supported on the activated carbon can improve the sedimentation.

In the conventional case, since the inorganic coagulant is added to raw water alone, the dispersion effect of the coagulant is low, so that uniform coagulation is difficult to occur. Coagulation effect is relatively increased.

On the other hand, conventionally, when organic matter is increased in water, activated carbon is added or the amount of flocculant is increased. When excessive algae organic matter is introduced, copper sulfate, which is designated as a water treatment agent in addition to activated carbon and flocculant, is sprayed on the influent water. In this case, copper components harmful to the human body may remain in the final treated water, so it is reluctant to use the purified water. However, when used by supporting the copper compound on the activated carbon, organic matter and copper components are firmly combined, so it is not only excellent in the ability to remove organic matter, but also harmful water to the human body in the treated water can produce high quality water.

The present invention relates to an activated carbon obtained by supporting a certain amount of inorganic coagulant on activated carbon.

The amount of the inorganic coagulant supported is 0.05 to 10.0 wt% of the weight of the activated carbon based on the metal component of the inorganic coagulant. The use of a large specific surface area of the activated carbon, the impregnation of the inorganic coagulant (impregnation) is to increase the removal effect of the organic and inorganic substances to increase the cohesive effect is to provide an activated carbon having a new cohesive performance. To date, there have been no examples of applying inorganic coagulant to activated carbon for water treatment. Inorganic coagulants are used for flocculation of suspended solids and activated carbon for adsorption of organic substances in water and wastewater treatment.

The present invention is a new concept of water treatment agent combining the adsorption characteristics of activated carbon and the coagulation characteristics of inorganic coagulant can increase the removal effect of organic and inorganic matter in water. Since an inorganic coagulant is supported on the surface of the activated carbon, the effect of raising the adsorption effect of the inorganic material can be exerted.

Activated carbon of the present invention improves the adsorption performance of organic or inorganic matter. The present invention includes supporting an aluminum or iron metal constituting the core metal in the inorganic coagulant on one or more activated carbons. It is also recommended to use copper compounds to remove algae organics.

The method of supporting the inorganic coagulant containing aluminum metal on the GAC is as follows. First, the inorganic coagulant to be supported is made into the aqueous solution as much as the required amount of metal, and then the activated carbon is slowly added and reacted. After the reaction, the mother liquor and the activated carbon were separated by filtration, and GAC (hereinafter referred to as Al-GAC) containing an inorganic coagulant containing aluminum metal was prepared by drying for about 20-30 minutes under a nitrogen stream.

Aluminum salt + GAC → Al-GAC ............. (I)

Al-GAC obtained in the above formula has been enhanced to increase the dispersing effect of the metal than the use of conventional activated carbon alone, the removal effect was significantly increased. In particular, due to the weight of the metal in the GAC itself, the precipitation effect increased significantly. GAC (hereinafter referred to as Fe-GAC) loaded with ferrous metal-containing inorganic coagulant was prepared by a similar procedure.

The method of simultaneously supporting an inorganic coagulant containing aluminum metal and ferrous metal on the GAC surface is as follows. First, determine the proper ratio of the two metals to be supported, bring them into solution, and then slowly add activated carbon to them. After the reaction, GAC (hereinafter referred to as Al-Fe / GAC) carrying the mother liquor and the inorganic coagulant containing the two metals were separated and dried for about 20-30 minutes under nitrogen stream to have the following general formula (II). Al-Fe / GAC products were prepared.

Aluminum salt + Iron salt + GAC → Al-Fe / GAC ..... (II)

Al-Fe / activated carbon loaded with two cohesive metals at the same time has excellent sedimentation effect as well as the ability to remove organic matter. In particular, sedimentation was lowered during algae generation. Al-Fe / GAC showed synergistic effect, which improved organic matter removal ability and sedimentation ability, and increased ammonia removal ability.

The loading of the inorganic coagulant containing copper on the GAC surface was carried out as follows. A copper sulfate (CuSO ₄ , molecular weight = 159.61, blue crystal) solution was reacted to the GAC surface under appropriate conditions to prepare GAC (hereinafter referred to as Cu-GAC) carrying an inorganic coagulant containing a copper component. The copper sulfate compound of the amount to be supported in the GAC is dissolved under appropriate conditions, and GAC is added gradually with stirring. Since the copper component is supported on the surface of activated carbon at a high rate, the adsorption time is completed for about 20-30 minutes. Next, the supported GAC and the mother liquor are separated, and the Cu-GAC thus obtained is dried under a nitrogen stream. The unreacted copper component could be obtained from the remaining solution to confirm the supported amount.

Copper sulfate + GAC → Cu-GAC ............. (III)

The Cu-GAC exhibited excellent performance of adsorption removal capability of organic material with Cu of 0.1% to 5wt%. It was observed that the surface area and pore distribution of Cu-GAC of this water treatment agent were almost unchanged from the activated carbon in the supported state, and the appearance was almost the same as the GAC in the supported state.

Cu-GAC having the above characteristics could be prepared from various copper compounds and maintained an excellent organic matter removal effect similar to Cu-GAC obtained in Formula [III]. In these manufacturing methods, the raw material of copper may be manufactured by replacing ethanol amine compound and copper triethanol amine complexes, which are currently registered as mixed water treatment agents of NSF. The removal effect of organic matters was lower than the use of copper sulfate in the removal effect of organic matters, but it was superior in terms of the effect when used alone without their support.

In addition, in order to support the metal in the form of an oxide, a metal loaded GAC is placed in an electric furnace, and the temperature is gradually increased, and the Cu metal is converted into an oxide form by firing under a nitrogen stream for uniform distribution of the metal in the temperature range of 300 to 700 ° C. It was supported. Copper sulfate supported on GAC as shown in the following formula (IV) is decomposed at high temperature to form CuO in the form of oxide and released under nitrogen atmosphere (25cc / min) in the form of SO ₂ gas. In general, since metal salts decompose into metal oxides and gaseous substances at high temperatures, the metal oxides can be easily supported on the GAC surface.

CuSO ₄ → CuO + SO ₂ ........................... (IV)

The method of supporting an aluminum metal and a copper metal simultaneously supported on GAC (hereinafter referred to as Al-Cu / GAC) is as follows. First, determine the proper ratio of the two metals to be supported and make it into a solution state. Then, under moderate reaction conditions, slowly add GAC and react for about 20 to 30 minutes. After the reaction, the mother liquor and Al-Cu / GAC were separated, dried under a nitrogen stream, and Al-Cu / GAC was prepared according to the following reaction formula (V).

Aluminum salt + copper sulfate + GAC → Al-Cu / GAC ........ (V)

GAC (hereinafter referred to as Fe-Cu / GAC) simultaneously loaded with iron and a copper metal was also prepared in the same manner as above.

Example

Example 1

1.45 g of ferric chloride (FeCl ₃ , molecular weight = 162.22) was dissolved in a beaker containing 0.5 L of distilled water, followed by stirring at a water temperature of 50 ° C. Then add 50 g of GAC (surface area 1100 m ² / g) with stirring to allow ferric chloride to be supported on the GAC surface. When about 25 minutes have elapsed, the mother liquor and iron-containing GAC are separated by filter paper and dried for 2 hours in a nitrogen stream at 60 ° C. to make a finished product. Organic matter removal effect and turbidity removal effect using 1wt% Fe-supported activated carbon (hereinafter referred to as Fe (1wt%)-GAC) and unsupported pure GAC (hereinafter referred to as Fe (0wt%)-GAC) Table 1 shows the results of the analysis.

Raw water: pH = 8.3, turbidity = 12.5 NTU, alkalinity = 51 mg / l, KMnO ₄ consumption = 16.5 mg / l ultraviolet extinction 0.122, Item Dosage (ppm) Aluminum Sulfate Input (ppm) Treated water KnO ₄ Consumption (mg / l) Ultraviolet absorption value (E-254) Turbidity (NTU) Alkalinity (mg / l) Fe (0wt%)-GAC 0 35 8.3 0.083 1.5 36.0 3 32 7.1 0.075 1.1 35.5 Fe (1wt%)-GAC 3 27 5.2 0.046 0.8 35.0 ※ ○ Aluminum sulfate [Al ₂ (SO ₄ ) ₃ ] is 8.2% based on Al ₂ O ₃ ○ Measurement of turbidity according to the method of ASTMD-1889-81 ○ NTU: amount of suspended solids in solution ( Nephelometric Turbidity Unit)

As shown in Table 1, when the same amount of activated carbon was added, the activated carbon with the metal had an excellent organic matter removal effect and the precipitation property was improved, and the turbidity removal effect was relatively improved. Potassium permanganate (KMnO ₄ : a measure of the concentration of organic matter) showed that the consumption of metal-supported activated carbon was lower, and the ultraviolet absorbance value, which is a standard indicating the concentration of organic matter, was also low. In addition, the consumption of aluminum sulfate, an inorganic coagulant, was also less when using activated carbon.

Example 2

11.0 g of solid aluminum sulfate (Al ₂ (SO ₄ ) ₂ .14H ₂ O, molecular weight = 594.4) is dissolved in a beaker containing 0.5 L of distilled water, and the water temperature is 50 DEG C, followed by stirring. Then add 50 g of PAC (surface area 980 m ² / g) with stirring to ensure that the aluminum sulfate is supported on the PAC surface. After about 25 minutes, the mother liquor and activated carbon (hereinafter referred to as Al (1wt%)-PAC) loaded with 1wt% of aluminum are separated using filter paper and dried in a nitrogen stream at 60 ° C to form a finished product. Table 2 shows the results of analyzing the organic matter removal effect and turbidity removal effect of Al (1w%)-PAC and unsupported PAC (hereinafter referred to as Al (0wt%)-PAC) obtained in the present invention.

Raw water: pH 8.5, Turbidity = 50 NTU, Alkaliness = 54 mg / l, KMnO ₄ Consumption = 17.5 mg / l Ultraviolet absorption value 0.182 Item Dosage (ppm) Ferric Chloride Input (ppm) Treated water KMnO ₄ Consumption (mg / l) Ultraviolet absorption value (E-254) Turbidity (NTU) Alkalinity (mg / l) Al (0wt%)-PAC 0 35 8.5 0.089 1.4 35.5 3 31 7.4 0.078 1.0 35.0 Al (1wt%)-PAC 3 25 5.6 0.051 0.8 36.2 ※ ○ Ferric chloride (FeCl ₃ ) uses 11% of trivalent iron.

Example 3

1.25 g of algae removal copper sulfate (CuSO ₄ , molecular weight = 159.61, blue crystals) used as a water treatment agent is dissolved in 0.5 L of distilled water, and the water temperature is 50 ° C., followed by stirring. Then add 50 g of GAC (surface area 1100 m ² / g) with gentle agitation so that copper sulfate is supported on the GAC surface. When about 25 minutes have elapsed, the mother liquor and Cu-GAC are separated by filter paper and dried at 60 ° C. for 2 hours in a nitrogen stream to form a finished product. Organic matter removal effect and turbidity of GAC (hereinafter referred to as Cu (1wt%)-GAC) having 1 wt% Cu content and pure GAC (hereinafter referred to as Cu (0wt%)-GAC) prepared in the present invention The results of analyzing the removal effect are shown in Table 3. KMnO ₄ consumption and UV absorbance were analyzed to measure organic matter content in raw water. The experiment was performed using the Jatest apparatus with the same raw water.

Raw water: pH = 8.0, Turbidity = 8.5NTU, Alkaliness 49 mg / l, KMnO ₄ Consumption = 15.1mg / l Ultraviolet absorption value 0.113 Item Dosage (ppm) PACl input amount (ppm) Treated water KMnO ₄ Consumption (mg / l) Ultraviolet absorption value (E-254) Turbidity (NTU) Alkalinity (mg / l) Cu (0wt%)-GAC 0 25 7.1 0.085 1.1 35.3 3 22 6.3 0.071 0.9 35.0 Cu (1wt%)-GAC 3 18 5.2 0.052 0.5 34.8 ※ ○ Poly Aluminum Chloride (PACl). PACl is based on Al ₂ O ₃ based on 10%. ○ Turbidity measurement according to the method of ASTMD-1889-81 ○ NTU: Suspension in solution (Nephelometric Turbidity Unit)

Example 4

0.63 g of copper sulfate (CuSO ₄ , molecular weight = 159.61, blue crystal) as a water treatment agent and 0.73 g of ferric chloride (FeCl ₃ ) used as an inorganic coagulant were dissolved in 0.5 L of distilled water in a small high speed stirrer, and the water temperature was 50 ° C. And add agitation until complete dissolution. Then, 50 g of GAC is added and reacted at the same time with high speed stirring. After about 15 minutes, the mother liquor, activated carbon (hereinafter referred to as Fe-Cu (1wt%) / GAC) loaded with 0.5wt% iron and 0.5wt% copper at the same time is separated using a funnel and nitrogen at 60 ° C. The product is dried by drying in air for 2 hours. The results of analyzing the algae organic matter removal effect and turbidity removal effect of Cu-Fe (1wt%) / GAC and GAC (denoted Cu-Fe (0wt%) / GAC) without any metal obtained in the present invention It is shown in Table 4.

Raw water: pH = 8.2, Turbidity = 31NTU, Alkaliness = 48 mg / l, KMnO ₄ Consumption = 11.3 mg / l, Ultraviolet absorption value = 0.122 Item Dosage (ppm) Ferric Sulfate Input (ppm) Treated water KMnO ₄ Consumption (mg / l) Ultraviolet absorption value (E-254) Turbidity (NTU) Alkalinity (mg / l) Fe-Cu (0wt%) / GAC 0 30 7.5 0.083 1.2 34.5 3 26 6.1 0.073 0.8 35.0 Fe-Cu (1wt%) / GAC 3 21 4.9 0.055 0.6 34.7 ※ ○ Ferric sulfate (Fe ₂ (SO ₄ ) ₃ ) of 18% of trivalent iron used.

Example 5

5.5 g of solid aluminum sulfate (Al ₂ (SO ₄ ) ₂ · 14H ₂ O, molecular weight = 594.4), an inorganic coagulant, and 0.63 g of copper sulfate were dissolved in a beaker containing 0.5 l of distilled water. Stir until it is added. Then 50 g of GAC (surface area 1100 m ² / l) are added slowly and slowly stirred with reaction. After about 25 minutes, GAC (hereinafter referred to as Al-Cu (1wt%) / GAC) loaded with mother liquor, 0.5wt% aluminum, and 0.5wt% copper at the same time is separated by filter paper, and nitrogen stream at 60 ℃. Dry for 2 hours to make a finished product. The biological oxygen demand (BOD) removal effect and turbidity removal effect of Al-Cu (1wt%) / GAC obtained from the present invention and GAC (hereinafter referred to as Al-Cu (0wt%) / GAC) without inorganic coagulant are shown. It is shown in Table 5.

Raw water: pH = 8.3, BOD = 50 mg / l, Turbidity = 20 NTU, alkalinity = 50mg / l Item Dosage (ppm) Aluminum sulfate injection amount (ppm) Treated water Turbidity (NTU) BOD (mg / l) Alkalinity (mg / l) Al-Cu (0wt%) / GAC 0 50 2.5 23 34.5 4 45 1.9 18 35.1 Al-Cu (1wt%) / GAC 4 39 1.2 12 35.6 ※ ○ Based on Al ₂ O ₃ of aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), 8.2%

Example 6

5.5 g of aluminum sulfate (Al ₂ (SO ₄ ) ₂ .14H ₂ O, molecular weight = 594.4) and 0.73 g of ferric chloride (FeCl ₃ ) are dissolved in a beaker containing 0.5 l of distilled water, and the water temperature is 45 ° C. Agitation is added until dissolution. Next, 50 g of ACF (surface area 1250 m ² / g) are squeezed into a circular shape having a diameter of about 10 mm, and then put into a stirrer to support the two metal components on the surface of the ACF. After about 25 minutes, the mother liquor, ACF (hereinafter referred to as Al-Fe (1wt%) / ACF) loaded with 0.5wt% aluminum and 0.5wt% iron at the same time, is separated using a filter paper. Dry for 2 hours to make a finished product. The results of applying Al-Fe (1wt%) / ACF and metal-free ACF (hereinafter referred to as Al-Fe (0wt%) / ACF) obtained in the present invention to the flocculation experiment showed that organic matter removal effect and turbidity removal The effects were as shown in Table 6.

Raw water: pH = 8.5, BOD = 95 mg / l, Turbidity = 40 NTU, alkalinity = 60mg / l Item Dosage (ppm) PACl input amount (ppm) Treated water Turbidity (NTU) BOD (mg / l) Alkalinity (mg / l) Al-Fe (0wt%) / ACF 0 45 3.5 23 40.5 5 41 2.7 18 41.2 Al-Fe (1wt%) / ACF 5 34 1.8 12 41.0 ※ ○ Poly Aluminum Chloride (PACl). The aluminum concentration of PACl is 10% based on Al ₂ O ₃

The activated carbon for water purification of the present invention not only effectively removes organic matter and suspended solids contained in raw water, but also has good effect of precipitation. In particular, when activated carbon containing an inorganic coagulant containing copper component was used as a water treatment agent of raw water containing algae organic matter, the algae organic matter removal effect was excellent.

Claims (2)

Activated carbon for water purification, in which an inorganic coagulant is supported on activated carbon in the range of 0.05 to 10.0 wt% based on the metal component in the inorganic coagulant for water treatment. The inorganic coagulant for water treatment according to claim 1 is ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, iron polysulfate, polyiron chloride, aluminum chloride, aluminum sulfate, polyaluminum chloride, aluminum nitrate, iron nitrate, copper sulfate, copper ethanolamine , copper triethanolamine, copper, copper nitrate, silver nitrate, silver chloride, sodium chloride aluminate (NaAlO _2), sodium silicate (NaSiO ₂₎ activated carbon water purification, characterized in that either or or a mixture thereof in the.