Technical Field

The subject of the invention is the method for the production of activated carbon with catalysts applied on the surface, enabling chemisorption processes of toxic substances contained in water, including chemical warfare agents, as well as the chemisorption of heavy metals, mainly mercury and lead.

Activated carbon, catalyzed by silver, copper, zinc and manganese compounds (sorbents) constitute an important element of water treatment devices adapted to using surface sources, the most exposed to chemical, biological and radioactive contamination.

Background Art

Polish patent description PL 192 700 B1 provides the information on the method for the production of activated carbon with germicidal properties which is characterized by the fact that before the saturation of activated carbon with ammonia-water solution of silver nitrate, concentrated nitric acid is added to active carbon and mixed for several minutes at intervals of one hour for a period of 24 hours, then the excess nitric acid is washed off with distilled water until the pH of the solution is determined and nitrate ions disappear from the filtrate, then the mixture is heated at the temperature ranging from 100°C to 120°C for 8 hours.

International Publication N<> WO 2012/102 610 A1 discloses method for preparing activated carbon comprising micropores, mesopores and macropores coated by catalytic material. This method comprising the following steps; (i) mixing "charcoal" with one or more organic nitrogen-containing compounds, (ii) drying the mixture and (iii) activating the dried mixture using steam, thereby producing catalytically active activated carbon. "Charcoal" is wood char in the form of charcoal chunks, charcoal chips, and/or charcoal powder. The dried mixture entering the steam activation in step (iii) is catalytically inactive. The process of the invention require small process steps and does not require the conventional carbonizing/oxidizing steps, but the types of coals, belonging to the category of "charcoal" in the meaning of the present application are precisely limited (derived from animal or vegetation substances).

Disclosure of Invention

The essence of the invention resides in the fact that impregnating solution containing copper or manganese or silver or zinc salts are introduced into activated carbon and then mixed to equalize the humidity of carbon and seasoned at room temperature for 1.5 up to 2.5 hours. Then impregnated activated carbon is dried at the temperature of 00°C to 50°C for 1.0 to 6.5 hours; subsequently, it is heated at the temperature from 180°C to 380°C for 1.5 to 2.5 hours.

In a first aspect of the present invention, the impregnation solution was constituted by the ammonia solution containing copper, manganese and silver salts. Salt solution containing copper is prepared through the mixing of alkaline copper carbonate with ammonium carbonate, then concentrated ammonia water and distilled or demineralized water is added and stirred to dissolve solids, and the solution containing manganese is obtained by mixing potassium permanganate with distilled or demineralized water and heating the mixture until the permanganate dissolves, while the mixture containing silver is obtained by dissolving silver nitrate in water. Solution containing silver is added to the solution containing manganese and then, the solution containing copper is added.

According to certain embodiments of the present invention, impregnated activated carbon is dried in fluid bed dryer preferably at the temperature of 120°C for 20 minutes and then heated in a drying chamber at the temperature of 200°C for 2.0 hours. According to certain embodiments of the present invention, impregnated activated carbon is dried in drum dryer preferably at the temperature of 120°C for 1 hour and then heated at the temperature of 200°C for 2.0 hours.

According to certain embodiments of the present invention, impregnated activated carbon with layer thickness not exceeding 2cm is dried in a drying chamber on a stainless steel tray, preferably at the temperature of 120°C for 4 hours and then heated at the temperature of 200°C for 2.0 hours.

According to certain embodiments of the present invention, impregnated activated carbon with layer thickness exceeding 2cm is dried in a drying chamber on a stainless steel tray, preferably at the temperature of 120°C for 6 hours and then heated at the temperature of 200°C for 2.0 hours. In a second aspect of the present invention, the impregnation solution is constituted by the solution containing zinc and silver salts, obtained through dissolving silver nitrate and zinc nitrate in water.

According to certain embodiments of the present invention, before introducing the impregnation solution to activated carbon, the surface of activated carbon is oxidized with nitric acid solution.

According to certain embodiments of the present invention, the surface of activated carbon is oxidized in a way that activated carbon is covered with 15% to 25%, preferably 20% nitric acid solution for 1 day, the covered carbon is stirred at intervals of 0.5 up to 1.5 hours, preferably every 1.0 hour, and oxidized carbon is filtrated and initially washed off with demineralized water, periodically modifying the direction of water flow through demineralization column, and then washed with distilled water. According to certain embodiments of the present invention, impregnated activated carbon is dried in a drying chamber on a stainless steel tray preferably at the temperature of 120°C for 6 hours and then heated at the temperature of 350°C for 2.0 hours. Best Modes for Carrying Out the Invention

Activated carbon - the carrier with the symbol R Ref. was activated according to the invention in a pilot plant scale.

The implementation of the invention are explained in the following examples.

EXAMPLE 1 Sample R Tok. 8

Step 1 preparative: - Preparation of the impregnation solutions

Solution containing copper: alkaline copper carbonate in the amount of 1 ,046 kg and ammonium carbonate in the amount of 0,84 kg were weighed, and then these reagents were thoroughly mixed. To the mixture was added ammonia water (25%) - 2,0 dm ³ and mixed adding water until the solids were dissolved.

Solution containing manganese: A stirred reactor was set at the workplace, !n a dry beaker with a capacity of 1 ,0 dm ³ , 0,686kg of potassium permanganate was weighed and moved through the funnel into the reactor. Measured off 12 dm ³ of water and transferred into the reactor with potassium permanganate. The mixture permanganate with water was heated with agitation to completely dissolve the permanganate.

Solution containing silver: In a beaker with a capacity of 0,250 dm ³ , 0.156 kg of silver nitrate was weighed and 1.2 dm3 of water was added and then stirred to completely dissolve the silver nitrate in water. The solution containing silver was added to the solution containing manganese and both were mixed, after which the solution containing copper was added and all was mixed. Step 2 - impregnation of the activated carbon

After mixing all the solutions in one container, prepared impregnating solution was poured into a container with 20 kg of activated carbon and stirred for several minutes to fully equalization of the humidity of carbon. The mixed carbon was seasoned at room temperature for 2 hours to homogenize the moisture content of coal and deposition on its catalyst. The mixed carbon was conditioned in the room temperature for 2 hours to homogenize the moisture content of coal and deposition on its surface a catalysts.

Step 3 - Drying and heating of the activated carbon

The impregnated in step 2 the activated carbon was transferred to a drum dryer and dried for 1 hour at the temperature of 120° C, whereupon the temperature was raised to 200° C and held for 2 hours.

The resulting activated carbon includes the following amounts of the metal catalysts:

> 3.0% copper,

> .2% manganese,

> 0.5% silver.

EXAMPLE 2 - Sample R Met. 13

Step 1 - Oxidation of the activated carbon

Measured off 5 portions of 4 kg of the activated carbon and placed in plastic PE containers with capacity of approx. 40 dm ³ . Then the activated carbon was flooded 15 dm ³ nitric acid solution 20% for 24 hours with stirring every 1 h.

Oxidized carbon was filtrated on funnel sieve and with initially washed 30 dm ³ of demineralized water, and then initially washed carbon was moved to a column with capacity of 0 - 12 dm ³ and washed with a stream of demineralized water with a rate of 20 - 30 dm ³ /h. The direction of flow of water through the column was changed every two hours until the disappearance of the reaction filtrate with diphenylamine.

By the column with such eluted the oxidized carbon slow!y passed 15 dm ³ of distilled water to remove chloride ions.

Step 2 - Impregnation of the activated carbon

For each 4 kg of the oxidized activated carbon weighed on 364g of silver nitrate and 364g of zinc nitrate and measured of 3,81 distilled water. The ingredients were mixed, and the resulting impregnation solution was used for flooding the oxidized activated carbon placed in a PVC bucket of 101. The mixture was stirred vigorously for several minutes.

Step 3 - Drying and heating of the activated carbon

The impregnated in step 2 the activated carbon placed on the stainless steel tray and seasoned for 2 hours at room temperature. Seasoned activated carbon was dried for 6 hours in a drying chamber at 120°C and then heated at the temperature of 350°C for two hours.

The resulting activated carbon includes the following amounts of the metal catalysts:

> 2.0% zinc,

> 1.0% silver.

Static parameters of the activated carbons

Parameter of the Unit of Activated carbon

No.

activated carbons measure R ef. R Tok.8 R Met. 3

1 Water content % 3 4 3

2 Reaction PH 7,86 8,8 7,8

The number of

3 cm ³ 53 46 46 methylene

4 The iodine number mg/g 1 140 972 1 045

Dynamic parameters (Utilities) of the activated carbons

Breakthrough time of the active carbon in R Tok. 8, coated by metal catalysts, to the potassium cyanide and chloroethyl ethyl sulfate (analog of mustard gas) are nearly four times higher with respect to the carbon before impregnation. This indicates the effectiveness of the activated carbon in removing toxic agents from water.

Tests of active carbon R Met. 13 showed almost 100% removal efficiency of mercury and approx. 90% removal efficiency of lead from water solutions.