|Company Name:||J & K SCIENTIFIC LTD. |
|Company Name:||Alfa Aesar |
|Potassium carbonate Chemical Properties|
|Potassium carbonate Usage And Synthesis|
|Outline||Potassium carbonate (chemical formula: K2CO3), also known as potash; its appearance is colorless crystal or white granules and is easily soluble in water with its solution being strongly alkaline. Cool its saturated solution with generating glassy monoclinic crystalline hydrate 2K2CO3 • 3H2O separated. It has a density of 2.043. It will lose its crystal water at 100 ℃. It is insoluble in ethanol, acetone and ether. It has a strong hygroscopic effect and can absorb carbon dioxide and water upon exposure to air to be converted into potassium bicarbonate. It can be generated through the reaction between potassium hydroxide with carbon dioxide to give. You can also obtain it through the heating reaction between potassium chloride and magnesium carbonate, water and carbon dioxide under pressure or obtain it through the impregnation of tung seed ash and plant ash. It is mainly used as the raw material for synthesis of decarbonization gas, electronic tubes, glass, enamel, printing, welding, film developing, inorganic salts and kinescope glass shell. The impure potassium carbonate base is usually called base, Tong base or pearl grey and is one kind of early species of potash.|
The above information is edited by the Chemicalbook of Dai Xiongfeng.
|Reference quality standards||Item Premium grade First grade Qualified II type |
Potassium carbonate (K2CO3) content ≥ 99.0% 98.5% 96.0% 99.0%
Chloride (KCl) content ≤ 0.01% 0.10% 0.20% 0.03%
Sulfur compounds (in K2SO4) content ≤0.01% 0.10% 0.15% 0.04%
Iron (Fe) content of ≤ 0.001% 0.003% 0.010% 0.001%
Water-insoluble content ≤ 0.02% 0.05% 0.10% 0.04%
Burning loss ≤ 0.60% 1.00% 1.00% 0.80%
|Content Analysis||To a pre-weighed weighing bottle with a plug, accurately weigh 1 g of dried sample measured according to the "loss on drying" assay and dissolve it in 50ml water. After adding of 2 drops of methyl red test solution (TS-149), stir continuously and titrate with 1mol/L hydrochloric acid titration until the solution turns into light pink. Heating the solution to boiling and further cool it down, continue to titrate to boiling until a pale pink color doesn’t disappears any more. Each Ml of 1mol / L hydrochloric acid is equivalent of 69.1 mg of potassium carbonate (K2CO3)
|Solubility of potassium carbonate in water||The maximum solubility per 100 g of water at different temperatures (℃): |
107g / 0 ℃; 109g / 10 ℃; 111g / 20 ℃; 114g / 30 ℃;
117g / 40 ℃; 126g / 60 ℃; 139g / 80 ℃; 156g / 100 ℃.
|Toxicity||ADI does not make special provision (FAO / WHO, 2001). |
LD50: 18.70mg / kg (rat, oral).
GRAS (FDA, §184.1619, 2000);
|Limited use||GB 2760-2001: pasta, beverages, processing aids; take the GMP as limit. |
FAO / WHO (1984): Low times concentrated milk, sweetened condensed milk, dilute cream (2g/kg when being used alone; apply 3g/kg when being used together with other stabilizers, calculated based on anhydrous matter); milk powder, cream powder 5g/kg ( calculated based on anhydride); jams and jellies, orange peel jelly (to maintain the Ph value being at 2.8 to 3.5); infant formula (according to GMP); chocolate 50g/kg (calculated based on the incorporated part from cocoa beans, cocoa nibs, cocoa liquor, cocoa cakes, etc.); cocoa powder, sugar-containing cocoa powder, cocoa nibs, cocoa liquor and cocoa cake 5 g/kg (calculated from non-fat cocoa and K2CO3 meter; can be used for the manufacture of cocoa and chocolate products).
|The maximum allowed amount as food additives and permitted maximum allowable residue limits|
|Chemical Properties||It belongs to monoclinic, and is white powder or granular crystal. It is easily soluble in water but insoluble in alcohol and ether.
|Production method||The ion exchange method: dubbed 250 g / L solution and adding a small amount of potassium carbonate to remove calcium and magnesium ions. Ammonium bicarbonate solution is also prepared at a concentration 200 g / L in water. Pass the potassium chloride solution through a countercurrent into ion exchange column, to make the sodium resin R-Na become potassium type RK, wash off the chlorine ion within the gap of the soft resin; after finishing washing, put through the ammonium bicarbonate solution downstream into the resin exchange column, making the resin become ammonium type R-NH4 and obtain a mixed dilute solution of potassium bicarbonate and ammonium bicarbonate; go through evaporation once to decompose the ammonium bicarbonate; evaporate once again to decompose most of the potassium bicarbonate into potassium carbonate; the precipitated potassium chloride crystal after cooling was filtered and removed; further go through evaporation for three times to 54°C and filter to remove the compound salt of potassium and sodium. The solution was subject to carbonation to convert the potassium carbonate into potassium bicarbonate; further go through crystallization, separation, washing, calcination to obtain the finished product. Its reaction steps are as below: |
R-Na + KCl → R-K + NaCl
R-K + NH4HCO3 → R-NH4 + KHCO3
2KHCO3 → K2CO3 + CO2 ↑+ H2O
Apply electrolysis to dissolve the potassium chloride to a concentration of 270 ~ 300 g/L with adding appropriate amount of potassium carbonate to remove the calcium and magnesium ions inside it. After the clarification of the solution, adjust to pH 8~10 with hydrochloric acid; perform electrolysis at the cell voltage of 2.8 ~ 3.5 V and the bath temperature of 60 ~ 70 ℃ to obtain the potassium hydroxide solution with a concentration of 10% to 15%; further go through evaporation and concentration to a 50% potassium hydroxide and cool down to 30 ~ 35 ℃; Recycle the precipitated potassium chloride for reuse. Dilute the concentrated alkali solution to about 44%, and perform pre-carbonization; when the concentration of potassium hydroxide reaches 30 g/L or less, filter to remove the precipitate of magnesium hydroxide and then go through concentration for removing sodium; then conduct the carbonization to obtain the crude potassium carbonate with further carbonation obtaining the potassium bicarbonate crystals; The crystals undergoes washing with water, centrifuge, calcination to obtain the refined product of potassium carbonate. Its reaction steps are as below:
2KCl + 2H2O [electrolysis] → 2KOH + Cl2 ↑ + H2 ↑
2KOH + CO2 → K2CO3 + H2O
K2CO3 + CO2 + H2O → 2KHCO3
2KHCO3 → K2CO3 + CO2 ↑ + H2O
The plant ash method mainly take advantage of various kinds of plant shell such as Kiriko shell, cotton seed hulls, tea and sunflower seed hulls for firing into plant ash. The plant ash is a mixture of potassium carbonate, potassium sulfate, and potassium chloride. They are separated by multiple steps including leaching, evaporation and crystallization. There are many ways for purification such as adding magnesium to remove phosphorus or put through carbon dioxide for pre-carbonization to remove the impurity or adding lime to remove phosphorus, aluminum and silicon. It needs evaporation for twice, cooling, separation, and further drying to obtain the finished product of potassium carbonate. Owing to the limitation in the sources of raw material, this method is not suitable for mass production and it has been eliminated.
Leblanc method: Mix the potassium, coal, limestone in a certain ratio, add water and stir, wherein the potassium chloride is maintained at 6% to 8%, the sodium salt is maintained in 8% to 10% and then subject to calcination at 900 ~ 1000 ℃ to obtain the black ash.
The black ash is pulverized and subject to hot water extraction. The immersion is further subject to evaporation to precipitate some part of unconverted potassium sulfate out; it was further sent to the carbonation tower for pre-carbonation after separation. Add the potassium permanganate into the carbonation solution to remove the impurities precipitate of aluminum, silicon, and iron; the filtrate was evaporated to the precipitation of potassium carbonate, sodium compound salt and impurities; the clarifying solution further undergoes secondary carbonation to obtain the crude potassium carbonate crystals; it further goes through filtering, water washing, and further calcination at 500 ~ 600 ℃ to obtain the finished potassium carbonate product. Its reaction processes are:
K2SO4 + 2C + CaCO3 → K2CO3 + CaS + 2CO2 ↑
K2CO3 + CO2 + H2O → 2KHCO3
2KHCO3 → K2CO3 + CO2 ↑+ H2O
Recrystallization method: dissolve the technical grade potassium carbonate in distilled water for solution purification; remove the impurities through filtration; the filtrate is further subject to concentration by evaporation, cooling crystallization, centrifugation, and drying to obtain the finished product of anhydrous potassium carbonate.
|Application||It can be applied to the washing and processing for the pre-exposed photosensitive material. |
It is mainly applied to the manufacturing of the kinescope glass of the electronics industry, the decarbonization of fertilizer production, and the manufacturing of potassium salt.
It can be used as analysis reagents, fluxing agent as well as the preparation of various kinds of potassium salts.
It can be used as reagents for analysis, baseline standard reagents and the fluxing agent of molten silicates and insoluble sulfates.
It can be used as a leavening agent in food; it can also be used for glass, printing and dyeing, soap, enamel, preparation of potassium salt, decarbonylation of synthetic ammonia as well as being applied to color TV industry.
It can be used as an alkaline agent and dough conditioner, and can also inhibit the souring of noodles. It can be applied to pasta food. Apply it in appropriate amount according to production requirement.
It can be used for the production of optical glass and can increase the transparency, strength and refractive co-efficiency of the glass. It can also be used in the production of welding electrodes and can prevent the phenomenon of breaking arc during welding. It can be used for the production of vat dyes and dyeing and the white discharge of ice dyeing. It can be used as the absorbent for removing hydrogen sulfide and carbon dioxide. When being mixed with soda ash, it can be used as a dry powder extinguishing agent.
It can also be used as the auxiliary material of acetone, and alcohol production and the antioxidant in the production of rubber. Its aqueous solution can be used for the scouring of cotton and the degreasing of wool. In addition, it can also be applied to the production of inks, pharmaceutical for photography, polyester, electroplating, leather, ceramic, building materials, crystal, potassium soap and medicine. Heavy potassium carbonate is mainly used as the raw material of production of kinescope glass shell and is widely used as the raw material of glass and special glass materials as well as being used for the decarbonization of chemical fertilizer.
|Chemical Properties||white powder or granules|
|General Description||An aqueous solution of potassium hydroxide. Corrosive to metals and tissue. Density 12.8 lb /gal. Used to make soaps, other potassium compounds, in liquid fertilizers.|
|Air & Water Reactions||Water soluble. Addition of water evolves heat.|
|Reactivity Profile||Potassium carbonate neutralizes acids exothermically to form salts plus water. Reacts with certain metals (such as aluminum and zinc) to form oxides or hydroxides of the metal and generate gaseous hydrogen. May initiate polymerization reactions in polymerizable organic compounds, especially epoxides. May generate flammable and/or toxic gases with ammonium salts, nitrides, halogenated organics, various metals, peroxides, and hydroperoxides. May serve as a catalyst. Reacts when heated above about 84°C with aqueous solutions of reducing sugars other than sucrose, to evolve toxic levels of carbon monoxide [Bretherick, 5th Ed., 1995].|
|Health Hazard||TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.|
|Fire Hazard||Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.|
|Potassium carbonate Preparation Products And Raw materials|