1 Introduction
English name : potassium pyrophosphate
English Name : Diphosphoric acid, tetrapotassium salt; Potassium Pyrophosphate; Tetra-Potassium Pyrophosphate; TKPP; Tetrapotassium pyrophosphate;  tetrapotassium diphosphate; diphosphoric acid, monopotassium salt
Formula : K4P2O7
Molecular Weight : 330.33
Specification: Industrial Grade : meet ZB/TG12006-88;
Food Grade : meet FAO / WHO, 1980; customer requirements
Packing: 25Kg double plastic woven bags ; customer requirements
Uses : industry for non-cyanide plating , surface treatment , high-grade detergents, paints , detergents , dispersants , buffers
Etc. ; food grade emulsifiers used in food processing , texture improving agents , chelating agents, quality -improving agent
2 Product Description
Also known as potassium pyrophosphate , potassium pyrophosphate, four white powder or a solid block . The relative density of 2.534 . Melting point 1109 ° C. Dissolved in water , the solubility 187g/100g water (25 ° C). Alkaline aqueous solution , 1% aqueous solution pH = 10.2. Insoluble in ethanol. Properties similar to other polyphosphates .
Dipotassium hydrogen melt loss of water molecules in the system at room temperature as a white crystalline powder or granules , have a strong moisture absorption in the air , easily soluble in water , but insoluble in ethanol , aqueous solution is alkaline, inhibition of food spoilage , fermentation action of a 1% aqueous solution of about pH 10.5,25 ℃ when 100g of water solubility of potassium pyrophosphate 187g, acid or alkaline hydrolysis into a solution of potassium phosphate is mixed with water to form a viscous slurry is . Condensed phosphates in combination with other more , e.g. 10% by potassium pyrophosphate , sodium pyrophosphate, 10% , 30% potassium tripolyphosphate , 30% sodium polyphosphate , sodium metaphosphate, 20% of the ratio formed ham, sausage bond agent , commonly used to prevent struvite produced canned fish , canned fruit to prevent discoloration , swelling of improving ice cream , the extraction amount of the raw coffee , ham, sausage yield, enhanced fish water holding capacity and improve the taste of noodles and increase yield , cheese prevent aging , in order to secure a smooth plating layer , the plating liquid formulation of industrial production are often very complex. Previously used as a complexing agent for the preparation of cyanide plating solution . However, due to the CN- toxic , electroplating workers’ health is very damaging , while the CN- containing wastewater emissions , emissions are also serious environmental pollution. So now the main use of non-cyanide plating plating , and this alternative cyanide complexing agent is potassium pyrophosphate .
All properties of potassium pyrophosphate with other polymeric phosphate , and sodium pyrophosphate similar, but larger solubility , energy and alkaline earth metals and heavy metal ion chelation occurred ; hard water with Ca2 +, Mg2 + in order to form a stable complex soften hard water , improving the ability to wash , to remove dirt . Also in the iron, lead , zinc, aluminum and other metal surface to form a protective film ; pyrophosphate ions (P2O74-) for finely divided solid dispersion having a strong ability to promote the fine , homogeneous mixing of trace substances . Low iron -based high-purity potassium pyrophosphate pH buffering capacity with a stable , long-term to maintain the pH value of the solution .
3 Preparation
And calcination of 30% food-grade phosphoric acid and is added to the slowly adding food grade potassium hydroxide solution under stirring and the reaction , pH control is preferably 8.4 , after the reaction solution was heated and added active carbon , insoluble matter was removed by filtration , the clear filtrate was heated to 120 ~ 124 ℃ and concentrated by evaporation , after cooling to 20 ℃ precipitated crystals were separated by centrifugation to obtain a dipotassium hydrogen phosphate trihydrate and heated to 120 ~ 130 ℃ removal of crystal water, becomes as dipotassium hydrogen phosphate anhydrous , add it to the calciner at 500 ~ 600 ℃ calcined polymerization by cooling , THF was prepared food products.
H3PO4 +2 KOH → K2HPO4 +2 H2O
2K2HPO4 = heat = K4P2O7 + H2O
Prepared THF finished with 0.1 mol / L silver nitrate when the reaction solution to precipitate the yellow silver orthophosphate did not appear to pass.
4 Technical Requirements
Appearance : White powder or lumps
2 Industrial potassium pyrophosphate should meet the requirements of Table 1 (ZB/TG12006-88)
Project Index
Premium grade First grade Qualified
Naphthalene (K4P2O7) phosphoric acid content ,% ≥ 96.0 95.0 94.0
Iron (Fe) content ,% ≤ 0.03 0.05 0.10
Water insoluble matter ,% ≤ 0.10 0.20 0.25
PH value ( 1% solution ) 10.0-10.7
Orthophosphate meet the test
3 food additive potassium pyrophosphate should comply with the requirements in Table 2 (FAO / WHO, 1980)
Project Index
Food Grade
THF (K4P2O7) content ,% ≥ 95.0
Content % ≤ 0.5 Loss on ignition
Water insoluble matter ,% ≤ 0.2
Arsenic (As) content ,% ≤ 0.0003
Heavy metals ( Pb) content ,% ≤ 0.002
Fluoride ( F ) content ,% ≤ 0.001
Lead ( Pb) content ,% ≤ 0.001
4 with potassium pyrophosphate plating shall comply with the requirements in Table 3 (HG/T3591-1999)
Project Index
THF (K4P2O7) content ,% ≥ 98.0
Iron (Fe) content % ≤ 0.01
Water insoluble matter ,% ≤ 0.10
PH value (10g / L aqueous solution ) 10.5 ± 0.5
Lead ( Pb) content ,% ≤ 0.003
Hull cell test (DK ≥ 10A/dm2 under plating ) qualified
5 shows
K4P2O7 · 3H2O colorless crystals or white powder. Hygroscopic in the air. Density 2.33 . Loss of two molecules of water of crystallization at 180 ℃ , the loss of all the crystal water at 300 ℃ . Nature and sodium pyrophosphate similar, but larger solubility . Soluble in water, soluble in ethanol. For tin, stained , clay and other refined . Dipotassium hydrogen melt loss of water molecules in the system.
CAS No:. 7320-34-5
6 Purpose
As emulsifiers, texture improving agents , chelating agents in the food industry , but also for the raw pasta with lye . Multi- condensed phosphates in combination with other commonly used to prevent struvite produce canned fish , fruits prevent discoloration ; increase the degree of swelling of ice cream , ham, sausage yield, ground fish holding capacity ; improve food taste and improve surface was rate, to prevent the cheese aging.