Preparation method of tripotassium iron oxalate trihydrate_Kain Industrial Additive

Overview^[1]

As a good photosensitizer, tripotassium iron oxalate trihydrate is a complex formed by Fe3+ and C2O42- through a series of coordination reactions. It is commonly used in the fields of chemical industry, photography and photocatalysts.

Currently, there are a large number of impurity iron ions in vanadium-containing solutions using oxalic acid as the leaching agent. These iron ions have a great impact on the subsequent further purification and enrichment of vanadium, which will consume the extraction chemicals and affect the quality of the final vanadium product. , it is difficult to obtain high-quality V2O5. Therefore, it is necessary to purify and remove iron from the vanadium-containing solution. At the same time, the vanadium-containing solution also contains a large amount of oxalate ions and a small amount of potassium ions. These three ions are all components of potassium iron trioxalate trihydrate. Tripotassium iron oxalate trihydrate is prepared by the solid-phase method of ferric chloride and potassium oxalate. Although the operation is simple and the crystal purity obtained is high, this method directly uses two simple compounds for synthesis, which is costly and complicated.

Tripotassium iron oxalate trihydrate was synthesized using ferric hydroxide, potassium oxalate and oxalic acid as raw materials. Although the operation is convenient and the purity of the obtained crystals is high, this method also directly uses three simple compounds for synthesis, which has high cost and process. complex. To sum up, those skilled in the art prepare tripotassium iron oxalate trihydrate by direct synthesis using a variety of existing simple compounds as raw materials. This method involves many types of pharmaceuticals and has high production costs. At present, there is no method for preparing tripotassium iron oxalate trihydrate using a vanadium-containing solution as a raw material and based on the impurity iron ions in the solution.

Preparation method^[1]

A method for preparing tripotassium iron oxalate trihydrate based on a vanadium-containing solution, where the vanadium-containing solution has: a vanadium concentration of 1 to 2 g/L; an iron concentration of 3 to 6 g/L; and an oxalate concentration of 10～20g/L; pH value is 2～5. The specific steps of the preparation method of tripotassium iron oxalate trihydrate based on vanadium-containing solution are:

(1) According to the material ratio of potassium ions in the crystallizing agent: iron ions in the vanadium-containing solution being (1~4):1, add the crystallizing agent into the vanadium-containing solution and heat it at 80~85°C Stir under the conditions for 0.5 to 1.0 hours to obtain a mixed solution.

(2) The mixed solution is allowed to stand for 3 to 10 hours at 0 to 10°C and protected from light, and the solid and liquid are separated to obtain filtrate I and filter cake I; the filtrate I is used for further purification and enrichment of vanadium. set.

(3) Wash the filter cake I with distilled water 2 to 3 times to obtain crude tripotassium iron oxalate trihydrate product.

(4) According to a liquid-to-solid ratio of 0.5 to 0.8 L/kg, stir the crude tripotassium iron oxalate trihydrate product with water at 50 to 60°C until dissolved to obtain crude tripotassium iron oxalate trihydrate. product solution.

(5) According to the volume ratio of the crude product solution of tripotassium iron oxalate trihydrate: anhydrous ethanol is 1: (0.5~0.8), mix the crude product solution of tripotassium iron oxalate trihydrate with the required volume ratio: Mix the anhydrous ethanol to obtain a recrystallized solution.

(6) Let the recrystallized solution stand for 3 to 10 hours at 0 to 10°C and protected from light, and separate the solid and liquid to obtain filtrate II and filter cake II.

(7) Wash the filter cake II with distilled water 2 to 3 times, and dry it at 60 to 90°C for 12 to 24 hours to obtain potassium iron trioxalate trihydrate crystals.

Prepared tripotassium iron oxalate trihydrate based on vanadium-containing solution: the yield is 70-75%, and the purity is greater than 99.6wt%; therefore, the purity of the crystallized product is high.