1. Wet the glass column filled with cation exchange resin with water, then wash it with 5mol/L hydrochloric acid solution, and then wash it with water. Let 20% of this sodium phosphate reagent slowly through the exchange of resin, the outflow of acid and wash combined, evaporation and concentration, and in the phosphorus pentoxide environment vacuum dehydration, cooling crystallization. Purity up to 98%.
2. Add 25% dilute sulfuric acid solution to about 5% barium hypophosphate solution while stirring, until Ba2+ ions are completely precipitated. After the precipitation is complete, the superserum is precipitated, heated, evaporated and concentrated to 10% of the unit volume. Maintain for 15min, then heat up to 130 ºC for 10min (note: do not boil during evaporation). Stop the heating, filter, and cool the filtrate to -2 ~ -3 ºC, and the resulting crystallization is the finished product.
3. Take 285g Ba(H2PO2)2 and dissolve it in 5L water, then take 100g concentrated sulfuric acid and dilute it with water for 3 to 4 times, then add it, stir well and leave it for a day. The solution is carefully siphoned out and evaporated on a porcelain evaporating dish until the remaining solution is only 1/10 of the original volume. It is then transferred to a platinum dish and vaporized under agitation until the solution temperature reaches 105 ° C. The solution is filtered while hot, the colorless filtrate is evaporated and concentrated under continuous agitation (do not heat to boiling), and the temperature is kept warm for 15min when the temperature rises to 110ºC. Continue to rise to 130ºC, heat for 10min. Slightly cold, strain into a ground glass bottle. Cool the glass bottle to several degrees below zero, and there is crystallization (if it does not crystallize, use a glass rod to rub the wall of the bottle and place it.
4. The phosphine produced by the action of calcium phosphide and dilute hydrochloric acid is passed into the stirred iodine suspension until the color of iodine disappears. After repeated distillation under reduced pressure (40mm), the iodine-hydrogen and hydrogen peroxide were steamed, and the remaining residue was pure hypophosphate.
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