Abstract:
The process for the production of Na_5P_3O_(10) from NaCl consists of the following steps: 1) liquid-liquid double decomposition (LLDD) of NaCl and H_3PO_4 with a long chain primary amine to prepare NaH_2PO_4, 2) LLDD of NaCl and H_3PO_4 with the same amine to prepare Na_2HPO_4, 3) separation of Na_2HPO_4 from the resulting aqueous solution by crystallization, 4) polymerization of NaH_2PO_4 and Na_2HPO_4 to produce Na_5P_3O_(10). The selection of extractant, the effects of composition of both phases and temperature on the conversion of H_3PO_4 to NaH_2PO_4 in LLDD, the mechanism of LLDD and the effect of the chloride content in the mixture of NaH_2PO_4 and Na_2HPO_4 on the purity of Na_5P_3O_(10) product are discussed. The results of bench scale experiment show that the total conversion of H_3PO_4 in LLDD is more than 97%, the content of NaCl in the intermediate product of Na_2HPO_4. 12H_2O is 0.34% and the purity of Na_5P_3O_(10) is 90.4%.