Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (5): 1134-1142.doi: 10.3866/PKU.WHXB201602194

• ARTICLE • Previous Articles     Next Articles

Solubility of NH4VO3 in NH4H2PO4-H2O and (NH4)3PO4-H2O Systems

Xu-Li GONG1,2,Chang-Qiao ZHANG1,*(),Peng-Ge NING2,*(),Hong-Bin CAO2,Yi ZHANG2   

  1. 1 School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
    2 Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2015-11-26 Published:2016-05-07
  • Contact: Chang-Qiao ZHANG,Peng-Ge NING;
  • Supported by:
    the Technology Support Program of China(2015BAB02B05);National Basic Research Program of China (973)(2013CB632605);National Natural Science Foundation of China(51425405)


The solubility of ammonium metavanadate (NH4VO3) in NH4H2PO4-H2O and (NH4)3PO4-H2O systems at T = 298.15-328.15 K was measured using the classic isothermal dissolution method. The densities and pH values of the solutions were also determined. The solubility of NH4VO3 decreased at first and then increased with increasing NH4H2PO4 or (NH4)3PO4 concentrations. This was considered to be caused by the common ionic effect, chemical reaction equilibrium and ionic activity. At T = 298.15 K, the solubility of NH4VO3 in the NH4H2PO4-H2O system was the highest, and was lower in the (NH4)3PO4-H2O system. The solubility in the (NH4)2HPO4-H2O system was the lowest. The mean ionic activity coefficients were calculated for the three phosphate solutions at C = 0.5 mol·kg-1 using the pH values and dissolution reaction constant. The mean ionic activity coefficients were the largest for the (NH4)2HPO4-H2O system, and were smaller for the (NH4)3PO4-H2O system. The mean ionic activity coefficients were the smallest for the NH4H2PO4-H2O system, which agrees with the solubility variations of NH4VO3 in the three phosphate systems.

Key words: NH4VO3, Solubility, NH4H2PO4 solution, (NH4)3PO4 solution