Solid − Liquid equilibria of two quaternary systems LiBr–NaBr–Li2SO4–Na2SO4–H2O and LiBr–KBr–Li2SO4–K2SO4–H2O at 298.15 K

In this paper, the solubility of unreported systems LiBr–NaBr–Li 2 SO 4 –Na 2 SO 4 –H 2 O, LiBr–KBr–Li 2 SO 4 –K 2 SO 4 –H 2 O and the subsystem LiBr–Li 2 SO 4 –H 2 O was measured by isothermal dissolution method at 298.15 K. Three phase diagrams are also given. It was found that the diagram of LiBr–Li 2 SO 4 –H 2 O system has only one invariant point of LiBr·2H 2 O + Li 2 SO 4 ·H 2 O. The phase diagram of LiBr–NaBr–Li 2 SO 4 –Na 2 SO 4 –H 2 O system includes eight crystallization regions LiBr·2H 2 O, Li 2 SO 4 ·H 2 O, NaBr·2H 2 O, NaBr, Na 2 SO 4 ·10H 2 O, Na 2 SO 4 , Li 2 SO 4 ·3Na 2 SO 4 ·12H 2 O, and Li 2 SO 4 ·Na 2 SO 4 . Five crystallization regions corresponded to two single salts KBr and K 2 SO 4 , two hydrate salts Li 2 SO 4 ·H 2 O and LiBr·2H 2 O, and one double salt Li 2 SO 4 ·K 2 SO 4 in LiBr–KBr–Li 2 SO 4 –K 2 SO 4 –H 2 O system. The relevant Pitzer parameter was obtained and the result predicted by Pitzer model was consistent with the experimental values.