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The Effect of Salts on the Dissolution of Monocalcium Phosphate
Author(s) -
Taylor A. W.,
Gurney E. L.
Publication year - 1965
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1965.03615995002900020013x
Subject(s) - monocalcium phosphate , dissolution , chemistry , phosphate , hydrolysis , nuclear chemistry , salt (chemistry) , inorganic chemistry , organic chemistry , fish <actinopterygii> , fish meal , biology , fishery
Additions of KCl, NH 4 NO 3 , or K 2 SO 4 to Ca(H 2 PO 4 ) 2 ·H 2 O so complicate the dissolution processes that the final distribution of the phosphate cannot be interpreted in terms of the simple system CaO‐P 2 O 5 ‐H 2 O as can the dissolution of Ca(H 2 PO 4 ) 2 ·H 2 O alone. In KCl and NH 4 NO 3 mixtures, formation of Ca 2 KH 7 (PO 4 ) 4 ·2H 2 O and Ca 2 (NH 4 )H 7 (PO 4 ) 4 ·2H 2 O lowers the pH of the initial solutions to < 1 and decreases the initial phosphate concentrations; in the later stages both salts hydrolyze to CaHPO 4 ·2H 2 O, but the amounts of phosphate remaining as this salt are less than that remaining from pure Ca(H 2 PO 4 ) 2 ·H 2 O. In mixtures containing K 2 SO 4 , Ca(H 2 PO 4 ) 2 ·H 2 O is rapidly decomposed with formation of syngenite, CaK 2 (SO 4 ) 2 ·H 2 O, and the phosphate is dissolved as KH 2 PO 4 . Sulfate decreases markedly the amount of residual phosphate.