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Removal of lead, cadmium and zinc from aqueous solutions by precipitation with sodium Di‐( n ‐octyl) phosphinate
Author(s) -
Esalah Jamaleddin O.,
Weber Martin E.,
Vera Juan H.
Publication year - 2000
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450780512
Subject(s) - phosphinate , cadmium , chemistry , zinc , inorganic chemistry , aqueous solution , precipitation , solubility , cadmium nitrate , sodium , metal , sodium nitrate , stability constants of complexes , zinc nitrate , nuclear chemistry , equilibrium constant , organic chemistry , fire retardant , physics , meteorology
Sodium di‐( n ‐octyl) phosphinate (NaL) was used as a precipitating agent to remove heavy metals from aqueous nitrate solutions. Cadmium, zinc and mixtures of lead, cadmium and zinc were precipitated in the form of PbL 2(s) , CdL 2(s) , and ZnL 2(s) . Lowering the pH of the feed solution reduced the removal of the metals as some of the phosphinate precipitated in the acid form as HL (S) . The removal of lead, cadmium, and zinc, from a solution containing the three metals gave a selectivity in the order Zn > Pb > Cd. Predictions of an equilibrium‐constant model, using measured solubility products of the precipitates and literature values of stability constants, gave metal removals, loss of precipitating agent, and equilibrium pH in good agreement with measured values.