Experimental determination of solubilities of lead oxalate (PbC2O4(cr)) in a NaCl medium to high ionic strengths, and the importance of lead oxalate in low temperature environments

In this study, the solubility product constant (log10 Kso) for crystalline lead oxalate (PbC2O4(cr)) pertaining to Reaction (I), and the formation constant of PbC2O4(aq) (log10 β1o) pertaining to Reaction (II),(I) PbC 2 O 4 cr = Pb 2 + + C 2 O 4 2 – (II) Pb 2 + + C 2 O 4 2 – = PbC 2 O 4 aq at infinite dilution, 298.15 K and 0.1 MPa, are determined as − 11.13 ± 0.15 (2σ) and 5.85 ± 0.10 (2σ), respectively, based on solubility data for PbC2O4(cr) in NaCl solutions up to 3.2 mol·kg− 1 (molal) evaluated using the Pitzer model. The above solubility product constant determined in this study is lower than the value of − 10.27 ± 0.30 (2σ) for log10 Kso evaluated from the literature data. The above log10 β1o agrees within the quoted uncertainties with the value of 5.44 ± 0.38 (2σ) derived in this study based on the literature data using the Brønsted–Guggenheim–Scatchard specific interaction theory (SIT) model. ition, based on solubility data for PbC2O4(cr) in NaCl solutions with 4.4 and 5.0 mol·kg− 1 produced in this work and in a K2C2O4 medium up to 0.51 mol·kg− 1 at 298.15 ± 2 K from the literature, this study also evaluates log10 β2o for the following reaction by using the Pitzer model,(III) Pb 2 + + 2 C 2 O 4 2 – = Pb C 2 O 4 2 2 – as 8.05 ± 0.15 (2σ). w parameters presented in this study would enable researchers to accurately predict solubilities of PbC2O4(cr) to high ionic strengths, up to 5.0 mol·kg− 1.