Extraction of oxalic acid

propandioic acid

succinic acid

maleic acid and malic acid with trialkylphosphine oxide(TRPO) dissolved in 1-octanol was studied.The experimental results showed that the complexing extraction equilibrium constants were dependent on pKa1 and hydrophobicity of the organic acids. By Fourier transform infrared spectroscopic (FTIR) analysis

it was found that the extraction process was mainly governed by hydrogen bonding solvation. There is hydrogen bonding between TRPO and 1-octanol

which retards the extraction process.A 1∶1 complex between TRPO and organic acids was formed according to mass action law

and a general expression of experimentally accessible extraction loading on the molar concentration scale was developed. Extraction equilibrium constants were obtained by correlating experimental data with the least square method. The calculated loading and organic acid concentrations were in good agreement with the experimental ones.