In this work, the reactive extraction equilibrium of p-nitrophenol (PNP) using tributylphosphate (TBP) dissolved in solvent naphtha and noctanol has been studied, respectively. The effects of equilibrium pH (pH eq ), initial TBP, and PNP concentrations on the distribution ratio (D) and the degree of extraction were discussed. The TBP/solvent naphtha showed higher D values than that of TBP/n-octanol. The larger D values were also observed at pH eq in the range of 2−5.5. pH eq had negligible influences on the structure of TBP/PNP complexes based on IR spectra analysis. TBP mainly reacted with the neutral form of PNP by forming 1:1 (TBP/PNP) complexes through a hydrogen bond between phosphoryl in TBP and hydroxyl in PNP. The model parameters were calculated by fitting the experimental data. D values calculated from the model were in good agreement with experimental ones. In addition, the back-extraction rate was found to be reached 99.9% using 50 mmol•kg −1 NaOH as stripping agent.

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