Recovery of Aniline from Wastewater by Solvent Extraction Enhanced with Salting-Out Effect

Nitrobenzene extraction enhanced by salting-out effect was employed to recover aniline from wastewater at 25°C. The batchwise experiments were conducted to elucidate the influence of various operating variables on the extracting performance, including acidity of wastewater, initial aniline concentration, ratios of solvent versus wastewater, extraction stages, concentrations and species of inorganic salts, such as NaCl, KCl, Na₂SO₄, CaCl₂ and K₂SO₄. High pH values and volume ratios of nitrobenzene/wastewater was more suitable for recovery of aniline. Besides, the recovery of aniline was significantly elevated with increasing concentrations of salts, whose promoting effects were in the following order: NaCl >Na₂SO₄ >K₂SO₄ > CaCl₂ >KCl on the weight basis of wastewater. It is remarkable that aniline in wastewater would be almost completely recovered by sequential five stages nitrobenzene extraction, promoted continuously by salting - out effect.