Ultrasound-assisted preparation of emulsion and its application in 1-naphthol wastewater treatment

Abstract

A stable emulsion with NaOH as the inner phase, sorbitan monooleate (span80) as the surfactant, and kerosene, cyclohexane, n-heptane, methylbenzene or p-xylene as the organic membrane phase, was prepared successfully by a magnetic stirring apparatus at low stirring speed (720rev min⁻¹) to make the pre-emulsion and then using the ultra-sonication devices. The separation efficiency in emulsion liquid membrane system to remove 1-naphthol was investigated. The parameters that affect the removal efficiency of 1-naphthol were studied systematically. At the optimal conditions, cyclohexane as the solvent phase, 2% NaOH as the inner phase, ultrasound time 5 minutes, the ratio of oil to inner phase 1:2, pH of feed phase without adjusted (pH = 6·4), contact time 15 minutes, ratio of emulsion to water 1:5, 1-naphthol removal can nearly reach 98% with a low level of 1·14% of emulsion leakage at 20 minutes.

Keywords:

• 1-naphthol
• Emulsion liquid membrane
• Ultrasound
• Emulsion leakage
• Sorbitan monooleate