Application of emulsion liquid membrane for the extraction of diclofenac and relationship with the stability of water-in-Oil emulsions

Abstract

In this work, Diclofenac (DCF) was removed from its aqueous solution using emulsion liquid membrane (ELM) prepared using n-heptane as an organic solvent, different types of carrier (Tri- n-octylamine, Tri- n-butylphosphate and Di-2-ethylhexyl phosphoric acid (D2EHPA) and mixed surfactant systems at different HLB (Hydrophilic Lipophilic Balance) values. Different stripping phases (NaOH, H₂SO₄, HCl, and HNO₃) were tested to study the stripping capacity. Effect of process parameters such as types of carrier, types and concentration of stripping phase, speed of homogenizer to prepare water in oil (w/o) emulsion and composition of surfactant mixture based on HLB value on the stability of w/o emulsion as well as on the extraction efficiency were examined. It was found that maximum extraction (< 95%) obtained with D2EHPA (2.0%w/v), 9500 rpm speed of homogenizer, mixed surfactant of HLB 6 (2.0%w/v) to give stable w/o emulsion and HNO₃ (0.001 M) as a stripping phase. The result obtained on w/o stability showed that the emulsion prepared with the mixed surfactant of HLB 6 was found to be stable up to 30 min which was due to formation of smallest droplet size of water in oil. On increasing the HLB value above 6 the droplets' size started increasing due to the inversion of stable w/o emulsion into unstable o/w emulsion.

Graphical Abstract

Highlights

• Potential of Emulsion Liquid Membrane (ELM) for the extraction of Diclofenac (DCF) from aqueous solutions was studied.

• Di-2-ethylhexyl phosphoric acid (D2EHPA), an acidic carrier was found to be the most suitable extractant in membrane phase for the extraction of DCF.

• Nitric acid was found to be the most efficient stripping reagent to strip DCF from the membrane phase.

• Hydrophilic-lipophilic balance was having a significant effect on the stability of ELM during the extraction process.

Keywords:

• Diclofenac
• emulsion liquid membrane
• HLB value
• stability