Extraction of neodymium from nitric acid feed solutions using an emulsion liquid membrane containing TOPO and DNPPA as the carrier extractants

• Nd extraction by emulsion liquid membrane was studied.
• DNPPA and TOPO mixture was used.
• The extraction, demulsification and swelling aspects were studied.
• The ELM method can be used for Nd recovery from acidic feeds.

The transport of Nd(III) from nitric acid medium across emulsion liquid membrane (ELM) using di-nonyl phenyl phosphoric acid (DNPPA) as the carrier extractant and Span 80 (sorbitol monoleate) as the surfactant in Petrofin as the diluent and sulphuric acid as the internal phase has been systematically investigated. The effect of different physical and chemical parameters such as stirring speed, neodymium concentration, external phase nitric acid concentration, extractant concentration, external to internal phase volume ratio, stripping agent concentration has been investigated on the extraction of Nd(III). The synergistic extraction of the metal ion has also been studied using mixtures of DNPPA and tri-n-octylphenyl phosphine oxide (TOPO) as the carrier extractants in the ELM. Quantitative extraction (>97%) of Nd(III) was observed with 0.3 M DNPPA + 0.13 M TOPO and 1% (v/v) Span 80 liquid membrane at external to internal phase volume ratio of 10 for a feed having 500 mg/L Nd(III) at 0.5 M nitric acid concentration. The mechanism of extraction of Nd(III) has also been discussed in the light of the results obtained.