Thiophosphinic extractant as sustainable carrier for microemulsions surfactant membrane facilitating Se(IV) permeation from acidic aqueous solution

Elimination of hazardous materials with emerging technologies like microemulsions surfactant membrane (MLSM) demonstrates a sustainable approach to environmental policies. This study utilizes Di-(2,4,4-trimethylpentyl) dithiophosphinic acid extractant (Cyanex 301) to prepare an efficient MLSM for the extraction of Selenium (IV) (Se(IV)) ions from a nitric acid medium in a single process (extraction-stripping). Batch liquid-liquid extraction results showed a 65% extraction efficiency for 1.26 × 10^⁻3M Se(IV) from 2 M HNO₃ within 30 min, using 0.02 M Cyanex 301 as the carrier/cyclohexane. The predominant species in nitric acid is SeO₃^2- and the mean value for extraction constant (k_ex) for Se(IV) extraction is (16.6 ± 0.5) × 10³ M^-2, obtained at various CY-301 concentrations. The highest stripping efficiency of 70% was achieved with a 0.5 M Na-dithionite solution. The MLSM-301 was synthesized using Cyanex 301/cyclohexane as organic phase, and Span 80 as the emulsifying agent, at a homogenizing speed of 13,500 rpm. The final membrane exhibited an average particle size of 6.8619 μm and a permeation efficiency of 90% for Selenium (IV) across MLSM-301 globules. The MLSM-301 demonstrated varying removal efficiencies for interacting ions in the order: Se > Te > Bi > Cu > Fe(III) under the given experimental conditions.