Gemini-Type Amphiphilic Ionic Liquid Based Self-assembled System For Extraction Of Au From HCI Medium

In this paper,the gemini surfactant will be combined with ionic liquid to construct the self-assembled system?W/O microemulsioin,reverse vesicles' and vesicles?for the extraction of Au???from hydrochloric acid medium in view of the problems in gold recovery,such as low content,difficulty in separating and the un-sufficient reprocessing.The microstructure and surface property of self-assembled system were characterized by conductivity,TSI values,zeta potential and TEM images and so on.The mechanism of extraction by three self-assembled system?W/O microemulsion,reverse vesicles and vesicles?was confirmed by the various methods?UV-vis,FT-IR,1H NMR,method of slope and job,zeta potential?.Main influence factors such as phase ratio,extraction equilibrium time,the concentration of ionic liquid on the extraction efficiency?E%?were explored.In the study,various methods have been employed for the stripping of gold.The investigation of extraction performance and structure-function relationship can provide a valid foundation for the Au industrialization extraction such as process design,equipment selection and condition optimization.First,a microemulsion with hydrochloric acid solution as the polar phase,n-heptane as the continuous phase,[C₁₄-4-C₁₄im]Br₂ as an ionic-liquid type imidazolium gemini surfactant and extractant,and n-amyl alcohol as cosurfactant was studied on Au???extractioa Compared to its corresponding monomer[C₁₄-mim]Br-based microemulsion for Au???extraction,the[C₁₄-4-C₁₄im]Br₂-based microemulsion system showed excellent extractability of Au???.The anion-exchange mechanism of Au?III?extraction was confirmed by the slope method and spectrum analysis?UV-vis,FT-IR and 1H NMR?.Main influence factors such as phase ratio,extraction equilibrium time,amylalcohol volume fraction and the concentration of ionic liquid on the extraction efficiency?E%?were explored.Moreover,[C₁₄-4-C₁₄im]Br₂-based water-in-oil microemulsion had high selectivity over a multimetal ion solution(Co?II?,Cu???,Fe???,Ni???,Sn???and Al???.Therefore,it is indicated that[C₁₄-4-C₁₄im]Br₂-based microemulsion provides an effective and potential approach for the separation and purification of Au???from HCl solution.Second,reverse vesicles were fabricated by self-assembly complexes of cationic gemini surfactants?12-2-12?and four anionic surfactants in chloroform phase.Reverse vesicles solution with bluish tinge exhibited opalescence appearance and TEM images confirmed that the spherical microstructure was enclosed by amphiphiles membrane.Then,modified method of continuous variation was emnployed to investigate the complexation of the extracted Au???by the self assembly system and the anion-exchange mechanism of Au???extraction was confirmed.In appropriate extraction conditions,the vesicles system showed excellent extractability of Au???.In addition,the reverse vesicles show a high selectivity for Au???over base metals ions(Co???,Cu???,Fe???,Ni???,Sn?IV?and Al???.The reducibility of extractants itself was employed to the striping of gold and satisfactory results were achieved.It can be rationally envisioned that sophisticated gold extraction may be achieved when reverse vesicles are rationally utilized.Last,a kind of self-assembled vesicles that composed of ionic liquid-type cationic gemini surfactant?12-3-12?and anionic biological surfactant?sodium deoxycholate,SDC?were constructed for Au???extraction.The appearance and microstructure of vesicles system were characterized by visual and TEM images.Compared to the zeta potential of pure vesicles system?+45±1 mV?,zeta potential of gold-loaded vesicles system reduced 15±1 mv?changed to +30± 1 mV?,which confirmed the mechanism of Au???was effectively extracted by vesicles through electrostatic interaction.The main influence factors including extraction equilibrium time,surfactants concentration,NaCl concentration,and pH on the extraction efficiency?E%?were explored.Furthermore,an effective method was devoted for Au?III?stripping.Through stepwise extraction and ligand-modified vesicles system,Au???,Cu???and Fe???were separated from a mixed solution successfully.In short,an effective and potential approach for the separation of Au?III?from HC1 solution was investigated in our work,which can be helpful for gold recovery and environmental improvement.