introduction of a new polymer inclusion membrane based upon mixed cellulose triacetate/poly vinylidene fluoride-co-hexafluoropropylene polymers and trioctylamine extractant for the extraction of bi(iii) from chloride solutions

In the present study, initally several types of blend polymer inclusion membranes including cta, pvdf, pvc and pvdf-hfp polymers containing tri octylamaine (toa) extractant as well as nitrophenyl octyl ether (npoe), dibutyl phthalate (dbp), tris(2-ethylhexyl) phosphate (tehp), diorctyl phthalate (dop) and tributyl phosphate (tbp) as plasticizer were prepared in different weight ratios. a membrane with 30 wt% of polymer cta, 35 wt% by weight of polymer pvdf-hfp, 25 wt% of extractant toa and 10 wt% of modifier tbp with suitable physical, mechanical and extraction properties was selected as the optimal membrane. the physical and mechanical properties of this membrane were investigated by measuring the contact angle, studying the elastic properties scanning electron microscopy, atomic force microscopy and thermogravimetric analysis [1, 2]. the studied membrane was capable of complete and selective extraction of bi(iii) ions from 50 ml of solution containing 20 mg.l-1 bismuth ion in 0.3 mol.l-1 hydrochloric acid solution for 120 minutes. by studying the stoichiometry of the extracted species, the mechanism of ion pair formation (toah+)2 (bicl52-) was confirmed. complete back extraction of the extracted ions was performed using a combination of 0.4 mol l-1 sodium carbonate and 0.1 mol l-1 ethylene diamine tetra acetic acid. the prepared membrane can be used for four continuous extraction and back extraction steps without reducing the efficiency. kinetic and isothermal studies of the extraction process were investigated and the results of these studies showed that the extraction data were well consistent with the quasi-second order model and proved the chemical adsorption of bismuth ions [2].