pertraction of mo(vi) through a ternary polymer inclusion membrane composed of cellulose triacetate/trioctyl amine/tributyl phosphare

Even though slm-based separation technique is an attractive alternative to conventional solvent extraction, these membranes suffer from poor stability. however, another type of liquid membranes called polymer inclusion membranes (pims) are known to be more stable than slms [1]. beside the wide application of these membranes in separation studies, they have been shown to be very useful technique in analytical chemistry scopes [2]. in this communication, the potential of a tributyl phosphate (tbp) plasticized polymer inclusion membrane (pim) including cellulose triacetate (cta) base polymer and trioctylamine (toa) as extractant has been appraised in the transport of molybdenum(vi) from sulfate solution, for the first time. the optimized membrane comprised of 40/25/35 wt% of cta, toa and tbp, respectively. it was transparent, flexible, homogenous, and mechanically stable. the optimized pim has been employed in a two compartment pertraction cell for the transport-separation of mo(vi) from acidic sulfate feed solution into the sodium hydrogen carbonate receiving phase. under the optimized conditions (feed phase: ph 1.4, 0.2 m na2so4; receiving phase: 1.14 m nahco3; stirring rate 650 rpm) a quantitative transport of mo(vi) (initial concentration 20 mg l-1) from the feed phase into the receiving phase has been achieved, after 24 h. it is reported that the main mo(vi) species under the optimized feed phase conditions is h2moo4 [3]. thus, the reactions at the first and second interfaces can be respectively considered as those represented in eqs. 1 and 2:h2moo4,aq + toapim [toah+][hmoo4-]pim(1)[toah+][hmoo4-]pim + 2nahco3,aq 2na+aq + moo42-aq + toapim + 2h2o + 2co2 (2)the highest permeability coefficient and initial flux of mo(vi) were 5.9×10-6 m s-1 and 1.24×10-6 mol m-2 s-1. the excellent selectivity demonstrated by the proposed system towards mo(vi) in the presence of zn(ii), co(ii), ni(ii), cd(ii), cr(iii), al(iii), cu(ii), bi(iii), fe(iii), and v(v) species allowed considering the developed pim for the recovery of mo(vi) from spent catalysts used in hydrodesulphurization process in petroleum industries [4].