Emulsion Liquid Membrane Technology To Remove The Simulation Of Heavy Metal Lead In Wet-process Phosphoric Acid

With the changes in market demand and limit the resources,energy,environment and other factors to purified wet phosphoric acid and phosphate-based inorganic phosphate production technology will gradually replace the traditional thermal phosphoric acid and phosphate production technology.Emulsion liquid membrane（ELM）separation technology is a new technology.In this article,remove lead ions from the simulation of wet process phosphoric acid by using emulsion liquid membranes technique,providing technical support in the field of application for the wet process phosphoric acid technology.In this paper,the stability of ELM system had been discussed first.Some parameters were studied,such as the concertration of surfactant T154,P204,Lan-113,the ratio between the volume of oil phase and the volume of water phase（ROi）,stirring speed and time through experiments.We found the optimal parameters for the stability of emulsion liquid membrane.The optimal transfer conditions were given as follows:the suitable composition of Span-80 liquid membrane was Span-80:P204:Paraffin:Kerosene =5:5:1:89（volume ratio）,the volume ratio of oil phase to the internal phase（Roi）was 1:1,the concentration of HC1 in internal phase was 4.0 mol·L^-1,the rev of stirrer 2000 r·min^-1,the time of stirrer 30 min.The suitable composition of Lan-113 liquid membrane was Lan-113:P204:Paraffin:Kerosene =7:5:1:87,Roi was 1:1,the concentration of HCl in internal phase was 4.0 mol·L^-1,the rev of stirrer 2000 r·min^-1,and the time of stirrer 30 min.The suitable composition of T154 liquid membrane was T154:P204:Paraffin:Kerosene =6:5:1:88,Roi was 1:1,the concentration of HC1 in internal phase was 4.0 mol·L^-1,the rev of stirrer 2000 r·min^-1,the time of stirrer 30 min.In this case,the demulsification of ELM system liquefaction rate was low and it means the system was more stable.After that,the transfer behavior of Pb（Ⅱ）was studied using the ELM system of T154-P204-paraffin-kerosene.Various factors affecting the migration rate of metal ions were investigated.The optimal conditions were summarized as follows,T154:P204:Paraffin:Kerosene =6:5:1:88（v/v）,the extraction of stirrer 300 r·min^-1,the concentration of HCl in internal phase was 4.0 mol·L^-1 and extraction time was15 min.the volume ratio of emulsion to the water phase（Rew）was 1:2.In this case,the extraction rate of Pb（Ⅱ）from the simulation of wet process phosphoric acid was up to 96%.After that,the orthogonal experiment was made in this paper,according to range analysis,seven factors in primary and secondary order was:the concentration of T154>the volume ratio of oil phase to the internal phase>the time of stirrer>the rev of stirrer>the volume ratio of emulsion to the water phase>the concentration of P204>the internal phase.Excellent level of the concentration of T154 was 6%,the concentration of P204 was 5%,the concentration of paraffin was 1%,the concentration of kerosene was 88%.the extraction of stirrer 300 r min^-1.the volume ratio of oil phase to the internal phase（Roi）was 1:1,the volume ratio of emulsion to the water phase（Rew）was 1:1,the concentration of HCl in internal phase was 4.0 mol/L and extraction time was 15 min.In these case,the extraction rate of Pb（Ⅱ）from the simulation of wet process phosphoric acid was about to 97.3%At last,demulsification experiments were carried out by ways of ultrasonic emulsion breaking,heating emulsion breaking and ultrasonic-heating unite emulsion breaking.It can be seen from the experimental results that the effect of ultrasonic-heating unite emulsion breaking was better than the single emulsion breaking.The breaking rate of this emulsion was 95%.And the recovery of oil phase was reused in emulsification,the extraction rate of Pb（Ⅱ）from the simulation of wet process phosphoric acid is above 80%after using 3 times.