Study On Separation Of Three Kinds Of Phenolic Compounds Through Supported Liquid Membrane Based On Ionic Liquids

Phenolic compounds are important industrial chemicals,which are widely used in manufacturing production. However,they are also prototype poisons which do toxic action to all the biont,make cell inactive and nervous system sick.Therefore the treatment of waste water containing phenolic compounds is a significant issue in the organic waste water treatment.Ionic liquids,an novel "green solvent",have special properties:good thermal stability,non volatile,nontoxic,noniflammable.A kind of imidazole hydrophobic ionic liquids 1-butyl-3-ethylimidazolium hexafluorophosphate([BEIM]+PF6-) was designed synthesised in this paper and the optimum synthesis conditions were esbalished.This kind of ionic liquids was used to take place of traditional organic solvents as membrane solvent in supported liquid membrane and the transport separation discipline of phenol,p-nitrophenol,2,4-dinitrophenol through supported liquid membrane based on ionic liquids(SILMs) was studied.The experimental results are as follows: 1 Synthesis of ionic liquids [BEIM]+PF6-The hydrophobic ionic liquids [BEIM]+PF6- was synthesised by microwave method, using n-bromobutane, N-ethelimidazolium, hexafluorophosphate as raw material.The optimum synthesis conditions were:the mole ratio of raw material n-bromobutane, N-ethelimidazolium, hexafluorophosphate was 1:1.2:1,T=95℃,t=4 min.The product synthesised in this experiment was proved to be ionic liquids [BEIM]+PF6- by IR to identify its structure,comparing with standard spectra. 2 The transport separation of three kinds of phenolic compounds through supported liquid membrane based on ionic liquids.The transport separation discipline of phenol,p-nitrophenol,2,4-dinitrophenol through a supported liquid membrane consisting of polyvinylidene fluoride membrane as the liquid membrane support and hydrophobic ionic liquids [BEIM]+PF6- as the membrane solution was studied.The transport separation experiment of phenol:the transport rate can be increased by reducing pH in feed phase,raising ionic strength in aqueous phase appropriately. The optimum transport separation conditions of phenol were:feed phase pH was 3.5,potassium sulfate as inorganic salt to adjust ionic strength to 0.2mol/L,the stripping solvent was sodium hydroxide with concentration of 0.2mol/L.Under these conditions,when initial concentration of phenol was 1.3×10-3mol/L,the transport rate of phenol was 79.4% at 120 min.The transport separation experiment of p-nitrophenol(p-NP):the transport rate can be increased by increasing pH in feed phase, ionic strength in aqueous phase, concentration of stripping solvent appropriately. The optimum transport separation conditions ofp-nitrophenol were:feed phase pH was 5.5, potassium sulfate as inorganic salt to adjust ionic strength to 0.25mol/L,the stripping solvent was sodium hydroxide with concentration of 0.15mol/L. Under these conditions, when initial concentration of phenol was 5.0×10-4mol/L,the transport rate was 64.2% at 120 min.The transport separation experiment of 2,4-dinitrophenol(DNP):the transport rate can be increased by increasing pH in feed phase,ionic strength in aqueous phase,concentration of stripping solvent appropriately. The optimum transport separation conditions of p-nitrophenol were:feed phase pH was 2.8,potassium sulfate as inorganic salt to adjust ionic strength to 0.2mol/L,the stripping solvent was sodium hydroxide with concentration of 0.15mol/L.Under these conditions, when initial concentration of phenol was 1.0×10-3mol/L,the transport rate was 71.6% at 120 min. 3 The transport process study of three kinds of phenolic compoundsThe equations related to permeation coefficient P of three kinds of phenolic compounds transporting through SILMs were established respectively.The transport process study of phenol:the equations withP-[H+],P-I,P-c of phenol, transporting through SILMs:PPh-OH=1.791×10-5(-lg[H+])-0.350,PPh-OH=1.262×10-5(I)-0.2037, PPh-OH=2.277×10-5cNaOH0.3205;and equation related to speed rate and concentration: vPh-OH=-1.3587c02+4.3603c0+0.0536.The transport process study ofp-nitrophenol:the equations withP-[H+],P-I of p-nitrophenol,transporting through SILMs:Pp-NP=2.783×10-6 (-lg[H+])0.115, Pp-NP=5.004×10-9(I)-4.647;and equation related to speed rate and concentration: Vp-NP=-0.0112c2+0.1121c+1.6805The transport process study of 2,4-dinitrophenol:the equations with P-[H+],P-I,P-c of 2,4-dinitrophenol,transporting through SILMs: PDNP=-0.0306(-lg[H+])2+0.191(-lg[H+])+4.6055,PDNP=3.4911(I)-0.1593, PDNP=3.2631cNaOH-0.2018...