Final Report Summary - ILMC (Preparation of ionic liquid microcapsule membranes loaded and their application in NMVOCs removal)
Literature survey was made to choose suitable ionic liquids (ILs), polymer shell material and solvents and a detailed report coined especially for volatile organic compounds (VOCs) removal using IL combined with membrane technology. ILs selected through preliminary investigation confirmed by COSMO analysis. From this analysis the optimal ILs to be used for our application (considering also the need of low miscibility IL in water) are the imidazolium pyridinium and phosphonium. Liquid-liquid extraction experiments of aromatic compound using this type of ILs were performed to evaluate their extraction capability. Polymeric microcapsules (MCs) were prepared with different polymers viz polyethersulfone (PES), polysulfone (PSF) and polyetheretherketone with card group (Peekwc) with and without ILs using conventional Non-Induced phase inversion (NIPS) combined with membrane process. Further improvement is made to increase the porous nature of MCs by adding polyvinylpyrrolidone PVPK17, as pore former, in the polymeric feed solution. Using the NIPS technique, microspheres were successfully prepared with IL (ILMCs) and pore former PVPK17 in the size range 900-1200 µm. ILMCs prepared with different ILs Imidazolium, pyridinium and phosphonium with different anions groups were utilised for the ILMCs preparation ([BMIM][PF6], [HMIM][PF6], [Hpy][PF6], Cyphosl IL 101,104,105,109 and [Deaebim] [TF2N], [APBIM] [TF2N], [Dmapbim] [TF2N]). Next step was to reduce the size of the ILMCs from 900 µm to less than 100 µm. membrane emulsification (ME) technique was applied for the size reduction of MCs and novel ILMCs were produced in the range of 20-50 µm. At a single stage operation emulsification and phase inversion process was achieved by ME technique, for the first time in literature, by suitably choosing the continuous phase. The optimal conditions for the preparation of ILMCs using ME, using a hydrophobic metallic membrane 5 µm pore size, are: 10wt % Peekwc/Cyphos IL 101, Paraffin, Dodecane, SY-Glyster PO-5S as a continuous phase. The stirring setup used was set to 5V shear stress with a 0.3 ml/min of flow rate. MCs and ILMCs were characterised in detail using analytical tools to confirm the smoothness, spherical and homogenous nature and loading of ionic liquid (scanning electron microscope (SEM), infrared (IR), thermogravimetric analysis (TGA), RAMAN). Preparation of glutaraldehyde (GA) cross-linked polyvinyl alcohol (PVA) flat sheet membrane to be used as membrane matrix to impregnate novel Ionic Liquid encapsulated microcapsules was also carried out. Characterisation of PVA-GA membranes were performed by conventional analytical tools. Then, flat sheet membrane of PVA containing ILMCs and flat sheet polymeric ionic liquid membranes prepared by phase inversion technique, using PES/ [BMIM][PF6]/PVPK17/DMSO polymer dope, were produced and characterised. The novel IL microcapsules were successfully evaluated and applied to different fields such as, VOCs removal from aqueous phase, scale control in petroleum chemistry, dye removal in textile effluent, phenolic content recovery from water olive mill waste, radioactive effluent treatment and green house gas emission control process. It is worth to mention the application of ILMCs in NMVOC (aromatic) removal from aqueous streams through adsorption process was performed in particular using toluene as target species to be removed from water. The most promising results were obtained by ILMCs using Cyphos IL 109 (10wt %) loaded in Peekwc (10wt %). Toluene adsorption percentage of about 50 % was obtained after two hours of stirring in batch. However, interesting results have been also detected using the polymer microspheres itself. Then, in another water treatment application, novel flat sheet IL and ILMCs membranes were tested for remazol blue 19 adsorption from aqueous streams. Maximum adsorption capacity (60 %) were found for PES/[BMIM][PF6]/PVPK17/DMSO membranes compared to PES/[BMIM][PF6]/PVPK17/DMF microcapsules (35 %).