Synthesis And Characterization Of Molecular Imprinting Polymer Microspheres For Selective Adsorption Of Syringaldehyde
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Date
2015-11
Authors
Balakrishnan, RB Sriprasanthi
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
The syringaldehyde based molecularly imprinted polymeric microspheres (MIP) were synthesized using distillation-precipitation polymerization technique, and their physico-chemical nature, specific recognition, adsorption and binding behaviours were investigated in the present thesis. Initially, the monomer for the MIP microspheres (syringaldehyde metacrylate) was synthesized and characterized using Fourier-Transform Infrared (FT-IR), 13C and 1H Nuclear Magnetic Resonance (NMR) technique for compound structural verification and its purity. Subsequently, the monomer was reacted with two different types of cross-linkers: ethylene glycol dimethyacrylate (EGDMA) and divinyl benzene (DVB) using acetonitrile as the solvent and azobisisobutyronitrile (AIBN) as initiator. The controlable variables such as duration of polymerization, ratio of cross-linker to monomer, types of cross-linkers and solvent volume were also investigated. FT-IR, Scanning Electronic Microscope (SEM) and Atomic Force Microscope (AFM) analysis were carried out to study the physico-chemical and structural properties of the MIP spheres. The binding capacity and the affinity of the synthesized MIPs were determined using the HPLC method. The chemical potential for adsorption and binding capacity of the MIP spheres were also investigated using Freundlich-Langmuir adsorption isotherms. The resultant MIP were found to be spherical with the size of 1.4-1.7 μm after 24 hours of polymerization. The polymer yield obtained for SDM-2 was 80.1% whereas for SDV-3 was 78.6%. These polymeric microspheres exhibited affinity and selectivity towards syringaldehyde when tested with a mixture of its analogues, vanillin and p-hydroxybenzaldehyde. The ratio of the cross linkers against monomer as well as volume of solvent greatly influenced the particle size and binding behaviour. The adsorption of non-imprinting polymers was found to be less than 5 μmol/g while the imprinting polymers showed about 80% adsorption at 40 ˚C for syringaldehyde. The chemical potential for adsorption of syringaldehyde is -22.69 kJ/mol, which is very high, in comparison to vanillin and p-hydroxybenzaldehyde for the SDM-2 imprinting polymer.
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Keywords
Molecular Imprinting