Synthesis of 1,4-Bis(chloromethyl)benzene Crosslinked Poly(vinyl imidazolium) and Its Adsorptivity for Phenol from Coal Tar†

Abstract

A new poly ionic liquid( PIL) type adsorbent, poly( vinyl-benzyl-imidazolium) chloride( P[VBnim]Cl) was prepared facilely with overall yield above 75% through free radical polymerization of1-vinylimidazole at 70 ℃ and cross-linking of the resulting polymer with 1,4-bis( chloromethyl) benzene via quaternization reaction in dimethylformamide( DMF) solvent. The as-prepared PIL was analyzed and characterized with respect to composition,structure,morphology and thermal stability by elemental analysis,gel permeation chromatography( GPC),Fourier transform infrared spectroscopy( FTIR),scanning electron microscope( SEM),physical absorption instrument and thermal gravimetric analysis /differential scanning calorimetry( TGA /DSC) technique. The molar ratio of 1,4-bis( chloromethyl) benzene to 1-vinylimidazole is about1∶ 3 in P[VBnim]Cl. The P[VBnim]Cl is a beige and fluffy fine powder with primary particle size of 50—80nm,being mesoporous material with specific surface area 13. 86 m2/g and average pore size 9. 94 nm. The PIL exhibits good thermal stability with its initial decomposition temperature being about 274 ℃. Adsorptivity for phenol from the model oil of low temperature coal tar was also studied. The P[VBnim]Cl was proved as an excellent adsorbent,being 2 to 10 times superior to the conventional active carbon at fixed other conditions.The excellent adsorptive property is mainly attributed to the chemical adsorption of the IL constituents at dilute phenol concentrations as well as the physical adsorption at higher phenol concentrations due to the porous architecture of P[VBnim]Cl. The used P[VBnim]Cl adsorbent can be regenerated easily with ethyl acetate,and used repeatedly with good adsorptivity.