Preperation Of Poly (Ionic Liquids) And Their Adsorptivity For Phenol From Coal Tar

Poly (ionic liquids)(PILs) is a special type of polyelectrolytes with ionic liquids (ILs) entities or ILs repeating units, and is becoming a research frontier in polymer chemistry and material science. In recent years, the unique properties of ILs has been used to various fields of chemistry, but their disadvantages have also been exposed at the same time, such as high viscosity, the designing limitation as liquid and potential environmental risks, etc. The appearance of PILs is expected to remove the bottlenecks of ionic liquids in practical applications. PILs combine the unique properties of ionic liquids and macromolecular architectures, providing novel functions in a multitude of applications.In this paper, five types of PILs have been prepared by using different synthetic methods, including hexamine group based PIL, vinylimidazolium based PIL, quaternary phosphonium based PIL, and PIL complex between PIL and multi-valent organic acids. The as-prepared PILs were analyzed and characterized with respect to composition, structure, morphology and thermal stability. The results indicate that the as-prepared PILs are all fluffy powders, several of which contain plentiful porosity. All the as-prepared PILs except hexamine group based PIL exhibit good thermal stability with their initial decomposition temperatures being about250℃300℃. This study preliminarily explores the preparation of PILs solid material, and lays foundation of the subsequent preparation of mesoporous PILs.Low-temperature coal tar contains rich phenolic compounds, the separation and recovery of phenolic compounds is of great importance for the efficient use of coal tars.In this paper, we studied the phenol adsorptivity of the as-prepared PILs which contains Cl-as anion for the model oil of low temperature coal tar. The PILs are proved as an excellent adsorbent, being several to dozens of times superior to the conventional active carbon at fixed other conditions. The excellent phenol adsorptivity of PILs is mainly attributed to the chemical adsorption mechanism, such as hydrogen bonding between Cl" in PILs and-OH in phenol, strong acid-base complexation between quaternary amine N and phenol, formation of eutectic liquid mixture between some PILs and phenol, and the resulting extraction effect, as well as the physical adsorption effect from porous structure of PIL. The effects of adsorption time, mass ratio between adsorbent and model oil, and adsorption temperature on adsorption efficiency are studied. We also compare the adsorption properties of the adsorbents through adsorptive isotherms, and analyze the adsorption mechanism in terms of interaction between adsorbents and phenol.