Extraction of Phenols from Water with Functionalized Ionic Liquids

Abstract

A series of hydroxyl-, benzyl-, and dialkyl-functionalized ionic liquids (ILs) were synthesized, and their extraction abilities for phenol, resorcinol, p-nitrophenol, guaiacol, and o-cresol were investigated. Results showed that the extraction efficiencies of the five phenols were significantly influenced by the pH values, salt added, phase ratio, and chemical structure of the IL. Phenols present in nonionized forms were preferable to transfer into IL phases. The anion/cation hydrogen-bonding characters of ILs were the main structural factors affecting the extraction efficiency, which also increased with increased hydrophobicity of phenols. These results are promising for the liquid−liquid extraction and enrichment of phenols in separation science and related industrial processes.

Removal of Rhodamine B from Water by Benzyl‐Functionalized Ionic Liquids

“…The P ow values of ILs used in this work were measured per the methods already reported [25,29]. Typically, the solutions of ILs (7.1 Â 10 À4 mol L À1 for each) were prepared with water saturated by octanol; 10 mL of the solution of a specific IL and 10 mL of octanol saturated with water were mixed under stirring for 30 min at 298 K. After phase separation by centrifugation, both the octanol and water phases were injected into the HPLC system.…”

“…It is well known that the water solubility of an IL with bis(trifluoromethylsulfonyl)imide anion (NTf 2 À ) is much lower than its BF 4 À and PF 6 À counterparts [25,27]. Additionally, the p-p stacking between ILs and aromatic compounds also contributes to efficient extraction [25,28].…”

“…It is well known that the water solubility of an IL with bis(trifluoromethylsulfonyl)imide anion (NTf 2 À ) is much lower than its BF 4 À and PF 6 À counterparts [25,27]. Additionally, the p-p stacking between ILs and aromatic compounds also contributes to efficient extraction [25,28]. Since rhodamine B has a large p conjugated planar structure, the incorporation of benzyl group into the IL cation maybe reinforce the p-p stacking between IL and rhodamine B and thus enhances the extraction efficiency.…”

“…The aims of this work were therefore to investigate whether the benzylfunctionalized ILs can improve the removal efficiency of rhodamine B as compared to the dialkylimidazolium-based ones and to dispose of the ILs after extraction. 4 Bzim]PF 6 ), and 1-butyl-3benzylimidazolium bis(trifluoromethylsulfonyl)imide ([C 4 Bzim] NTf 2 ) were synthesized as described previously [25]. All of the other chemicals were of analytical grade unless stated otherwise.…”

Effect of 1‐ethyl‐3‐methylimidazolium acetate on the oxidation of caffeic acid benzyl ester: An electrochemical and theoretical study

“…Because of their unique characteristics, ILs are applied in synthesis, [2,3] catalysis and extraction processes. [4,5] The use of ILs in the extraction of value-added compounds from natural sources has attracted the attention of several research groups. [6][7][8] For example, since ILs can dissolve cellulose, they allow an easier access to a wide range of bioactive compounds present in plants such as terpenes, alkaloids, fats, and phenolic compounds.…”