Hi there, 

SImply check the attached file (DOI: 10.1039/b906995j) , there are more details about your question.

With you success,

Dear Nour mahmoud EL-mahdy

Generally ,ILs are composed  by combination of large, usually asymmetric cation and smaller anion such as 1-butyl-3-imidazolium hexafluorophosphate.  you can prepared it  commercially from sigma aldrich company , or synthesized it based on attached manuscript link, (Phosphonium ionic liquids: design, synthesis and evaluation of biodegradability) . However, in ILs synthesis, purity of final product is very critical.

Good Luck

http://pubs.rsc.org/en/content/articlelanding/2009/gc/b913057h#!divAbstract

Hi,

You may buy Phosphonium Ionic Liquids at Alfa Chemistry.

https://www.alfa-chemistry.com/products/phosphonium-ionic-liquids-153.htm