NISCAIR Online Periodicals Repository Collection: IJC-A Vol.49A(05-06) [May-June 2010]

An unusal effect of charcoal on the purification of alkylimidazolium iodide room temperature ionic liquids

Sat, 29 May 2010 22:58:59 GMT

Title: An unusal effect of charcoal on the purification of alkylimidazolium iodide room temperature ionic liquids

Authors: Srivastava, Nitin; Shukla, Madhulata; Saha, Satyen

Abstract: Activated charcoal, commonly used for purification of ionic liquids is found, for the first time, to severely contaminate 1-butyl 3-methyl imidazolium iodide with iodine species during the conventional purification process. Surprisingly, the contaminants which includes I, reduces the viscosity of the ionic liquid considerably as compared to externally added molecular iodine, making it extremely promising for electrochemical applications.

Page(s): 757-761

Studies on interaction of ionic liquids with cyclodextrins in aqueous solution

Sat, 29 May 2010 22:58:59 GMT

Title: Studies on interaction of ionic liquids with cyclodextrins in aqueous solution

Authors: Li, Hong-Gang; Zhang, Qian; Zhao, Qiang; Liu, Min; Liu, Jie; Sun, De-Zhi

Abstract: Interactions between -, -, -CDs and two ionic liquids, 1-butyl-3-methylimidazolium tetrafluroborate ([bmim][BF₄]) and 1-octyl-3-methylimidazolium tetrafluroborate ([omim][BF₄]), have been studied with titration microcalorimetry and UV and NMR spectra at 298.15 K. The results are discussed in terms of the hydrophobic interaction of CD molecular cavity with alkyl chain of IL cation and the change in iceberg structure formed by water molecules existing around the hydrophobic tail of the ionic liquids. The stoichiometry of CDs with the two ionic liquids is 1:1 and 1:2 except that of -CD with [omim][BF₄], which is only 1:1. The binding process of -CD with both the ionic liquids is entropy driven, while that of -CD and -CD with the ionic liquids is characterized by both enthalpy favorable and entropy favorable processes. The ¹H NMR spectra reveal that chemical shift data of all protons in -CD, -CD and -CD molecules move to high field in the presence of ionic liquids. UV absorbance for the CD-IL systems has been detected, which indicates that the inclusion complex is formed through weak interaction.

Page(s): 752-756

Ionic liquid incorporated polymer electrolytes for supercapacitor application

Sat, 29 May 2010 22:58:59 GMT

Title: Ionic liquid incorporated polymer electrolytes for supercapacitor application

Authors: Pandey, G P; Kumar, Yogesh; Hashmi, S A

Abstract: Recent advances in the study of ionic liquids based gel polymer electrolytes have been briefly reviewed in view of their electrochemical applications, particularly, their application as electrolytes in supercapacitors. The incorporation of ionic liquids in gel polymer electrolytes, instead of organic solvents like propylene carbonate, ethylene carbonate, etc., provide added effect in terms of their thermal, electrical and electrochemical stabilities. Recent studies on poly(ethylene oxide) based polymer electrolyte plasticized with ionic liquid and ionic liquid incorporated poly(vinylidene fluoride- co-hexafluoropropylene) based gel polymer electrolytes have been summarized. A special description has been given of supercapacitors (electrical double layer capacitors), studied in our laboratory, based on multiwalled carbon nanotubes, activated charcoal powder electrodes and optimized gel/polymer electrolytes. Comparative studies indicate that PVdF-HFP based gels are superior electrolytes to develop electrical double layers capacitors (in terms of higher capacitances and lower resistive values) over PEO based plasticized polymer electrolytes.

Page(s): 743-751

Density and ultrasonic sound speed measurements for N,N-dimethylformamide with ionic liquids

Sat, 29 May 2010 22:58:59 GMT

Title: Density and ultrasonic sound speed measurements for N,N-dimethylformamide with ionic liquids

Authors: Attri, Pankaj; Reddy, P Madhusudhan; Venkatesu, P

Abstract: To understand the molecular interactions between N,N-dimethylformamide with two families of ionic liquids, the thermophysical properties such as densities and ultrasonic sound speeds have been measured over the entire composition range at 25 ^oC under atmospheric pressure. The materials investigated in the present study include two families of ionic liquids, viz., ammonium salts and imidazolium salts. Diethyl ammonium acetate, triethyl ammonium acetate, triethyl ammonium dihydrogen phosphate and triethyl ammonium sulphate are the ammonium salts while 1-benzyl-3-methylimidazolium chloride belongs to the imidazolium family. The intermolecular interactions and structural effects are analyzed on the basis of the measured and derived properties. A qualitative analysis of the results are discussed in terms of the ion-dipole interactions, ion-pair interactions and hydrogen bonding between the ionic liquids and N,N-dimethylformamide molecules.

Page(s): 736-742