Electropolishing of Stainless Steels in a Choline Chloride Based Ionic Liquid: An Electrochemical Study With Surface Characterisation Using SEM and Atomic Force Microscopy

We have studied the anodic dissolution (electropolishing) of various stainless steel alloys in an ionic liquid comprising a 2 : 1 stoichiometric mix of ethylene glycol (EG) and choline chloride. We have used a combination of electrochemical and spectroscopic methods together with in situ liquid probe microscopy. We discuss the role and influence of the surface oxide passivation layer, characterized here by X-ray photoelectron spectroscopy (XPS) and linear sweep voltammetry, on the polishing process. We address the question of dealloying during the polish in order to contribute to our understanding of the viability of the ionic liquid as a replacement industrial electropolishing medium; the current commercial process uses a corrosive mixture of phosphoric and sulfuric acids. Also, we present data from ex situ and in situ liquid AFM studies giving both a qualitative and quantitative insight into the nature and scale of morphological changes at the steel surface during the polishing process

Deep Eutectic Solvents Formed between Choline Chloride and Carboxylic Acids: Versatile Alternatives to Ionic Liquids

Deep Eutectic Solvents (DES) can be formed between a variety of quaternary ammonium salts and carboxylic acids. The physical properties are significantly affected by the structure of the carboxylic acid but the phase behavior of the mixtures can be simply modeled by taking account of the mole fraction of carboxylic acid in the mixture. The physical properties such as viscosity, conductivity, and surface tension of these DES are similar to ambient temperature ionic liquids and insight into the cause of these properties is gained using hole-theory. It is shown that the conductivity and viscosity of these liquids is controlled by ion mobility and the availability of voids of suitable dimensions, and this is consistent with the fluidity of other ionic liquids and molten salts. The DES are also shown to be good solvents for metal oxides, which could have potential application for metal extraction

Novel Solvent Properties of Choline Chloride/ Urea Mixtures

Eutectic mixtures of urea and a range of quaternary ammonium salts are liquid at ambient temperatures and have interesting solvent properties

Preparation of novel, moisture-stable, Lewis acidic ionic liquids containing quaternary ammonium salts with functional side chains

A range of novel, moisture-stable, Lewis-acidic ionic liquids has been prepared by mixing appropriate molar ratios of MCl[subscript 2] (M = Zn and/or Sn) and quaternary ammonium salts of formula [Me[subscript 3]NC[subscript 2]H[subscript 4]Y]Cl (Y = OH, Cl, OC(O)Me, OC(O)Ph); the influence of substituent Y and metal M on the physical properties of the melts has been investigated