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A cavity model of the effect of a solvent on thermodynamic parameters of dimerization of polar species in non-polar liquids has been developed and compared to experimental data. Bulk solution data have been collected for stearic acid in cyclohexane and in toluene to quantify the extent of self-association of the acid in terms of the dimer self-dissociation constant, Kd. Composition and temperature-dependent experimental data have been collected to determine Kd, the enthalpy of dissociation, and temperature-dependent infrared molar absorption coefficients. The interaction of stearic acid with small amounts of water present in non-aqueous solvents is also addressed and quantified with a hetero-dissociation (or dehydration) constant, Kh. Existing data for acetic acid are also considered. The model connects Kd and Kh to the vapor-phase association equilibria. Solute dipole-solvent quadrupole interactions are shown to have a major effect on Kd in quadrupolar liquids, such as toluene, benzene, and CS2. This work provides important background as a prelude to adsorption studies of these additives from non-aqueous solvents to solid surfaces with relevance to commercial fluids, such as oil-based corrosion inhibitors and friction modifiers. Moreover, the presented theory of the solvent effect on Kd is a first step to generalization of standard implicit solvent models in computational chemistry (such as the polarizable continuum model) to media of significant quadrupolar strength. This is expected to be particularly important for polar species dissolved in CO2 relevant for carbon capture and storage where appropriate models do not currently exist.

Supplementary data table 2: Concentrations of selected elements in parts per million (ppm) for sandstone samples belonging to the Fell Sandstone Formation across the northern Pennine Basin. Bdl, below limit of detection.

Supplementary data table 3: Concentrations of selected element oxides in weight per cent (wt. %) for sandstone samples belonging to the Fell Sandstone Formation across the northern Pennine Basin. Bdl, below limit of detection.

Supplementary data table 1: Borehole data with derivation and web links.

The adsorption of 4-n-nonylphenol (4NP), carvacrol, and ethanol onto the surface of iron oxide from nonaqueous solutions is presented. It is found that adsorption of 4NP from alkanes is strong and proceeds to monolayer formation, where the molecules are essentially "upright". However, at high relative concentrations, ethanol successfully out-competes 4NP for the iron oxide surface. Estimates of the enthalpy and entropy of binding of 4NP were found to be exothermic and entropically disfavored. Sum frequency generation vibrational spectroscopy data indicate some evidence of binding through a phenolate anion, despite the nonpolar, nonaqueous solvent. Carvacrol is also found to adsorb as a monolayer where the molecules are lying "flat". The adsorption of ethanol onto iron oxide from dodecane was investigated through the use of quantitative NMR, which is a convenient analytical technique for measuring adsorption isotherms. It was concluded that ethanol does not form adsorbed monolayers on the surface. Instead, it partitions onto the surface as a surface-enhanced local phase separation related to its poor solubility in alkane solvents.

This work investigates the corrosion of offshore structural steel surfaces over particularly short timescales. The focus is on the short-term effects between surface treatment and coating application (typically several hours). Offshore structures are exposed to an aggressive marine environment, where substrates will be contaminated by aerosols containing salts within hours, even under mild weather conditions. Localised corrosion studies of the anodic and cathodic regions of S355 steel surfaces undergoing salt drop corrosion are characterised. Significantly, the corrosion products are found to grow rapidly and are inhomogeneous, porous, and amorphous. They evolve to higher oxidation state oxides quickly with corrosion time. Therefore, microscopic corrosion products will form on newly exposed substrates in marine environments, even before the protective paint is applied.