Colloidal particles act in many ways like surfactant molecules, particularly if adsorbed to a fluid–fluid interface. Just as the water or oil-liking tendency of a surfactant is quantified in terms of the hydrophile–lipophile balance (HLB) number, so can that of a spherical particle be described in terms of its wettability via contact angle. Important differences exist, however, between the two types of surface-active material, due in part to the fact that particles are strongly held at interfaces. This review attempts to correlate the behaviour observed in systems containing either particles or surfactant molecules in the areas of adsorption to interfaces, partitioning between phases and solid-stabilised emulsions and foams.

Particles as surfactants—similarities and differences

This paper reviews recent progress made in identifying electrocatalysts for carbon dioxide (CO2) reduction to produce low-carbon fuels, including CO, HCOOH/HCOO−, CH2O, CH4, H2C2O4/HC2O4−, C2H4, CH3OH, CH3CH2OH and others. The electrocatalysts are classified into several categories, including metals, metal alloys, metal oxides, metal complexes, polymers/clusters, enzymes and organic molecules. The catalyts' activity, product selectivity, Faradaic efficiency, catalytic stability and reduction mechanisms during CO2 electroreduction have received detailed treatment. In particular, we review the effects of electrode potential, solution–electrolyte type and composition, temperature, pressure, and other conditions on these catalyst properties. The challenges in achieving highly active and stable CO2 reduction electrocatalysts are analyzed, and several research directions for practical applications are proposed, with the aim of mitigating performance degradation, overcoming additional challenges, and facilitating research and development in this area.

A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels

Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

 Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles Therefore, it is necessary to understand the distribution between the phases According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references It is also available at http://wwwhenrys-laworg 

/pdf/compilation-of-henry-s-law-constants-version-4-0-for-water-58il9q0ogv.pdf

Compilation of Henry's law constants (version 4.0) for water as solvent

1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

The system carbon dioxide‐water is of great scientific and technological importance. Thus, it has been studied often. The literature for the solubility of carbon dioxide in water is vast and interdisciplinary. An exhaustive survey was conducted and approximately 100 experimental investigations were found that reported equilibrium data at pressures below 1 MPa. A model based on Henry’s law was used to correlate the low pressure data (those up to 1 MPa). The following correlation of the Henry’s constants (expressed on a mole fraction basis) was developed ln(H21/MPa)=−6.8346+1.2817×104/T−3.7668×106/T2 +2.997×108/T3 The correlation is valid for 273<T<433 K(0<t<160 °C) where T is in K. Any experimental data that deviated significantly from this model were duly noted.

The Solubility of Carbon Dioxide in Water at Low Pressure

The solubility of CO2 in a 30 mass % monoethanolamine (MEA) solution has been measured at eight temperatures between 0 and 150°C at partial pressures of CO2 ranging from 0.001 to 20,000 kPa. The data have been correlated using the Deshmukh-Mather (1981) model.

The solubility of CO2 in a 30 mass percent monoethanolamine solution

The University of Alberta measured the solubilities of H/sub 2/S and CO/sub 2/ in 1.0, 2.0, and 4.28 kmol/m/sup 3/ aqueous solutions of methyldiethanolamine (MDEA) for temperature and acid-gas partial pressures ranging from 100/sup 0/ to 250/sup 0/F and 0.001 to 8600 kPa, respectively, used the procedure presented by Kent and Eisenberg to correlate the solubility data, and, calculated enthalpies of solution from the experimental results. Aqueous solutions of MDEA are attractive solvents for the selective removal of H/sub 2/S from process streams containing CO/sub 2/ and hydrocarbons.

Solubility of hydrogen sulfide and carbon dioxide in aqueous methyldiethanolamine solutions

A mathematical model for equilibrium solubility of hydrogen sulfide and carbon dioxide in aqueous alkanolamine solutions

The University of Alberta measured the partial pressure of carbon dioxide over aqueous monoethanolamine solutions (1.0, 2.5, 3.75, and 5.0 N) at temperatures of 25/sup 0/, 40/sup 0/, 60/sup 0/, 80/sup 0/, 100/sup 0/, and 120/sup 0/C. Partial pressures of CO/sub 2/ ranged between 0.2 and 6616 kPa. The results, which extend previously published data to higher partial pressures, were compared with two methods of prediction based upon a thermodynamic model.

Alan E. Mather

Papers

The Solubility of Carbon Dioxide in Water at Low Pressure

The solubility of CO2 in a 30 mass percent monoethanolamine solution

Solubility of hydrogen sulfide and carbon dioxide in aqueous methyldiethanolamine solutions

A mathematical model for equilibrium solubility of hydrogen sulfide and carbon dioxide in aqueous alkanolamine solutions

Equilibrium between carbon dioxide and aqueous monoethanolamine solutions