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A chemical-free option to reduce membrane fouling is the use of electrical fields for membranes. To maximize the strength of the electric field in compact membrane module constructions, electrically conductive membranes are preferred to only conductive supports. Conductive, porous membranes are sintered from polyetherimide powder particles that are surface-covered with multi-walled carbon nanotubes (MWCNT). The fusion of the surface-covered particles forms a conductive MWCNT network in the composite, with a large number of inter-MWCNT contacts. Membranes with a high specific electrical conductivity of up to 2.28 Sm−1 at a concentration of 3.0 wt% MWCNT are produced in an adapted sintering process. The sintering behavior of decorated particles depends on the coverage of the polymer particles with MWCNT.

A method is presented for the production of carbon nanomaterials from carbon dioxide in a low temperature process. In this method, carbon dioxide is irradiated with an ultraviolet laser at the conditions of critical opalescence where light is scattered and absorbed. Spherical carbon nanoparticles are obtained under these conditions on metal substrates without any additional catalyst near room temperature. The particles are of approximately uniform shape and size of around 100 nm. Some of the particles form clusters. The method is reproducible on different substrates. Quantum chemical calculations have been employed in order to elucidate the role of critical opalescence and of the substrate. The calculations show that the presence of molecular clusters at the critical point is essential in decreasing the excitation energy. The dissociation reaction most likely occurs on the surface of the substrate, where the excitation energy is decreased even further.

We develop a low temperature, organic solvent-free method of producing iron containing carbon (Fe@C) nanoparticles. We show that Fe@C nanoparticles are self-assembled by mixing ferrocene with sub-critical (25.0 °C), near-critical (31.0 °C) and super-critical (41.0 °C) carbon dioxide and irradiating the solutions with UV laser of 266-nm wavelength. The diameter of the iron particles varies from 1 to 100 nm, whereas that of Fe@C particles ranges from 200 nm to 1 μm. Bamboo-shaped structures are also formed by iron particles and carbon layers. There is no appreciable effect of the temperature on the quantity and diameter distributions of the particles produced. The Fe@C nanoparticles show soft ferromagnetic characteristics. Iron particles are crystallised, composed of bcc and fcc lattice structures, and the carbon shells are graphitised after irradiation of electron beams.

The adsorption of dimethyl(1,5-cyclooctadiene)platinum on porous supports in supercritical carbon dioxide was investigated. Silica gel tablets and a monolithic material were used as the solid suppo...

The solubility of a variety of metal acetylacetonate, tetramethylheptanedionate, cyclopentadienyl and cyclooctadiene complexes in supercritical carbon dioxide was measured. The complexes included the metals potassium, rubidium, titanium, zirconium, vanadium, chromium, manganese, iron, ruthenium, osmium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, and zinc. The solubility experiments were carried out with a dynamic-gravimetric method at 333 K in the pressure range from 10 MPa to 30 MPa. The pressure dependence of solubility is presented and the influence of the ligand is discussed. The influence of the metal on solubility was investigated systematically in terms of the oxidation state of the metal, the size of the metal atom and the magnetic moment. The solubility of metal complexes depends on the ligand as well as on the metal atom. An increase in solubility can be observed with increasing number of ligands per centre atom and with increasing oxidation state. In an identical complex structure, solubility is influenced by the molecular size and the valence electron configuration of the metal centres.

The adsorption of carbon dioxide on hydrotalcite-like compounds was investigated. Two different powdered hydrotalcites were used containing the cations nickel and iron. The powdered materials were screened for carbon dioxide adsorption using a thermogravimetric method and it was found that NiMgAl (Sample 1) hydrotalcite has the largest capacity for CO2, adsorbing 1.58 mmol g−1 at 20 °C, and highest rate of adsorption of up to 0.17 mmol g−1 min−1. This represented an increase of 53% in adsorption capacity, compared with NiMgAlFe (Sample 2). In order to improve the rheological behaviour of hydrotalcite paste for extrusion, hydrotalcite powders were combined with boehmite alumina (70:30 and 50:50 ratios of hydrotalcite:boehmite) before extrusion into pellets suitable for use in a fixed bed adsorber. These pellets were then re-crushed and further tested by thermogravimetric methods. The effects of temperature, composition and pre-treatment of the hydrotalcites on the adsorption of carbon dioxide and nitrogen are reported. At 20 °C, the amount of carbon dioxide adsorbed was between 2.0 and 2.5 mmol g−1 for all the hydrotalcite/alumina samples in this study, although this decayed rapidly with increasing temperature. The results are compared with silica gel as a common sorbent reference, and with literature values. Hydrotalcite/alumina samples have thermal stability and a high adsorption capacity for carbon dioxide over a wide range of temperatures. The composition of the hydrotalcite/alumina pellets investigated in this study has less effect upon the adsorption behaviour compared with the non-calcined hydrotalcite powder, thus allowing a wide choice of pellet compositions to be used.

Carbon nanomaterials have become increasingly important for many applications, including sensors, electronics, biomedical materials and functional composites. Currently their production is based on hydrocarbons or graphite and requires very high temperatures. Here we present a method for the synthesis of carbon nanomaterials from carbon dioxide. Unlike previously described methods, our synthesis method works near room temperature. Carbon dioxide is irradiated at its critical point, producing spherical carbon nanoparticles even without the use of a catalyst. We examine the influence of irradiation parameters and different metals and catalysts on the nanocarbon production. Together with analysis of the fluid phase, this allows us to draw some conclusions on the carbon dioxide dissociation mechanism.

Several inexpensive and non-toxic solvents with low vapour pressures were investigated for their suitability as alternative solvents for the absorption of carbon dioxide from flue gas. The solvents include poly(ethylene glycol)s, poly(ethylene glycol) ethers, poly(ethylenimine) and glycerol-based substances. Solvent properties such as thermal stability, solubility of carbon dioxide and selectivity over nitrogen were investigated in a systematic study using a thermogravimetric analyser. Absorption results are reported for pure carbon dioxide and nitrogen as well as a mixture of both gases. Desorption and long-term sorption behaviour are also discussed. Glycerol and poly(ethylene glycol)s show a high solubility of carbon dioxide. Due to the high viscosity of the solvent, carbon dioxide absorption in poly(ethylenimine) is very slow in spite of the presence of favourable amine groups. PEG 300 was found to be the best solvent in this study and shows a high carbon dioxide solubility as well as good selectivity over nitrogen. The advantages of high stability, low solvent loss and low desorption energy of PEG 300 may outweigh its lower absorption capacity compared to the state-of-the-art solvent monoethanolamine, making it a potentially advantageous solvent for industrial carbon dioxide absorption processes.

The vapour pressures of several ionic liquids, liquid polymers and derivatives of glycerol were investigated by thermogravimetric analysis (TGA). The experimental method is described and discussed. Vapour pressure data for various solvents with low vapour pressures are reported at 100–120 °C. The thermogravimetric method for vapour pressure measurement is useful for the rapid screening of solvents. Ionic liquids have a low but detectable vapour pressure at 100–120 °C. The vapour pressures of liquid polymers such as poly(ethylenimine) and polyethylene glycols are in the same range, which might make these substances a less expensive alternative to ionic liquids.