Industrial applications and current trends in supercritical fluid technologies

Supercritical fluids have a great potential for wide fields of processes Although CO2 is still one of the most used supercritical gases, for special purposes propane or even fluorinated-chlorinated fluids have also been tested. The specific characteristics of supercritical fluids behaviour were analyzed such as for example the solubilities of different components and the phase equilibria between the solute and solvent. The application at industrial scale (decaffeinating of tea and coffee, hop extraction or removal of pesticides from rice), activity in supercritical extraction producing total extract from the raw material or different fractions by using the fractionated separation of beverages (rum, cognac, whisky, wine, beer cider), of citrus oils and of lipids (fish oils, tall oil) were also discussed. The main interest is still for the extraction of natural raw materials producing food ingredients, nutraceuticals and phytopharmaceuticals but also cleaning purposes were tested such as the decontamination of soils the removal of residual solvents from pharmaceutical products, the extraction of flame retardants from electronic waste or precision degreasing and cleaning of mechanical and electronic parts. An increasing interest obviously exists for impregnation purposes based on supercritical fluids behaviour, as well as for the dying of fibres and textiles. The production of fine particles in the micron and submicron range, mainly for pharmaceutical products is another important application of supercritical fluids. Completely new products can be produced which is not possible under normal conditions. Supercritical fluid technology has always had to compete with the widespread opinion that these processes are very expensive due to very high investment costs in comparison with classical low-pressure equipment. Thus the opinion is that these processes should be restricted to high-added value products. A cost estimation for different plant sizes and different applications was also analyzed

12th European meeting on supercritical fluids : new perspectives in supercritical fluids, materials, nanoscience and processing ; proceedings

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Supercritical CO2 impregnation of polyethylene components for medical purposes

Modem hip and knee endoprosthesis are produced in titanium and to reduce the friction at the contact area polymer parts, mainly ultra-high molecular weight polyethylene (UHMW-PE), are installed. The polyethylene is impregnated with a-tocopherol (vitamin E) before processing for remarkable decrease of oxidative degradation. Cross linked UHMW-PE offers much higher stability, but a-tocopherol cannot be added before processing, because a-tocopherol hinders the cross linking process accompanied by a heavy degradation of the vitamin. The impregnation of UHMW-PE with a-tocopherol has to be performed after the cross linking process and an accurate concentration has to be achieved over the cross section of the whole material. In the first tests UHMW-PE-cubes were stored in pure a-tocopherol under inert atmosphere at temperatures from 100 to 150 °C resulting in a high mass fraction of a-tocopherol in the edge zones and no constant concentration over the cross section. For better distribution and for regulating the mass fraction of a-tocopherol in the cross linked UHMW-PE material supercritical CO2 impregnation tests were investigated. Again UHMW-PE-cubes were impregnated in an autoclave with a-tocopherol dissolved in supercritical CO2 at different pressures and temperatures with variable impregnation times and vitamin E concentrations. Based on the excellent results of supercritical CO2 impregnation standard hip and knee cups were stabilized nearly homogeneously with varying mass fraction of a-tocopherol

Supercritical fluid dyeing of polycarbonate in carbon dioxide

In this work, the applicability of the supercritical CO 2 dyeing process on polycarbonate pellets was inves- tigated by the use of two azo-disperse dyes; disperse red 1 (DR1) and disperse red 13 (DR13). Experiments were performed in the range of 100–300 bar and 40 ◦ C–60 ◦ C with 3–24 h of impregnation time. Dyeing took place in a high pressure vessel and kinetics was studied and explained. Impregnation efficiency on the polymer pellets was measured by UV–vis spectroscopy. The process was successfully applied and resulted in an entirely, equally deep-dyed polymer with excellent dyeing fixation. Arising from the different sol- ubility and chemical structure of the dyes, their sorption kinetics was found to be different. Maximal dye uptake obtained with DR1 and DR13 were 0.010 wt% and 0.055 wt% respectively, with respect to the mass of the polymer. New solubility data for DR13 in supercritical CO 2 has also been measured and partition coefficients ( K c ) for the dyes between the fluid and the polymer phase were calculated

ATF936, a novel oral calcilytic, increases bone mineral density in rats and transiently releases parathyroid hormone in humans.

Parathyroid hormone (PTH), when injected daily as either the intact hormone PTH(1-84) or the active fragment PTH(1-34) (teriparatide), is an efficacious bone anabolic treatment option for osteoporosis patients. Injections lead to rapid and transient spikes in hormone exposure levels, a profile which is a prerequisite to effectively form bone. Oral antagonists of the calcium-sensing receptor (calcilytics) stimulate PTH secretion and represent thus an alternative approach to elevate hormone levels transiently. We report here on ATF936, a novel calcilytic, which triggered rapid, transient spikes in endogenous PTH levels when given orally in single doses of 10 and 30mg/kg to growing rats, and of 1mg/kg to dogs. Eight weeks daily oral application of 30mg/kg of ATF936 to aged female rats induced in the proximal tibia metaphysis increases in bone mineral density, cancellous bone volume and cortical and trabecular thickness as evaluated by computed tomography. In healthy humans, single oral doses of ATF936 produced peak PTH levels in plasma after a median time of 1h and levels returned to normal at 24-h post-dose. The average maximum PTH concentration increase from baseline was 1.9, 3.6, and 6.0-fold at doses of 40, 70, and 140mg. ATF936 was well tolerated. The sharp, transient increase in PTH levels produced by the oral calcilytic ATF936 was comparable to the PTH profile observed after subcutaneous administration of teriparatide. In conclusion, ATF936 might hold potential as an oral bone-forming osteoporosis therapy

Controlling concentration of bioactive components in cat's claw based products with a hybrid separation process

Supercritical fluid extraction (SFE) with and without entrainer combined with organic solvent extraction was used for fractionation of bioactive natural products as alkaloids and antioxidants from cat's claw (Uncaria tomentosa (Willd.) DC.) bark. Extracts obtained from this plant have a number of beneficial effects, including anti-inflammatory or immune stimulator. The aim of this work was to obtain extracts of enriched and limited alkaloid concentrations, good antioxidants and tannin agents. The results demonstrated that a hybrid process involving SFE is a selective method to obtain an oxindole alkaloid rich fraction (186.0 ± 3.2 mg total pentacyclic oxindole alkaloids/g extract) and a product enriched in tannins (23.8 ± 1.9% tannin content in extract) and antioxidants (IC50 = 5.88 ± 0.54 μg/ml extract)