Acid-modified clinoptilolite as a support for palladium–copper complexes catalyzing carbon monoxide oxidation with air oxygen
Samples of natural clinoptilolite were modified by an acid–thermal method at nitric acid concentrations of 0.25, 0.5, 1.0, and 3.0 M and a contact time of 30 min. A series of catalysts, K2PdCl4–Cu(NO3)2–KBr/S (S = 0.25H-CLI, 0.5H-CLI, 1H-CLI, and 3H-CLI) was obtained. All samples were investigated by X-ray phase and thermogravimetric analysis, FT-IR spectroscopy, water vapor ad/desorption and pH metric method. Besides, K2PdCl4–Cu(NO3)2–KBr/S samples were tested in the reaction of low-temperature carbon monoxide oxidation. It have been found that, owing to special physicochemical and structural-adsorption properties of 3H-CLI, it promotes formation of the palladium–copper catalyst providing carbon monoxide oxidation at the steady-state mode down to CO concentrations lower than its maximum permissible concentration at air relative humidity varied within a wide range.
Monitoring the effect of hydrothermal treatments on the structure of a natural zeolite through a combined XRD, FTIR, XRF, SEM and N2-porosimetry analysis
Abstract A natural zeolite specimen, consisting mainly of heulandite type-II and mordenite, was succumbed to NH 4 + and/or H + -exchange followed by one or two calcination steps and further acid leaching. In an attempt to examine the effect of each treatment on the starting material as well as on pre-modified (intermediate) samples, varied calcination temperatures, contact times and solutions concentrations were applied. On the grounds of the properties and expected behavior of pure substances, a combined XRD, FTIR, XRF, SEM and N 2 -porosimetry analysis enabled the monitoring and comprehension of the phenomena taking place during each treatment, despite the obscurity inherent in each individual analysis when dealing with impure materials. In general, the behavior of the typical counterbalancing ions Na + , K + , Mg 2+ and Ca 2+ , the Fe 3+ content, the extraction of Al 3+ from the lattice and the removal of amorphous Al-substances were found to be crucial factors concerning the properties of the modified samples.
Body sculpturing.
Significant improvements in body contour can be accomplished by surgical procedures having reliable, predictable results. Similar to the modern sculptor of inanimate art forms, plastic surgeons have utilized new materials and devised new techniques to achieve aesthetic improvement of the face, trunk, and extremities. The goals of the surgical sculptor are perhaps more challenging than those of the pure artistic sculptor, not only because they must result in improved appearance but also because the surgeon is limited at all times by considerations of regional anatomy, the availability of viable tissue materials, and the safety of his patient.