Search results for "ADSORPTION"

Chemical Properties of Element 105 in Aqueous Solution: Halide Complex Formation and Anion Exchange into Triisoctyl Amine

2017

Studies of the halide complexation of element 105 in aqueous solution were performed on 34-s 262Ha produced in the 249Bk(18-O,5n) reaction. The 262Ha was detected by measuring the fission and alpha activities associated with its decay and the alpha decays of its daughter, 4.3-s 258Lr. Time-correlated pairs of parent and daughter alpha particles provided a unique identification of the presence of 262Ha. About 1600 anion exchange separations of 262Ha from HCl and mixed HC1/HF solutions were performed on a one-minute time scale. Reversed-phase micro-chromatographic columns incorporating triisooctyl amine (TIOA) on an inert support were used in the computer-controlled liquid chromatography appa…

Buildup of Ultrathin Multilayer Films by a Self-Assembly Process: II. Consecutive Adsorption of Anionic and Cationic Bipolar Amphiphiles and Polyelec…

1991

We have recently reported on the consecutive physisorption of anionic and cationic bipolar amphiphiles onto charged surfaces, adsorbed out of aqueous solutions [1]. Here, we extend our previous concept to multipolar compounds such as polyelectrolytes. In contrast to the bipolar amphiphile system, it is not necessary to separate single charges by a rigid unit, when the polyelectrolyte is adsorbed from sufficiently concentrated solutions. In this case the physisorbed layer does not bind with all ionic groups to the surface and exposes free ionic groups at the new film/solution interface. Therefore a polyelectrolyte layer can replace a layer of bipolar amphiphiles in the consecutive buildup of…

Fast Measurements of Adsorption on Porous Materials Using Jäntti's Method

1999

In 1972, Jäntti et al. formulated a method to shorten the time taken for adsorption measurements. We suggested at the Kiev International Conference on Vacuum Microbalance Techniques (1999) that the applicability of this method could be widened by considering a number of parallel adsorptions. There is, however, a more complicated but perhaps more interesting variant possible when extra mass transport is considered to occur in series. Such an application could involve adsorption within a porous structure where diffusion must be considered as a process occurring in series with adsorption on the surface.

Adsorption of atomic and molecular oxygen on the LaMnO3(001) surface: ab initio supercell calculations and thermodynamics.

2008

We present and discuss the results of ab initio DFT plane-wave supercell calculations of the atomic and molecular oxygen adsorption and diffusion on the LaMnO(3) (001) surface which serves as a model material for a cathode of solid oxide fuel cells. The dissociative adsorption of O(2) molecules from the gas phase is energetically favorable on surface Mn ions even on a defect-free surface. The surface migration energy for adsorbed O ions is found to be quite high, 2.0 eV. We predict that the adsorbed O atoms could penetrate the electrode first plane when much more mobile surface oxygen vacancies (migration energy of 0.69 eV) approach the O ions strongly bound to the surface Mn ions. The form…

Fine chemistry by TiO2 heterogeneous photocatalysis

2021

Abstract Heterogeneous TiO2 photocatalysis is a promising technology based on the capability of the semiconducting material to generate charges upon irradiation of suitable energy. The photogenerated electrons and holes, in turn, induce redox reactions involving species adsorbed on the surface of the photocatalyst, giving rise to chemical transformations. The presence of highly oxidizing radicals, thus generated, has long led to consider TiO2 photocatalysis only a nonselective oxidation process. In fact, so far it is possible to find in the literature many examples of its use in the field of environmental remediation aimed at the degradation of harmful molecules, although the studies are al…

The Role of the Energetics of Adsorption in Kinetic Studies

1981

Adsorptionsvoltammetrische Bestimmung von Titan

1986

Investigation on the Adsorption of N2 Ar, CO and CH4 on Aluminophosphates

1994

Abstract Adsorption isotherms at different temperatures and isothermal micro-calorimetric curves were measured for N2 Ar, CO, and CH4 on various molecular sieves as VPI-5, MCM-9, AlPO4-8, AlPO4-H, AlPO4-5, SAPO-5, AlPO4-39, AlPO4-C. It was shown that the isosteric heats of adsorption correlated with the pore-sizes of the studied molecular sieves.

Adsorptionseffekte als Fehlerquellen bei Lichtzerstreuungsmessungen

1956

Es werden die Einflusse der Adsorption von Hochpolymeren aus den Losungen auf Lichtzerstreuungsmessungen untersucht. Zunachst wird die Adsorption aus Losung an Glaswolle und Glaspulver in verschiedenen Losungsmitteln gemessen. Es zeigt sich, das sowohl Konzentrationserniedrigung, bestimmt im Differentialrefraktometer, wie auch eine Abnahme des Molekulargewichtes, aus der Lichtzerstreuung bestimmt, infolge selektiver Adsorption auftreten. Beim Schutteln der Losungen tritt als weiterer Effekt ein Abbau der Kettenmolekule ein. Beim Filtrieren von Losungen nehmen durch Adsorption im Filter Konzentration und Molekulargewicht ab. Die Abnahme wachst mit der Feinheit des Filters, d. h. mit seiner O…

Adsorption Properties of Nax and Bax Zeolites: Correlation between Structural and Thermodynamic Results on Para- and Meta-xylene Adsorption

1996

A comparison is made between NaX and BaX adsorption properties starting from crystallographic data and thermodynamic measurements. Adsorption isotherms and differential adsorption heats of pure para- and meta-xylenes in NaX and BaX zeolites are interpreted in the light of crystallographic results.