Search results for "DSO"
showing 10 items of 1609 documents
Effect of Heat on the Adsorption Properties of Silica Gel
2012
Published version of an article in the journal: International Journal of Engineering and Technology. Also available from the publisher at: http://www.ijetch.org/papers/416-T886.pdf Open access. Adsorption properties of silica gel have been attributed to the surface hydroxyl groups of silica gel. Some hydroxyl groups are free standing and called free silanol groups. Some are hydrogen bonded to neighbouring silanol groups. Christy has shown that a high silanol number and a balanced concentration proportionality between these two different types of hydroxyl groups is necessary for effective adsorption of water molecules. Thermal treatment of silica gel samples alters the proportions of these g…
Separation of palladium and silver from E-waste leachate : effect of nitric acid concentration on adsorption to Thiol scavenger
2022
The development of recovery techniques for metals present in low concentrations in E-waste, such as silver and palladium, is important from the aspect of the circular economy. Adsorption of palladium and silver was studied in detail in a batch process with silica-based Thiol scavenger from nitric acid leachate of waste printed circuit boards (PCBs). High adsorption efficiencies of Pd(II) and Ag(I), >97%, were reached in nitric acid concentrations below 3 mol L−1. At higher acid concentrations, adsorption efficiency of Ag(I) decreased drastically which enables the separation of Ag(I) and Pd(II) based on nitric acid concentration in sample solution. Pd(II) and Ag(I) followed pseudo 2nd order …
Zinc Adsorption by Activated Carbon Prepared from Lignocellulosic Waste Biomass
2019
Sawdust was used as a precursor for the production of biomass-based activated carbon. Carbonization and activation are single-stage processes, and steam was used as a physical activation agent at 800 °
Algunas consideraciones en torno a la Evaluación del Sistema Educativo y a lo que ésta comporta
1994
In this article we considere the reasons for evaluating the educational system. The quality of education is a preoccupation of the governments, specially in time of crisis and of educational reforms and this quality needs and evaluation of all the educational system. In Spain the National Institute of Quality and Evaluation has been recently created in order to carry out this evaluation. We reflect about the subject and also about the methods and the agents of this evaluation. We ask for a democratic and cooperative evaluation.
Adsorption of anionic dyes onto natural, thermally and chemically modified smectite clays
2014
Abstract The aim of this study was to determine the adsorption capacity of the smectite clays (from the overburden of the lignite deposit in Belchatow) for two anionic dyes, i.e. Reactive Blue 81 (RB-81) and Direct Blue 74 (DB-74). Additionally, the influence of the thermal and chemical (acid and alkali) clay modifications on the amount of bonded dyes was investigated. The adsorption capacity of the clay (natural and modified) was different for studied dyes and depended on the initial concentration and modification type. All the modified clays adsorbed the dyes at pH>pHPZC as the negatively charged surfaces of their particles (in accordance with the formula: AOH ↔ AO- + H+) prevented the…
Papildsods- tiesību ierobežošana
2015
Bakalaura darba „Papildsods – tiesību ierobežošana” mērķis ir izpētīt papildsoda, tiesību ierobežošanas, regulējumu Krimināllikumā, cenšoties atklāt, vai tas ir pietiekošs un pilnīgs, kā arī, kāda ir šī papildsoda piemērošana praksē un vai tas sasniedz Krimināllikumā 36.pantā paredzēto soda mērķi. Darba ietvaros autors veic papildsoda – tiesību ierobežošanas – izpēti, kā arī tika veikta literatūras, normatīvo aktu un publiski pieejamo materiālu, t.sk., arī tiesu prakses analīze saistībā ar šo soda veidu. Analizējot darba gaitā izmantotos materiālus, tiek secināts, ka šis soda veids aizvien biežāk tiek piemērots gan tiesas nolēmumos, kā viens no papildsoda veidiem, kā arī vairāki tiesību zin…
Nuevos materiales moleculares multifuncionales conmutables con transición de espín
2022
Este trabajo de Tesis Doctoral se centra en la síntesis y caracterización de nuevos materiales moleculares conmutables basados en FeII, los cuales presentan el fenómeno de transición de espín (spin crossover, SCO). El objetivo principal de esta tesis doctoral ha sido el diseño y estudio de nuevos materiales multifuncionales de FeII que combinan el comportamiento SCO con otra propiedad físico-química de interés. La estrecha interrelación entre el fenómeno SCO y dicha propiedad ha sido seguida y estudiada por estudios magnéticos, cristalográficos y calorimétricos, entre otros. El capítulo 1 de esta tesis describe los conceptos teóricos más importantes del fenómeno SCO, donde los centros SCO e…
On the adsorption and reactivity of element 114, flerovium
2022
Flerovium (Fl, element 114) is the heaviest element chemically studied so far. To date, its interaction with gold was investigated in two gas-solid chromatography experiments, which reported two different types of interaction, however, each based on the level of a few registered atoms only. Whereas noble-gas-like properties were suggested from the first experiment, the second one pointed at a volatile-metal-like character. Here, we present further experimental data on adsorption studies of Fl on silicon oxide and gold surfaces, accounting for the inhomogeneous nature of the surface, as it was used in the experiment and analyzed as part of the reported studies. We confirm that Fl is highly v…
Comparison of the Richardson and BCS models of superconductivity based on calculations of ground state energies
2017
Suprajohtavuuden Richardsonin ja BCS mallien vertailu perustilojen laskettujen energioiden perusteella. Suprajohtavuus on edelleen aktiivinen tutkimuksen alue, koska sen tarjoamista mahdollisuuksista huolimatta sitä ei vielä ymmärretä kokonaisvaltaisesti. Tässä pro gradu -tutkielmassa käyn läpi perusteet kahdelle suprajohtavuuden mallille, Richardsonin ja BCS malleille. BCS teoria on ensimmäinen ja käytetyin mikroskooppinen suprajohtavuuden teoria. Richardsonin malli on harvemmin käytetty malli, josta saadaan redusoidun BCS Hamiltonin operaattorin tarkat ominaistilat. Lasken molempien mallien perustilojen energiat sekä redusoidulle että täydelle BCS Hamiltonin operaattorille. Sama lasketaan…
The Jäntti approach to adsorption with increasing gas pressure
2002
Jäntti introduced a method of calculating equilibrium adsorption from measurements where the pressure of the gas was varied in a stepwise manner. His aim was to shorten the time necessary for a given measurement. The method was applied to gas/solid systems in which simple adsorption processes occurred and where the number of adsorption sites was infinite. The present paper discusses the case where no adsorption is possible on an already occupied site (Langmuir isotherm) while the number of positions available for adsorption is considered limited. The advantages of using a gas pressure that increases linearly with time are evident for studies with this limitation. It is shown that such meas…