Download or read book ETUDE THEORIQUE DE LA STRUCTURE ET DE LA REACTIVITE DU DIOXYDE DE TITANE written by ADIL.. FAHMI and published by . This book was released on 1993 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: DANS LE BUT D'ETUDIER L'ORIENTATION DE LA CRISTALLISATION DE TIO#2 EN PRESENCE D'ACIDES CARBOXYLIQUES, NOUS AVONS D'ABORD ETUDIE LES DEUX PHASES LES PLUS STABLES (LE RUTILE ET L'ANATASE) PUIS LES PROPRIETES D'ADSORPTION. LES DIFFERENCES D'ENERGIE ENTRE CES DEUX PHASES APPARAISSENT DES LORS QUE L'ON PERMET DES DEFORMATIONS ANGULAIRES. CELLES-CI RESULTENT D'UN COMPROMIS ENTRE L'ENVIRONNEMENT LOCAL DU TITANE (OCTAEDRIQUE) ET CELUI DE L'OXYGENE (TRIANGULAIRE). SUR UNE SURFACE PROPRE DU DIOXYDE DE TITANE, IL Y A DES SITES ACIDES DE LEWIS (LES ATOMES DE TITANE INSATURES) QUI PERMETTENT L'ADSORPTION DE MOLECULES HYDROXYLEES (H#2O, MEOH ET HCO#2H). CETTE ADSORPTION EST DISSOCIATIVE A CAUSE DE LA PRESENCE D'ATOMES D'OXYGENES TRES BASIQUES. LORSQUE L'ADSORPTION EST MOLECULAIRE, LA LIAISON ADSORBAT-SUBSTRAT EST IONIQUE ET FAIBLE. SON ENERGIE DEPEND DE LA BASICITE DE LA MOLECULE ET DE LA CHARGE SUR L'ATOME DE TITANE. LORSQUE L'ADSORPTION EST DISSOCIATIVE, LES LIAISONS ENTRE LES FRAGMENTS DE L'ADSORBAT ET LE SUBSTRAT SONT COVALENTES ET FORTES. L'ENERGIE D'ADSORPTION AINSI QUE LE MECANISME DE DISSOCIATION DEPENDENT DU CARACTERE ACIDO-BASIQUE DE LA SURFACE PROPRE. L'ETUDE DE L'ADSORPTION D'ACIDES POLYFONCTIONNELS (EX. L'ACIDE MALIQUE) MET EN EVIDENCE L'IMPORTANCE DE L'ENERGIE DE DEFORMATION DES ADSORBATS: CEUX-CI DOIVENT ADOPTER UNE CONFORMATION REPLIEE POUR QUE LA MOLECULE PUISSE S'ADSORBER PAR PLUSIEURS FONCTIONS
Download or read book STRUCTURE ET PROPRIETES AMPHOTERES DE GELS DE DIOXYDE DE TITANE written by CHRISTINE.. KERTESZ and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: L'ETUDE PORTE SUR LA COMPREHENSION DES PHENOMENES RESPONSABLES DE LA RETENTION PAR LE DIOXYDE DE TITANE, D'IONS EN SOLUTION. ON CHERCHE NOTAMMENT A CORRELER LA STRUCTURE DU SOLIDE A SES PROPRIETES AMPHOTERES EN SOLUTION AQUEUSE. UN ETAT DES CONNAISSANCES SUR LA FORMATION DE GELS D'OXYDES MINERAUX ET SUR LEUR STRUCTURE EST DONNE. DIFFERENTS MODES DE SYNTHESE DE GELS DE DIOXYDE DE TITANE SONT PRESENTES. LE MATERIAU SELECTIONNE EST CARACTERISE PAR DIFFRACTION DE RAYONS X, MICROSCOPIE ELECTRONIQUE, MESURE DE POROSITE PAR BET. UN MODELE A DEUX PHASES PRENANT EN COMPTE LA NATURE POREUSE DU SOLIDE ET PERMETTANT D'APPLIQUER LA LOI D'ACTION DE MASSE EST ADOPTE. L'ETUDE DES PROPRIETES AMPHOTERES DE L'OXYDE EST REALISEE PAR LA TECHNIQUE DE TITRAGE POTENTIOMETRIQUE. LES BOUCHES A HYSTERESIS OBSERVEES ENTRE LES TITRAGES ALLER ET RETOUR SONT ATTRIBUEES A LA LENTEUR DES REACTIONS DE NEUTRALISATION ACIDO-BASIQUE. LES PRINCIPALES CARACTERISTIQUES DU SOLIDE (POINT ISOELECTRIQUE, CAPACITE DE RETENTION D'ANIONS ET DE CATIONS) SONT AINSI DETERMINEES. LES VALEURS TROUVEES SONT CONFIRMEES PAR ANALYSE PAR ACTIVATION NEUTRONIQUE ET MICROANALYSE X. UN EXAMEN DE LA CINETIQUE DES REACTIONS DE NEUTRALISATION MONTRE QUE, SELON L'INTENSITE DE L'AGITATION DE LA SUSPENSION, L'ETAPE LIMITANT LA VITESSE PEUT ETRE SOIT LA DIFFUSION DANS LE FILM SOIT LA DIFFUSION DANS LA PARTICULE. DANS CE DERNIER CAS, LES COEFFICIENTS MOYENS DE DIFFUSION DES IONS DANS LE SOLIDE SONT EVALUES
Download or read book Proc d de synth se du dioxyde de titane analyse et mod lisation des solutions titane sulfate influence des ultrasons sur la pr cipitation written by Fabien Baillon and published by . This book was released on 2002 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les dioxydes de titane sont couramment employés au sein de l'industrie chimique, notamment en tant que poudres pigmentaires. Le procédé de précipitation, basé sur l'hydrolyse thermique d'une solution de sulfate de titanyle en milieu sulfurique, conduit préférentiellement à la phase cristalline anatase du TiO2. Afin de préciser les mécanismes d'apparition du solide lors de ce procédé, nous avons mené une étude de la structure chimique des solutions de titane-sulfate, rnais aussi montré et quantifié l'existence de sultato-complexes de titane par spectroscopie Raman. Suite à cette analyse expérimentale, nous avons proposé une démarche de modélisation pour prédire les concentrations des espèces en solution conduisant à la formation du solide. Par ailleurs, il a été montré que l'application d'ultrasons pouvait accélérer la nucléation dans des solutions sursaturées. Ainsi, nous avons étudié l'influence de l'insonification des solutions de sulfate de titanyle lors du procédé de précipitation. Nous avons effectivement mis en évidence que la nucléation peut être stimulée par cavitation acoustique, et permettre d'éviter l'introduction de germes cristallins. En outre, la présence d'ultrasons conduit à la structure rutile du dioxyde de titane, et nous avons cherché à identifier les mécanismes pouvant expliquer l'impact de l'insonification lors de la condensation de la phase solide.
Download or read book Proceedings written by and published by . This book was released on 1960 with total page 1456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Actes Du Deuxi me Congr s International de Catalyse Paris 1960 written by and published by . This book was released on 1961 with total page 1464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flexoelectricity in Liquid Crystals written by Agnes Buka and published by World Scientific. This book was released on 2013 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.
Download or read book Modern Surface Organometallic Chemistry written by Jean-Marie Basset and published by John Wiley & Sons. This book was released on 2009-07-10 with total page 725 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering everything from the basics to recent applications, this monograph represents an advanced overview of the field. Edited by internationally acclaimed experts respected throughout the community, the book is clearly divided into sections on fundamental and applied surface organometallic chemistry. Backed by numerous examples from the recent literature, this is a key reference for all chemists.
Download or read book Applied Mineralogy in the Mining Industry written by W. Petruk and published by Elsevier. This book was released on 2000-11-29 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: Techniques of performing applied mineralogy investigations, and applications and capabilities of recently developed instruments for measuring mineral properties are explored in this book intended for practicing applied mineralogists, students in mineralogy and metallurgy, and mineral processing engineers. The benefits of applied mineralogy are presented by using in-depth applied mineralogy studies on base metal ores, gold ores, porphyry copper ores, iron ores and industrial minerals as examples. The chapter on base metal ores includes a discussion on the effects of liberation, particle sizes and surfaces coatings of Pb, Cu, Fe, Ca and So4- on the recoveries of sphalerite, galena and chalcopyrite. The chapter on gold discusses various methods of determining the quantities of gold in different minerals, including 'invisible' gold in pyrite and arsenopyrite, so that a balance of the distribution of gold among the minerals can be calculated. This book also discusses the roles of pyrite, oxygen, moisture and bacterial (thiobacillus ferrooxidans) on reactions that produce acidic drainage from tailings piles, and summarizes currently used and proposed methods of remediation of acidic drainage.
Download or read book X Ray and Neutron Reflectivity Principles and Applications written by Jean Daillant and published by Springer Science & Business Media. This book was released on 2003-07-01 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reflection of and neutrons from surfaces has existed as an x-rays exp- imental for almost it is in the last technique fifty Nevertheless, only years. decade that these methods have become as of enormously popular probes This the surfaces and interfaces. to be due to of several appears convergence of intense different circumstances. These include the more n- availability be measured orders tron and sources that can over (so reflectivity x-ray many of and the much weaker surface diffuse can now also be magnitude scattering of thin films and studied in some the detail); growing importance multil- basic the realization of the ers in both and technology research; important which in the of surfaces and and role roughness plays properties interfaces; the of statistical models to characterize the of finally development topology its and its characterization from on roughness, dependence growth processes The of and to surface scattering experiments. ability x-rays neutro4s study four five orders of in scale of surfaces over to magnitude length regardless their and also their to ability probe environment, temperature, pressure, etc. , makes these the choice for buried interfaces often probes preferred obtaining information about the microstructure of often in statistical a global surfaces, the local This is manner to complementary imaging microscopy techniques, of such studies in the literature witnessed the veritable by explosion published the last few Thus these lectures will useful for over a resource years.
Download or read book The Six Marys written by Witness Lee and published by Living Stream Ministry. This book was released on 1982 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Reactor Physics written by Alain Hébert and published by Presses inter Polytechnique. This book was released on 2009 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Risk Assessment in the Process Industries written by Robin Turney and published by IChemE. This book was released on 1996 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this updated and amplified edition, Dr Pitblado answers the crucial questions of risk analysis: what can go wrong?; what are the effects and consequences?; and how often will it happen'.
Download or read book Africa Since 1935 written by Unesco. International Scientific Committee for the Drafting of a General History of Africa and published by Univ of California Press. This book was released on 1999 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hardcover edition of volume 8 was published in 1994. This paperback edition is the eighth and final volume to be published in the UNESCO General History of Africa. Volume 8 examines the period from 1935 to the present, and details the role of African states in the Second World War and the rise of postwar Africa. This is one of the most important books in the entire series, and as such, it is an unabridged paperback.
Download or read book Satellite Situation Report written by Goddard Space Flight Center. Office of Public Affairs and published by . This book was released on 1977 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Nanosafety written by Ulla Vogel and published by Elsevier. This book was released on 2013-12-17 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Nanosafety: Measurement, Exposure and Toxicology, written by leading international experts in nanosafety, provides a comprehensive understanding of engineered nanomaterials (ENM), current international nanosafety regulation, and how ENM can be safely handled in the workplace. Increasingly, the importance of safety needs to be considered when promoting the use of novel technologies like ENM. With its use of case studies and exposure scenarios, Handbook of Nanosafety demonstrates techniques to assess exposure and risks and how these assessments can be applied to improve workers' safety. Topics covered include the effects of ENM on human health, characterization of ENM, aerosol dynamics and measurement, exposure and risk assessment, and safe handling of ENM. Based on outcomes from the NANODEVICE initiative, this is an essential resource for those who need to apply current nanotoxicological thinking in the workplace and anyone who advises on nanosafety, such as professionals in toxicology, occupational safety and risk assessment. - Multi-authored book, written by leading researchers in the field of nanotoxicology and nanosafety - Features state-of-the-art physical and chemical characterization of engineered nanomaterials (ENM) - Develops strategies for exposure assessment, risk assessment and risk management - Includes practical case studies and exposure scenarios to demonstrate how you can safely use ENM in the workplace
