1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

MCM-41 siliceous molecular sieves were used to test the applicability of the Kelvin equation for nitrogen adsorption in cylindrical pores of the size from 2 to 65 nm It was shown that the Kelvin equation for the hemispherical meniscus, corrected for the statistical film thickness, is in quite good agreement with an experimental relation between the pore size and the capillary condensation pressure The agreement can be made quantitative in the pore size range from ca 2 to 65 nm, if a simple correction to the Kelvin equation is introduced The required statistical film thickness curve (t-curve) was calculated using nitrogen adsorption data for large pore MCM-41 samples and the obtained results were extrapolated using an adsorption isotherm for a macroporous silica gel Moreover, an accurate analytical representation of the t-curve was found Since both the corrected Kelvin equation for cylindrical pores and the t-curve have simple analytical forms, they can conveniently be used in a variety of methods 

Application of large pore MCM-41 molecular sieves to improve pore size analysis using nitrogen adsorption measurements

This review article presents the fundamental and practical aspects of water adsorption in Metal–Organic Frameworks (MOFs). The state of the art of MOF stability in water, a crucial issue to many applications in which MOFs are promising candidates, is discussed here. Stability in both gaseous (such as humid gases) and aqueous media is considered. By considering a non-exhaustive yet representative set of MOFs, the different mechanisms of water adsorption in this class of materials are presented: reversible and continuous pore filling, irreversible and discontinuous pore filling through capillary condensation, and irreversibility arising from the flexibility and possible structural modifications of the host material. Water adsorption properties of more than 60 MOF samples are reported. The applications of MOFs as materials for heat-pumps and adsorbent-based chillers and proton conductors are also reviewed. Some directions for future work are suggested as concluding remarks.

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Water adsorption in MOFs: fundamentals and applications

Structural and magnetic properties, methods of synthesis, and applications of seven iron(III) oxide polymorphs, including rare beta, epsilon, amorphous, and high-pressure forms, are reviewed. Thermal transformations resulting in the formation of iron oxides are classified according to different parameters, and their mechanisms are discussed. 57Fe Mossbauer spectroscopy is presented as a powerful tool for the identification, distinction, and characterization of individual polymorphs. The advantages of Mossbauer spectroscopy are demonstrated with two examples related to the study of the thermally induced solid-state reactions of Fe2(SO4)3.

Iron(III) Oxides from Thermal ProcessesSynthesis, Structural and Magnetic Properties, Mössbauer Spectroscopy Characterization, and Applications†

The discovery of periodic mesoporous MCM-41 and related molecular sieves has attracted significant attention from a fundamental as well as applied perspective. They possess well-defined cylindrical/hexagonal mesopores with a simple geometry, tailored pore size, and reproducible surface properties. Hence, there is an ever-growing scientific interest in the challenges posed by their processing and characterization and by the refinement of various sorption models. Further, MCM-41-based materials are currently under intense investigation with respect to their utility as adsorbents, catalysts, supports, ion-exchangers, and molecular hosts. In this article, we provide a critical review of the developments in these areas with particular emphasis on adsorption characteristics, progress in controlling the pore sizes, and a comparison of pore size distributions using traditional and newer models. The model proposed by the authors for adsorption isotherms and criticalities in capillary condensation and hysteresis is found to explain unusual adsorption behavior in these materials while providing a convenient characterization tool.

Recent advances in processing and characterization of periodic mesoporous MCM-41 silicate molecular sieves

The thermal decomposition of synthetic acicular microcrystals of α-FeOOH has been investigated by nitrogen adsorption isotherms, powder X-ray diffraction patterns, and electron microscopic observation. The surface area of the microcrystals determined from the nitrogen isotherms increases remarkably with the progress of decomposition. The highest surface area is obtained on a sample decomposed in vacuo at 300°C for 4 hr. On samples calcined at temperatures higher than 300°C, their surface areas decrease significantly. It has been found from de Boer's t plot that the marked increase in surface area can be attributed to the formation of approximately uniform slitshaped micropores, their width being estimated to be 0.82 nm. The presence of such micropores has been confirmed by electron microscopic observation. The marked decrease in surface area accompanies the disappearance of micropores and the appearance of macropores. The nonuniform broadening of the X-ray diffraction peaks for the sample decomposed at 300°C can be explained on the basis of the slit-shaped micropores developed along the c axis of the α-FeOOH microcrystals.

Micropore formation due to thermal decomposition of acicular microcrystals of α-FeOOH

Analysis of Nitrogen Adsorption Isotherms for a Series of Porous Silicas with Uniform and Cylindrical Pores: A New Method of Calculating Pore Size Distribution of Pore Radius 1-2 nm

Analysis of adsorption isotherms of water vapor for nonporous and porous adsorbents

The surface interaction of water vapor with the hydroxylated and dehydroxylated surfaces of silica gel and porous silica glass has been investigated by measuring the adsorption and desorption isotherms of water vapor at 20°C. On the dehydroxylated surfaces, true adsorption equilibrium was not obtained in the first adsorption isotherms because of slow chemisorption, but the first desorption ones held true equilibrium. The chemisorbed water determined from the last point of the first desorption isotherm increases as the pretreatment temperature increases until 600°C, and then decreases. From comparison between the chemisorbed water and the amount of water eliminated by thermal treatment, the degree of the rehydroxylation on both silica gel and porous silica glass has been determined. The rehydroxylation is reversible below 400°C, and not reversible above 400°C; the higher the pretreatment temperatures, the less the degree of rehydroxylation. After obtaining the first desorption isotherm, the second desorption one was measured on the rehydroxylated surface. The physisorbed water at monolayer coverage was estimated by applying the BET equation to the second desorption isotherm. The relationship between physisorbed water and the underlying hydroxyl group was examined.

Hiromitu Naono

Papers

Micropore formation due to thermal decomposition of acicular microcrystals of α-FeOOH

Analysis of Nitrogen Adsorption Isotherms for a Series of Porous Silicas with Uniform and Cylindrical Pores: A New Method of Calculating Pore Size Distribution of Pore Radius 1-2 nm

Analysis of adsorption isotherms of water vapor for nonporous and porous adsorbents

Determination of physisorbed and chemisorbed waters on silica gel and porous silica glass by means of desorption isotherms of water vapor

Thermal decomposition of γ-FeOOH fine particles