The Adsorption of Phosphate on Mica Surfaces

<p>The surface chemistry of the 001 face of cleaved mica sheets was studied with a view to understanding some of the fundamental processes underlying the phenomenon of fixation of phosphate by soils. Radiochemical techniques were developed to make quantitative studies of the adsorption, an important part of these being practical procedures for obtaining sufficient cleanliness and freedeom from airborne contamination. Lack of uniformity of adsorption, as shown by autoradiography, was taken to indicate contamination, and techniques were developed to avid this. Other techniques enabled the continuous monitoring of the sample during adsorption or desorption kinetic experiments. It was shown that adsorption of phosphate on the untreated mica sheets was low, but the adsorption was greatly enhanced if the mica had been treated with aqueous solutions of certain cations such as gallium, aluminium and iron. Form the measurement of the amount of phosphate adsorbed, as a function of the conditions of aluminium treatment, it was concluded that the phosphate could be absorbed by at least three different processes, all of which could be of importance in phosphate fixation by soils. As well as these processes, which occurred on clean, flat, mica surfaces, there were others, involving the edges of mica and sheets, and unknown, but probably organic, films on both mica and air-water surfaces. These could all be of comparable importance in soils. The kinetic measurements of phosphate adsorption and desorption on aluminium-treated mica indicated that many hours were required for attainment of equilibrium, and were quantitatively consistent with the hypothesis that in some cases the adsorption and desorption kinetics were controlled by diffusion of phosphate into particles of some material, possibly a hydrous oxide, adsorbed on the mica. The existence of such particles was supported by the fact that up to one phosphate molecule per two square Angstrom units of mica surface was adsorbed, (and this did not appear to be a value at which the surface was saturated.) Kinetic measurements of 67 Ga sorption processes were consistent with diffusion of gallium through a thin water film, with a diffusion coefficient several orders of magnitude lower than that of single ions in free solution. This may indicate that the gallium was adsorbing as particles, in agreement with the requirements of the phosphate experiments.</p>

The Adsorption of Phosphate on Mica Surfaces

<p>The surface chemistry of the 001 face of cleaved mica sheets was studied with a view to understanding some of the fundamental processes underlying the phenomenon of fixation of phosphate by soils. Radiochemical techniques were developed to make quantitative studies of the adsorption, an important part of these being practical procedures for obtaining sufficient cleanliness and freedeom from airborne contamination. Lack of uniformity of adsorption, as shown by autoradiography, was taken to indicate contamination, and techniques were developed to avid this. Other techniques enabled the continuous monitoring of the sample during adsorption or desorption kinetic experiments. It was shown that adsorption of phosphate on the untreated mica sheets was low, but the adsorption was greatly enhanced if the mica had been treated with aqueous solutions of certain cations such as gallium, aluminium and iron. Form the measurement of the amount of phosphate adsorbed, as a function of the conditions of aluminium treatment, it was concluded that the phosphate could be absorbed by at least three different processes, all of which could be of importance in phosphate fixation by soils. As well as these processes, which occurred on clean, flat, mica surfaces, there were others, involving the edges of mica and sheets, and unknown, but probably organic, films on both mica and air-water surfaces. These could all be of comparable importance in soils. The kinetic measurements of phosphate adsorption and desorption on aluminium-treated mica indicated that many hours were required for attainment of equilibrium, and were quantitatively consistent with the hypothesis that in some cases the adsorption and desorption kinetics were controlled by diffusion of phosphate into particles of some material, possibly a hydrous oxide, adsorbed on the mica. The existence of such particles was supported by the fact that up to one phosphate molecule per two square Angstrom units of mica surface was adsorbed, (and this did not appear to be a value at which the surface was saturated.) Kinetic measurements of 67 Ga sorption processes were consistent with diffusion of gallium through a thin water film, with a diffusion coefficient several orders of magnitude lower than that of single ions in free solution. This may indicate that the gallium was adsorbing as particles, in agreement with the requirements of the phosphate experiments.</p>

Energy Harvesting Materials and Structures for Smart Textile Applications: Recent Progress and Path Forward

A major challenge with current wearable electronics and e-textiles, including sensors, is power supply. As an alternative to batteries, energy can be harvested from various sources using garments or other textile products as a substrate. Four different energy-harvesting mechanisms relevant to smart textiles are described in this review. Photovoltaic energy harvesting technologies relevant to textile applications include the use of high efficiency flexible inorganic films, printable organic films, dye-sensitized solar cells, and photovoltaic fibers and filaments. In terms of piezoelectric systems, this article covers polymers, composites/nanocomposites, and piezoelectric nanogenerators. The latest developments for textile triboelectric energy harvesting comprise films/coatings, fibers/textiles, and triboelectric nanogenerators. Finally, thermoelectric energy harvesting applied to textiles can rely on inorganic and organic thermoelectric modules. The article ends with perspectives on the current challenges and possible strategies for further progress.

Current-voltage and spectral characteristics of heterostructures of fullerene-water system – N-isoamylisatin 4-methylphenylhydrazone

The paper presents the transmission and absorption spectra of electromagnetic radiation for thin films obtained by pouring from solutions of fullerene-water system and N-isoamylisatin 4-methylphenylhydrazone in chloroform. The method of obtaining, synthesis, microscopy of carbon and organic films is described. Shown are the spectra of the interaction of electro-magnetic radiation with thin films in the vision (400–920 nm) and IR (650–4000 cm-1) ranges. The optimal thicknesses of the active layers of the heterostructure based on aqueous solutions of fullerene and N-isoamylisatin 4-methylphenylhydrazone were determined, which made it possible to obtain the maximum increase in conductivity.