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Abstract  

DNA adsorbed very low amount of water at low relative humidities, amount of adsorption increased to 140% at 98% relative humidity at 25°C. Heat of adsorption was 109 kJ mol-1 H2O for the increase of moisture content from 0 to 1.96%. At higher moisture contents the heat released approached heat of condensation of water vapour on free liquid surface, 40 kJ mol-1 H2O.

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and adsorptive, shape and size of pores, etc. Aristov et al. [ 8 ] obtained sorption behavior of water vapor on Fuji RD silica gels which have 820 m 2 g −1 BET surface areas and particle size between 0.3 and 1.0 mm using CAHN 2000 thermo

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water vapor adsorption isotherm. References 1. Elmchaouri , A , Simonot-Grange , MH , Mahboub , R . Water vapour adsorption onto Ca 2+ Camp-Berteau montmorillonite

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Abstract  

The interaction between samples of metallic zinc and water vapour was studied gravimetrically, both in the absence and in the presence of oxygen. The experimental total mass gain vs. time curves exhibited two plateaus, whose heights increased with, elevations both of relative humidity and of temperature. The amount of product retained on the surface after desorption was also determined as a function of time. The product was identified as hydrated zinc oxide. In the runs conducted without oxygen, the retained product curves displayed a time delay with respect to the total mass gain curves. In the presence of oxygen, however, there was practically only one chronogravimetric curve. This behaviour is interpreted on the basis of a common mechanism involving the formation of an intermediate precursor oxide, which is more readily formed in the presence of oxygen than in its absence. A set of mathematical equations was derived, from which the rate constants for both processes were obtained. The second step was ascribed to a further weak adsorption of water.

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Summary A novel instrument for high temperature thermogravimetric measurements in atmospheres containing high water vapour contents was developed in a collaboration between Netzsch and Risø National Laboratory. The development of the instrument was initiated to facilitate the investigation of high temperature corrosion of steels in humidified atmospheres. The instrument consists of a standard thermal analyser unit, including a new water vapour furnace, balance and sample carrier. The design of the instrument is discussed and thermogravimetric measurements on a Fe78Cr22 steel are presented.

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performances in a Mediterranean climate. Aristov et al. [ 18 ] have proposed and tested a new methodology of studying the kinetics of water vapor sorption/desorption on pellets of composite sorbent SWS-1L (CaCl 2 in silica KSK) placed on a metal plate. Many

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soft-chemistry approach was developed to prepare hydrogen titanate nanotubes. Layered titanate-K 2 Ti 2 O 5 was used as precursor and treated with water vapour. After removing potassium ion in acid solution, hydrogen titanate nanotubes were formed. If

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Abstract  

Two types of films consisting of sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) as film forming materials and glycerin as plasticizer were prepared, characterized and their water vapour sorption properties were determined. The water sorption isotherms of the films were measured using a magnetic suspension balance. Results show that diffusion of water vapour in NaCMC based film is faster than that in HPC based films, due to the heterogeneous structure and larger pore dimensions of the NaCMC films.

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Abstract  

Water vapour adsorption on polymers affects their processing behaviour and useful properties. Water vapour adsorption on organic polymers, silk, Nylon 6 fibres in undrawn and permanent set forms, polyester micro fibres, plasticised PVC films with 60 phr dioctylphthalate (DOP) and inorganic polymer sepiolite particles were investigated in this study. The materials were examined using the BET equation. The surface areas of silk, cast Nylon 6 and muss Nylon 6 were determined as 108, 46 and 23 m2 g–1, respectively. Sepiolite did not fit BET equation. Polyester and PVC adsorbed very small amounts of moisture.

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Abstract  

The gravimetric measurement of the moisture content of solids is discussed in comparison to other usual methods. Results of measurements of silica gel are reported. Furthermore, we inform on standardisation work.

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