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1. Factors Influencing the Kinetics of Water Vapour Adsorption on Activated Carbons

Author

Y. Boutillara, L. Richelet, L.F. Velasco, and P. Lodewyckx

Subjects
activated carbon, kinetics, water adsorption, LDF model, air flow, relative humidity, Chemistry, QD1-999
Abstract

The performance of porous carbon materials as sorbents is often compromised by the presence of humidity. Studying the kinetics of water vapour adsorption on activated carbons will undeniably help to overcome this issue. This has been approached in this work by evaluating the influence of several operational factors on the dynamic adsorption of water vapour in these materials. Specifically, different carbon types, particle sizes, air flows and ambient conditions (temperature and relative humidity (RH)) were systematically investigated. The impact of each isolated parameter on both the maximum water uptake and the uptake rate was analyzed by fitting the experimental data to the Linear Driving Force (LDF) kinetic model. The results show that except for the particle size, the studied variables play a role in the water sorption kinetics, although to a different extent. It was also confirmed that the LDF model can adequately describe the kinetics of water vapour adsorption independently of the experimental conditions. Finally, the complete water vapour adsorption process can be described by this model, obtaining a different value of the kinetic constant for the sequential stages, involving different adsorption mechanisms.

Published
2021
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2. Modified sorbents based on walnut shell for sorption of toxic gases

Author

Seitkhan Azat, L.F. Velasco, P. Lodewyckx, A. R. Kerimkulova, and Z. A. Mansurov

Subjects
010302 applied physics, Sorbent, Chemistry, Nanoporous, chemistry.chemical_element, Sorption, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Adsorption, Chemical engineering, 0103 physical sciences, medicine, Texture (crystalline), 0210 nano-technology, Cobalt, Carbon, Activated carbon, medicine.drug
Abstract

In this article, low-cost carbon-based nanoporous materials were synthesized and impregnated in order to offer a sufficient protection for a wide range of toxic chemicals. The microstructure analysis of the samples reveals that the activation promotes the formation of a higher number of small pores and the development of a spongy texture of the sorbents leading thus to an increase in carbon content. The activated samples have apparent micro-mesoporosity confirmed by the corresponding isotherms of low-temperature adsorption of nitrogen. Furthermore, it has been shown that the activation procedure leads to samples with different acidity and this surface property has a marked influence on the performance of the materials. The results of a breakthrough time study for vapors of inorganic and organic substances indicate that the impregnations with Cu and Co are the most suitable for obtaining a universal sorbent. In this regard, an activated carbon impregnated with cobalt that can outperform commercial reference materials intended for this specific application has been developed in this work.

Published
2022

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