Abstract
With an experimental setup of near-infrared process analytical chemistry, a competitive adsorption process of orthoxylene and aniline vapor onto silica gel has been revealed in the paper. The mixture vapor of orthoxylene and aniline has been introduced into a quartz adsorption bed, which was filled with adsorbent of silica gel and monitored continuously by a near-infrared spectrometer. Based on near-infrared spectra recorded during the adsorption process and chemometrics methodologies, the competitive adsorption process has been studied completely as well as clearly: 1) at about 62 minutes the adsorption achieved its equilibrium or stable state with aniline concentration of 0.22 g/g, and without any orthoxylene; 2) othoxylene was adsorbed first, but then rapidly replaced by aniline; 3) the adsorption of aniline resulted from the hydrogen bonds between aniline’s amino groups and silica gel’s silanol groups while that of orthoxylene was due to physical adsorption; 4) aniline was adsorbed vertically on the silica gel but orthoxylene laid evenly; 5) some surface of silica gel was more active for adsorption than others.
Highlights
From the standpoint of chemistry and chemical engineering, a complete understanding of a process of gas-solid adsorption process means: 1) thermodynamic of the process, such as its equilibrium concentration; 2) kinetics of the process, mainly, the adsorption rate of every adsorbate at any time; 3) the interaction between adsorbate and adsorbent, and 4) the adsorption state, namely, how the gas molecules are adsorbed on the surface of adsorbent [1,2,3]
Thermodynamic and kinetic of the process is indispensable to designing or operating industrial adsorption equipment, while the interaction between adsorbate adsorbent as well as the adsorption state are important for chemists to comprehend the mechanism of the adsorption process completely
The experimental setup is demonstrated in Figure 1: a small quartz rectangle cell that has been filled with silica granules and monitored by a spectrometer probe, and the gas introduced is the vapor mixture composed of orthoxylene, aniline and nitrogen gas
Summary
From the standpoint of chemistry and chemical engineering, a complete understanding of a process of gas-solid adsorption process means: 1) thermodynamic of the process, such as its equilibrium concentration; 2) kinetics of the process, mainly, the adsorption rate of every adsorbate at any time; 3) the interaction between adsorbate and adsorbent, and 4) the adsorption state, namely, how the gas molecules are adsorbed on the surface of adsorbent [1,2,3]. A number of traditional methods have been employed to study the thermodynamic or kinetics of adsorption process for a long time [4,5,6]. Information recorded in this way is synchronous, making it possible to combine all information for understanding the mechanism of an adsorption process much more clearly and thoroughly
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