Adsorption of Chlorinated Compounds (Chlorobenzene, Chloroform, and Carbon Tetrachloride) on Microporous SiO₂, Ag-Doped SiO₂and Natural and Dealuminated Clinoptilolites

Abstract

Adsorption isotherms of chloroorganic compounds on natural and dealuminated clinoptilolite zeolites, as well as on pure and Ag-doped microporous SiO 2 , were measured by a gas chromatography technique. The SiO 2 microporous solids were synthesized by the sol-gel method from tetraethoxysilane and in the presence of methanol. Dealuminated clinoptilolite zeolites were obtained by means of HCl treatment of a natural precursor. Adsorption of chlorinated compounds (C x H y Cl z ), such as chlorobenzene, chloroform, and carbon tetrachloride, on SiO 2 , Ag-doped SiO 2 and on the clinoptilolite zeolites was studied in the temperature range of 398-498 K. The Freundlich and Dubinin-Astakhov adsorption equations approximately fitted the C x H y -Cl z adsorption data, within the selected temperature range. The energies of interaction between chlorinated adsorbates and microporous SiO 2 , Ag-doped SiO 2 , and clinoptilolite substrates were evaluated from the isosteric heats of adsorption (q st ), which were found to obey the following decreasing order: q st (chlorobenzene) > q st (chloroform) > q st (carbon tetrachloride).

Adsorption of Polychlorinated Aromatics in EMT-Type Zeolites: A Combined Experimental-Simulation Approach

“…Concerning porous carbons, Li et al applied thermo-gravimetric analysis to investigate the gas-phase chlorobenzene adsorption in activated carbons, whereas Bell et al determined the influence of surface functional groups on the adsorption properties of several PClAs within microporous carbons . Concentrating on zeolite adsorbents, Hernandez et al used the inverse gas chromatography technique to describe the adsorption of chlorobenzene in dealuminated clinoptilolite . Furthermore, applying the pulse chromatography technique, Canet et al examined the adsorption of volatile organic compounds including chlorobenzene in faujasites (FAUs), by revealing that the zeolite chemical composition can influence the adsorption isotherms, especially in the Henry domain.…”

“…28 Concentrating on zeolite adsorbents, Hernandez et al used the inverse gas chromatography technique to describe the adsorption of chlorobenzene in dealuminated clinoptilolite. 29 Furthermore, applying the pulse chromatography technique, Canet et al 30 examined the adsorption of volatile organic compounds including chlorobenzene in faujasites (FAUs), by revealing that the zeolite chemical composition can influence the adsorption isotherms, especially in the Henry domain. Finally, some of us recently described the adsorption of dichlorobenzene (DClB) in the *BEA and/or FAU-type zeolites, respectively, from the experimental 23,24 and simulation points of view.…”

Prediction of Adsorption Equilibrium of VOCs onto Hyper-Cross-Linked Polymeric Resin at Environmentally Relevant Temperatures and Concentrations Using Inverse Gas Chromatography

“…Recently, it has been proved that inverse gas chromatography (IGC) is a straightforward and very sensitive technique for the characterization of porous adsorbent. − Compared with traditional gravimetric and volumetric methods, the smaller amount of adsorbent and the shorter experimental time were required for IGC measurements at the finite concentration to determine adsorption isotherms. However, it is noted that the adsorbent-packed column temperature of IGC such as 343–548 K, − is generally higher than the operation temperature of adsorption units in practical engineering application. Moreover, the VOCs concentrations measured in IGC are far lower than the emission concentration of VOCs from manufacturing facilities. − For the design of a reliable adsorption system, therefore, it is necessary to predict the adsorption isotherms at environmentally relevant temperatures and concentrations (corresponding to practical environmental systems) according to the adsorption equilibrium data obtained using IGC.…”

Adsorption characteristics of carbon tetrachloride from aqueous solution onto polyacrylonitrile-based activated carbon fiber

“…The maximum concentration level of CT is set at 5 and 2 µg/L in safe drinking water act [1] and standards for drinking water quality (GB 5749-2006), respectively. Many kinds of methods were applied to removing CT from water or wastewater, such as reductive dechlorination [2], biodegradation [3], oxidation [4], ultrasonic destruction [5], photoelectrochemical degradation [6], and adsorption [7]. Adsorption is one of the most effective and widely used techniques because of its relatively simple design, easy operation and simple regeneration.…”