Competitive adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5

Abstract

Adsorption equilibria of methyl tert-butyl ether (MTBE)/toluene (TOL), and 1,2-dichloroethane (DCE)/MTBE binary mixtures in aqueous solution on ZSM-5 were measured over a wide range of concentrations. In comparison with the single-component data, the loading of all of the three compounds was reduced in the presence of a second component in the mixture. The binary system was described by a competitive dual site Langmuir adsorption isotherm. The model was chosen on the basis of the results obtained from X-ray diffraction studies of the adsorbent material loaded with equimolar binary mixtures. Rietveld structure refinements provide information about the relative position of molecules inside the structure after TOL-MTBE and DCE-MTBE mixture adsorption. The short intermolecular distances between the adsorption sites of MTBE, DCE and TOL inside the zeolite framework clearly prevent the simultaneous occupancy of one site by more than one component, when these compounds are adsorbed from binary mixtures

Insights into Adsorption of Chlorobenzene in High Silica MFI and FAU Zeolites Gained from Chromatographic and Diffractometric Techniques

“…It can be seen that the kinetics of the adsorption process was very fast; the equilibrium was reached in about 10 min. Similar behaviors were also observed for the adsorption of other aqueous contaminants, such as dichloroethane and toluene onto ZSM-5 and Y zeolites [5][6][7][8][9][10]13].…”

“…We have previously verified [5][6][7][8][9][10]13] that uptake data of the investigated zeolites can be fitted by the pseudo-second order model as:…”

“…It has been already shown that adsorption of organics in aqueous solutions onto ZSM-5 hydrophobic zeolites are well fitted by the Langmuir equation [5,6,8,13], that assumes monolayer adsorption onto energetically equivalent adsorption sites and negligible sorbate-sorbate interactions. The relationships describing the Langmuir isotherm is [38]:…”

“…Actually, the physical method based on adsorption processes is a recuperative method exploited for in situ water treatments which combines high flexibility of the system, efficiency even at low concentration levels, low energy, cheap operating costs, and possible waste reductions [3]. Different adsorbent materials can be employed, and their efficiency depends on the host-guest interactions between sorbent and sorbate [4][5][6][7][8][9][10][11][12][13]. In general, carbonaceous adsorbents are low cost materials, widely employed in remediation technology.…”

“…The main advantages are related to their high surface area and porous structure, high specific capacity and organic pollutants selectivity. Additionally, fast kinetics, mechanical, biological and chemical stability make them promising and efficient adsorbents [4,[6][7][8][26][27][28]. Furthermore, their high thermal stability guarantees the possibility of regeneration through thermal treatments in order to reintroduce them in new adsorption processes [5,[29][30][31][32][33].…”