Volatile Organic Compounds (VOCs) are water pollutants of concern, due to their widespread occurrence in natural and drinking waters and to their adverse effects on human health [1]. The adsorption efficiency of hydrophobic zeolites toward unary mixtures of VOCs in water has already been proved [2-3]. Different contaminants have been investigated (i. e. methyl tert-butyl ether, toluene, 1,2-dichloroethane and chlorobenzene) which were selected to represent different VOC classes: oxygenated, aromatics, chlorinated aliphatics and chlorinated aromatics, respectively. Since usually multiple pollutants coexist in the environment, the quantification of competitive interactions is important to predict the adsorption capability of materials for complex aqueous mixtures. This study aims to evaluate the adsorption of binary mixtures of VOCs in aqueous solutions on a commercial hydrophobic zeolite ZSM-5. To investigate the kinetics and the thermodynamics of the adsorption process, equilibrium measurements were carried under different operative conditions and structural analysis was performed on the loaded zeolite. The results showed that the adsorption capabilities of ZSM-5 for all the compounds were reduced in the presence of a second component in the mixture, in comparison with the single-component data, indicating a competitive adsorption. The binary system was described by a competitive dual site Langmuir adsorption isotherm, according to the results obtained by structural analysis. It has been found that each site inside the zeolite framework cannot be occupied simultaneously by more than one component, because of the short intermolecular distances among the adsorption sites. [1] Volatile Organic Compounds in the Nation’s Ground Water and Drinking-Water Supply Wells; Circular 1292, 2006, U.S. Geological Survey [2] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani, Microporous and Mesoporous Materials, 215, 175-182.(2015) [3] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today (2015), in press
COMPETITIVE ADSORPTION OF VOCs FROM AQUEOUS SOLUTIONS ON HYDROPHOBIC ZEOLITES
SARTI, Elena;PASTI, Luisa;CAVAZZINI, Alberto;MARTUCCI, Annalisa;RODEGHERO, Elisa;
2016
Abstract
Volatile Organic Compounds (VOCs) are water pollutants of concern, due to their widespread occurrence in natural and drinking waters and to their adverse effects on human health [1]. The adsorption efficiency of hydrophobic zeolites toward unary mixtures of VOCs in water has already been proved [2-3]. Different contaminants have been investigated (i. e. methyl tert-butyl ether, toluene, 1,2-dichloroethane and chlorobenzene) which were selected to represent different VOC classes: oxygenated, aromatics, chlorinated aliphatics and chlorinated aromatics, respectively. Since usually multiple pollutants coexist in the environment, the quantification of competitive interactions is important to predict the adsorption capability of materials for complex aqueous mixtures. This study aims to evaluate the adsorption of binary mixtures of VOCs in aqueous solutions on a commercial hydrophobic zeolite ZSM-5. To investigate the kinetics and the thermodynamics of the adsorption process, equilibrium measurements were carried under different operative conditions and structural analysis was performed on the loaded zeolite. The results showed that the adsorption capabilities of ZSM-5 for all the compounds were reduced in the presence of a second component in the mixture, in comparison with the single-component data, indicating a competitive adsorption. The binary system was described by a competitive dual site Langmuir adsorption isotherm, according to the results obtained by structural analysis. It has been found that each site inside the zeolite framework cannot be occupied simultaneously by more than one component, because of the short intermolecular distances among the adsorption sites. [1] Volatile Organic Compounds in the Nation’s Ground Water and Drinking-Water Supply Wells; Circular 1292, 2006, U.S. Geological Survey [2] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani, Microporous and Mesoporous Materials, 215, 175-182.(2015) [3] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today (2015), in pressI documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
