The enormous and rapid development of the chemical and agrochemical industries during the last century has resulted in the release of a large number of chemical compounds into the environment. Aquatic ecosystems are especially vulnerable because water bodies are frequently used, directly or indirectly, as recipients of potentially toxic liquids and solids from domestic, agricultural and industrial wastes. Removal of fuel-based compounds from natural water is of considerable interest due to the harmful effects of these pollutants on the environment, even at very low concentration [1]. Among this category of compounds, toluene, 1,2-dichloethane and methyl-tert-buthyl-ether are of special relevance since are toxic and commonly found in natural water. Research on hydrocarbon removal has been mainly focussed on single components from air matrix, whereas the studies involving aqueous dilute solutions are few [2-5]. Adsorption is a reliable alternative to eliminate these organic compounds from wastewaters because of the flexibility of the system, low energy and cheap operation costs. Moreover, the process does not induce the formation of oxidation intermediates which are, to date, mostly unknown. The presence of natural organic matter can significantly affect organic pollutant adsorption by either competing for adsorption sites, or restricting access to (micro)pores. This work is a part of a wider project whose purpose is to study the interaction and mobility of ground water pollutants adsorbed in the zeolites pores. Organophilic synthetic zeolites which are cheap and available on the market, differing in topology, channel systems and free window apertures, and fuel-based-pollutants differing in chemical properties and molecular dimensions, were tested. In particular, structural evidences of adsorption from dilute solutions into organophilic zeolite as well as the competitive role of humic acid monomers, the effect of the temperature in the adsorption processes will be discussed. The selected adsorbents were commercial as-synthesized hydrophobic ZSM-5 and Y zeolites with high SiO2/Al2O3. Kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. X-ray powders patterns were collected before and after adsorption on a Bruker D8 Advance diffractometer equipped with SOL-X detector. Thermal analyses (TG and DTA) were performed in air up to 900°C at 10°C/min. Infrared spectra were collected on a Thermo Electron Corporation FT Nicolet 5700 Spectrometer. This combined diffractometric, thermogravimetric, chromatographic and spectroscopic study allowed us to: 1) measure the sorption capacity of hydrophobic zeolite materials weighed against organic pollutants dissolved in water; 2) characterise the structure after contaminants adsorption; 3) localise the organic species in the zeolite channel systems; 4) highlight the role of humic acid monomers in the pollutants removal; 5) probe the interaction between the adsorbate and the zeolite framework. The very favorable adsorption kinetics along with the effective and highly irreversible adsorption into zeolite pores make these cheap and environmental friendly materials applicable for the treatment of water contaminated with fuel-based pollutants. References. [1] Trindade P.V.O., Sobral L.G. , Rizzo A.C.L., Leite S.G.F. (2005) Chemosphere, 58, 515–522; [2] L.Abu-Lail, J. A. Bergendahl, R. W. Thompson, Journal of Hazardous Materials 2010, 178, 363-369. [3] Martucci A., Pasti L., Nassi M., Alberti A., Arletti R., Bagatin R., Vignola R., Sticca, R. (2012) Micropor. Mesopor. Mater. 148, 174-183. [4] Arletti, R., Martucci, A., Alberti, A., Pasti, L., Nassi, M., Bagatin, R. (2012) Journal of Solid State Chemistry, 194, 135-142.[5] Pasti L., Martucci A., Nassi M., Cavazzini A., Alberti A., Bagatin, R. (2012) Microporous and Mesoporous Materials, 160, 182-193.
FUEL-BASED POLLUTANTS REMOVAL FROM WATER: STRUCTURAL EVIDENCES OF ADSORPTION INTO HIGH SILICA ZEOLITES
MARTUCCI, Annalisa;PASTI, Luisa;
2014
Abstract
The enormous and rapid development of the chemical and agrochemical industries during the last century has resulted in the release of a large number of chemical compounds into the environment. Aquatic ecosystems are especially vulnerable because water bodies are frequently used, directly or indirectly, as recipients of potentially toxic liquids and solids from domestic, agricultural and industrial wastes. Removal of fuel-based compounds from natural water is of considerable interest due to the harmful effects of these pollutants on the environment, even at very low concentration [1]. Among this category of compounds, toluene, 1,2-dichloethane and methyl-tert-buthyl-ether are of special relevance since are toxic and commonly found in natural water. Research on hydrocarbon removal has been mainly focussed on single components from air matrix, whereas the studies involving aqueous dilute solutions are few [2-5]. Adsorption is a reliable alternative to eliminate these organic compounds from wastewaters because of the flexibility of the system, low energy and cheap operation costs. Moreover, the process does not induce the formation of oxidation intermediates which are, to date, mostly unknown. The presence of natural organic matter can significantly affect organic pollutant adsorption by either competing for adsorption sites, or restricting access to (micro)pores. This work is a part of a wider project whose purpose is to study the interaction and mobility of ground water pollutants adsorbed in the zeolites pores. Organophilic synthetic zeolites which are cheap and available on the market, differing in topology, channel systems and free window apertures, and fuel-based-pollutants differing in chemical properties and molecular dimensions, were tested. In particular, structural evidences of adsorption from dilute solutions into organophilic zeolite as well as the competitive role of humic acid monomers, the effect of the temperature in the adsorption processes will be discussed. The selected adsorbents were commercial as-synthesized hydrophobic ZSM-5 and Y zeolites with high SiO2/Al2O3. Kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. X-ray powders patterns were collected before and after adsorption on a Bruker D8 Advance diffractometer equipped with SOL-X detector. Thermal analyses (TG and DTA) were performed in air up to 900°C at 10°C/min. Infrared spectra were collected on a Thermo Electron Corporation FT Nicolet 5700 Spectrometer. This combined diffractometric, thermogravimetric, chromatographic and spectroscopic study allowed us to: 1) measure the sorption capacity of hydrophobic zeolite materials weighed against organic pollutants dissolved in water; 2) characterise the structure after contaminants adsorption; 3) localise the organic species in the zeolite channel systems; 4) highlight the role of humic acid monomers in the pollutants removal; 5) probe the interaction between the adsorbate and the zeolite framework. The very favorable adsorption kinetics along with the effective and highly irreversible adsorption into zeolite pores make these cheap and environmental friendly materials applicable for the treatment of water contaminated with fuel-based pollutants. References. [1] Trindade P.V.O., Sobral L.G. , Rizzo A.C.L., Leite S.G.F. (2005) Chemosphere, 58, 515–522; [2] L.Abu-Lail, J. A. Bergendahl, R. W. Thompson, Journal of Hazardous Materials 2010, 178, 363-369. [3] Martucci A., Pasti L., Nassi M., Alberti A., Arletti R., Bagatin R., Vignola R., Sticca, R. (2012) Micropor. Mesopor. Mater. 148, 174-183. [4] Arletti, R., Martucci, A., Alberti, A., Pasti, L., Nassi, M., Bagatin, R. (2012) Journal of Solid State Chemistry, 194, 135-142.[5] Pasti L., Martucci A., Nassi M., Cavazzini A., Alberti A., Bagatin, R. (2012) Microporous and Mesoporous Materials, 160, 182-193.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
