BTEX and chlorinated aromatic hydrocarbons seriously contribute to surface and groundwaters pollution, mainly due to crude oil spill and to leakages from industrial wastewaters [1]. Sorption based technologies were demonstrated to be efficient and economical methods for the removal of these contaminants. Among the large number of inorganic adsorbents, the efficiency of organophilic zeolites for the removal of organic contaminants from dilute aqueous solutions has been proved [2, 3]. Due to their chemical composition and to the possibility to be completely regenerated at low temperatures, zeolites can be considered environmental friendly materials. In this work, hydrophobic zeolites ZSM-5 and Y, which differ in framework topology and channels system, were tested for the adsorption of aromatic hydrocarbons (toluene and chlorobenzene) and the results revealed high saturation capacities and fast kinetics. Since the presence of natural organic matter (NOM) can affect organic pollutants adsorption, the effect of lignin derivatives phenolic compounds on the adsorption properties was investigated. Molecular dimensions of the selected NOM monomers (caffeic acid and para-hydroxybenzaldheyde) are smaller than adsorbent pores size and similar to that of organic pollutants. Consequently, the phenolic compounds can be hosted into the zeolite frameworks. Experimental results, indeed, confirm that both caffeic acid and para-hydroxybenzaldheyde are highly adsorbed on zeolites. However, competitive adsorption of mixtures of organic pollutant and NOM monomer on zeolites shows that aromatic hydrocarbons are preferentially adsorbed. The selectivity and efficiency of the selected zeolites towards organic pollutants in presence of NOM make these adsorbents promising in remediation technologies of natural waters.
COMPETITIVE ADSORPTION OF ORGANIC POLLUTANTS AND LIGNIN DERIVATIVES PHENOLIC COMPOUNDS ON HYDROPHOBIC ZEOLITES
SARTI, Elena;PASTI, Luisa;MARTUCCI, Annalisa;CAVAZZINI, Alberto
2015
Abstract
BTEX and chlorinated aromatic hydrocarbons seriously contribute to surface and groundwaters pollution, mainly due to crude oil spill and to leakages from industrial wastewaters [1]. Sorption based technologies were demonstrated to be efficient and economical methods for the removal of these contaminants. Among the large number of inorganic adsorbents, the efficiency of organophilic zeolites for the removal of organic contaminants from dilute aqueous solutions has been proved [2, 3]. Due to their chemical composition and to the possibility to be completely regenerated at low temperatures, zeolites can be considered environmental friendly materials. In this work, hydrophobic zeolites ZSM-5 and Y, which differ in framework topology and channels system, were tested for the adsorption of aromatic hydrocarbons (toluene and chlorobenzene) and the results revealed high saturation capacities and fast kinetics. Since the presence of natural organic matter (NOM) can affect organic pollutants adsorption, the effect of lignin derivatives phenolic compounds on the adsorption properties was investigated. Molecular dimensions of the selected NOM monomers (caffeic acid and para-hydroxybenzaldheyde) are smaller than adsorbent pores size and similar to that of organic pollutants. Consequently, the phenolic compounds can be hosted into the zeolite frameworks. Experimental results, indeed, confirm that both caffeic acid and para-hydroxybenzaldheyde are highly adsorbed on zeolites. However, competitive adsorption of mixtures of organic pollutant and NOM monomer on zeolites shows that aromatic hydrocarbons are preferentially adsorbed. The selectivity and efficiency of the selected zeolites towards organic pollutants in presence of NOM make these adsorbents promising in remediation technologies of natural waters.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
