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Sorption Of Perfluorooctane Sulfonate On Sediment And Its Effect On Sorption Of Other Organic Contaminants

Posted on:2011-03-21Degree:MasterType:Thesis
Country:ChinaCandidate:X X HaoFull Text:PDF
GTID:2121360305955590Subject:Environmental Engineering
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Sorption of organic pollutants by soil or sediment plays an important role in their transport, fate and bioavailability in natural environment. Perfluorooctane Sulfonate (PFOS) is a new member of persistent organic pollutants (POPs), but its sorption and potential effects on sorption of other organic pollutants are still unclear. The further understanding of the interaction mechanism between PFOS and other organic pollutants will help us to evaluate and predict the complicated performance and ecological risk of organic pollutants in the environment, and will provide scientific basis for regulation, control, and remediation of organic pollutants.Based on the sorption of PFOS on sediment, the sorptions of PFOS and other three organic contaminants were investigated. At first, the effects of pH,Ca2+and black charcoal (BC) on sorption of PFOS on sediment were investigated, in addition, sorption of PFOS on combusted sediment was discussed detailedly. Besides, sorption of PFOS and other three organic contaminants (nitrobenzene, phenonthrene and nonylphenol) on sediment were studied to find the mechanism of complex pollution. The main conclusions of this dissertation are as follows:(1) Sorption of PFOS was well fitted by Freundlich isotherm equation and the results showed that sorption of PFOS on the sediment is nonlinear, which is the result of partition and surface sorption;(2) In the natural state (pH=7.96), sorption capacity of PFOS was the least; stronger acidity or alkaline resulted in greater sorption capacity. Because of salting out effect and surface charge of sediment, more PFOS was adsorbed when Ca2+existed and sorption capacity increased with the increasing of Ca2+concentration;(3) After the sediment being combusted, sorption capacity of PFOS decreased distinctly, and sorption was more nonlinear. BC did not show a strong adsorption capacity of PFOS. Two different sources of BC both increased the sorption capacity of PFOS, and BC1> BC2, which was consistent with their specific surface area. Sorption was more nonlinear when BC concentration increased;(4) At low concentrations, PFOS inhibited the sorption of nitrobenzene on the sediment; but at high concentration PFOS promoted the sorption. For phenonthrene and nonylphenol sorption, the influence of PFOS was just on the contrary:low PFOS concentrations promoted the sorption and high PFOS concentrations inhibited the sorption. This was related to the Kd values of the organic pollutants. The adding sequence had more influence on inhibition of the adsorption, and this further proved that the competitive sorption of PFOS was the main reason which leaded to the reduction of organic pollutants sorption capacity on the sediment. The effect of PFOS on the sorption of other contaminants on sediment is the result of two mechanism:increasing the organic content to raise and competing to decrease the sorption number;(5) Nonylphenol affected the sorption of PFOS most in the three organic pollutants. This was related to its unique structure and other sorption mechanisms.These results provided reliable data and theoretical basis for understanding and predicting the transfer behavior of PFOS and other organic pollutants (nitrobenzene, phenonthrene and nonylphenol) in complex pollution cases.
Keywords/Search Tags:PFOS, Sorption, BC, Nitrobenzene, Phenanthrene, Nonylphenol
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