Preparation Of Cyclodextrin-Triolein Embedded Cellulose Acetate Membrane And Its Uptake Efficiency Of Dissolved PAHs In Aqueous Solution

This dissertation is composed of four chapters.Chapter one is the preface.First,the properties,sources,fate of polycyclic aromatic hydrocarbons(PAHs) and its effects on human and environment were present.The progress on bioavailability of PAHs and its estimated methods,especially the semi-permeable membrane device(SPMD) method,were introduced.The determination methods of PAHs were then discussed.Besides,the structure, properties of cyclodextrins(CDs) and their applications to environmental science were also introduced.Finally,the proposal of dissertation was illuminated.Chapter two is the preparation and characterization of a novel passive sampling membrane,cyclodextrin-triolein embedded cellulose acetate membrane(C-TECAM). On the basis of the triolein embedded cellulose acetate membrane(TECAM),β-CD was introduced to C-TECAM as a novel pore-forming material.C-TECAM was prepared by wet phase inversion technique in which triolein andβ-CD were embedded.C-TECAM was ivory-white apparently and 115-122μm in thickness. C-TECAM was hydrophilic with water content between 64.83%-65.77%and porosity between 33.80%-35.65%.The mechanical strength of C-TECAM was improved 38.22%averagely compared to cellulose acetate membrane.C-TECAM was stable in typical acidic and basic conditions(pH=4.49-9.18) and in organic solvents such as hexane and cyclohexane,except dichloromethane.Chapter three is the establishment of simultaneous determination of Naphthalene (Na),Anthracene(An) and Benzo(a)pyrene(BaP) by synchronous fluorimetry.With the new method,Na,An and BaP can be simultaneously determined in a mixture aqueous solution and in a mixture cyclohexane solution respectively.The linear ranges for the determination of Na,An and BaP in aqueous solution were 0.5-20.0μg/L,0.5-20.0μg/L and 0.5-5.0μg/L with the limits of detection 0.37,0.021 and 0.048μg/L,respectively and the relative standard deviations were less than 10% (n=5).Satisfactory recovery experimental results were between 84.4%-123.9%in spiked water samples.The advantage of the established method was sensitive and did not necessitate a complex pretreatment.It could be a simple,sensitive and rapid method to investigate the accumulation efficiency of C-TECAM to PAHs in aquatic environment and be a useful method for further on-line study.On the other hand, simultaneous determination of Na,An and BaP by synchronous fluorimetry in cyclohexane solution was also established to study the accumulation efficiency of C-TECAM from the membrane phase.As the fluorescence quantum yield of PAHs was higher in cyclohexane solution,apparatus parameters were changed to get a corresponding sensitivity in cyclohexane solution as well as that in aqueous solution. The linear ranges for the determination of Na,An and BaP in cyclohexane were 5.0-80.0μg/L,2.0-80.0μg/L and 2.0-80.0μg/L with the limits of detection 0.62,0.056 and 0.082μg/L,respectively and the relative standard deviations were less than 5% (n=5).Satisfactory recovery experimental results were between 90.8%-103.8%in spiked cyclohexane samples.Chapter four is the laboratory simulated exposure experiment of C-TECAM to Na,An and BaP.The exposure of C-TECAM to three PAHs in aquatic environment was studied in static exposure system by synchronous fluorimetry.Na,An and BaP could be accumulated rapidly by C-TECAM,concentrations of three PAHs increased in C-TECAM while those decreased in aqueous solution till uptake equilibrium. Equilibrium time was directly proportional to octane-water partition coefficient (logK_ow).Na,with logK_ow 3.45,could reach equilibrium in about 2 hours,while An and BaP,with logK_ow 4.54 and 6.35,needed 6 and 12 hours to equilibrium, respectively.C-TECAM was proved to be a more rapid accumulation method which could shorten equilibrium time compared to "sandwich" SPMD.The equilibrium concentrations of Na,An and BaP were increased with the introduction ofβ-CD to C-TECAM.Meanwhile,the uptake rates of Na and An were decreased and the uptake rate of BaP were improved with the addition of 0.5%β-CD.The membrane-water partition coefficient(logK_m) of three PAHs in C-TECAM was linear correlated to their logK_ow as well as bioconcentration factors(logK_BCF).Besides,C-TECAM could be regeneration for another accumulation of three PAHs.The results indicated that C-TECAM could be a more efficient and economic method for the estimation of the bioavailable concentrations of PAHs.