Rapid Determination Of Freely Dissolved Concentrations Of Organic Pollutants Based On Nanomaterials

Freely dissolved concentration(Cfree)decides the migration,distribution and bioaccumulation of various compounds in environment and therefore is considered as a crucial parameter for environmental chemistry,pharmacology and toxicology.The determination of Cfree is a key for explaining environmental process and bioavailability of compounds.Negligible-depletion extraction has been widely used for the determination of freely dissolved pollutants but is suffered from long equilibraction time.Thus,it is of great significant to develop novel methods for rapid determination of freely dissolved concentrations.Nanomaterials have been widely used to adsorb environmental pollutants because of their unique properties such as high specific surface area,uniform size,adjustable pore size and easy to be functionalized.The equilibrium can be reached in a short time since large contact area of nanomaterials extremely increases the mass transfer of compounds from sample solution to absorbents.Magnetic mesoporous nanomaterials could be used for selectively extraction of free forms of compounds through volume exclusive effects,but bound forms would be hindered to access into the pore channels.Moreover,magnetic property also provides a convenient way for collecting absorbents after the extraction process.In this paper,to solve the drawback of negligible depletion-solid phase microextraction method(nd-SPME),novel methods were proposed for quick deteminaiton of freely dissolved concentrations of various pollutants using nanomaterials.Main studies are as follows:1.In this study,core-shell polyacrylate-ferriferrous oxide magnetic microspheres(Fe3O4@PA)were synthesized using hydro-thermal method and applied for fast evaluating freely dissolved concentrations of polycyclic aromatic hydrocarbons(PAHs).Results showed that the synthesized Fe3O4@PA magnetic microspheres have large surface area(58.5 m2/g),high pore volume(0.10 cm3/g),uniform pore size(7.08 nm)and and thin coating layer(50 nm),indicating that equilibrium could be achieved in a short time.Freely dissolved PAHs can be selectively extracted by synthesized Fe3O4@PA magnetic microsphere because of their mesoporous structure.Uniform pore size(7.08 nm)inhibit the extraction of bound forms of PAHs into pore channels.Equilibrium is achieved within 29 min(t90%)using the proposed method in comparison with 139 h(t90%)using nd-SPME method.The sorption coefficients(logKBSA)of PAHs to bull serum albumin(BSA)range from 3.36 to 4.87,which are consistent with the values measured by nd-SPME(logKBSA=3.53-5.08).The freely dissolved concentrations of PAHs(Cfree)in spiked human serum samples are in the range of 0.69-1.92?g/L.which are in agreement with the results measured by nd-SPME(Cfree=0.56-2.11 pg/L)This study provides a feasible method for rapid determination of freely dissolved PAHs in human serum.2.In this study,Fe3O4@MIL-100(Fe)core-shell microspheres were prepared using solvothermal method by layer-by-layer assembly and applied for for quick determination the sorption coefficients of OPEs to DOM in aquatic phase.The synthesized microspheres were characterised by SEM.TEM.XRD and BET.The mesoporous structures of the as-synthesized microspheres hindered the extraction of OPEs which associated humic acid due to the volume exclusion effect.While,the freely dissolved OPEs can access into the mesoporous and then be extracted by MIL-100(Fe).Because of owing small pore size(4.81 nm),large surface area(141 m2/g),high pore volume(0.17 cm/g),and ultra-thin MOFs layers,Fe3O4@MIL-100(Fe)core-shell magnetic microspheres have large contact area with analytes in aqueous phase and therefore the diffusion distance was largely shortened.Besides,the microspheres can be conveniently collected after the extraction process by applying a magnetic field.The equilibration time(t90%)for these studied OPEs was only 24 min based on the proposed method in compared with 35 h by using nd-SPME.The sorption coefficients(logKDOC)of OPEs to humic acid were ranged from 3.84-5.28,which were highly consistent with the results by using traditional nd-SPME method.3.In this study,a novel method was developed for one-step detection of freely dissolved methyl parathion(MP)and sorption coefficients of MP to HAs in the environmental water using electrochemical sensor based on ERGO/?-cyclodextrin modified electrode.(3-cyclodextrin with specific structure improve the dispersing performance of ERGO on electrode surface.ERGO/(3-cyclodextrin composites have large surface area and trace amounts,indicating that equilibrium could be achieved in a short time.The redox reaction happened on the electrode surface after freely dissolved MP in aqueous solution is adsorbed with ERGO/?-cyclodextrin composites through ?-? interactions,and then the current signal is considered as the change of freely dissolved MP.The sample collection,analysis and determination were simultaneously completed without the sample pretreatment reducing the sample loss in the pretreatment process and the whole process does not need to use organic solvents.The equilibration time(t90%)for MP was only 30 min based on the proposed method in compared with 6 h by using nd-SPME.The sorption coefficients(logKDOC)of MP to humic acid with two different sources were 4.23 and 4.27,respectively,which were basicly consistent with the results by using traditional nd-SPME method.The freely dissolved concentrations of MP(Cfree)in spiked water samples are in the range of 3.96-4.44 ?g/L,which are in agreement with the results measured by nd-SPME(Cfree=4.17-4.76 ?g/L).