The Study On The Detection And Removal Of Environmental Pollutants

Due to the extensive applications of many organics in industry and life,more and more organics become persistent pollutants in the environment,such as perfluorinated compounds?PFCs?,polycyclic aromatic hydrocarbons?PAHs?and dyes.Because of their persistence,bioaccumulation and high toxicity,they have caused serious impacts on human beings and the ecological environment.Hence,it is important to detect and remove these pollutants.In view of this problem,this study proposed the relevant efficient analytical detection method and adsorption removal technologies,which mainly included the following parts:1.This chapter focused on developing a rapid,efficient and eco-friendly method for the analysis of perfluoroalkyl carboxylic acids?PFCAs?in aqueous matrices.The proposed method was based on esterification of PFCAs by isobutyl chloroformate followed by dispersive liquid-liquid microextraction?DLLME?of the derivatives.Quantitation of the derivatized PFCAs was carried out by gas chromatography-mass spectrometry with electron ionization.Under the optimal conditions,PFCAs could be determined in linear ranges of 1-1000 ng mL^-1 with good correlation coefficients?r²>0.9905?.The limits of detection and limits of quantification ranged from 0.9 ng mL^-1-3.0 ng mL^-1 and 2.7 ng mL^-1-9.0 ng mL^-1,respectively.The method showed satisfactory reproducibility with intra-day and inter-day relative standard deviations?RSDs?in the range of 3.4%-14.6%and 3.5%-17.2%,respectively.It was successfully applied to determine PFCAs in several river and lake waters,ranging from 8.47 ng mL^-1 to 150.14 ng mL^-1.2.In this chapter,the hydrophobic melamine foam?HMF?was proposed as the solvent holder for liquid-liquid microextraction?LLME?purpose.The HMF contained3D mesh structure with ultralight,compressible and hydrophobic properties.When it was used as the solvent holder,it had merits of enhanced extraction efficiency because of the large contact area between the extractant phase and sample solution,convenient collection of the extractant phase by compressing the foam,and reusability of the foam.The HMF-LLME combined with gas chromatography-mass spectrometry?GC-MS?was applied for the determination of polycyclic aromatic hydrocarbons?PAHs?in environmental water samples.Under the optimized conditions,the proposed method showed linear ranges of 0.01-50.00 ng mL^-1 with good correlation coefficients?r>0.99?,low limits of detection(0.4-3.0 pg mL^-1),and good precision with intra-day and inter-day relative standard deviations in the range of 6.1%-13.7%and 5.3%-15.0%,respectively.The HMF retained good performance after 10 cycles'usages,demonstrating excellent reusability.The proposed HMF-LLME method provided comparable results with the United States Environmental Protection Agency Method on real water samples but with more operational convenience,less consumption of organic solvent and low cost.The HMF was suitable as the solvent holder for LLME purpose with accurate,convenient,rapid,eco-friendly and reusable properties.3.The graphene oxide-encapsulated large-pore silica?FT-SiO₂@GO?with hierarchical porous structure was facilely prepared and used to remove methylene blue?MB?from the aqueous.After loading GO,FT-SiO₂@GO still possessed high surface area and macropores,resulting in higher adsorption capacity and adsorption rate towards MB than A-SiO₂@GO.Adsorption kinetics followed with the pseudo-second-order kinetics model,while adsorption isotherms both fitted well with the Langmuir model and Freundlich model.The maximum adsorption capacity of MB on FT-SiO₂@GO was up to 404.60 mg g^-1 which was higher than that of many previously reported adsorbents.The high adsorption capacity was mainly attributed to the synergistic effect of the large amount of oxygen-containing functional groups and the interconnected three-dimensional hierarchically porous network.More interestingly,the proposed FT-SiO₂@GO could be effectively regenerated and repeatedly utilized.The FT-SiO₂@GO could be a promising adsorbent in practical applications for wastewater treatment.