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Application of Functionalized Magnetic Nanopaticles in Removal and Analysis of Environmental Pollutants

Author: WangZuoZuo
Tutor: MengZhaoFu
School: Northwest University of Science and Technology
Course: Applied Chemistry
Keywords: Magnetic nanoparticles adsorption solid-phase extraction environmentalpollutants
CLC: X50
Type: Master's thesis
Year: 2012
Downloads: 342
Quote: 0
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Abstract


With the development of sociality, industry production, agriculture production and life ofpeople engender environmental pollutions. The pollutants affect healthy of people directly orindirectly. Therefore, the distribution and removal of poisonous and harmful pollutants hasgreat significance in the water environment. Magnetic nanomaterials have large surface area,great adsorption capacity and easy magnetic separation ability. Therefore, it has greatapplication prospects in many fields of scientific research. The objective of this paper is tostudy the application of functionalized magnetic nanoparticles in removal and analysis ofenvironmental pollutants.Alkylphenol, phthalates is common persistent organic pollutants in the water environment.In addition, the environmental pollution for extensive use of antiotics and the problem ofbacterial resistance have attactted more attention. In recent years, pollution levels and theremoval of antiotics become focus. In this section, we have successfully prepared core/shellstructured carbon-encapsulated magnetic nanoparticles （CMNPs） with a two-step method byusing inorganic iron salt and glucose solution as precursor substance. We have utilized X-rayphotoelectron spectroscopy, infrared spectroscopy, X-ray diffraction and Raman analysis toexamine the surface properties of CMNPs synthesized at different temperature. The obtainedCMNPs are used to adsorb or preconcentrate bisphenol A （BPA）,4-n-nonylphenol （4-NP）,4-tert-octylphenol （4-OP）, diethyl phthalate （DEP）, dipropyl phthalate （DPP）, dibutylphthalate （DBP） dicyclohexyl phthalate （DCHP）, dioctyl phthalate （DOP）, sulfonamide,tetracyclines and quinolones antibiotics from water samples. The adsorption or extractionbehaviors of CMNPs to analytes are controlled by the content of oxygen-containing speciesand graphitized carbon on carbon shell of CMNPs. CMNPs prepared at200oC have ampleoxygen-containing species （80%） on surface and favor the adsorption and extraction ofquinolones antibiotics. CMNPs heated at300-500oC with the graphitization efficiency ofcarbon shell lower than50%exhibit great preconcentration performance to BPA,4-NP,4-OP,DBP, DCHP, DOP, tetracyclines and quinolones antibiotics. CMNPs prepared at850oC arehighly graphitized （80%） and have strong adsorption affinity to all model analytes, however,they only can quantitatively extract highly polar sulfonamide antibiotics and moderately polarDEP, DPP due to hard desorption of other model analytes. In this chapter, the removal efficiency of chlortetracycline （CTC） from aquaticenvironment by magnetic carbon nanoparticles prepared at850oC （Fe3C/Fe@C） wasinvestigated. The results showed that Fe3C/Fe@C exhibited ultrahigh adsorption ability toCTC. The adsorption behavior of CTC on Fe3C/Fe@C fitted the pseudo-second-order kineticmodel, and the adsorption equilibrium was achieved within24h. The adsorption ability ofCTC increased with solution pH at pH3.5-7.5, but decreased with further increase of pH （pH7.5-8.5）. CTC adsorption decreased with solution temperature and increased with ionicstrength. As the concentration of coexisting humic acid in solution ranged in10-50mg·L-1,the adsorption ability of CTC on Fe3C/Fe@C was only decreased by10-20%. Under theoptimal conditions （pH=7.5, T=293K）, the maximum adsorption capacity of CTC onFe3C/Fe@C calculated by Langmuir was909mg·g-1, which was significantly higher thanthose obtained on sediment or minerals. More importantly, Fe3C/Fe@C adsorbed with CTCcan be collected from water sample under a magnetic field rapidly for special disposal, whichavoids secondary pollution of water. These results indicate that Fe3C/Fe@C is a potentiallyefficient, green adsorbent for removal of tetracycline antibiotics from aquatic environment.Polycyclic aromatic hydrocarbons （PAHs） is a well-known environmental pollutant, havedrawn a considerable amount of attention due to their carcinogenicity and endocrinedisrupting activity. Therefore, it is necessary to develop highly selective and sensitiveextraction methods that are capable of determining the concentration of these analytes in avariety of matrixes. In this section, a new Fe3O4/polydopamine （Fe3O4/PDA） core-shellstructured magnetic nanoparticle material has been successfully developed as magneticsolid-phase extraction sorbent in dispersion mode for the determination of trace polycyclicaromatic hydrocarbons （PAHs） in environmental samples. The sorbents possess highadsorption capacity and extraction efficiency to PAHs due to strong adsorption ability ofpolydopamine layer and large surface area of nanoparticles. Under optimized conditions, only20mg of sorbents are required to extract PAHs from1000mL water samples. The detectionlimits of PAHs are in the range of1.2to2.1ng·L-1. The accuracy of the method was evaluatedby the recoveries of environmental samples. Good recoveries （76.4-107.3%） with low relativestandard deviations from1.0to9.7are achieved. To the best of our knowledge, thismethodology has not been employed previously in the extraction determination of traceamounts of PAHs from large-volume water samples.

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