چكيده به لاتين
The aim of the present thesis was to synthesis magnetic nanosorbents based on metal-organic framework and multiwalled carbon nanotubes. In this regards, four different nanosorbents were synthesized and characterized and then applied in removal and extraction of heavy metal ions from various samples.
In the first part, magnetic multiwalled carbon nanotubes functionalized with 8-aminoquinoline was synthesized and applied to the preconcentration of Cd(II), Pb(II) and Ni(II) ions. The parameters affecting preconcentration were optimized by a Box-Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount, and pH value) were selected as the main factors affecting sorption, and four variables (type, volume and concentration of the eluent; elution time) were selected for optimizing elutionThe LODs were 0.09, 0.72, and 1.0 ng mL-1 for Cd(II), Ni(II), and Pb(II) ions, respectively. The relative standard deviations were < 5.1%. The sorption capacities (in mg g-1) were in the range of 150-201. The composite was successfully applied to the rapid extraction of trace quantities of heavy metal ions in fish, sediment, soil, and water samples.
In the second part, a novel magnetic metal-organic framework (MOF) prepared from dithizone-modified Fe3O4 nanoparticles and a copper-(benzene-1,3,5-tricarboxylate) MOF and its use in the preconcentration of Cd(II), Pb(II), Ni(II), and Zn(II) ions. The limits of detection are 0.12, 0.39, 0.98, and 1.2 ng mL-1 for Cd(II), Zn(II), Ni(II), and Pb(II) ions, respectively and the RSDs were <4.5%. The adsorption capacities (in mg g-1) were in the range of 98-206. The magnetic MOF nanocomposite has a higher capacity than the Fe3O4/dithizone conjugate. This magnetic MOF nanocomposite was successfully applied to the rapid extraction of trace quantities of heavy metal ions in four different real samples.
In the third part, a magnetic metal-organic framework for preconcentration of Hg(II) was synthesized. The material is obtained from magnetite (Fe3O4) nanoparticles that were modified with 4-(5)-imidazoledithiocarboxylic acid and then reacted with trimesic acid and Cu(II) acetate to form the metal-organic framework capable of extracting Hg(II). The results showed the sorption process to obey the Langmuir model. The findings can be well described by pseudo second-order kinetics. Under the optimal conditions, the limit of detection for Hg(II) was 10 ng L-1. The relative standard deviations are <8.3%. The nanocomposite was successfully applied to the rapid extraction of trace amounts of mercury ions from fish and canned tuna samples.
In the forth section, a novel magnetic metal-organic framework (MOF-199/dithiocarbamate modified magnetite nanoparticles composite) was synthesized and utilized for speciation analysis of As(III) and As(V) via determination by electrothermal atomic absorption spectrometry. The synthesized sorbent represented selectivity toward As(III) at pH = 3 while As(V) remained in the initial solution. Under the optimal conditions the limit of detection, and relative standard deviation of the method for As(III) were 1.2 ng L-1, and <8.4%, respectively. Finally, the outlined method was successfully employed to rapid extraction and speciation analysis of As(III) and As(V) in water samples and total arsenic in rice and canned tuna samples.
Keywords: Metal-organic framework, Magnetic nanocomposite, Heavy metals, Extraction, Removal.
