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Synthesis of Magnetic Functional Nanomaterials for Removal of Environmental Pollutants

Author: OuZuoZuo
Tutor: ChenHongLi
School: Lanzhou University
Course: Analytical Chemistry
Keywords: Magnetic nanoparticles Heavy metal ions 4-octylbenzene sulfonate Methylene blue Adsorption Magnetic separation
CLC: X703
Type: Master's thesis
Year: 2012
Downloads: 318
Quote: 2
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Abstract


In recent years, with continued population growth and industrial development, waste water discharge has become one of the major issues of the world and its pollution problem is also impressive. Adsorbent materials are generally used to remove pollutants from the water due to their larger specific surface area, high surface energy and high adsorption capacity. But the separation of adsorbent and adsorbate is difficult and most of the adsorbent has the shortage of short life and bad regeneration, which limits the practical application of them in wastewater treatment. The magnetic functional materials have the advantages of high adsorption efficiency and being easily separated from sample solution using an external magnetic field. On the basis of the previous work, magnetic functional nanomaterials are synthesized and used for the removal of heavy metal ions (such as Pb2+), surfactants (such as sodium4-octylbenzene sulfonate) and dyes (such as methylene blue). Their adsorption characteristics are also sdudied. This dissertation consists of four chapters. The major contents are as follows:Chapter1The toxicity of heavy metal ions, surfactants and dyes is simply introduced, and the advantages and disadvantages of the current treatment methods for the removal of these environmental pollutants are brief summerized. A brief overview of the properties and preparation methods of magnetic nanomaterials as adsorbent are given.Chapter2Bifunctional Fe3O4@MgSiO3sub-microspheres with superparamagnetic property and high affinity toward metal ions were successfully synthesized via a solvothermal method using Fe3O4@SiO2as a self-template, and well characterized by means of TEM, XRD, FT-IR, VSM and N2adsorption isotherms. The as-prepared Fe3O4@MgSiO3sub-microspheres were then assessed as the adsorbent for Pb2+removal in water, and various factors influencing the adsorption of Pb2+were investigated including pH, equilibrium time and initial metal ion concentration. The results indicated that Fe3O4@MgSiO3sub-microspheres had a mean diameter of240 nm and high superparamagnetic cores, which endowed them with useful magnetic responsivity. Moreover, the large specific surface was beneficial for their strong affinity toward toxic metal ions. The pseudo-second-order equation could describe well the adsorption kinetics with correlation coefficients greater than0.999. The maximum adsorption capacity for Pb2+was calculated to be242.1mg/g based on Langmuir model. Furthermore, the as-prepared Fe3O4@MgSiO3showed an acceptable reusability using NaOH or Mg2+solution as the desorbing agent.Chapter3Modified Fe3O4nanoparticles with polyaniline are easily synthesized. The as-prepared Fe3O4@PANI were well characterized by means of TEM, FT-IR and VSM. Taking advantages of the magnetism and the rich amino groups of nano-materials, Fe3O4@PANI is then assessed as the adsorbent for the removal of sodium4-octylbenzene sulfonate (Cg) in water. Various factors including the solution pH, equilibrium time and C8initial concentration were investigated to access their effects on the adsorption performance. The adsorption characteristics of adsorption kinetics and isothermal adsorption are studied. Using ammonia as the desorption agent, the as-prepared Fe3O4@PANI showed an acceptable reusability.Chapter4In this experiment, bifunctional Fe3O4@NiSiO3sub-microspheres with superparamagnetic property are successfully synthesized via a solvothermal method using Fe3O4@SiO2as a self-template, and well characterized by means of TEM, FT-IR and VSM. The effects of solution pH, reaction time and initial concentration of methylene blue on the adsorption are studied. Adsorption kinetics data of Methylene blue meet the pseudo-second-order equation well and this suggests that chemical adsorption is the rate-controlling step in the adsorption process. The adsorption date of methylene blue fit the Langmuir isotherm well, indicating that the adsorbent surface is homogeneous, and methylene blue is a monolayer adsorbed on the surface of the adsorbent.

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CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
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