Dissertation > Excellent graduate degree dissertation topics show

Preparation of Electrospun Micro/Nano-Materials for Adsorption of Heavy Metals from Aqueous Solution

Author: WuTingCao
Tutor: WangCe
School: Jilin University
Course: Polymer Chemistry and Physics
Keywords: Electrospinning Micro/nano-materials Magnetic materials Adsorption Heavy metals
CLC: X703
Type: PhD thesis
Year: 2013
Downloads: 92
Quote: 0
Read: Download Dissertation

Abstract


Heavy metal contaminations in water systems are one of the serious environmentalproblems throughout the world. Most of heavy metal ions are highly toxic, even at very lowconcentrations. These metal ions are non-degradable and can accumulate in living organisms,causing several disorders and diseases. Therefore, the removal of heavy metal ions fromaqueous solutions is very important to protect the environment and public health.Recently, micro/nano-materials are of great interest to be developed as efficientadsorbents for heavy metal ions in water. A large number of advanced techniques have beendeveloped to fabricate micro/nano-materials with well-controlled morphology and chemicalcomposition. Among these techniques, electrospraying and electrospinning seem to be thesimplest and most versatile techniques capable of generating micro/nano-materials, andhave attracted a great deal of attention in recent years.Micro/nano-materials produced by electrospraying and electrospinning methods haveinteresting properties, such as high specific surface area, porous surface structure, highchemical strength, good mechanical properties, and favorable morphology for recoveryand recycling. So electrospun micro/nano-materials could be used as effective adsorptivematerials.In this thesis, a series of micro/nano-materials with different structures and functionshave been prepared by combining the electrospraying and electrospinning techniques withthe subsequent process of heat treatment, acidic-dissolution, and chemical modification. Then,these electrospun micro/nano-materials are used for adsorption of heavy metals such ascopper, arsenic from aqueous solution. Detailed research results are listed as follows: 1. Anatase mesoporous titanium nanofibers （m-TiO2NFs） have been synthesizedfrom calcination of the as-spun TiO2/Polyvinyl pyrrolidone （PVP）/Pluronic123（P123）composite nanofibers at450oC in air for3h. An investigation of Cu（II） adsorption ontom-TiO2NFs has been demonstrated. The pH effect, adsorption kinetics, and adsorption isothermsare examined in batch experiments. Experimental data were analyzed using pseudo-firstorder and pseudo-second order kinetic models. It was found that adsorption kinetics were thebest fitting by a pseudo-second order kinetic model. The optimum pH for Cu（II）adsorption was found to be6.0. The adsorption equilibrium data were analyzed by theLangmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models, whichrevealed that the Freundlich isotherm is the best-fit isotherm for the adsorption of Cu（II）.Compared to the TiO2NFs （regular anatase titanium nanofibers） in the same experimentalconditions to elucidate the role of the mesoporous structure of m-TiO2NFs, experimentalresults showed that the m-TiO2NFs had a better adsorption capacity for Cu（II） ions. Thisstudy may lead to a simple and effective method for fabricating porous materials andm-TiO2NFs can be a very promising material for removing Cu（II） ions from aqueoussolution.2. TiO2nanofibers （NFs） with different phases such as amorphous, anatase, mixedanatase rutile, and rutile have been prepared by combining the electrospinning techniquewith the subsequent process of heat treatment or acidic-dissolution method. The obtainedTiO2nanofibers are characterized by a Fourier transform infrared spectrometer （FT-IR）,X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, scanning electronmicroscopy （SEM）, transmission electron microscopy （TEM）, and N2adsorption desorptionisotherm measurements. Phase-structure effects of the electrospun TiO2NFs on As（III）adsorption behaviors have been investigated. The results showed a significant effect ofthe phase structures of TiO2NFs on As（III） adsorption rates and capacities. AmorphousTiO2NFs have the highest As（III） adsorption rate and capacity in the investigated samples,which can be attributed to higher surface area and porous volume. This research providesa simple and low-cost method for phase-controlled fabrication of TiO2NFs and applicationfor the effective removal of arsenic from aqueous solution.3. Poly（acrylo-amidino ethylene amine）（PAEA） nanofiber membranes have beensynthesized by combining the electrospinning technique and subsequent chemicalmodification. The membranes were used to remove As（V） from aqueous solution. Theadsorption followed pseudo second-order kinetic models well and Langmuir isotherm model could be well-described the experimental equilibrium data. The PAEA nanofibersare effective for As（V） adsorption at pH3. The maximum Langmuir adsorption capacityof the PAEA nanofibers with As（V） is76.92±1.03mg.g-1, which is much higher thanthat of the PAEA microfibers (27.62±0.50mg.g-1) in the same experimental conditions.The adsorption rate of the PAEA nanofibers is faster than that of PAEA microfibers due toits higher specifc surface area. The PAEAnanofibers can be used as an effective adsorbentfor the removal of As（V） in aqueous solution due to high adsorption capacity and shortadsorption time to achieve equilibrium.4. Porous chitosan（CS）/magnetite（Fe3O4）/ferric hydroxide（Fe（OH）3） microsphere asnovel and low-cost adsorbents for the removal of As（III） have been synthesized via theelectrospraying technology by a simple process of two steps. The adsorption kinetics andequilibrium isotherms were investigated in batch experiments. The Langmuir, Freundlichisotherm, and pseudo-second order kinetic models agree well with the experimental data.The adsorption of As（III） onto the CS/Fe3O4/Fe（OH）3microspheres occurred rapidly andreached adsorption equilibrium after about45min. The maximum adsorption capacity of theCS/Fe3O4/Fe（OH）3microspheres, calculated by the Langmuir isotherm model, was8.47±0.18mg.g-1, which is higher than that of the CS/Fe3O4/Fe（OH）3prepared by theconventional method (4.72±0.04mg.g-1). The results showed that the CS/Fe3O4/Fe（OH）3microspheres had a high adsorption capacity for As（III） and a high separation efficiencydue to their microporous structure and superparamagnetic characteristics. The compositematerials, therefore, are significant for water purification.

Related Dissertations

  1. Density Functional Theory Study of Dimethyl Ether Adsorption on the Low-Index Pt Surface,O485
  2. Preparation of Based on the Phenolic Resin of Activated Carbon and Adsorption-Photopcatalytical Character of Supported TiO2,TQ424.19
  3. Competitive Adsorption of Phenolic/Ethanol onto Silica Fiber Effected by Ultrasound in RTM Process,TB332
  4. The Preparation and Research of Magnetically Separable TiO2 Photocatalyst Nanofibers,TB383.1
  5. Studies on Synthesis, Characterization and Properties of Fe-V Co-doped TiO2 Catalyst,O614.411
  6. Establishment of ELISA for Detecting Cd-MT of Pteria Penguin and Preliminary Study of ELISA-kit,X835
  7. Numerical Study on Phosphorus Distribution in Water Environment of the Three Gorges Reservoir,X832
  8. Uptake and Accumulation of Heavy Metals of Pistia Stratiotes and Eicharnia Crassipes under Combinated Pollution Condition,X173
  9. ( Hydroxy) Iron Oxide and the removal of arsenic in drinking water,O614.811
  10. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  11. Under microaerobic conditions closed calcium carbide furnace exhaust COS gas adsorption purification,X781
  12. Ion Exchange Removal of Hexavalent Selenium in Raw Water,X703
  13. Study on the Chimisorption Removal of FCC Gasoline Sulfur Compound,TE624.55
  14. Preparationandapplication of Pan-Based Amphoteric Ion Exchange Fiber,TQ342.31
  15. Study on the Preparation of Medical Grade Glycerol from the By-product of Jatropha Biodiesel,TQ223.163
  16. Experiment Study of the Biogas Purification Process by Zeolite Filling Washing,TQ221.11
  17. Study on the Synthesis and Adsorption Behaviour of Chitosan Derivative,TS254.9
  18. Preparation of Activated Carbon from Tobacco Stems and Application for Low Concentration Phosphine Adsorption,X712
  19. Risk Analysis and Mitigation Experiment of Heavy Metal Pollution in Croplands in Vicinity of Pollution Sources,X820.4
  20. Adsorption Effects of Phosphate and Chromium from Aqueous Solution by Adsorption Using LDH and Mg/Fe/Al Modified Montmorillonites,X703
  21. Optimization Design Andapplication of Extracting Methods of Maize (Zea Mays L.) Volatile Compounds,S513

CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
© 2012 www.DissertationTopic.Net  Mobile