Title page for etd-0812117-120359


[Back to Results | New Search]

URN etd-0812117-120359
Author Sian-jhang Lin
Author's Email Address No Public.
Statistics This thesis had been viewed 5363 times. Download 0 times.
Department Environmental Engineering
Year 2016
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Effect of structural characteristics on adsorption of pharmaceuticals by graphene oxide-iron oxide nanocomposite material
Date of Defense 2017-07-18
Page Count 106
Keyword
  • Adsorption kinetics
  • Graphene oxide
  • Iron oxide
  • Pharmaceutical
  • Molecular structure
  • Adsorption isotherm
  • Abstract Pharmaceuticals and personal care products (PPCPs) have been detected in the environment repeatedly and are known to be difficultly removed in conventional wastewater treatment technologies. Graphene oxide (GO), due to its large surface area and modifiable functional groups, has the potential to be applied as a novel wastewater treatment technology. Considered the nano-size of GO material, the GO-iron oxide (GO/Fe3O4) composite with high adsorption capacity was synthesized by co-precipitation in this study, assisting in its quickly removal from the water phase with a magnetic force after treatment. The feasibility of this composite to remove pharmaceuticals in waters was investigated, with respect to the effects of the molecular structures of pharmaceuticals and preparation of the composite. The pharmaceuticals of interest included diclofenac, metformin, and propranolol. The Hummers method was employed to prepare the GO, following by synthesis to generate the GO/Fe3O4 suspension and particles with different iron contents. As to the physicochemical characteristics of the composites, the GO/Fe3O4 possessed a GO content from 15 % to 40 %, a surface area from 302 to 407 m2/g, fraction of the micro-pore with a diameter below 2 nm from 7 % to 25 %, showing a different result from those published. For the adsorption isotherms, at pH 6, the adsorption performance followed the order of propranolol > diclofenac > metformin by using the GO/Fe3O4 with low iron content (S2.5). Given its three-dimensional structure, metformin was less possible to be adsorped into the micro pores of the GO/Fe3O4. However, propranolol possesses naphthalene-like two-dimensional functional group, enhancing its adsorption by the micro-pores of the GO/Fe3O4. By increasing the iron content of the composites, the adsorption of diclofenac was better than that of propranolol. The chlorines on the benzene ring of diclofenac reducing the electronic density of diclofenac was one possible explanation for the enhanced adsorption. For the GO/Fe3O4 suspension as the adsorbent, the adsorption performance of propranolol was the best, whereas diclofenac was less adsorbed when the suspension possessed low iron contents. By increasing the iron content of the the adsorbent, the adsorption of diclofenac became the best, with the metformin adsorption was the worst. Both negative charges of diclofenac and GO/Fe3O4 suspension at low iron contents inhibited the diclofenac adsorption at a neutral pH, while the adsorption of the other two pharmaceuticals still occurred via electric attraction. When the iron content of the adsorbent increased (e.g.,S72), the surface charge of the suspension became neutral enhanced the diclofenac adsorption. The adsorptions of pharmaceuticals followed the pseudo-second-order equation, implying the effects of the pharmaceutical concentration and GO/Fe3O4 n the reaction rate. The adsorption onto particles reached equilibrium after 360 minutes when using the powder adsorbents, whereas the adsorption onto suspension reached equilibrium in 60 minutes. By changing the reaction pH, the surface charge of a pharmaceutical varied in accordance with its acid dissolution constant (pKa), varying the adsorption capacity. For both particle or suspension, the optimal adsorption occurred when the surface charges of the adsorbent and pharmaceutical were negative and positive, respectively. The findings of this study provided insights into the feasibility of using GO/Fe3O4 composites as a novel adsorbent to remove pharmaceuticals in waters, with respect to the effects of certain operation factors and preparation of the composite.
    Key words : Graphene oxide; Iron oxide; Pharmaceutical; Molecular structure; Adsorption isotherm; Adsorption kinetics
    Advisory Committee
  • Shu-kuang Ning - chair
  • Chun-hu Chen - co-chair
  • Wei-hsiang Chen - advisor
  • Files
  • etd-0812117-120359.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2017-09-13

    [Back to Results | New Search]


    Browse | Search All Available ETDs

    If you have more questions or technical problems, please contact eThesys