Total coliform and E.Coli disinfection using silver-coated magnetite nanoparticles | |
| Author | Sumeth Wongkiew |
| Call Number | AIT Thesis no.EV-13-30 |
| Subject(s) | Nanoparticles Magnetite |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-13-30 |
| Abstract | Silver nanoparticles have an effective antimicrobial property and magnetite nanoparticles have magnetic property under the presence of magnetic field. Silver nanoparticles have been studied to immobilize on the magnetite nanoparticles in order to synergize the properties of magnetite and silver nanoparticles. In this study, the silver-coated magnetite nanoparticles were focused on high amount product, E.coli and total coliform disinfection efficiency in diluted septic wastewater with some related conditions, and the feasibility to recover the nanoparticles. In part one, magnetite nanoparticles (Fe3O4) were synthesized by co-precipitation method using ferrous sulfate (Fe2SO4) in ammonium hydroxide solution. The optimized concentration of Fe2+ was 0.4 molar of Fe2+. Morphology of the magnetite nanoparticles is spherical shape with 261 nm mean diameter. After that, high product of silver-coated magnetite nanoparticles with 410 nm mean diameter were synthesize with 6% (by weight) of silver nanoparticles coated, by silver reduction method. The coupling agent between silver and magnetite nanoparticles was from MPTMS (3-mercaptopropyltrimethoxysilane). In part two, two disinfection empirical models in the case of concentration-log removal efficiency were statistically modeled. Ratio of E.Coli per total coliform before disinfection (E/T value) affected the ratio of log E.Coli removal per log total coliform removal. Silver-coated magnetite nanoparticles disinfection efficiency was better than magnetite nanoparticles without silver coating. Mixing can increase the disinfection efficiency only for high concentration silver-coated magnetite nanoparticles. The kinetic model for E.Coli disinfection was close to the kinetic power law model. Low disinfection efficiency of silver-coated magnetite nanoparticles was found in high solids wastewater (>10,000 mg/L). In part three, 0.2-Tesla magnetic field was used to separate silver-coated magnetite nanoparticles with different flow rates and concentrations. The magnetic field under the chamber can effectively separate the magnetite nanoparticles retaining in the chamber after flows stopped. The concentration of silver-coated magnetite nanoparticles cannot be detected or less than 1 mg/L after 5 minutes. This shows that it is feasible to develop to a bigger scale of experiment. Electromagnetic field might be applied to increase the magnetic separation performance. Silver-coated magnetite nanoparticles are recommended to synthesize under sonication instead of magnetic stirrer in order to improve the efficiency of silver coating and decrease the agglomeration of nanoparticles under the synthesis to make the particles smaller. Moreover, on and off electromagnetic field are expected to improve magnetic field strength in order to increase the performance of magnetic separation and recovery part. |
| Year | 2013 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Visvanathan, C.;Hornyak, Louis; |
| Scholarship Donor(s) | Thailand (HM Queen); |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2013 |