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Author: search.filters.author.Pratontep, SirapatSubject: search.filters.subject.SPIONs

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    Microfluidic magnetic switching valves based on aggregates of magnetic nanoparticles: Effects of aggregate length and nanoparticle sizes
    (2017-01-15)
    Jiemsakul, Thanakorn
    ;
    Manakasettharn, Supone
    ;
    Kanharattanachai, Sivakorn
    ;
    Wanna, Yongyuth
    ;
    Wangsuya, Sujint
    We demonstrate microfluidic switching valves using magnetic nanoparticles blended within the working fluid as an alternative microfluidic flow control in microchannels. Y-shaped microchannels have been fabricated by using a CO<inf>2</inf> laser cutter to pattern microchannels on transparent poly(methyl methacrylate) (PMMA) sheets covered with thermally bonded transparent polyvinyl chloride (PVC) sheets. To examine the performance of the microfluidic magnetic switching valves, an aqueous magnetic nanoparticle suspension was injected into the microchannels by a syringe pump. Neodymium magnets were then employed to attract magnetic nanoparticles and form an aggregate that blocked the microchannels at a required position. We have found that the maximum volumetric flow rate of the syringe pump that the magnetic nanoparticle aggregate can withstand scales with the square of the external magnetic flux density. The viscosity of the fluid exhibits dependent on the aggregate length and the size of the magnetic nanoparticles. This microfluidic switching valve based on aggregates of magnetic nanoparticles has strong potentials as an on-demand flow control, which may help simplifying microfluidic channel designs.
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    Efficiency of SPIONs functionalized with polyethylene glycol bis(amine) for heavy metal removal
    (2016-09-15)
    Wanna, Yongyuth
    ;
    Chindaduang, Anon
    ;
    Tumcharern, Gamolwan
    ;
    Phromyothin, Darinee
    ;
    Porntheerapat, Supanit
    Hybrid magnetic nanoparticles based on poly(methylmethacrylate) (PMMA) and super-paramagnetic iron oxide nanopaticles (SPIONs) with selective surface modification has been developed for heavy metal removal by applying external magnetic fields. The nanoparticles were prepared by the emulsion polymerization technique in an aqueous suspension of SPIONs. The hydrolysis of carboxyl functional group was then applied for grafting polyethylene glycol bis(amine)(PEG-bis(amine)) onto the PMMA-coated SPIONs. The morphology, the chemical structure and the magnetic properties of the grafted nanoparticles were investigated. The efficiency of the hybrid nanoparticles for heavy metal removal were conducted on Pb(II), Hg(II), Cu(II) and Co(II) in aqueous solutions.The metal concentration in the solutions after separation by the hybrid nanoparticles was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results show the heavy metal uptake ratios of 0.08, 0.04, 0.03, and 0.01 mM per gramme of the grafted SPIONs for Pb(II), Hg(II), Cu(II), and Co(II), respectively. A competitive removal of Cu(II), Pb(II), Co(II) and Hg(II) ions in mixed metal salt solutions has also been studied.The heavy metal removal efficiency of the hybrid nanoparitcles was found to depend on the cation radius, in accordance with capture of metal ions by the amine group.
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    Preparation and characterization of PEG bis(amine) grafted PMMA/SPION composite nanoparticles
    (2016-03-01)
    Wanna, Yongyuth
    ;
    Pui-ngam, Rachineewan
    ;
    Nukeaw, Jitti
    ;
    Chindaduang, Anon
    ;
    Tumcharern, Gamolwan
    We report novel magnetic composite nanoparticles for heavy metal ion separation. Superparamagnetic iron oxide nanoparticles (SPIONs) and were coated with poly(methylmethacrylate) (PMMA) by emulsion polymerization process in the aqueous suspension of SPIONs. In addition, the hydrolysis of carboxylic functional groups onto the PMMA-coated SPIONs was grafted with Polyethylene glycol bis(amine). Then, the functional group structures were investigated by Fourier transforms infrared spectroscopy (FTIR). The morphology of PMMA/SPIONs was determined by transmission electron microscopy (TEM) and atomic force microscope (AFM). The magnetic property was investigated by the vibrating sample magnetometer (VSM). The metal concentration in the solution after separation using the nanoparticles was determined by inductivity coupled plasma optical emission spectrometer (ICP-OES). Furthermore, we demonstrate that the efficiencies of the heavy metal ion removal for Cu(II), Mn(II), Zn(II), Cd(II), Pb(II), Co(II) and Ni(II) are 80.0%, 57.7%, 54.3%, 40.0%, 34.8%, 32.5% and 30.2% by weight, respectively. The nanoparticles also exhibit some selectivity for copper, manganese and zinc. The results show that the composite nanoparticles are extremely promising for heavy metal ion separation.