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Subject: search.filters.subject.Magnetic nanoparticles

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    Kinetics of dye removal using Fe3O4 nanoparticles and pulsed white-LED illumination
    (2019-01-01)
    Damrongsak, Pattareeya
    ;
    Klongratog, Bhanupol
    ;
    Hoomsuk, Sirichai
    ;
    Locharoenrat, Kitsakorn
    Removal of dyes with the aid of photocatalytic nanomaterials illuminated with continuous-light sources has been given substantial attention in the recent years. In the present work we study the efficiency of dye degradation using some alternative photocatalytic nanoparticles under condition of pulsed illumination. Our specific purpose is to investigate the removal of rhodamine 6G dye basing on suspended Fe<inf>3</inf>O<inf>4</inf> solution. The experiments are carried out in the batch mode when the effect of the exposition time (ranging from 30 to 150 min) on the dye removal is examined under both continuous and pulsed white-LED illuminations. Different pulsed-light frequencies and duty cycles are tested. We estimate the concentration of rhodamine 6G in the mixed solution following from its absorption spectrum measured with a UV-Vis spectrometer and determine in this manner the percentage of dye removal. Our main conclusion is that Fe<inf>3</inf>O<inf>4</inf> nanoparticles enable removing efficiently the rhodamine 6G dye under pulsed white-LED illumination. In particular, more than 90% of the dye is removed when the duty cycle is equal to 25% and the frequency to 30 kHz. The equilibrium state of this process is achieved in about 60 min.
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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.