Browsing by Autor "M. Arellano"

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    Effect of Particle Size on the Swelling and Compression Modulus of Nanostructured Polyacrylamide Hydrogels
    (Taylor & Francis, 2015) Abraham G. Alvarado; M. Arellano; M. Rabelero; J. E. Puig; J. C. Sánchez-Díaz
    The effects of concentration and size of polyacrylamide (PAM) nanoparticles on the swelling behavior and compression modulus of nanostructured polyacrylamide hydrogels are examined here. These hydrogels are made by free radical polymerization in an aqueous solution of acrylamide and a crosslinking agent containing dispersed crosslinked PAM nanoparticles of different sizes, previously made by inverse emulsion or microemulsion polymerization. Faster swelling rate and larger equilibrium swelling are observed as particle content increases or the nanoparticle size diminishes. The compression modulus depends on the concentration and size of the disperse nanoparticles: it is larger for hydrogels containing smaller particles at similar concentrations, and it increases as the nanoparticle concentration augments. Moreover, the nanostructured hydrogels have larger compression modulus than those of the conventional ones having similar swelling.
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    High gradient magnetic separation applied to tin minerals
    (IEEE Magnetics Society, 1978) M. Arellano; G.Z. Zambrana
    The present work reports the application of wet High Gradient Magnetic Separation, HGMS, to the recovery of weakly paramagnetic particles of very small dimensions. Pure minerals of different iron content were recovered magnetically with applied magnetic field intensities of up to 19 kOe under various conditions of flow velocity and separating matrix density. Tourmaline mineral, the main impurity in tin ore, can be recovered with a maximum of 63% efficiency in a single passing of HGMS at maximum field and 6 cm/sec flow velocity whereas cassiterite mineral (SnO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) from the same ore deposit and particle size can be recovered with 37% efficiency. With a second passing of HGMS tourmaline was recovered with an increase of 14% in efficiency. From these results it seems possible that one could separate tourmaline minerals from cassiterite minerals with the appropriate conditions of magnetic field intensity, flow velocity and separating matrix density.