Fe3O4
Kinetics, Equilibrium and Thermodynamic Studies on the Adsorptive Removal of Nickel, Cadmium and Cobalt from Wastewater by Superparamagnetic Iron Oxide Nanoadsorbents
Mon, 2014-05-19 10:52 — Nashaat N. NassarBecause of its unique properties, such as specific functionality and large specific surface area, iron oxide nanoadsorbents had showed potential for energy and environmental applications. This work investigated the adsorptive removal of different metal ions from wastewater by superparamagnetic iron oxide nanoadsorbents (Fe3O4). Batch-adsorption technique was employed to assess the kinetic behaviour and adsorption equilibrium of cadmium, cobalt and nickel. Accordingly, the effect of the following variables on the adsorption reaction was tested, namely: solution pH, contact time and temperature. Metal ion adsorption was found to be highly pH dependent with a maximum uptake achieved around pH 5.5. Kinetic studies showed that adsorption was fast and equilibrium was achieved in less than 60 min. The external mass transfer kinetic model was applied to the experimental results and provided reasonable overall volumetric mass transfer coefficients. Adsorption isotherms were determined and appropriately described by the Freundlich and Langmuir models, with a better fit to the Freundlich model. The amount of metal ion adsorbed increased as the temperature increased, suggesting an endothermic adsorption process. The thermodynamics studies indicated that the adsorption process was spontaneous and endothermic in nature. © 2011 Canadian Society for Chemical Engineering
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TwitterIron Oxide Nanoparticles for Rapid Adsorption and Enhanced Catalytic Oxidation of Thermally Cracked Asphaltenes
Thu, 2014-05-15 14:07 — Nashaat N. NassarThermally cracked asphaltenes from Athabasca vacuum residue produced at four different process severities were investigated for adsorption and subsequent catalytic oxidation. Fe3O4 nanoparticles were used for the removal of these four different thermally cracked asphaltenes from toluene solutions by a batch-adsorption technique followed by subsequent catalytic oxidation. Asphaltene adsorption kinetics and isotherms are presented. Further, the catalytic effect of nanoparticles on asphaltene oxidation has been addressed. Adsorption was rapid as equilibrium was achieved within 10 min. The equilibrium adsorption data fit well to the Langmuir model. It was found that the adsorption rate, affinity and capacity depend on the molecular weight (MW) of the asphaltenes. Adsorption rate and capacity were highest for the lower MW molecules while adsorption affinity was strongest for the larger MW molecules. In addition, in the absence of nanoparticles, the four thermally cracked asphaltenes oxidized differently. However, when adsorbed onto Fe3O4 nanoparticles their oxidation behavior became similar, showing the enhanced catalytic effect of nanoparticles.
