Browsing by Author "Hmidi, Nuri"

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High-performance iron oxide-graphene oxide nanocomposite adsorbents for arsenic removal
(2017-01-01) Ye, Zhibin; Su, Hui; Hmidi, Nuri
We report the synthesis of a new range of iron oxide-graphene oxide (GO) nanocomposites having different iron oxide content (36–80 wt%) as high-performance adsorbents for arsenic removal. Synthesized by co-precipitation of iron oxide on GO sheets that are prepared by an improved Hummers method, the iron oxide in the nanocomposites is featured primarily in the desirable form of amorphous nanoparticles with an average size of ca. 5 nm. This unique amorphous nanoparticle morphology of the iron oxide beneficially endows the nanocomposites with high surface area (up to 341 m2 g-1 for FeOx-GO-80 having the iron oxide content of 80 wt%) and predominant mesopore structures, and consequently increased adsorption sites and enhanced arsenic adsorption capacity. FeOx-GO-80 shows high maximum arsenic adsorption capacity (qmax) of 147 and 113 mg g−1 for As(III) and As(V), respectively. These values are the highest among all the iron oxide-GO/reduced GO composite adsorbents reported to date and are also comparable to the best values achieved with various sophisticatedly synthesized iron oxide nanostructures. More strikingly, FeOx-GO-80 is also demonstrated to nearly completely (>99.98%) removes arsenic by reducing the concentration from 118 (for As(III)) or 108 (for As(V)) to < 0.02 μg L−1, which is far below the limit of 10 μg L−1 recommended by the World Health Organization (WHO) for drinking water. The excellent adsorption performance, along with their low cost and convenient synthesis, makes this range of adsorbents highly promising for commercial applications in drinking water purification and wastewater treatment.
Production and characterization of polystyrene resins containing fine activated carbon particles
(2017-11-20) Hmidi, Nuri
The development of high capacity adsorbent using engineered activated carbon fines technology, and their ability to extract gold from solution is presented. The unique feature of these adsorbents is their ability to adsorb gold ions from low concentration solutions like mine effluent as well as from leached solutions in gold mills. Production of polystyrene ion exchange resins containing fine activated carbon particles denoted, PSAC, (Polystyrene Activated Carbon) and their gold stripping kinetics were studied. Polystyrene beads were prepared by simple suspension polymerization. However, addition of fine activated carbon (AC) during suspension polymerization was not successful in producing small beads, but rather a conglomerated mass, which was then broken up and shaped into smaller beads. PSAC beads were also produced by co-extrusion of polystyrene with activated carbon and by physical adsorption of activated carbon onto raw polystyrene beads in an autoclave at a temperature above the glass transition temperature of polystyrene. Stripping tests were performed which identified the latter bead type as being the most promising form of PSAC bead for future research. The work was aimed at optimizing the production of the beads in terms of their physical and chemical properties. This work led to the development of a new polystyrene/activated carbon ion exchange bead as an alternative to pure activated carbon. A mini-elution column was also designed to carry out the test work to study the performance of beads and loaded fine carbon stripping parameters under typical industrial conditions. Further development of this research may lead to a new method of stripping loaded fine carbon on mine sites as part of the existing gold milling and extracting circuits.