This is a Demo Server. Data inside this system is only for test purpose.

WOS

Permanent URI for this collectionhttp://65.108.157.135:4000/handle/123456789/9

Browse

Browsing WOS by Author "Akbey, Umit"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Article
    Citation - WoS: 1
    Citation - Scopus: 4
    Experimental modeling of antimony sulfides-rich geothermal deposits and their solubility in the presence of polymeric antiscalants
    (Pergamon-elsevier Science Ltd, 2022) Karaburun, Emre; Sozen, Yigit; Ciftci, Celal; Sahin, Hasan; Baba, Alper; Akbey, Umit; Demir, Mustafa M.; Demir, Mustafa
    Antimony (Sb)-rich geothermal deposits have been observed in many geothermal power plants worldwide. They occur as red-colored, sulfidic precipitates disturbing energy-harvesting by clogging the geothermal installations. In order to prevent the formation of this scale, information on its physicochemical features is needed. For this purpose, Sb-rich sulfide-based deposits were synthesized at controlled conditions in a pressurized glass reactor at geothermal conditions (135 degrees C and 3.5 bar). Various polymeric antiscalants with different functional groups, such as acrylic acid, sulphonic acid, and phosphonic acid groups were tested for their effect on Sb sulfide solubility. An additional computational study was performed to determine the binding energy of Sb and S atoms to these groups. The results suggest that sulfonic acid groups are the most affective. Therefore, it was concluded that these macromolecule containing sulfonic acid groups and poly (vinyl sulfonic acid) derivatives could potentially act as antiscalants for the formation of antimony sulfide.
  • Thumbnail Image
    Article
    Citation - WoS: 32
    Surfactant-assisted formation of organophilic CeO2 nanoparticles
    (Elsevier Science Bv, 2012) Tunusoglu, Ozge; Munoz-Espi, Rafael; Akbey, Umit; Demir, Mustafa M.; Demir, Mustafa
    We report a simple one-pot method to prepare organically functionalized CeO2 nanoparticles by controlled chemical precipitation. The particles were nucleated by mixing aqueous solutions of Ce(NO3)(3)center dot 6H(2)O and ammonia at room temperature. Different small organic molecules were chosen as capping agents and injected into the reaction medium at the beginning of the synthesis: 3-(mercaptopropyl) trimethoxy silane (MPS), hexadecyltrimethyl ammonium bromide (CTAB), 3-mercapto propionic acid (3-MPA), and thioglycolic acid (TGA). The resulting nanocrystals were quasi-spherical and had a narrow mean size distribution with an average size smaller than 10 nm. Dynamic nuclear polarization enhanced NMR (DNP-NMR) and FTIR measurements suggested a chemical grafting of the surfactant and a homogeneous surface modification. The colloidal stabilities were characterized by dynamic light scattering and zeta potential measurements. The stabilization by aliphatic groups was tested with a frequently used hydrophobic monomer, methyl methacrylate. According to the results. CTAB is the most effective of the used stabilizing surfactant. The mechanism of formation of the organophilic CeO2 nanoparticles is discussed. (C) 2011 Elsevier B.V. All rights reserved.