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  • Küçük Resim
    Öğe
    Amine-modified halloysite nanotube embedded PEI cryogels as adsorbent nanoarchitectonics for recovery of valuable phenolic compounds from olive mill wastewater
    (Elsevier Ltd, 2024) Demirci, Şahin; Sağbaş Suner, Selin; Yılmaz, Selehattin; Bağdat, Sema; Tokay, Feyzullah; Şahiner, Nurettin
    Here, natural tubular clays, halloysite nanotubes (Hal), were modified with ethylenediamine (EDA), triethylenetetramine (TETA), pentaethylenehexamine (PEHA), and polyethyleneimine (PEI) to enhance their adsorption capabilities for phenolic compound for the treatment of olive mill wastewater (OMWW). Among the modified Hal adsorbents, Hall-PEHA adsorbent demonstrated a higher surface charge of +15.9 ± 1.9 mV and a larger surface area of 24.8 m2/g. The hydroxytyrosol, tyrosol, and oleuropein adsorption from their 1000 mg/L 10 mL single aqueous solutions were determined as 696 ± 44, 536 ± 36 and 91 ± 22 mg/g, respectively. Furthermore, it was determined that 90 ± 8%, 45 ± 0%, and 35 ± 3% of hydroxytyrosol, tyrosol, and oleuropein phenolic compounds were recovered from their 10 mL of 1000 mg/L aqueous mixture solution. On the other hand, the Hal-PEI adsorbents were able to adsorb 7.1 ± 1.2, 3.3 ± 0.5 and 0.5 ± 0.05 mg/g of hydroxytyrosol, tyrosol, and oleuropein compounds, respectively, from the actual OMWW. These values correspond to approximately 85 ± 8%, 71 ± 10%, and 70 ± 7% of the total amount of these compounds present in the OMWW. The PEI cryogel composite system, where Hal-PEHA was embedded into PEI cryogels (Hal-PEHA@PEI), exhibited improved adsorption amount for hydroxytyrosol, tyrosol, and oleuropein compounds from the actual OMWW compared to Hal-PEHA alone. The Hal-PEHA@PEI composite system adsorption amount was determined as 7.6 ± 1.6, 3.4 ± 0.2 and 0.7 ± 0.02 mg/g of hydroxytyrosol, tyrosol, and oleuropein compounds, respectively. These values correspond to approximately 90 ± 3%, 73 ± 3%, and 92 ± 3% of the total amount of these compounds present in the OMWW.
  • Küçük Resim
    Öğe
    Removal of Cd(II), Co(II), Cr(III), Ni(II), Pb(II) and Zn(II) ions from wastewater using polyethyleneimine (PEI) cryogels
    (Academic Press, 2023) Bağdat, Sema; Tokay, Feyzullah; Demirci, Şahin; Yılmaz, Selehattin; Şahiner, Nurettin
    The removal of the target analytes, Cd(II), Co(II), Cr(III), Ni(II), Pb(II), and Zn(II) from contaminated waters was achieved using super porous polyethyleneimine (PEI) cryogels as adsorbent. The optimum values of the sample pH and contact time were determined as 4.0 and 90 min, respectively, for the removal of the analytes. The adsorption capacities of the sorbent were between 19.88 and 24.39 mgg−1 from 10 mL of 50 mgL−1 target metal ion solutions. The sorption kinetics of metal ions were fitted with the pseudo-second-order model. The adsorption isotherms of the target analytes into PEI cryogel were well-fitted to the Langmuir isotherm model as expected from the material homogeneity. The selectivity of the PEI cryogel in the presence of Na+, Ca2+, Mg2+, NO3 −, K+ and Cl− ions even at high concentrations was tested, and the tolerance limits were satisfactory enough, e.g., the adsorption of the target analytes was even not affected in the presence of 2000 mgL−1 Ca2+, K+, Na+, Cl− and 5000 mgL−1 NO3 − ions. The PEI cryogels were successfully utilized in different industrial wastewater samples that were spiked with a known amount of analytes. The removal of the analytes from wastewater samples was in the following ranges 91.94–99.86% for Cd(II), 89.59–99.89% for Co(II), 80.35–99.76% for Cr(III), 92.02–99.84% for Ni(II), 83.28–99.86% for Pb(II), and 82.94–98.24% for Zn(II), respectively. The presented novel removal strategy offers a selective, efficient, and easy application for target metal ions from industrial wastewater samples.