Yazar "Yavuz, Omer" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • [ X ]
    Öğe
    Nitrogen- and oxygen-doped carbon particles produced from almond shells by hydrothermal method for efficient Pb(II) and Cd(II) adsorption
    (Springer Heidelberg, 2024) Saka, Cafer; Tegin, Ibrahim; Kahvecioglu, Kubra; Yavuz, Omer
    In this study, a two-step method was applied to obtain an effective adsorbent for cadmium (Cd) (II) and lead (Pb)(II) adsorption. The first stage includes the production of activated carbon (AC) from almond shells, which is agricultural waste, by microwave heating and potassium hydroxide (KOH) chemical agent. The second stage includes nitrogen and oxygen doping by hydrothermal heating treatment of the obtained ACs with nitric acid. The obtained materials were characterized by thermogravimetric/differential thermal analyser (TG-DTA); Fourier transform infrared spectroscopy (FTIR); scanning electron microscope (SEM); energy-dispersive spectroscopy (EDS); C, H, N, S elemental analysis; and nitrogen adsorption analyses. The adsorption performance, mechanism, kinetics, and thermodynamics of nitrogen- and oxygen-doped activated carbons were evaluated. The obtained isotherm and kinetic results showed that the adsorption of Cd (II) and Pb (II) on nitrogen- and oxygen-doped ACs followed Langmuir isotherm and pseudo-second-order kinetics. The adsorption capacity values (Qm) obtained for Cd (II) and Pb (II) adsorption were 106.38 mg/g and 76.33 mg/g, respectively.
  • [ X ]
    Öğe
    Phosphorus and oxygen co-doped carbon particles based on almond shells with hydrothermal and microwave irradiation process for adsorption of lead (II) and cadmium (II)
    (Springer Heidelberg, 2023) Kahvecioglu, Kubra; Tegin, Ibrahim; Yavuz, Omer; Saka, Cafer
    In this study, the production of activated carbon based on almond shells by microwave heating with KOH activation and then the modification of activated carbon with phosphorus and oxygen as a result of hydrothermal heating with phosphoric acid were carried out to increase the Cd(II) and Pb(II) adsorption efficiency. The resulting materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analyzer (TG-DTA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and nitrogen adsorption. Adsorption performance, kinetics and thermodynamics of phosphorus, and oxygen-doped activated carbons were evaluated. The results showed that the adsorption of both Cd(II) and Pb(II) on phosphorus and oxygen-doped activated carbons obeyed the Langmuir isotherm and pseudo-second-order kinetics. The adsorption capacity values (Q(m)) obtained from the Langmuir isotherm for Cd(II) and Pb(II) adsorption were 185.18 mg/g and 54.64 mg/g, respectively. At the same time, the adsorption mechanism of Pb(II) and Cd(II) on the respective adsorbents was evaluated. As a result of phosphorus and oxygen atoms, Lewis base sites on carbon atoms and Lewis acid sites on phosphorus atoms are likely to form on the surface. These Lewis base sites can act as important active sites in adsorption reactions, especially of positively charged Pb(II) and Cd(II) ions.
  • Küçük Resim
    Öğe
    Removal of Cadmium and Lead from Aqueous Solution by Calcite
    (Pol. J. Environ. Stud., 2007) Yavuz, Omer; Guzel, Remziye; Aydın, Fırat; Tegin, İbrahim; Ziyadanoğulları, Recep
    The removal of toxic cadmium(II ) and lead(II ) from aqueous solutions was investigated using calcite, which is inexpensive and widespread over the globe, as the effective inorganic adsorbent. The experimental data of the removal equilibrium were correlated by either the Langmuir or Freundlich equations. Results indicate that the Langmuir model gave a better fit to the experimental data than the Freundlich equation. Maximum adsorption capacities were determined as 18.52 mg/g Cd and 19.92 mg/g Pb for natural calcite at 25°C, respectively.