Meslek Yüksekokulları

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Biosorption Studies of Mushrooms for Two Typical Dyes
(Journal of the Turkish Chemical Society, Section A: Chemistry, 2020) Yıldırım, Ayfer; Acay, Hilal
This study investigated the adsorption behaviour of two cationic dyes, methylene blue (MB) and malachite green (MG) onto Pleurotus ostreatus, Armillaria tabescens, and Morchella conica mushrooms. The effects of contact time, initial dye concentration, and solution pH (3-11) were also determined. The adsorption on all mushrooms attained equilibrium within 120 min for both MB and MG. To evaluate the experimental kinetics data, the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics equations were utilised. The pseudo-first-order kinetic model demonstrated a good fit with all adsorption kinetics. The Langmuir and Freundlich isotherm models were used to analyse the mechanism of the adsorption isotherm. The adsorption equilibrium isotherm was in a good agreement with the Freundlich model. Thermodynamic parameters such as ΔH enthalpy variation, ΔS entropy variation, and ΔG free Gibbs energy variation were calculated at 303-323 K. The results suggested that the Pleurotus ostreatus mushroom was the most suitable adsorbent for both cationic dyes’ removal.
INVESTIGATING ANTIMI CROBIAL ACTIVITY OF SILVER NANOPARTICLES PRODUC ED THROUGH GREEN SYN THESIS USING LEAF EXTRACT O F COMMON GRAPE ( VITIS VINIFERA
(2019) Acay, Hilal; Baran, Mehmet Fırat; Eren, Abdullah
In this study, a direct approach to fabricating silver nanoparticles (AgNPs) via the leaf extract of common grape (Vitis vinifera) has been demonstrated. The produced particles were found with a maximum wavelength of 452.47 nm, spherical shape and the crystal size of 18.53 nm through UV-Visible spectrophotometry, XRD (X-ray diffraction) and SEM (Scanning electron microscopy) characterization methods. Furthermore, the functional groups involved in the reduction were specified with FTIR (Fourier transform infrared spectroscopy), the elemental compounds were identified with EDX (Energy dispersive X-Ray spectroscopy) and the degradation points were determined with TGA-DTA (Thermal gravimetric analysis) methods. AgNPs were found to be effective against hospital pathogens, namely Gram-negative Escherichia coli ATCC 25922, Gram-positive Staphylococcus aureus ATCC 29213 and Candida albicans fungus at the concentrations of 0.314, 0.078 and 0.334 g mL-1, respectively.
Kinetic and isotherm investigation into the removal of heavy metals using a fungal-extract-based bio-nanosorbent
(Environmental Technology and Innovation, 2020) Yıldırım, Ayfer; Acay, Hilal; Baran, Mehmet Fırat
Adsorption is very economical and environmentally friendly method that is commonly accepted as a promising technique for the removal of heavy metals. In this study a fungal-extract-based (FE-CB) bio-nanosorbent was prepared and used as an efficient biosorbent for the removal of heavy metals, namely Cu(II) and Ni(II), from aqueous solutions. FE-CB was characterized by scanning electron microscope, Brunauer–Emmett–Teller surface area and porosity analyzer, Fourier transform infrared, x-ray diffraction, differential scanning calorimeter, thermalgravimetric analysis and zeta potential. The Brunauer–Emmett–Teller surface area, pore volume and average pore diameter of FE-CB were 7.43 m2/g, 0.060 cm3/g, and 2.82 nm, respectively. The adsorbtion properties of FE-CB onto both Cu(II) and Ni(II) were investigated in terms of biosorbent dosage, temperature, initial concentration of Cu(II) and Ni(II) ions, pH and contact time in the batch experiments. The dependence of the biosorption mechanism on pH was revealed and the optimum pH was determined as 6 for Ni(II) and 5 for Cu(II). The Langmuir and Freundlich isothermal models and the kinetic Pseudo-first-order and Pseudo-second-order kinetic models were used to describe the adsorption performance of FE-CB. The activation energy was calculated by pseudo-second-order rate constants. In addition, thermodynamic parameters, standard Gibbs free energy, standard enthalpy and standard entropy were analyzed using the (Van't Hoff equation). The biosorption process was found to be spontaneous, favorable and endothermic.

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Browsing Meslek Yüksekokulları by Author "Acay, Hilal"