Yasemin Turhan

Removal of methylene blue from aqueous solutions using phosphoric acid activated carbon produced from hazelnut husks

In this study, activated carbon (HHPAAC) was prepared from hazelnut husks using phosphoric acid activation and characterized by some physicochemical analyses. Surface area and zero point charge of pH (pHPZC) were found to be 770 m2 g−1 and 4.5, respectively. Removal of methylene blue (MB) from aqueous solution was performed using a batch technique for determination of the effects of initial pH, contact time, dosage, and temperature. Adsorption of MB was elevated with increasing pH and temperature. The equilibrium data were analyzed by Langmuir and Freundlich equations, and it was found that the data were reasonably well represented by the former with an adsorption capacity of 204 g kg−1. Change in Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH), were also calculated. Adsorption kinetics were pseudo-second order.

Efficient Removal of Cd(II) from Aqueous Solution by Dehydrated Hazelnut Husk Carbon

In this study, removal of Cd(II) ions from aqueous solutions by dehydrated hazelnut husk carbon (DHHC) was investigated. In batch adsorption process, effective parameters such as pH, contact time, amount of DHHC, and initial concentration were studied. Optimum pH value and contact time were found to be 5.0 and 60 minutes, respectively. Adsorption data were applied to Langmuir and Freundlich adsorption isotherms. Cd(II) adsorption reasonably followed the Langmuir model with a maximum capacity of 61.35 mg g−1. Furthermore, kinetic data obtained for Cd(II) adsorption were found to correlate with the pseudo-second-order kinetic model. Finally, a single-stage batch adsorber was designed in order to treat wastewater model solution. These results showed that DHHC could be used as an effective adsorbent for the removal of Cd(II) from wastewater.

Thermodynamics and kinetics of adsorption of a cationic dye onto sepiolite

AbstractThe adsorption kinetics and thermodynamics of Maxilon Red GRL (MR-GRL), a cationic textile dye, onto sepiolite were investigated in aqueous solution in a batch system. The effect of contact time, stirring speed, initial dye concentration, initial solution pH, ionic strength, and temperature was studied. The initial tested concentrations of MR-GRL solution were 1.5 × 10−3, 2.0 × 10−3 and 2.5 × 10−3 mol/L. The effect of pH was analyzed in the pH range from 5 to 10. The effect of ionic strength was investigated at 0.001–0.100 mol/L NaCl salt concentrations. The experiments were carried out at 288, 298, 308, and 318 K set with a thermostat. The all parameters significantly influenced the adsorption rate and capacity. Experimental data were fitted to pseudo-first order, second-order, Elovich equation, mass transfer, and intra-particle diffusion models. The adsorption kinetics data showed that this process can be described by the pseudo-second-order model, from which the rate constant and the adsorption...

Biological properties of PMMA/nHAp and PMMA/3-APT-nHAp nanocomposites

ABSTRACT In this study, nanocomposite-implant materials with the filler materials, which are nanohydroxyapatite (nHAp) and nHAp modified by [3-(2-aminoethilamino)propyl]trimethoxysilane, using poly(methylmethacrylate) as a matrix according to the melting method, were synthesized. The nanocomposites were characterized using X-ray diffraction, Fourier transform infrared spectroscopy–attenuated total reflectance, scanning electron microscopy, transmission electron microscopy, differential thermal analysis/thermogravimetric analysis, and differential scanning calorimetry devices. Experimental results showed that the thermal stability of nanocomposites increased, and they were hemocompatible, had no negative effect on antioxidant enzymes, and had antibacterial activity. GRAPHICAL ABSTRACT

Characterization, adsorption, and electrokinetic properties of modified sepiolite

AbstractThe metal ion adsorption and electrokinetic properties of sepiolite modified by 3-(trimetoxysilyl)propyl metaacrylate was studied. The characterization of modified sepiolite was made by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron micrograph (SEM), and differential thermal analysis/thermogravimetry (DTA/TG). The adsorption behavior of Fe(III), Mn(II), Co(II), Zn(II), Cu(II), and Cd(II) metal ions on modified sepiolite from aqueous solutions was investigated as a function of equilibrium pH, temperature, and ionic strength. The adsorption experiments were carried out using a batch method. The initial and final concentrations of heavy metals were determined by means of atomic absorption spectrophotometry. The zeta potential of the modified sepiolite suspensions was measured as a function of metal ion concentration and equilibrium pH using a Zeta Meter 3.0. The results showed that the amount of adsorbed metal ions increased with solution pH, and tha...