Şahika Sena Bayazit

Magnetic Multi-Wall Carbon Nanotubes for Methyl Orange Removal from Aqueous Solutions: Equilibrium, Kinetic and Thermodynamic Studies

The magnetic iron oxide nanoparticles (SPION) were prepared using the co-precipitation method. The magnetically modified multi-wall carbon nanotubes (MWCNT) were obtained by the same method. The magnetic nanoparticles were used as adsorbents for methyl orange (MO) removal from aqueous solutions. The surface properties of adsorbents were analyzed by XRD, TGA, FTIR, and SEM. The adsorption was carried out on batch type. The kinetic, equilibrium and thermodynamics parameters were obtained by experimental results. The maximum adsorption capacity was obtained at pH 3 for both of the adsorbents. Theoretical adsorption capacities were found as 0.31 mg/g for SPION and 10.54 mg/g for MWCNT/SPION composites from Langmuir isotherm parameters. The MWCNT/SPION composites can adsorb 95% of methyl orange from water. The kinetic parameters and thermodynamic parameters were calculated.

A comperative study for adsorption of methylene blue from aqueous solutions by two kinds of amberlite resin materials

Abstract An organic dye, methylene blue (MB), was separated from a model aqueous solution by using adsorption method with low cost resin adsorbents. The adsorption of MB was studied with Amberlite XAD-16 and Amberlite XAD-7 HP. The aim of the study is to achieve a high removal value of the dye and comparing these two adsorbents for MB adsorption. Adsorption of MB was investigated in terms of equilibrium and kinetics conditions. Adsorption isotherms were determined and correlated with equations such as Freundlich, Langmuir and Temkin isotherm models. Langmuir isotherm has good agreement with R 2 value over 0.99. Pseudo second order model was fitted for this adsorption system. Here we showed that 99% removal of MB can be achieved with Amberlite XAD-16. SEM studies revealed the morphological observations of the unloaded adsorbent and the changes in the adsorbed polymeric resin. FTIR spectrums of adsorbents before and after the adsorption supported the SEM results.

Adsorptive removal of malachite green and Rhodamine B dyes on Fe3O4/activated carbon composite

ABSTRACT This study demonstrates the adsorption experiments of toxic dyes malachite green (MG) and Rhodamine B (RB) on Fe3O4-loaded activated carbon (AC). AC, which is known to be a high-capacity adsorbent, was aimed to be easily separated from aqueous media by loading it with Fe3O4. Fe3O4-loaded AC was prepared by the coprecipitation method and named magnetic activated carbon (M-AC), and the produced M-AC was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), and pHpzc analyses. MG and RB adsorption by the M-AC was performed separately by batch technique and the effects of adsorbent amount, solution pH, and initial dye concentration on the adsorption were explored. Maximum removal efficiencies were found to be 96.11% for MG and 98.54% for RB, and the Langmuir isotherm model was the most fitted isotherm model for the adsorption. The kinetic and thermodynamic studies showed that the adsorption proceeded via the pseudo-second-order kinetic model and endothermic in-nature for both dyes. GRAPHICAL ABSTRACT

Oxalic acid removal from wastewater using multi-walled carbon nanotubes: Kinetic and equilibrium analysis

ABSTRACT Oxalic acid adsorption from aqueous solution is studied in this work. Multi-walled carbon nanotubes (MWCNT) were used as an adsorbent. The investigated adsorption variables are equilibrium time, initial acid concentration, and temperature. The experimental results were presented using equilibrium isotherm and kinetic models. The used equilibrium models are Langmuir, Freundlich, and Temkin adsorption isotherms. And the kinetic models are Elovich, Lagergren pseudo-first-order and pseudo-second-order kinetic models. The thermodynamics studies were carried out at three different temperatures: 278, 298, and 318 K. Langmuir isotherm was the best fitted equilibrium model for the experimental data. The all applied kinetic models fitted the data suitably. GRAPHICAL ABSTRACT