Mehmet Doğan

Adsorption kinetics of methyl violet onto perlite

This study examines adsorption kinetics and activation parameters of methyl violet on perlite. The effect of process parameters like contact time, concentration of dye, temperature and pH on the extent of methyl violet adsorption from solution has been investigated. Results of the kinetic studies show that the adsorption reaction is first order with respect to dye solution concentration with activation energy of 13.2 kJ mol(-1). This low activation energy value indicates that the adsorption reaction is diffusion controlled. The activation parameters using Arrhenius and Eyring equations have been calculated. Adsorption increases with increase of variables such as contact time, initial dye concentration, temperature and pH.

Adsorption of methylene blue onto hazelnut shell: Kinetics, mechanism and activation parameters.

The adsorption kinetics of methylene blue (MB) on the hazelnut shell with respect to the initial dye concentration, pH, ionic strength, particle size and temperature were investigated. The rate and the transport/kinetic processes of MB adsorption were described by applying the first-order Lagergren, the pseudo-second-order, mass transfer coefficient and the intraparticle diffusion models. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. Significant increases in initial adsorption rate were observed with the increase in temperature followed by pH and initial MB concentration. The intraparticle diffusion was found to be the rate-limiting step in the adsorption process. Adsorption activation energy was calculated to be 45.6kJmol(-1). The values of activation parameters such as free energy (DeltaG(*)), enthalpy (DeltaH(*)) and entropy (DeltaS(*)) were also determined as 83.4kJmol(-1), 42.9kJmol(-1) and -133.5Jmol(-1)K(-1), respectively.

ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ONTO PERLITE

Adsorption of methylene blue from aqueous solutionsonto unexpanded and expanded perlite samples activatedby H2SO4 and NaCl solutions has beeninvestigated, to assess the possibility of usingperlite for removing cationic dyes from aqueoussolutions. The effects of pH and temperature of dyesolution on the adsorption capacities have beenevaluated. The experimental data were correlatedreasonably well by the Langmuir adsorption isothermand the isotherm parameters (Qm and K) have beencalculated. The removal efficiency (P) anddimensionless separation factor (R) have shown thatperlite can be used for removal of methylene blue fromaqueous solutions, but unexpanded perlite is more effective.

Removal of methyl violet from aqueous solution by perlite

The use of perlite for the removal of methyl violet from aqueous solutions at different concentration, pH, and temperature has been investigated. Adsorption equilibrium is reached within 1 h. The capacity of perlite samples for the adsorption of methyl violet was found to increase with increasing pH and temperature and decrease with expansion and increasing acid-activation. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions and the experimental data were correlated reasonably well by the adsorption isotherm of Langmuir. The order of heat of adsorption corresponds to a physical reaction. It is concluded that the methyl violet is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless separation factor (R) have shown that perlite can be used for removal of methyl violet from aqueous solutions, but unexpanded perlite is more effective.

The Removal of Victoria Blue from Aqueous Solution by Adsorption on a Low-Cost Material

The use of perlite for the removal of victoria blue from aqueous solution at different concentration, ionic strength, pH and temperature has been investigated. Adsorption process is attained to the equilibrium within 1 h. It is found that the adsorption capacity of perlite samples for the removal of victoria blue increased by increasing pH and temperature, and decreased by expansion and ionic strength. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions, and the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir, and the isotherm parameters (Qm and K) have been calculated for perlite samples as well. It is concluded that victoria blue is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless seperation factor (R) have shown that perlite can be used for removal of victoria blue from aqueous solutions, but unexpanded perlite is more effective.

Adsorption kinetics of maxilon yellow 4GL and maxilon red GRL dyes on kaolinite

Kaolinite, a low-costly material, is the most abundant phyllosilicate mineral in highly weathered soils. In this work, the adsorption kinetics of maxilon yellow 4GL (MY 4GL) and maxilon red GRL (MR GRL) dyes on kaolinite from aqueous solutions was investigated using the parameters such as contact time, stirring speed, initial dye concentration, initial pH, ionic strength, acid-activation, calcination and solution temperature. The equilibrium time was 150 min for both dyes. The results showed that alkaline pH was favorable for the adsorption of MY 4GL and MR GRL dyes and physisorption seemed to play a major role in the adsorption process. It was found that the rate of adsorption decreases with increasing temperature and the process is exothermic. The adsorption kinetics followed the pseudo-second-order equation for both dyes investigated in this work with the k(2) values lying in the region of 1.79 x 10(4) to 107.87 x 10(4)g/mol min for MY 4GL and 3.44 x 10(4) to 72.09 x 10(4)g/mol min for MR GRL. The diffusion coefficient values calculated for the dyes were in the range of 3.76 x 10(-9) to 62.50 x 10(-9)cm(2)/s for MY 4GL and 1.98 x 10(-9) to 44.00 x 10(-9)cm(2)/s for MR GRL, and are compatible with other studies reported in the literature. The thermodynamic activation parameters such as the enthalpy, entropy and free energy were determined. The obtained results confirmed the applicability of this clay as an efficient adsorbent for cationic dyes.

Dissolution kinetics of colemanite in oxalic acid solutions

Abstract Colemanite is one of the most important underground riches of Turkey, having approximately 60% of the world boron deposits, and it has a large portion in the deposits. When colemanite having a 2CaO·3B 2 O 3 ·5H 2 O formula is mined naturally, it contains various clay minerals. In this study, the dissolution of colemanite in aqueous oxalic acid solutions was investigated in a batch reactor employing the parameters of stirring speed, particle size, temperature and acid concentration. It was found that the dissolution rate increases with increasing temperature and decreasing particle size. The conversion rate increased until 250 mol m −3 with increasing acid concentration and then decreased with increasing acid concentration. No important effect of stirring speed was observed. The dissolution kinetics of colemanite was examined according to heterogeneous and homogeneous reaction models, and it was found that the dissolution rate was controlled by product layer (or ash layer) diffusion process. The activation energy of the process was determined to be 9.50 kcal mol −1 . The experimental data were tested by graphical and statistical methods and it was found that the following model best fit the experimental data t = t *[1−3(1− X ) 2/3 +2(1− X )].

Dissolution Kinetics of Ulexite in Aqueous Edta Solutions

Abstract The dissolution kinetics of ulexite in aqueous disodium Ethylene Diamine Tetra Acidic Acid (EDTA) solutions has been investigated with respect to the effects of particle size, solution concentration, pH of solution, calcination temperature and reaction temperature. The rate of the reaction decreases as the particle size and pH of the solution increase, but the rate increases with an increase in both solution concentration and reaction temperature. The sample pre-heated at 140 °C has the highest dissolution rate. The rate of the dissolution can be expressed according to the unreacted shrinking core model with changing fluid phase concentration.On a etudie la cinetique de dissolution de lulexite dans des solutions de bisodium aqueux dEDTA, en rapport avec leffet de taille de particule, de concentration et de pH de la solution ainsi que des temperatures de calcination et de reaction. Le taux de reaction diminue avec une augmentation de la taille de particule et de pH de la solution, mais le taux ...

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...