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Neşe Oztürk

Publications and source records attributed to Neşe Oztürk.

3 recordsLinked to original sources
PubMed2005

Adsorption of boron from aqueous solutions using fly ash: batch and column studies.

In the present paper, boron removal from aqueous solutions by adsorption was investigated. Fly ash particle size used in adsorption experiments was between 250 and 400 microm. During the experimental part of this study, the effect of parameters such as pH, agitation time, initial boron concentration, temperature, adsorbent dosage and foreign ion on boron removal were observed. In addition, adsorption kinetics, adsorption isotherm studies and column studies were made. Maximum boron removal was obtained at pH 2 and 25 degrees C. Thermodynamic parameters such as change in free energy (DeltaG degrees), enthalpy (DeltaH degrees), entropy (DeltaS degrees) were also determined. As a result of the kinetic studies, it was observed that the adsorption data conforms to the second degree kinetics model. In the isotherm studies, Langmuir and Freundlich isotherm models were applied and it was determined that the experimental data conformed to Langmuir isotherm model. Batch adsorbent capacity (q(o)) was calculated as 20.9 mg/g. The capacity value for column study was obtained by graphical integration as 46.2 mg/g. The Thomas and the Yoon-Nelson models were applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design.

Adsorption↗
PubMed2004

Nitrate removal from aqueous solution by adsorption onto various materials.

In this study sepiolite, sepiolite activated by HCl, slag and powdered activated carbon were used as adsorbent with a particle size was between 71 and 80 microm (200-170 mesh). NaNO3 solution (100 mg/l) was used in batch adsorption experiments for nitrate removal. First kinetic studies were carried out and it was determined that slag was not effective for nitrate removal, then contact time, pH and adsorbent dosage effects on nitrate removal by adsorption were investigated using other adsorbents except slag. The equilibrium time was found to be 30, 45, 5 min for sepiolite, powdered activated carbon and activated sepiolite, respectively. The most effective pH value for nitrate removal was 2 for powdered activated carbon. pH value did not affect nitrate removal significantly for other adsorbents. Adsorbent dosages were varied from 5 to 20 g/l solutions. An increase in adsorbent dosage increased the percent removal of nitrate. A series of isotherm studies were undertaken and the data evaluated for compliance with the Langmuir and Freundlich isotherm models. To investigate the adsorption mechanisms, three simplified kinetic models, i.e., first-, second-order and intraparticle diffusion were tested. Adsorption followed second-order rate kinetics. The correlation coefficients for second order kinetic model are greater than 0.996. Experimental data show that sepiolite activated by HCl was effective for nitrate removal.

Adsorption↗