Yıldırım, Yılmaz | Demircioğlu, Nuhi | Kobya, Mehmet | Bayramoğlu, Mahmut

Article | 2002 | Environmental Pollution118 ( 3 ) , pp.411 - 417

A non-linear simple air-quality model was developed by applying the continuity equation for the air control volume over Erzurum city center and tested using daily average values of SO2 and meteorological data obtained during the winter seasons in Erzurum, Turkey from 1994 to 1998. Model parameters are estimated by non-linear regression analysis. Agreement between model predictions and measured data was found very satisfactory with standard deviations less than 20 µg/m3. © 2002 Elsevier Science Ltd. All rights reserved.

Kobya, Mehmet | Demirbaş, Erhan | Demircioğlu, Nesli | Yıldırım, Yılmaz | Yıldız, Şevki Yalçın

Article | 2004 | Desalination160 ( 3 ) , pp.253 - 262

Coupled transport of thiocyanate ions through a liquid membrane containing quaternary ammonium chloride salts in chloroform was examined. The influences of the carrier type in the membrane phase on the coupled transport of thiocyanate ions were investigated. The kinetics of the coupled transport were analyzed in the formalism of two consecutive irreversible first-order reactions and the kinetic parameters (k1d, k2m, k2a, Rmmax, tmax, Jdmax, Jamax,) were also calculated. For the coupled transport of thiocyanate ions, quaternary ammonium chloride salts having different carbon atom numbers (Cn) used as carriers were found to increase t . . .hiocyanate ions transport efficiency with increasing carbon atom numbers. Tetradecyl trimethylammonium chloride (TDTMACl), hexadecyl trimethylammonium chloride (HDTMACl), and tetraoctyl ammonium chloride (TOACl) were found to be the most effective carrier types for transport of thiocyanate ions when Cn is greater than 16. The activation energies for maximum membrane entrance and exit fluxes were calculated as 32.45 kJ/mol and 34.75 kJ/mol, respectively. The values of the activation energy indicate that the process is controlled by species diffusion Daha fazlası Daha az

Kobya, Mehmet | Demirbaş, Erhan | Geboloğlu, Uğur | Öncel, Mehmet Salim | Yıldırım, Yılmaz

Article | 2013 | Desalination and Water Treatment51 ( 34-36 ) , pp.6676 - 6687

In this investigation, arsenic removal from drinking water using electrocoagulation (EC) in a batch mode was studied by response surface methodology (RSM). The RSM was applied to optimize the operating variables viz. current density (CD, A/m2), operating time (tEC, min) and arsenic concentration (Co, µg/L) on arsenic removal in the EC process using iron electrodes. The combined effects of these variables were analyzed by the RSM using quadratic model for predicting the highest removal efficiency of arsenic from drinking water. The proposed model fitted very well with the experimental data. R2 adjusted correlation coefficients (AdjR2 . . .: 0.93) for arsenic removal efficiency showed a high significance of the model. The model predicted for a maximum removal of arsenic at the optimum operating conditions (112.3 µg/L, 5.64 A/m2 and 5 min) after the EC process was 93.86% which corresponded to effluent arsenic concentration of 6.9 µg/L. The minimum operating cost (OC) of the EC process was 0.0664 €/m3. This study clearly showed that the RSM was one of the suitable methods for the EC process to optimize the best operating conditions for target value of effluent arsenic concentration (<10 µg/L) while keeping the OC (energy and electrode consumptions) to minimal. © 2013 © 2013 Balaban Desalination Publications Daha fazlası Daha az