The effects of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes

In this study, the effect of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes has been investigated. For this aim, experiments have been carried out controlled initial pH values within the range of 3-9. Effects of initial pH have been analyzed on efficiencies of phosphate removal and energy consumptions. From obtained results, it was found that optimal initial pH is 3. Besides, experiments have been carried out controlled system pH. Effects of system variables have been analyzed on constant pH. From obtained results in these experiments, it was found that optimal system pH is 7. (c) 2006 Elsevier B.V. All rights reserved

Effects of acceptor phase and donor phase properties on sodium ions transport from aqueous solutions using liquid membrane systems

In this study, the effects of the acceptor phase and the donor phase properties on sodium ion transport were examined in bulk liquid membrane systems. In the experiments, toluene and a mixture of toluene-dichloromethane (90-10%, v/v) containing 1 × 10-3 M DB18C6 (dibenzo18crown6) was used as the membrane. In order to examine the effects of different the acceptor phases, firstly H2SO4, HCl, HNO3, CH3COOH and distilled water were used as the acceptor phases. Furthermore, the experiments were performed by using various acid concentrations such as 2, 0.2 and 0.02 M of acids, as the acceptor phase. In the second part of the study, the effect of donor phase on sodium ion transport was examined. For this examination, Na2SO4, NaNO3, NaOH and NaCl were applied. In order to determine the effect of the donor phase concentration, the experimentation was performed using 1.08 × 10-2, 2.17 × 10-2, 3.26 × 10-2 and 4.34 × 10-2 M concentrations of Na+ in form of NaCl. Finally, nonsteady-state kinetics was applied on all data obtained from the experiments and reaction constants (k1, k2, and k3) and the values of the Rmax, tmax, k1/k2 were calculated. Consequently, it was determined that the type and the concentration of the acceptor phase and the donor phase solutions were significant for transport efficiency in liquid membrane systems. The most efficient transport was obtained by applying 2 M H2SO4 and 2.17 × 10-2 M Na+ in form of NaCl. Besides, It was observed that there was a significant effect of the anion attached to the cation on transport efficiency. © 2007 Elsevier B.V. All rights reserved.Cumhuriyet Üniversitesi: M-183This study was supported by Research Fund of Cumhuriyet University, Turkey (Project code: M-183)

A mathematical modeling of sulphur dioxide pollution in Erzurum City

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

The effects of current density and phosphate concentration on phosphate removal from wastewater by electrocoagulation using aluminum and iron plate electrodes

In this study, effects of initial phosphate concentrations and current densities on the phosphate removal by electrocoagulation using either aluminum or iron plate as electrodes were investigated

Effect of organic solvent type on the removal of nitrate ion using liquid membrane technique

In this study, the removal of nitrate ions from aqueous solutions with liquid membrane technique has been investigated for different organic solvent types in which solubilized tetradecyl trimethyl ammonium bromide (TDTMABr) as carrier. n-butyl alcohol, chloroform, and mixture of chloroform + n-hexane (n-hexane 85% + chloroform 15%) were used as organic solvent. Kinetic parameters (k(1d), k(2m), k(2a), t(max), R-m(max), J(m)(max), J(a)(max)) were calculated from obtained data. time R-a values of mixture, butyl alcohol, and chloroform are 0.81, 0.78, and 0.55, respectively. Similarly R-d, R-m, and t(max) values of the mixture equal to 0.14, 0.04, and 87.92 min, respectively. This behavior of the system shows the organic solvent type is an effective parameter on separation yield. It can be concluded that the mixture is the most effective organic solvent type among the investigated ones, because liquid membrane systems should be operated within the range of having the R-m, R-d, and t(max) values are minimum while R-a values are maximum

Effect of initial pH on the removal of humic substances from wastewater by electrocoagulation

This investigation deals with the effect of initial pH batch removal of synthetically prepared wastewater having high concentration of humic substances by electrocoagulation method using plate electrodes. The effects of initial pH on an electrocoagulation system may be twofold. These are distribution of aluminum hydrolysis product, transformation of humic substance related to the initial pH and finally the effects of the gel layer especially in high humic substance concentrations and high initial pH formed on the anode surface. It has been observed that initial humic substance concentration and initial pH are highly effective on the removal rate and efficiency. For example, in the range of 200-500 mg L-1, decrese in the removal efficiency was observed due to gel layer formation on the surface of the anode surface. This get formation especially starts at an initial concentration of 120 ing L-1; thickness and effect of the layer increase as concentration increases. In order to prevent this gel formation, initial pH of the wastewater was adjusted to 5.0 and high removal efficiencies were observed. Thus, the system should be operated at low pH values (i.e. 5.0) at high concentrations. (C) 2007 Elsevier B.V. All rights reserved