A. Savaş Koparal

Electrocoagulation of vegetable oil refinery wastewater using aluminum electrodes

Electrocoagulation with aluminum electrodes was used to treat the vegetable oil refinery wastewater (VORW) in a batch reactor. The effects of operating parameters such as pH, current density, PAC (poly aluminum chloride) dosage and Na(2)SO(4) dosage on the removal of organics and COD removal efficiency have been investigated. It has been shown that the removal efficiency of COD increased with the increasing applied current density and increasing PAC and Na(2)SO(4) dosage and the most effective removal capacity was achieved at the pH 7. The results indicate that electrocoagulation is very efficient and able to achieve 98.9% COD removal in 90 min at 35 mAcm(-2) with a specific electrical energy consumption of 42 kWh(kgCOD(removed))(-1). The effluent was very clear and its quality exceeded the direct discharge standard.

Propham mineralization in aqueous medium by anodic oxidation using boron-doped diamond anode : Influence of experimental parameters on degradation kinetics and mineralization efficiency

This study aims the removal of a carbamate herbicide, propham, from aqueous solution by direct electrochemical advanced oxidation process using a boron-doped diamond (BDD) anode. This electrode produces large quantities of hydroxyl radicals from oxidation of water, which leads to the oxidative degradation of propham up to its total mineralization. Effect of operational parameters such as current, temperature, pH and supporting electrolyte on the degradation and mineralization rate was studied. The applied current and temperature exert a prominent effect on the total organic carbon (TOC) removal rate of the solutions. The mineralization of propham can be performed at any pH value between 3 and 11 without any loss in oxidation efficiency. The propham decay and its overall mineralization reaction follows a pseudo-first-order kinetics. The apparent rate constant value of propham oxidation was determined as 4.8 x 10(-4)s(-1) at 100 mA and 35 degrees C in the presence of 50mM Na(2)SO(4) in acidic media (pH: 3). A general mineralization sequence was proposed considering the identified oxidation intermediates.

Removal of disperse dye from aqueous solution by novel adsorbent prepared from biomass plant material

The adsorption of Disperse Orange 25 (3-[N-ethyl-4-(4-nitrophenylazo) phenylamino] propionitrile) onto activated carbon was investigated in a batch system with respect to contact time, carbon dosage, pH and temperature from aqueous solutions. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The Langmuir isotherm model agrees with the experimental data well. Maximum adsorption capacity (qmax) of Disperse Orange 25 onto adsorbent was 118.93mgg(-1) at 20 degrees C. The first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated as well. The experimental data fitted very well to pseudo-second-order kinetic model. The results show that activated carbon prepared from Euphorbia rigida by sulfuric acid chemical activation could be employed as low-cost material to compare with commercial activated carbon for the removal of disperse dyes from effluents.

Hybrid processes for the treatment of cattle-slaughterhouse wastewater using aluminum and iron electrodes

Electrocoagulation (EC) of cattle-slaughterhouse wastewater, which is characterized by (i) high turbidity (up to 340 Nephelometric turbidity units), (ii) increased chemical oxygen demand (COD) concentration (4200 mg L(-1)), and (iii) a dark color, was investigated with the purpose of lowering the turbidity and COD concentration to levels below the permitted direct-discharge limits. Iron and aluminum were used as electrode materials. Experiments were conducted to evaluate the effects of current density, initial pH, and supporting electrolyte (Na(2)SO(4)) dosage on the performance of the system. COD removal increased with increase in current density. The original pH of wastewater (7.8) was found to be preferable for both the electrode materials. Higher concentrations of Na(2)SO(4) caused an increase in COD removal efficiency, and energy consumption was considerably reduced with increasing conductivity. Hybrid processes were applied in this work to achieve higher COD removal efficiencies. In the case of aluminum electrode, polyaluminum chloride (PAC) was used as the coagulant aid for the aforesaid purpose. COD removal of 94.4% was obtained by adding 0.75 g L(-1) PAC. This removal efficiency corresponded to effluent COD concentration of 237 mg L(-1), which meets the legal requirement for discharge from slaughterhouses in Turkey. In the case of iron electrode, EC was conducted concurrent with the Fenton process. As a result, 81.1% COD removal was achieved by adding 9% H(2)O(2). Consequently, hybrid processes are inferred to be superior to EC alone for the removal of both COD and turbidity from cattle-slaughterhouse wastewater.

Assessment of the levels of heavy metal pollution in roadside soils of Eskisehir, Turkey

A detailed study was conducted to determine the current status of the heavy metals Cd, Cu, Cr, Fe, Hg, Mn, Ni, Pb, and Zn in Eskisehir, Turkey. The 15 different locations (n =270) studied were specifically selected to identify the effects of soil pollution on the tramway, which has been in service since December 2004 for public transportation in Eskisehir. The samples were taken from three different lines: tramway-only lines, traffic-only lines, and both traffic and tramway lines. The pollution level was estimated based on the geoaccumulation index (I(geo)), the enrichment factor (EF), the pollution index, and the integrated pollution index (IPI). The values for the IPI were in the following order: Pb > Zn > Cu > Fe > Mn > Ni > Cr > Cd, but mercury was not detected at any sample point. These indexes for metals in the soils under consideration correlated with either low or median levels of pollution. In addition, descriptive statistics were provided for the heavy metals under consideration, and box-plots were constructed and interpreted for all measured indices.

Antibacterial functionalization of cotton and polyester fabrics with a finishing agent based on silver-doped calcium phosphate powders

Textiles are suitable materials for the growth of pathogenic microorganisms. Therefore, various antibacterial finishes have already been developed for textile products. In this work an antibacterial finishing agent containing calcium phosphate-based silver-doped powder was developed for the functionalization of textiles and applied to 100% cotton and 100% polyester knitted fabric samples. Firstly, silver-doped antibacterial powder was synthesized by using a wet chemical method. A size reduction process was applied for reducing the particle size of the powder from micron size to submicron scale. The aqueous dispersion was stabilized by coating the powder surfaces with polyethylene glycol. In order to obtain laundering durability, an aqueous emulsion of an acrylic copolymer was added to the antibacterial solution. The resultant product was applied to all fabric samples by a conventional pad-dry-cure method. The treated fabrics were washed 20 times and the antibacterial efficiency was evaluated after each 10 laundry cycles according to the JIS-L 1902:2002 method against Gram (-) E. coli bacteria. To see the effect of antibacterial finishing on the physical properties of fabrics, the bursting strength, air permeability and color efficiency of the treated and untreated samples were measured and compared. It was found that the antibacterial solution did not affect significantly the bursting strength and color efficiency values of the fabrics, while air permeability was decreased. On the other hand, treated fabric samples preserved their strong antibacterial activities against E. coli after 20 laundry cycles.

Electrochemical antimony removal from accumulator acid: results from removal trials in laboratory cells.

Regeneration of spent accumulator acid could be an alternative process for crystallization, neutralisation and disposal. Therefore, for the first time in a study of the possibilities of electrochemical removal of antimony and accumulator acid regeneration on a laboratory scale, two synthetic and several real systems containing sulfuric acid of concentrations ranging between 28% and 36%, and antimony species were tested. Discontinuous electrochemical reactors with anion exchange membranes were successfully used in these experiments, which were conducted at a temperature of 35°C. Removal of antimony using cells that were not divided by a separator, however, was not possible. In selected experiments, by varying the electrode material, type of electrolyte, and cell current, the concentration of antimony could be reduced from the range of 5 ppm to 0.15 ppm. This resulted in current efficiencies between 0.00002% and 0.001%, and in specific electroenergy demands between 100 Wh L(-1) and 2000 Wh L(-1). In other experiments on substances with antimony contents up to 3500 mg L(-1), the current efficiencies obtained were more than a thousandfold higher. In contrast to the formally high relative energy consumption parameters absolute demand parameters are relatively small and favour the electrochemical method in small scale application. Besides plate electrodes, 3D-cathodes were used. Copper- and graphite cathodes produced the best results.

Removal of Nitrate from Aqueous Solutions by Electrodialysis

In this work the removal of the nitrate from water was carried out by electrodialysis. In the experiments the effect of the applied voltage, pH value, initial nitrate concentration and duration of treatment on the removal rate of nitrate have been investigated. The results obtained from experiments have indicated that nitrate can be removed effectively applying electrodialysis.

Analyses of the modulatory effects of antibacterial silver doped calcium phosphate-based ceramic nano-powder on proliferation, survival, and angiogenic capacity of different mammalian cells in vitro.

In this study, the antibacterial, cytotoxic, and angiogenic activities of silver doped calcium phosphate-based inorganic powder (ABT or PAG) were systematically investigated. ABT powders containing varying silver content were fabricated using a wet chemical manufacturing method. Antibacterial efficiencies of the ABT powders were investigated using a standard test with indicator bacteria and yeast. The cytotoxic effects of ABT on three different fibroblast cells and human umbilical vein endothelial cells (HUVECs) were assessed using MTT assay. ABT powder exhibits concentration-related cytotoxicity characteristics. Apoptotic activity, attachment capability, and wound healing effects were examined on fibroblasts. The angiogenic activity of ABT was investigated by tube formation assay in HUVECs; 10 μg ml(-1) and 100 μg ml(-1) concentrations of the highest metal ion content of ABT did not disrupt the tube formation of HUVECs. All these tests showed that ABT does not compromise the survival of the cells and might impose regeneration ability to various cell types. These results indicate that silver doped calcium phosphate-based inorganic powder with an optimal silver content has good potential for developing new biomaterials for implant applications.