Papers by Serdar Suut Çelebi
Pure and Applied Chemistry, 1997
Electroanalytical applications based on the electrochemical behavior of the redox polymer, poly(v... more Electroanalytical applications based on the electrochemical behavior of the redox polymer, poly(viny1ferrocenium) perchlorate (PVF+C104-) coated as a film on Pt surfaces, are described. This chemically modified surface is electroactive due to the existence of f e m c e n i u d f e m n e sites in its structure. Electrooxidation and electroreduction of other depolarizen can also take place through this polymeric film. Anions such as iodide, thiocyauate and cyanide are incorporated in the polymeric structure as a result of anion exchange. Ancdic stripping of the anions from'the film can be canied out after the initial preconcentration. Catalytic reduction and oxidation of anthracene occur on the PVFcClO4-coated Pt surface in acetonitrildTBAP medium. An enzyme such as glucose oxidase could be immobilized in the polymeric matrix and this surface could be used for the amperometric determination of glucose under aerobic conditions. Coimmobilization of two enzymes, glucose oxidase and invertase, in the same polymeric matrix allows for the development of an amperometric sucrose sensor.
Desalination and Water Treatment, 2012
A simplifi ed time dependent mathematical model was developed for an industrial a full-scale two ... more A simplifi ed time dependent mathematical model was developed for an industrial a full-scale two stage anaerobic wastewater treatment plant of a sugar factory under unsteady conditions. As an overall approach, a two-step (acidogenesis and methanogenesis) instantaneous mass balance was considered in the model. The reactor equations employed were based on continuous fl ow well-mixed conditions. Kinetic parameters related to acidogenic and methanogenic reactions were imported from literature studies. The kinetic model was used to simulate MLVSS (mixed liquor volatile suspended solids), VFA (volatile fatty acid) and COD (chemical oxygen demand) equivalent glucose concentrations in hydrolysis tank, and MLVSS, VFA and gas production in anaerobic tank by making use of data from the full-scale anaerobic methane production plant. The model satisfactorily predicted the measured variables in the hydrolysis tank, but prediction was poor for variables in the anaerobic tank. The model has limitations in anaerobic reactions, which are basically due to model kinetic parameters unspecifi c to sugar factory wastewater.
Reactive Polymers, 1992
Magnetic polystyrene beads were synthesized by a modified suspension polymerization technique. Th... more Magnetic polystyrene beads were synthesized by a modified suspension polymerization technique. The beads consisted of iron powder entrapped in the polymer backbone. The photooxidation of the magnetic polystyrene beads was achieved under UV irradiation in order to obtain functionalized solid support matrices to be used for the immobilization of urease (EC 3.5.1.5). Enzyme immobilization experiments revealed that unirradiated beads were not suitable for direct coupling reactions. Under similar immobilization conditions, direct covalent linkage of enzyme occurred on photooxidized magnetic polystyrene beads. It is found that this immobilized enzyme is efficient in catalyzing decomposition of urea and the photooxidized magnetic polystyrene beads might bring several interesting applications to downstream separations processes.
Amperometric enzyme electrode for l(+)-lactate determination using immobilized l(+)-lactate oxidase in poly(vinylferrocenium) film
Sensors and Actuators B: Chemical, 2002
The steady-state amperometric measurements of l(+)-lactate was performed by an enzyme electrode w... more The steady-state amperometric measurements of l(+)-lactate was performed by an enzyme electrode which was developed by using immobilization of the l(+)-lactate oxidase (LOx) in poly(vinylferrocenium) (PVF+), film coated on a Pt electrode. The effects of temperature, pH, polymer film thickness and enzyme concentration were investigated. The linear concentration range was found to be between 0.05 and 0.60mM for this enzyme
Amperometric enzyme electrode for sucrose determination prepared from glucose oxidase and invertase co-immobilized in poly(vinylferrocenium)
Journal of Electroanalytical Chemistry, 1995
Co-immobilization of two enzymes, glucose oxidase and invertase, in polyvinyl(ferrocenium) perchl... more Co-immobilization of two enzymes, glucose oxidase and invertase, in polyvinyl(ferrocenium) perchlorate (PVF+ClO−4) film led to the development of a simple, sensitive, stable and low-cost sucrose sensor. Invertase catalyses the conversion of sucrose to α-glucose and β-fructose. Phosphate ions used in the medium catalyse the conversion of α-glucose to β-glucose, eliminating the need for the commonly used third enzyme, mutarotase, for
Amperometric enzyme electrode for aerobic glucose monitoring prepared by glucose oxidase immobilized in poly(vinylferrocenium)
Journal of Electroanalytical Chemistry, 1995
... [14] H. Giilce, H. Ozy6riik and A. Yildiz, Ber. Bunsenges. Phys. Chem., 98 (1994) 228. [15] H... more ... [14] H. Giilce, H. Ozy6riik and A. Yildiz, Ber. Bunsenges. Phys. Chem., 98 (1994) 228. [15] H. Giilce, H. C)zy6rfik and A. Yildiz, Ber. Bunsenges. Phys. Chem., 98 (1994) 828. ... Chem., 60 (1988) 2473. [30] PD Hale, T. Inagaki, HI Karen, Y. Okamoto and TA Skotheim, J. Am. Chem. ...
Journal of Bioactive and Compatible Polymers, 2001
In this study, magnetic polystyrene particles were prepared by using a solvent evaporation techni... more In this study, magnetic polystyrene particles were prepared by using a solvent evaporation technique. Particles 500-595 mm in size were used as a biofilm carrier in a fluidized bed for the biodegradation of an organic carbon source in wastewater. Activated sludge seeds were used as a mixed culture of microorganisms to obtain biofilms on the magnetic polystyrene particles. Fluidized bed experiments were performed at constant dissolved oxygen concentration, pH and temperature. The magnetic particles allowed operation of the column in a magnetic field at high liquid flow rates; hence, external diffusion limitations on biofilm surfaces were lowered. Biofilm formation on the suspended particles was quite successful and allowed effective removal of the substrate.
Enzyme and Microbial Technology, 2000
Glucoamylase (EC 3.2.1.3. from Aspergillus niger) was immobilized onto the magnetic polystyrene p... more Glucoamylase (EC 3.2.1.3. from Aspergillus niger) was immobilized onto the magnetic polystyrene particles including active groups. These particles were used in a magnetically stabilized fluidized bed reactor, and performance of this reactor was investigated. Magnetically stabilized fluidized bed reactor was made of a jacketed glass column and a coaxial selenoid covering the whole column as the magnetic field source. An axial and homogeneous magnetic field was introduced to the column by using direct current. The effects of flow rate and magnetic field intensity on the particle behaviour in the column were investigated. The optimum operational conditions for magnetically stabilized fluidized bed reactor were determined and the activity performance of the immobilized glucoamylase in the reactor was researched. Higher activities were obtained at low magnetic field intensities because of no additional diffusion problems coming from particle agglomeration occured in the column when the magnetic field intensity was high. It was found that the fluid flow rate in the column must be as low as possible because higher flow rates require higher magnetic field intensities to keep the particles in the column.
Enzyme and Microbial Technology, 2000
In this study, the effects of magnetic field on activity of activated sludge in wastewater treatm... more In this study, the effects of magnetic field on activity of activated sludge in wastewater treatment were investigated in a batch reactor system containing synthetic wastewater. The medium pH and the direct current (DC) magnetic field strength were changed in the ranges of 6.0 to 8.5 and 8.9 to 46.6 mT, respectively. Experiments were also conducted operating at pulsed DC and alternating current. The changes in the substrate (i.e. glucose) and microorganism concentrations were followed. The highest substrate removal and microorganisms growth rates were observed at pH 7.5. The difference between the substrate removal rates of experiments performed with magnetic field and without it was the maximum at this pH, which was about 44%. The substrate removal rate was first increased by increasing the magnetic field strength, and reached the maximum at 17.8 mT, and decreased with further increase. Application of pulsed DC magnetic field did not change significantly the activity of system, hereas using alternating current magnetic field instead of DC form even caused slight decrease in the activity.
Influence of magnetic field on the kinetics of activated sludge
Environmental Technology, 2004
This investigation was performed as a background study for magnetically stabilized fluidized bed ... more This investigation was performed as a background study for magnetically stabilized fluidized bed biofilm reactors for wastewater treatment. The aim of this study is to show the influence of magnetic field application on microbial growth and to use a simplified method in batch wise study to determine this influence on the biological kinetic parameters. The kinetic parameters of mu(max), K(s), Y(x/s) and m of the activated sludge on glucose removal as a model substrate for wastewater treatment were determined in a simple way by using the data of only one batch experiment at a definite condition. At the same condition, instead of the difficult, expensive and time consuming several continuous steady state studies with different influent substrate concentrations the results of only one batch experiment of two identical reactors, one with and the other without magnetic field application, could be enough for the evaluation. It was found that kinetic parameters were changing with magnetic field strengths of 8.9, 17.8, 24.4, 36.6 and 46.6 mT and 17.8 mT is the optimum strength for biological glucose removal under the studied conditions. While mu(max) and m are increasing with the application of optimum magnetic field strength of 17.8 mT, K(s) and Y(x/s) are decreasing implying that average affinity of microorganisms present in activated sludge to the substrate and their growth rates are increasing but a smaller amount of sludge corresponding to the amount of substrate removal was produced with the application of magnetic field. This result shows an improvement in the treatment efficiency by the application of magnetic field.
Kinetics of invertase immobilised on poly(phe-lys) coated polystyrene beads
Biotechnology Techniques, 1996
... The basic surface modification agent; poly(phe-lys), the enzyme; invertase (EC3.2.1.26), cros... more ... The basic surface modification agent; poly(phe-lys), the enzyme; invertase (EC3.2.1.26), cross-linking agent; glutaraldehyde (25% w/v aqueous solution), solvents, buffer'components and other standard reagents was purchased from Sigma (UK). ...
Applied Biochemistry and Biotechnology, 1991
Immobilization of glucoamylase (EC 3.2.1.3) on Celite R649 biocatalyst carrier for hydrolysis of ... more Immobilization of glucoamylase (EC 3.2.1.3) on Celite R649 biocatalyst carrier for hydrolysis of maltose and maltodextrin has been investigated in both packed bed and recirculated batch reactors. The kinetics parameters on the hydrolysis of maltose were estimated from the packed bed reactor. It is found that this immobilized enzyme is as efficient as the soluble enzyme in catalyzing hydrolysis of maltose. However, it is less efficient than the soluble enzyme in hydrolyzing 30% (w/v) maltodextrin, giving a maximum dextrose equivalent (DE) value of 96.0% instead of 98.2%.
A Rapid Method for Determination of Vitamins D2 and D3 in Pharmaceutical Preparations by HPLC
Journal of Liquid Chromatography & Related Technologies, 2001
In this study, a rapid, simple, and economical reversed phase liquid chromatographic method was d... more In this study, a rapid, simple, and economical reversed phase liquid chromatographic method was described for the determination of vitamin D2 and vitamin D3 in pharmaceutical preparations. The pharmaceutical formula of vitamin D2 is prepared by mixing with filling material, and that of vitamin D3 is prepared by dissolving in herbal oil. Before injection to HPLC the vitamin D2 sample was extracted with diethyl ether and the extract was cleaned by centrifugation; the vitamin D3 sample was prepared by dissolving it in an appropriate amount of tetrahydrofuran (THF). The vitamin content of vitamin D2 and vitamin D3 samples was determined by reversed phase liquid chromatography. Ultra Violet-Visible (UV-VIS) detector and C-18 column were used for this purpose. Vitamin D2 and impurities were completely resolved by the mixture of methanol-acetonitrile as mobile phase with a flow rate of 1.0 mL/min. The best resolution of vitamin D3 from interferences could be achieved by the gradient mixture of methanol and THF as the mobile phase at 1.0 mL/min flow rate. Mean recoveries of vitamin D2 ranged from 99.65% to 105.48% with an overall mean of 102.54% for different spiking levels. The limits of detection for vitamin D2 and vitamin D3 in their preparation were found to be <0.43 μg/g and <1.02 μg/mL respectively.
Characterization of glucoamylase immobilized on magnetic poly(styrene) particles
Enzyme and Microbial Technology, 1998
Glucoamylase (EC 3.2.1.3. from Aspergillus niger) which is widely used in industry was immobilize... more Glucoamylase (EC 3.2.1.3. from Aspergillus niger) which is widely used in industry was immobilized directly in one step onto low-cost magnetic poly(styrene) particles including active groups. Glucoamylase in both free and immobilized forms was used to hydrolyze maltose. For both forms, the temperature of 50°C and pH 4.5 were found as the optimum conditions in the aspects of activity and
Uploads
Papers by Serdar Suut Çelebi