Browsing by Author "Okumus, Veysi"

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Anoxybacillus sp. SO B1-Immobilized Amberlite XAD-16 for Solid-Phase Preconcentration of Cu(II) and Pb(II) and Their Determinations by Flame Atomic Absorption Spectrometry
(TAYLOR & FRANCIS INC, 2015) Dündar, Abdurrahman; Ozdemir, Sadin; Dolak, Ibrahim; Okumus, Veysi; Dundar, Abdurrahman; Ziyadanogullari, Berrin; Aksoy, Zehra; Onat, Ruken
A new method for the determination of Cu(II) and Pb(II) by flame atomic absorption spectrometry (FAAS) after preconcentrating on a column containing Anoxybacillus sp. SO B1-immobilized Amberlite XAD-16 was developed. The functional groups of Anoxybacillus sp. SO B1 immobilized on Amberlite XAD-16 were characterized in KBr tablets by Fourier transform infrared (FT-IR) spectrometry. Various parameters such as pH, amount of the adsorbent, eluent type and volume, and flow rate of the sample solution were studied. The optimum pH values of quantitative sorption for Cu(II) and Pb(II) were found to be pH 7.0 and 5.0 and Cu(II) and Pb(II) ions could be quantitatively eluted with 5.0ml of 1.0mol L-1 HCI and 10.0ml of 0.25mol L-1 HNO3, respectively. Recoveries of Cu(II) and Pb(II) were found to be 100.9 +/- 1.57% and 100.3 +/- 0.49% (N = 5), the limits of detection of Cu(II) and Pb(II) in the determination by FAAS (3s, N = 10) were found to be 0.8 and 1.6 mu g L-1, respectively. The proposed enrichment method was applied for metal ion determination from water samples such as two parts of Tigris River water in Diyarbakir and Elazig, Lake of Hazar in Elazig, and tap water in Diyarbakir. Furthermore, the accuracy of the proposed method was verified by studying the analytical recovery and by analyzing certified reference material (NCS-DC 73350 leaves of poplar).
Antioxidant Properties of Cultured Mycelia from Four Pleurotus Species Produced in Submerged Medium
(TAYLOR & FRANCIS INC, 2013) Dündar, Abdurrahman; Okumus, Veysi; Ozdemir, Sadin; Yildiz, Abdunnasir
The ethanolic extracts of dried cultured mycelia of Pleurotus ostreatus, Pleurotus eryngii, Pleurotus florida, and Pleurotus sajor-caju were analyzed for antioxidant activity in different systems. Tests used are as follows: reducing power, free radical scavenging, superoxide anion radical scavenging, total antioxidant activity, metal chelating activitiy, etc.; total phenolic content was determined. The percentage inhibition of P. ostreatus, P. eryngii, P. florida, and P. sajor-caju at 20 mg/mL concentration on peroxidation in a -carotenelinoleic acid system was 57.19, 60.68, 62.12, and 58.81%, respectively. The reducing power of P. eryngii was higher than the other samples, and its value was 0.86 at 10 mg/mL concentration. P. ostreatus and P. sajor-caju proved to be better at scavenging superoxide anion radicals than the P. eryngii and P. florida. In the scavenging effect of DPPH radical test, P. ostreatus showed the highest activity potential and P. sajor-caju showed the strongest metal chelating capacity.
Biosorption of chlorophenoxy acid herbicides from aqueous solution by using low-cost agricultural wastes
(TAYLOR & FRANCIS INC, 2015) Dündar, Abdurrahman; Celik, K. Serdar; Ozdemir, Sadin; Dundar, Abdurrahman; Kilinc, Ersin
The potential biosorption abilities of apple shell (AS), orange peel (OP), banana peel (BP), and millet waste (MW) as a bio-waste material to remove 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4-dichlorophenoxy propanoic acid (2,4-DP), and 2,4-dichlorophenoxy butyric acid (2,4-DB) from aqueous solution were investigated in batch condition. Optimum biosorption conditions were determined as a function of contact time, pH of the solution, amount of biomass, and initial pesticide concentrations. The concentrations of the pesticides in the remaining solutions were simultaneously determined by high performance thin layer chromatography. Langmuir and Freundlich models were applied to describe the biosorption isotherm of the pesticides by agricultural wastes. The experimental adsorption data were fitted to Langmuir adsorption models (r(2)>0.99). It was found that adsorption of 2,4-DP was higher for all biosorbent. The highest maximum adsorption capacities of 2,4-DP were found as 40.08, 22.71, 33.26, and 45.45mg/g, respectively, for AS, OP, BP, and MW. Maximum adsorption capacity was obtained for 2,4-D as OP>MW>BP>AS, 2,4-DP as MW>AS>BP>OP, and 2,4-DB as OP>AS>BP>MW. From the results, it can be said that MW was an effective biosorbent for removal of 2,4-DP and OP was an effective biosorbent for removal of 2,4-D and 2,4-DB through the studied pesticides. Optimum biosorption conditions were determined as 60min of contact time, 100mg of biomass, AS at pH 6.0, OP at pH 6.0, MW at pH 7.0, and BP at pH 7.0. FT-IR was employed to understand the surface properties of biosorbents. According to the results, agricultural wastes have high adsorption capacity.
Metallo Phthalocyanines bearing 2-Isopropyl-6-methylpyrimidin-4-yloxy Substituents: Synthesis, Characterization, Aggregation Behavior, Antioxidant and Antibacterial Activity, and Electronic Properties
(WILEY-V C H VERLAG GMBH, 2014) Dündar, Abdurrahman; Dede, Emrah; Gumus, Selcuk; Dundar, Abdurrahman; Okumus, Veysi
A novel phthalonitrile derivative bearing 2-isopropyl-6-methylpyrimidin-4-yloxy substituents at peripheral positions was synthesized by a nucleophilic substitution reaction. Metallophthalocyanines were obtained from the reaction of the novel phthalonitrile with metal Zn, Cu, Co, and Ni salts. The characterization of the compounds was performed using elemental analysis as well as UV/Vis, FT-IR, and H-1-NMR spectroscopy. The aggregation behaviors of phthalocyanine complexes were also investigated. These metallophthalocyanines do not show any aggregation behavior between 10 (4)-10 (6) M concentration range in THF. The antioxidant activities of the synthesized compounds were evaluated using three different tests: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, metal chelating activity, and reducing power assays. All the compounds exhibited various antioxidant activities. In addition, antimicrobial activity of the compounds was tested over four gram positive and two gram negative bacteria. Moreover, the ground-state geometries of the complexes were optimized using density functional theory (DFT) methods at B3LYP/6-31G(d,p) level in order to obtain information about the 3D arrangements and electronic structure.
Preconcentration of metal ions using microbacteria
(SPRINGER WIEN, 2013) Dündar, Abdurrahman; Okumus, Veysi; Dundar, Abdurrahman; Kilinc, Ersin
This review (160 refs). covers the current state of the art of microbacteria-based sorbents for preconcentration of metal ions at trace levels. We highlight advantages and major challenges of the techniques and discuss future perspectives of both batch and column-based methods. Particular attention is paid to the preconcentration of metal ions using resin-immobilized microbacteria for solid phase extractions. We also discuss detection methods including UV-vis spectrophotometry, FAAS, ICP-OES and ICP-MS. Analytical figures of merit are compared, and examples are given for the application to a variety of samples including food, beverages, alloys, water, soil, and geological samples.
Preconcentration of Sn in Real Water Samples by Solid Phase Extraction Based on the Use of Helvella leucopus as a Fungal Biomass Prior to its Determination by ICP-OES
(ATOMIC SPECTROSCOPY, 2013) Dündar, Abdurrahman; Dundar, Abdurrahman; Ozdemir, Sadin; Okumus, Veysi
Recently, biosorbents of biological origin such as fungus, algae, and bacteria have found special application as packing material in solid phase extraction (SPE). In this study, an alternative SPE method was developed and validated for the preconcentration of Sn prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES). Helvella leucopus, a fungal biomass, was used as the biosorbent in the column studies. Experimental parameters, such as pH and flow rate of the solution, amounts of biosorbent and resin, and volume of the sample solution which affects the analytical results, were investigated. Effects of possible interfering ions on the SPE preconcentration of Sn were investigated. The sensitivity of ICP-OES was improved 47.1 times for Sn. The LOD and LOQ values were 0.06 and 0.21 ng respectively. Linearity was obtained in the concentration range of 1.0-30 ng mL(-1) for Sn. The loading capacity of Helvella leucopus immobilized Amberlite XAD-4 was 10.4 mg g(-1). The concentrations of Sn in the water samples from the Tigris River were determined using the developed method and validated by analysis of the certified reference material NWTM-26.3 Fortified Water sample.
Preconcentration with Bacillus subtilis-Immobilized Amberlite XAD-16: Determination of Cu2+ and Ni2+ in River, Soil, and Vegetable Samples
(TAYLOR & FRANCIS INC, 2015) Dündar, Abdurrahman; Ozdemir, Sadin; Kilinc, Ersin; Dundar, Abdurrahman; Yuksel, Uyan; Baysal, Zubeyde
Solid-phase extraction (SPE) method was developed for the preconcentration of Cu2+ and Ni2+ before their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). Bacillus subtilis-immobilized Amberlite XAD-16 was used as biosorbent. Effects of critical parameters such as pH, flow rate of samples, amount of Amberlite XAD-16 and biosorbent, sample volume, eluent type, and volume and concentration of eluent on column preconcentration of Cu2+ and Ni2+ were optimized. Applicability of the method was validated through the analysis of the certified reference tea sample (NCS ZC73014). Sensitivity of ICP-OES was improved by 36.4-fold for Cu2+ and 38.0-fold for Ni2+ by SPE-ICP-OES method. Limit of quantitation (LOQ) was found to be 0.7 and 1.1ng/ml for Cu2+ and Ni2+, respectively. Concentrations of Cu2+ and Ni2+ were determined by ICP-OES after application of developed method. Relative standard deviations (RSDs) were lower than 4.9% for Cu2+ and 7.9% for Ni2+. The Tigris River that irrigates a large agricultural part of Southeast Turkey is polluted by domestic and industrial wastes. Concentrations of Cu2+ and Ni2+ were determined in water, soil, and some edible vegetables as a biomonitor for heavy metal pollution.
Production and characterization of thermostable alpha-amylase from thermophilic Anoxybacillus flavithermus sp nov SO-19
(WILEY-V C H VERLAG GMBH, 2016) Dündar, Abdurrahman; Okumus, Veysi; Ulutas, Mehmet Sefa; Dundar, Abdurrahman; Akarsubasic, Alper Tunga; Dumontet, Stefano
This study was concerned with isolation and identification of thermophilic bacteria from hot spring in Afyonkarahisar (Gecek) and optimization of a-amylase production, partial purification of alpha-amylase, and characterization of extracellular enzyme from isolated thermophilic strain 19. To characterize and identify the thermophilic isolated bacteria, morphological analysis and biochemistry tests were studied. Besides, for classification 16S rRNA gene, G-C content and DNA-DNA hybridization analysis were performed. These results indicated that strain 19 is a novel species, Anoxybacillus flavithermus sp. nov. The effects of different fermentation conditions, such as incubation time, temperature, and pH, different carbon and nitrogen sources, and surfactants on a-amylase production were investigated. Various parameters such as temperature and temperature stability, pH and pH stability, detergents and surfactants, different starches, and metal ions on influence of enzyme characterization were assayed. About 93, 87, and 81% of the activities were retained after heating the partially purified enzyme solution at 50, 60, and 70 for 240 min, respectively. Enzyme was excessively inhibited by Hg2+ (6%). The enzyme was activated by Co2+ (212%) and Mg2+ (142%). Enzyme degradated 82% of starch content in apple juice at 70 degrees C in 30 min. The molecular weight of enzyme was estimated as 96 kDa.
Selective preconcentration of Lanthanum(III) by Coriolus versicolor immobilised on Amberlite XAD-4 and its determination by ICP-OES
(TAYLOR & FRANCIS LTD, 2014) Dündar, Abdurrahman; Okumus, Veysi; Dundar, Abdurrahman; Celik, Kadir Serdar; Yuksel, Uyan; Kilinc, Ersin
Coriolus versicolor, a wood fungus, was immobilised on Amberlite XAD-4 and used as solid-phase biosorbent for preconcentrations of rare earth elements. La(III), Th(IV), U(IV) and Ce(III) were subjected to solid-phase extraction procedure. We observed that La(III) was selectively preconcentrated, while other ions remained in solution at pH 6.0. 5.0mL of 1.0molL(-1) HCl was used to elaute La(III) from column. 250mg of C. versicolor loaded on 1000mg of XAD-4 was optimised as solid-phase matrix. Concentrations of ions in solutions were determined by inductively coupled plasma- optical emission spectrometry (ICP-OES). The calibration plot after preconcentration was linear in the range from 1.0 to 50.0ngmL(-1) for La(III). Limit of detection was found as 0.27ngmL(-1) for La(III) by SPE method. Relative standard deviation was found lower than 6.7% for 1.0ngmL(-1) of La(III) solution (n=10). The sensitivity of ICP-OES was improved by a factor of 46.8. The applicability of the method was validated through the analysis of certified reference samples of tea (NCS ZC-73014) and spinach (NCS ZC-73013).
Simultaneous preconcentrations of Co2+, Cr6+, Hg2+ and Pb2+ ions by Bacillus altitudinis immobilized nanodiamond prior to their determinations in food samples by ICP-OES
(ELSEVIER SCI LTD, 2017) Ozdemir, Sadin; Kilinc, Ersin; Celik, Kadir Serdar; Okumus, Veysi; Soylak, Mustafa
A novel solid phase extraction method was developed for simultaneous preconcentration-separation of Co2+, Cr6+, Hg2+ and Pb2+ ions prior to their determinations in food samples by ICP-OES. Thermophilic Bacillus altitudinis immobilized nanodiamond was used as a new biosorbent. SEM and FT-IR analysis were studied to characterize the biosorbent. The optimum pH values of quantitative biosorption for Co2+, Cr6+, Hg2+ and Pb2+ were found to be 5.0, 6.0, 6.0 and 6.0, respectively. A flow rate of 3.0 mL min(-1) was selected as optimum for all metal ions. 5 mL of 1 mol/L HCl was used as eluent. Preconcentration factor was achieved as 80. LODs were calculated as 0.071, 0.023, 0.016 and 0.034 ng mL(-1), respectively for Hg2+, Co2+, Cr6+ and Pb2+. The biosorption capacities were calculated for Co2+, Cr6+, Hg2+ and Pb2+ as 26.4, 30.4, 19.5, and 35.2 mg/g, respectively. The developed method was successfully applied to food samples to determine analyte concentrations. (C) 2016 Published by Elsevier Ltd.
Synthesis and Characterization of a New Difunctional Ligand and Its Metal Complexes: An Experimental, Theoretical, Cyclic Voltammetric, and Antimicrobial Study
(TAYLOR & FRANCIS INC, 2015) Dündar, Abdurrahman; Ilhan, Salih; Oztomsuk, Abdussamet; Seyitoglu, M. Salih; Levent, Abdulkadir; Okumus, Veysi; Dundar, Abdurrahman
A new difunctional Schiff base ligand and its some metal complexes were synthesized. The compounds were characterized by elemental analysis, H-1-NMR, C-13-NMR, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis techniques. Additionally, DPPH scavenging, metal chelating and antibacterial activity of compounds were examined via in vitro methods. The lowest DPPH scavenging activity observed by Co(II) as 36.28% and highest was ligand as 52.00%. A cyclic voltammetric study was also carried out to determine redox potentials of the compounds. Some theoretical studies such as H-1-NMR, HOMO-LUMO, and mapped electron density of the ligand were also carried out successfully.
Thermophilic Geobacillus galactosidasius sp nov loaded gamma-Fe2O3 magnetic nanoparticle for the preconcentrations of Pb and Cd
(ELSEVIER SCI LTD, 2016) Ozdemir, Sadin; Kilinc, Ersin; Okumus, Veysi; Poli, Annarita; Nicolaus, Barbara; Romano, Ida
Thermophilic bacteria, Geobacillus galactosidasius sp nov. was loaded on gamma-Fe2O3 magnetic nanoparticle for the preconcentrations of Pb and Cd by solid phase extraction before ICP-OES. pH and flow rate of the solution, amounts of biosorbent and magnetic nanoparticle, volume of sample solution, effects of the possible interferic ions were investigated in details. Linear calibration curves were constructed in the concentration ranges of 1.0-60 ng mL (1) for Pb and Cd. The RSDs of the method were lower than 2.8% for Pb and 3.8% for Cd. Certified and standard reference samples of fortified water, wastewater, poplar leaves, and simulated fresh water were used to accurate the method. LOD values were found as 0.07 and 0.06 ng mL (1) respectively for Pb and Cd. The biosorption capacities were found as 34.3 mg g (1) for Pb and 37.1 mg g (1) for Cd. Pb and Cd concentrations in foods were determined. Surface microstructure was investigated by SEM-EDX. (C) 2015 Elsevier Ltd. All rights reserved.
The Use of Fungal Biomass Agaricus bisporus Immobilized on Amberlite XAD-4 Resin for the Solid-Phase Preconcentration of Thorium
(TAYLOR & FRANCIS INC, 2014) Dündar, Abdurrahman; Okumus, Veysi; Dundar, Abdurrahman; Kilinc, Ersin
Solid-phase extraction method was developed for the preconcentration of thorium (Th). Fungal biomass Agaricus bisporus was immobilized to Amberlite XAD-4 as solid-phase sorbent. The critical parameters such as pH of the sample solution, flow rate of the sample, volume of the sample, and the effect of major ions that affect the preconcentration of thorium in this system were evaluated. The optimum pH for the sorption of Th is 6.0, and quantitative elution occurs with 1.0mol L-1HCl. The loading capacity was determined as 0.079mmol g(-1). The optimized method was validated through analysis of the certified reference material of tea leaves (NCS ZC73014) and successfully applied to the determination of Th in a real ore sample with satisfactory results.