Browsing by Author "Uzun, Lokman"
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Item Heavy metal removal from synthetic solutions with magnetic beads under magnetic field(Taylor & Francis, 2008) Senel, Serap; Uzun, Lokman; Denizli, Adil; Kara, Ali; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; G-5151-2012; AAG-6271-2019; 7102824859The aim of this study is to prepare magnetic beads which can be used for the removal of heavy metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate-vinyl imidazole) [m-poly(EGDMA-VIM)] beads were produced by suspension polymerization in the presence of magnetite Fe3O4 nano-powder. The specific surface area of the m-poly(EGDMA-VIM) beads was found to be 63.1 m(2)/g with a size range of 150-200 m in diameter and the swelling ratio was 85%. The average Fe3O4 content of the resulting m-poly(EGDMA-VIM) beads was 12.4%. The maximum binding capacities of the m-poly(EGDMA-VIM) beads were 32.4 mg/g for Cu2+, 45.8mg/g for Zn2+, 84.2 mg/g for Cd2+ and 134.5 mg/g for Pb2+. The affinity order on mass basis is Pb2+ > Cd2+ > Zn2+ > Cu2+. Equilibrium data agreed well with the Langmuir model. pH significantly affected the binding capacity of the magnetic beads. Binding of heavy metal ions from synthetic wastewater was also studied. The binding capacities were 26.2 mg/g for Cu2+, 33.7 mg/g for Zn2+, 54.7 mg/g for Cd2+ and 108.4 mg/g for Pb2+. The magnetic beads could be regenerated up to about 97% by treating with 0.1 M HNO3. These features make m-poly(EGDMA-VIM) beads a potential candidate for support of heavy metal removal under magnetic field.Item Microcontact imprinted surface plasmon resonance sensor for myoglobin detection(Elsevier, 2013-10-01) Uzun, Lokman; Denizli, Adil; Osman, Bilgen; Beşirli, Necati; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Anabilim Dalı.; ABF-4791-2020; 15221651200; 6507924888In this study, we prepared surface plasmon resonance (SPR) sensor using the molecular imprinting technique for myoglobin detection in human serum. For this purpose, we synthesized myoglobin imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-t-tryptophan methyl ester) [poly(HEMA-MATrp)] nanofilm on the surface of SPR sensor. We also synthesized non-imprinted poly(HEMA-MATrp) nanofilm without myoglobin for the control experiments. The SPR sensor was characterized with contact angle measurements, atomic force microscopy, X-ray photoelectron spectroscopy, and ellipsometry. We investigated the effectiveness of the sensor using the SPR system. We evaluated the ability of SPR sensor to sense myoglobin with myoglobin solutions (pH 7.4, phosphate buffer) in different concentration range and in the serum taken from a patient with acute myocardial infarction. We found that the Langmuir adsorption model was the most suitable for the sensor system. The detection limit was 87.6 ng/mL. In order to show the selectivity of the SPR sensor, we investigated the competitive detection of myoglobin, lysozyme, cytochrome c and bovine serum albumin. The results showed that the SPR sensor has high selectivity and sensitivity for myoglobin.Item Poly(ethylene glycol dimethacrylate-n-vinyl imidazole) beads for heavy metal removal(Elsevier Science Bv, 2004-01-30) Uzun, Lokman; Denizli, Adil; Kara, Ali; Beşirli, Necati; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; AAG-6271-2019Poly(ethylene glycol dimethacrylate-n-vinyl imidazole) [poly(EGDMA-VIM)] hydrogel (average diameter 150-200 mum) was prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) with n-vinyl imidazole (VIM). The copolymer hydrogel bead composition was characterized by elemental analysis and found to contain 5 EGDMA monomer units each VIM monomer unit. Poly(EGDMA-VIM) beads had a specific surface area of 59.8 m(2)/g. Poly(EGDMA-VIM) beads were characterized by swelling studies and scanning electron microscopy (SEM). These poly(EGDMA-VIM) beads with a swelling ratio of 78% were used for the heavy metal removal studies. Chelation capacity of the beads for the selected metal ions, i.e., Cd(II), Hg(II) and Pb(II) were investigated in aqueous media containing different amounts of these ions (10-750 mg/l) and at different pH values (3.0-7.0). Chelation rate was very fast. The maximum chelation capacities of the poly(EGDMA-VIM) beads were 69.4 mg/g for Cd(H), 114.8 mg/g for Pb(II) and 163.5 mg/g for Hg(II). The affinity order on molar basis was observed as follows: Hg(H) > Cd(II) > Pb(II). Chelation behavior of heavy metal ions could be modelled using both the Langmuir and Freundlich isotherms. pH significantly affected the chelation capacity of VIM incorporated beads. Chelation of heavy metal ions from synthetic wastewater was also studied. The chelation capacities are 45.6 mg/g for U(II), 74.2 mg/g for Hg(H) and 92.5 mg/g for Pb(II) at 0.5 mmol/l initial metal concentration. Regeneration of the chelating-beads was easily performed with 0.1 M HNO3. These features make poly(EGDMA-VIM) beads potential candidate adsorbent for heavy metal removal: (C) 2003 Elsevier B.V. All rights reserved.Item Poly(hydroxyethyl methacrylate) based affinity membranes for in vitro removal of anti-dsDNA antibodies from SLE plasma(Elsevier, 2010-07-01) Uzun, Lokman; Yavuz, Handan; Çelik, Hamdi; Denizli, Adil; Osman, Bilgen; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; ABF-4791-2020; 15221651200The preparation of polymeric membrane using affinity technology for application in blood filtration devices is described here. DNA attached poly( hydroxyethyl methacrylate) (PHEMA) based microporous affinity membrane was prepared for selective removal of anti-dsDNA antibodies from systemic lupus erythematosus (SLE) patient plasma in in vitro. In order to further increase blood-compatibility of affinity membrane, aminoacid based comonomer N-methacryloyl-L-alanine (MAAL) was included in the polymerization recipe. PHEMAAL membrane was produced by a photopolymerization technique and then characterized by swelling tests and scanning electron microscope (SEM) studies. Blood-compatibility tests were also performed. The water swelling ratio of PHEMAAL membrane increased significantly (133.2%) compared with PHEMA (58%). PHEMAAL membrane has large pores around in the range of 5-10 mu m. All the clotting times increased when compared with PHEMA membrane. Loss of platelets and leukocytes was very low. DNA loading was 7.8 mg/g. There was a very low anti-dsDNA-antibody adsorption onto the plain PHEMAAL membrane, about 78 IU/g. The PHEMAAL-DNA membrane adsorbed anti-dsDNA-antibody in the range of 10-68 x 10(3) IU/g from SLE plasma. Anti-dsDNA-antibody concentration decreased significantly from 875 to 144 IU/ml with the time. Anti-dsDNA-antibodies could be repeatedly adsorbed and eluted without noticeable loss in the anti-dsDNA-antibody adsorption amount.Item Removal of heavy-metal ions by magnetic beads containing triazole chelating groups(Wiley, 2009-11-15) Uzun, Lokman; Yılmaz, Erkut; Denizli, Adil; Kara, Ali; Osman, Bilgen; Beşirli, Necati; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; AAG-6271-2019; 7102824859; 15221651200; 6507924888The aim of this study was to prepare magnetic beads that could be used for the removal of heavy-metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) [m-poly (EGDMA-VTAZ)] beads were produced by suspension polymerization in the presence of a magnetite Fe3O4 nanopowder. The specific surface area of the m-poly(EGDMAVTAZ) beads was 74.8 m(2)/g with a diameter range of 150-200 mu m, and the swelling ratio was 84%. The average Fe3O4 content of the resulting m-poly(EGDMA-VTAZ) beads was 14.8%. The maximum binding capacities of the m-poly (EGDMA-VTAZ) beads from aquous solution were 284.3 mg/g for Hg2+, 193.8 mg/g for Pb2+, 151.5 mg/g for Cu2+, 128.1 mg/g for Cd2+, and 99.4 mg/g for Zn2+. The affinity order on a mass basis was Hg2+ > Pb2+ > Cu2+ > Cd2+> Zn2+. The binding capacities from synthetic waste water were 178.1 mg/g for Hg2+, 132.4 mg/g for Pb2+, 83.5 mg/g for Cu2+, 54.1 mg/g for Cd2+, and 32.4 mg/g for Zn2+. The magnetic beads could be regenerated (up to ca. 97%) by a treatment with 0.1 M HNO3. These features make m-poly(EGDMA-VTAZ) beads potential supports for heavy-metal removal under a magnetic field.Item Synthesis and characterization of poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) copolymer beads for heavy-metal removal(Wiley, 2006-12-05) Uzun, Lokman; Tüzmen, Nalan Nalan; Karabakan, Abdulkerim; Denizli, Adil; Kara, Ali; Beşirli, Necati; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Kimya Bölümü.; AAG-6271-2019; 7102824859; 6507924888We prepared poly(ethylene glycol dimethacrylate-l-vinyl-1,2,4-triazole) [poly(EGDMA-VTAZ)] beads (average diameter = 150-200 mu m) by copolymerizing ethylene glycol dimethacrylate (EGDMA) with 1-vinyl-1,2,4-triazole (VTAZ). The copolymer composition was characterized by elemental analysis and found to contain five EGDMA monomer units for each VTAZ monomer unit. The poly(EGDMA-VTAZ) beads had a specific surface area of 65.8 m(2)/g. Poly(EGDMA-VTAZ) beads were characterized by Fourier transform infrared spectroscopy, elemental analysis, surface area measurements, swelling studies, and scanning electron microscopy. Poly(EGDMAVTAZ) beads with a swelling ratio of 84% were used for the heavy-metal removal studies. The adsorption capacities of the beads for Cd(II), Hg(II), and Pb(II) were investigated in aqueous media containing different amounts of these ions (5-750 mg/L) and at different pH values (3.0-7.0). The maximum adsorption capacities of the poly(EGDMA-VTAZ) beads were 85.7 mg/g (0.76 mmol/g) for Cd(II), 134.9 mg/g (0.65 mmol/g) for Pb(II), and 186.5 mg/g (0.93 mmol/g) for Hg(II). The affinity order toward triazole groups on a molar basis was observed as follows: Hg(II) > Cd(II) > Pb(II). pH significantly affected the adsorption capacity of the VTAZ-incorporated beads. The equilibrium data were well fitted to the Redlich-Peterson isotherm. Consideration of the kinetic data suggested that chemisorption processes could have been the rate-limiting step in the adsorption process. Regeneration of the chelating-beads was easily performed with 0.1M HNO3.Item Vinyl imidazole carrying metal-chelated beads for reversible use in yeast invertase adsorption(Elsevier Science BV, 2005-12-01) Uzun, Lokman; Denizli, Adil; Osman, Bilgen; Kara, Ali; Beşirli, Necati; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Kimya Bölümü.; AAG-6271-2019; ABI-3951-2020; 15221651200; 7102824859; 6507924888Poly(ethylene glycol dimethacrylate-n-vinyl imidazole) [poly(EGDMA-VIM)] hydrogel (average diameter 150-200 mu m) was prepared copolymerizing ethylene glycol dimethacrylate (EGDMA) with n-vinyl imidazole (VIM). Poly(EGDMA-VIM) beads had a specific surface area of 59.8 M-2/g. Poly(EGDMA-VIM) beads were characterized by swelling studies and scanning electron microscope (SEM). Cu2+ ions were chelated on the poly(EGDMA-VIM) beads (452 mu mol Cu2+/g), then the metal-chelated beads were used in the adsorption of yeast invertase in a batch system. The maximum invertase adsorption capacity of the poly(EGDMA-VIM)-Cu2+ beads was observed as 35.2 mg/g at pH 4.5. The adsorption isotherm of the poly(EGDMA-VIM)-Cu2+ beads can be well fitted to the Langmuir model. Adsorption kinetics data were tested using pseudo-first- and -second-order models. Kinetic studies showed that the adsorption followed a pseudo- second-order reaction. The value of the Michaelis constant K-m of invertase was significantly larger upon adsorption, indicating decreased affinity by the enzyme for its substrate, whereas V-max was smaller for the adsorbed invertase. The optimum temperature for the adsorbed preparation of poly(EGDMA-VIM)-CU2+- invertase at 50 degrees C, 10 degrees C higher than that of the free enzyme at 40 degrees C. Storage stability was found to increase with adsorption. Adsorbed invertase retains an activity of 82% after 10 batch successive reactions, demonstrating the usefulness of the enzyme-loaded beads in biocatalytic applications.