Acrylonitrile butadiene styrene ( ABS) is a hard and light polymeric material widely used in comp... more Acrylonitrile butadiene styrene ( ABS) is a hard and light polymeric material widely used in computer, electronics, automotive and construction industry. In this study, alkoxy silane terminated urethane acrylate functional oligomer was synthesized from perfloro alcohol. Coronated ABS sheets were coated with the various formulations containing sol-gel mixture, acrylated resin including fluor and other reactive components. ABS sheets were cured by using UV-light. The performance of coatings was investigated by applying various physical tests on coated sheets.
We focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by add... more We focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by adding different percentages (wt%) of huntite to PAN. The composites were characterized using thermogravimetric analysis, differential scanning calorimetry, fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy techniques. It was clearly seen that the composites of PAN/huntite have better thermal stability than pure PAN. The effect of the huntite adding to Polyacrylonitrile (PAN) on dc conductivity and dielectric constant was also investigated. Dc conductivity values were increased with increasing temperature. Activation energy values were calculated depending on huntite contents in PAN. Relative dielectric constant values varied in the range of 16.5–21.2 at room temperature at 100 kHz frequency depending on huntite concentrations. All the electrical measurements were performed in dark and vacuum ambient between the temperatures of 295 and 523 K. Dielectric measur...
In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimid... more In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimide (PI) was prepared with pyromellitic dianhydride (PMDA) and 4,4'-oxydianline (4,4'-ODA) in the solution of N,N-dimethylformamide (DMF). Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were then subjected to enzyme immobilization. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM). Chemical structure of PMDA-ODA PI membranes was characterized by FTIR. SEM and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. Immobilization efficiency and enzyme activity of alpha-amylase was examined at various pH values (3.0 - 8.0) and temperatures (15 - 80 degrees C). Immobilization yield was found to be 285.45 mg per gram for the modified polyimide films. Enzyme assays demonst...
The use of polymers is finding a significant place in development of sensors. Better selectivity ... more The use of polymers is finding a significant place in development of sensors. Better selectivity and rapid measurements have been achieved by replacing classical sensor materials with functions of polymers. Several receptors have been employed to detect glucose in fluorescence sensors, and these include enzymes such as glucose oxidase, glucose dehydrogenase and hexokinase/glucokinase, bacterial glucose-binding protein, and boronic acid derivatives. Boronic acid has a important role in the design of glucose sensors. The sensing membrane was prepared with p-Vinylphenylboronicacid (VPBA), Hydroxyethylmethacrylate (HEMA) and Poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 0.1 ppm and 0.7 ppm. It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The optical sensor was stable, cost effective, easy to prepare, rapid and si...
ABSTRACT Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber m... more ABSTRACT Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber membranes (NFm) were synthesized by a combination of UV radiation and an electrospinning technique. The PVA/MA/ATM NFm were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Brunauer–Emmert–Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersion spectrometry (EDS). These membranes were used for adsorption–desorption of platinum (Pt(IV)) and palladium (Pd(II)) from a fire assay (FA) leaching waste solution, and the effect of process parameters such as pH of solution, contact time, NFm dosage, temperature, and adsorption isotherms and kinetics studies on the recovery of Pt(IV) and Pd(II) from the waste solution were investigated. The adsorption equilibrium data fit better using the Langmuir model than the Freundlich model. Maximum adsorption capacities, Q max, at 45 °C were found to be 69.93 and 112.36 mg/g for Pt(IV) and Pd(II), respectively. The activation energies (E a) of Pt(IV) and Pd(II) were 27.90 and 20.29 kJ/mol, respectively. The best desorption reagent was a 1.0 M HCl–1.0 M thiourea (TU) solution for both Pd(II) and Pt(IV). Reusability studies showed that the adsorption capacity can remain up to 90 % after five times of usage. This study provides a promising NFm with an effective adsorption property for Pt(IV) and Pd(II) ions.
ABSTRACT In this study, a novel three functional chain extender (TATATRIOL) was synthesized from ... more ABSTRACT In this study, a novel three functional chain extender (TATATRIOL) was synthesized from the reaction of 1,3,5-tri(prop-2-en-1-yl)-1,3,5-triazinane-2,4,6-trione (TATA) with 2-sulfanylethanol. Then new thermoplastic polyurethanes (TPUs) were synthesized by a one-step bulk polymerization from the reaction of 1,1′-methanediylbis(4-isocyanatocyclohexane) (H12MDI), a poly(ethylene adipate) based polyester polyol and a chain extender. Butane-1,4-diol (BD) and the newly synthesized monomer, TATATRIOL, were used as chain extenders. The effects of TATATRIOL on the properties of the TPU were investigated and compared to those of the TPU prepared with BD. The TPUs which derived from the sulfur containing chain extender displayed lower modulus and high elongation at break values than the analogous TPUs derived from BD. Moreover sulfur containing TPUs exhibited higher thermal stability.
International Journal of Polymeric Materials and Polymeric Biomaterials, 2015
ABSTRACT In this study, we prepared photo-crosslinked modified HAP (hydroxy apatite)/polyvinyl al... more ABSTRACT In this study, we prepared photo-crosslinked modified HAP (hydroxy apatite)/polyvinyl alcohol (PVA) composite nanofiber scaffold for cell growth applications. HAP was synthesized and then modified with 4-vinylbenzene boronic acid (VBBA) to obtain 4-VBBA-HAP. By means of the simultaneous UV electrospinning technique 4-VBBA-HAP/PVA composite was obtained. The structure and morphology of electrospun membranes were investigated by scanning electron microscopy) and Fourier transform infrared spectroscopy technique. Nanofibers were treated with collagen solution via the spraying method. For the cell culture applications ECV304 and SAOS cells were seeded on the chosen electrospun fibrous scaffolds.
ABSTRACT The aim of this study was to improve thermal stability, mechanical, and surface properti... more ABSTRACT The aim of this study was to improve thermal stability, mechanical, and surface properties of bisphenol A dicyanate ester (BADCy) with the addition of bisphenol P dicyanate ester (BPDCy) and colemanite. The cyanate esters (BADCy and BPDCy) were prepared from diphenol compound (bisphenol A or bisphenol P) and cyanogen bromide in the presence of triethylamine. The chemical structure of the synthesized cyanate esters was investigated by fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR) techniques. The cyanate esters/colemanite composites having various ratios of BADCy, BPDCy, and colemanite were prepared. Thermal stability of the samples was evaluated by thermogravimetric analysis and differential scanning calorimetry. The samples were characterized with the following analyses: gel content, water absorption capacity, and stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy—energy dispersive spectrometer mapping. Finally, the obtained results prove that the prepared composites have good thermal, mechanical, and surface properties and that they can be used in many applications such as the electronic devices, materials engineering, and other emergent.
IOP Conference Series: Materials Science and Engineering, 2014
ABSTRACT In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reactio... more ABSTRACT In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA).
IOP Conference Series: Materials Science and Engineering, 2014
ABSTRACT In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond fil... more ABSTRACT In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond films with improved thermal and mechanical properties was developed. Surface phosphorylation of nano-diamond was performed in dichloromethane. Phosphorylation dramatically enhanced the thermal stability of nano-diamond. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized with 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-oxydianiline (4,4'-ODA) in the solution of N,N- dimethylformamide (DMF). Pure BTDA-ODA polyimide films and phosphorylated nanodiamond containing BTDA-ODA PI films were prepared. The PAA displayed good compatibility with phosphorylated nano-diamond. The morphology of the polyimide (PI)/phosphorylated nano-diamond was characterized by scanning electron microscopy (SEM). Chemical structure of polyimide and polyimide (PI)/phosphorylated nano-diamond was characterized by FTIR. SEM and FTIR results showed that the phosphorylated nano-diamond was successfully prepared. Thermal properties of the polyimide (PI)/phosphorylated nanodiamond was characterized by thermogravimetric analysis (TGA). TGA results showed that the thermal stability of (PI)/phosphorylated nano-diamond film was increased.
ABSTRACT This work describes the preparation and characterization of a new thiol-ene hydrogel by ... more ABSTRACT This work describes the preparation and characterization of a new thiol-ene hydrogel by photoinitiated polymerization of pentaerythritoltetrakis(3-mercaptopropionate) (Penta3MP4), acrylic acid (AAc) and poly(ethylene glycol) dimethacrylate (PEGDA) as monomers and photo initiator(2,2-dimethoxy-2-phenylacetophenon) for its use as adsorbent. The thiol-ene hydrogel was characterized by using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Real-Time Fourier Transform Infrared Spectroscopy (RT-FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analyze (TGA) techniques; the swelling behavior and gelation ratio of hydrogel were also investigated. The adsorption capability of the hydrogel against Au(III) ions was investigated. The effects of pH, agitation time, initial metal ion concentration and different metal ions on adsorption capacity were examined. Equilibrium studies have been carried out to determine the capacity of the hydrogel for adsorption of Au(III) ions, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherms constants. Equilibrium data were found to fit very well with Langmuir model. The reusability of the hydrogel was also investigated and the preconcentration factor of the hydrogel was determined. The proposed method was applied to Dikili Geothermal Water and computer circuit board scrap. The analytical performance of the method was also determined.
ABSTRACT The sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VP... more ABSTRACT The sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VPBA), hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 2.78 × 10−4 mM and 5.56 × 10−3 mM with a limit of detection of 0.89 × 10−5 mM, and limit of quantification 3.17 × 10−3 mM (n = 7). It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The proposed sensor was then applied successfully for the determination of glucose in blood samples.The optical sensor was stable, cost effective, easy to prepare, rapid and simple for the determination of glucose.
ABSTRACT α-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glut... more ABSTRACT α-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glutaraldehyde (GA) activation. 3,3′,4,4′-Benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4′-oxydianline (4,4′-ODA) based polyimide membranes were obtained via thermal imidization. Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were subjected to enzyme immobilization after GA activation. Immobilization efficiency and enzyme activity of α-amylase was examined at various pH (3.0–8.0) and temperature (15–80°C). The storage stability and reusability of immobilized α-amylase were investigated. Immobilization yield was found as 359.53 mg per gram of modified polyimide films. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermo stability than the free one. The storage stability and reusability improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 79.98% of its activity after 30 days. These results confirmed that α-amylase was successfully immobilized and gained more stable character compared to the free enzyme.
Acrylonitrile butadiene styrene ( ABS) is a hard and light polymeric material widely used in comp... more Acrylonitrile butadiene styrene ( ABS) is a hard and light polymeric material widely used in computer, electronics, automotive and construction industry. In this study, alkoxy silane terminated urethane acrylate functional oligomer was synthesized from perfloro alcohol. Coronated ABS sheets were coated with the various formulations containing sol-gel mixture, acrylated resin including fluor and other reactive components. ABS sheets were cured by using UV-light. The performance of coatings was investigated by applying various physical tests on coated sheets.
We focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by add... more We focused on polyacrylonitrile (PAN)/huntite composites to reinforce the polymer prepared by adding different percentages (wt%) of huntite to PAN. The composites were characterized using thermogravimetric analysis, differential scanning calorimetry, fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy techniques. It was clearly seen that the composites of PAN/huntite have better thermal stability than pure PAN. The effect of the huntite adding to Polyacrylonitrile (PAN) on dc conductivity and dielectric constant was also investigated. Dc conductivity values were increased with increasing temperature. Activation energy values were calculated depending on huntite contents in PAN. Relative dielectric constant values varied in the range of 16.5–21.2 at room temperature at 100 kHz frequency depending on huntite concentrations. All the electrical measurements were performed in dark and vacuum ambient between the temperatures of 295 and 523 K. Dielectric measur...
In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimid... more In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimide (PI) was prepared with pyromellitic dianhydride (PMDA) and 4,4'-oxydianline (4,4'-ODA) in the solution of N,N-dimethylformamide (DMF). Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were then subjected to enzyme immobilization. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM). Chemical structure of PMDA-ODA PI membranes was characterized by FTIR. SEM and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. Immobilization efficiency and enzyme activity of alpha-amylase was examined at various pH values (3.0 - 8.0) and temperatures (15 - 80 degrees C). Immobilization yield was found to be 285.45 mg per gram for the modified polyimide films. Enzyme assays demonst...
The use of polymers is finding a significant place in development of sensors. Better selectivity ... more The use of polymers is finding a significant place in development of sensors. Better selectivity and rapid measurements have been achieved by replacing classical sensor materials with functions of polymers. Several receptors have been employed to detect glucose in fluorescence sensors, and these include enzymes such as glucose oxidase, glucose dehydrogenase and hexokinase/glucokinase, bacterial glucose-binding protein, and boronic acid derivatives. Boronic acid has a important role in the design of glucose sensors. The sensing membrane was prepared with p-Vinylphenylboronicacid (VPBA), Hydroxyethylmethacrylate (HEMA) and Poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 0.1 ppm and 0.7 ppm. It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The optical sensor was stable, cost effective, easy to prepare, rapid and si...
ABSTRACT Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber m... more ABSTRACT Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber membranes (NFm) were synthesized by a combination of UV radiation and an electrospinning technique. The PVA/MA/ATM NFm were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Brunauer–Emmert–Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersion spectrometry (EDS). These membranes were used for adsorption–desorption of platinum (Pt(IV)) and palladium (Pd(II)) from a fire assay (FA) leaching waste solution, and the effect of process parameters such as pH of solution, contact time, NFm dosage, temperature, and adsorption isotherms and kinetics studies on the recovery of Pt(IV) and Pd(II) from the waste solution were investigated. The adsorption equilibrium data fit better using the Langmuir model than the Freundlich model. Maximum adsorption capacities, Q max, at 45 °C were found to be 69.93 and 112.36 mg/g for Pt(IV) and Pd(II), respectively. The activation energies (E a) of Pt(IV) and Pd(II) were 27.90 and 20.29 kJ/mol, respectively. The best desorption reagent was a 1.0 M HCl–1.0 M thiourea (TU) solution for both Pd(II) and Pt(IV). Reusability studies showed that the adsorption capacity can remain up to 90 % after five times of usage. This study provides a promising NFm with an effective adsorption property for Pt(IV) and Pd(II) ions.
ABSTRACT In this study, a novel three functional chain extender (TATATRIOL) was synthesized from ... more ABSTRACT In this study, a novel three functional chain extender (TATATRIOL) was synthesized from the reaction of 1,3,5-tri(prop-2-en-1-yl)-1,3,5-triazinane-2,4,6-trione (TATA) with 2-sulfanylethanol. Then new thermoplastic polyurethanes (TPUs) were synthesized by a one-step bulk polymerization from the reaction of 1,1′-methanediylbis(4-isocyanatocyclohexane) (H12MDI), a poly(ethylene adipate) based polyester polyol and a chain extender. Butane-1,4-diol (BD) and the newly synthesized monomer, TATATRIOL, were used as chain extenders. The effects of TATATRIOL on the properties of the TPU were investigated and compared to those of the TPU prepared with BD. The TPUs which derived from the sulfur containing chain extender displayed lower modulus and high elongation at break values than the analogous TPUs derived from BD. Moreover sulfur containing TPUs exhibited higher thermal stability.
International Journal of Polymeric Materials and Polymeric Biomaterials, 2015
ABSTRACT In this study, we prepared photo-crosslinked modified HAP (hydroxy apatite)/polyvinyl al... more ABSTRACT In this study, we prepared photo-crosslinked modified HAP (hydroxy apatite)/polyvinyl alcohol (PVA) composite nanofiber scaffold for cell growth applications. HAP was synthesized and then modified with 4-vinylbenzene boronic acid (VBBA) to obtain 4-VBBA-HAP. By means of the simultaneous UV electrospinning technique 4-VBBA-HAP/PVA composite was obtained. The structure and morphology of electrospun membranes were investigated by scanning electron microscopy) and Fourier transform infrared spectroscopy technique. Nanofibers were treated with collagen solution via the spraying method. For the cell culture applications ECV304 and SAOS cells were seeded on the chosen electrospun fibrous scaffolds.
ABSTRACT The aim of this study was to improve thermal stability, mechanical, and surface properti... more ABSTRACT The aim of this study was to improve thermal stability, mechanical, and surface properties of bisphenol A dicyanate ester (BADCy) with the addition of bisphenol P dicyanate ester (BPDCy) and colemanite. The cyanate esters (BADCy and BPDCy) were prepared from diphenol compound (bisphenol A or bisphenol P) and cyanogen bromide in the presence of triethylamine. The chemical structure of the synthesized cyanate esters was investigated by fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR) techniques. The cyanate esters/colemanite composites having various ratios of BADCy, BPDCy, and colemanite were prepared. Thermal stability of the samples was evaluated by thermogravimetric analysis and differential scanning calorimetry. The samples were characterized with the following analyses: gel content, water absorption capacity, and stress-strain test. Hydrophobicity of the samples was determined by the contact angle measurements. Moreover, the surface morphology of the samples was investigated by a scanning electron microscopy—energy dispersive spectrometer mapping. Finally, the obtained results prove that the prepared composites have good thermal, mechanical, and surface properties and that they can be used in many applications such as the electronic devices, materials engineering, and other emergent.
IOP Conference Series: Materials Science and Engineering, 2014
ABSTRACT In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reactio... more ABSTRACT In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA).
IOP Conference Series: Materials Science and Engineering, 2014
ABSTRACT In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond fil... more ABSTRACT In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond films with improved thermal and mechanical properties was developed. Surface phosphorylation of nano-diamond was performed in dichloromethane. Phosphorylation dramatically enhanced the thermal stability of nano-diamond. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized with 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-oxydianiline (4,4'-ODA) in the solution of N,N- dimethylformamide (DMF). Pure BTDA-ODA polyimide films and phosphorylated nanodiamond containing BTDA-ODA PI films were prepared. The PAA displayed good compatibility with phosphorylated nano-diamond. The morphology of the polyimide (PI)/phosphorylated nano-diamond was characterized by scanning electron microscopy (SEM). Chemical structure of polyimide and polyimide (PI)/phosphorylated nano-diamond was characterized by FTIR. SEM and FTIR results showed that the phosphorylated nano-diamond was successfully prepared. Thermal properties of the polyimide (PI)/phosphorylated nanodiamond was characterized by thermogravimetric analysis (TGA). TGA results showed that the thermal stability of (PI)/phosphorylated nano-diamond film was increased.
ABSTRACT This work describes the preparation and characterization of a new thiol-ene hydrogel by ... more ABSTRACT This work describes the preparation and characterization of a new thiol-ene hydrogel by photoinitiated polymerization of pentaerythritoltetrakis(3-mercaptopropionate) (Penta3MP4), acrylic acid (AAc) and poly(ethylene glycol) dimethacrylate (PEGDA) as monomers and photo initiator(2,2-dimethoxy-2-phenylacetophenon) for its use as adsorbent. The thiol-ene hydrogel was characterized by using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Real-Time Fourier Transform Infrared Spectroscopy (RT-FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analyze (TGA) techniques; the swelling behavior and gelation ratio of hydrogel were also investigated. The adsorption capability of the hydrogel against Au(III) ions was investigated. The effects of pH, agitation time, initial metal ion concentration and different metal ions on adsorption capacity were examined. Equilibrium studies have been carried out to determine the capacity of the hydrogel for adsorption of Au(III) ions, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherms constants. Equilibrium data were found to fit very well with Langmuir model. The reusability of the hydrogel was also investigated and the preconcentration factor of the hydrogel was determined. The proposed method was applied to Dikili Geothermal Water and computer circuit board scrap. The analytical performance of the method was also determined.
ABSTRACT The sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VP... more ABSTRACT The sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VPBA), hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 2.78 × 10−4 mM and 5.56 × 10−3 mM with a limit of detection of 0.89 × 10−5 mM, and limit of quantification 3.17 × 10−3 mM (n = 7). It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The proposed sensor was then applied successfully for the determination of glucose in blood samples.The optical sensor was stable, cost effective, easy to prepare, rapid and simple for the determination of glucose.
ABSTRACT α-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glut... more ABSTRACT α-amylase was covalently immobilized on functionalized polyimide (PI) membranes via glutaraldehyde (GA) activation. 3,3′,4,4′-Benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4′-oxydianline (4,4′-ODA) based polyimide membranes were obtained via thermal imidization. Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were subjected to enzyme immobilization after GA activation. Immobilization efficiency and enzyme activity of α-amylase was examined at various pH (3.0–8.0) and temperature (15–80°C). The storage stability and reusability of immobilized α-amylase were investigated. Immobilization yield was found as 359.53 mg per gram of modified polyimide films. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermo stability than the free one. The storage stability and reusability improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 79.98% of its activity after 30 days. These results confirmed that α-amylase was successfully immobilized and gained more stable character compared to the free enzyme.
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Papers by Memet Kahraman