Aqueous solutions of caffeine were treated with ozone and gamma irradiation. The amounts of remai... more Aqueous solutions of caffeine were treated with ozone and gamma irradiation. The amounts of remaining caffeine were determined after solid phase extraction as a function of absorbed dose and ozonation time. In addition to this, some important parameters such as inorganic ions, chemical oxygen demand (COD) dissolved oxygen and total acidity changes were followed. Caffeine (50 ppm) is found to be completely decomposed at 3.0 kGy and 1.2 kGy doses in the absence of H2O2 and in 1.20 mM H2O2 solutions, respectively. In the case of gamma irradiation after ozonation, 50 ppm caffeine was removed at 0.2 kGy when the solution was ozonized for 100 s at a rate of 10 g O3 h–1 in 400 mL 50 ppm paracetamol solution.
Using different types and concentrations of crosslinkers, acrylamide (AAm) hydrogels have been pr... more Using different types and concentrations of crosslinkers, acrylamide (AAm) hydrogels have been prepared with chemical initiation and gamma irradiation techniques. The effects of the preparation method, crosslinkers type and concentration on swelling behavior of AAm hydrogels were investigated. Swelling was performed in distilled water and followed gravimetrically. Swelling parameters such as equilibrium swelling degree, equilibrium water content (EWC), maximum swelling, initial swelling rate, diffusion exponent and coefficient, and network parameters such as molecular mass between crosslinks, crosslink density, mesh size, and porosity were calculated and evaluated. The range of equilibrium swelling degree of AAm hydrogels was varied from 255% to 1450% depending upon the preparation method, crosslinker type, and crosslinker concentration. The diffusion of water into AAm hydrogels was found to be nonFickian.
Electrical conductivity of blends and composites of poly(vinyl chloride) (PVC) with nonconducting... more Electrical conductivity of blends and composites of poly(vinyl chloride) (PVC) with nonconducting polyaniline (PANI) increases when they are subjected to γ-rays or UV radiation. This is attributed to a radiation-induced dehydrochlorination (loss of HCl) of PVC, which in turn oxidizes (dopes) PANI within the PVC matrix causing the increase in electrical conductivity of these films. XPS, UV-vis-NIR and FTIR spectroscopic methods are used to characterize and verify this novel process. After the films are subjected to γ-rays (or UV radiation) the intensities in the XPS spectra of both -N +and Clpeaks increase, confirming the increase in charged species within the PVC matrix. Similar observations attributable to radiation-induced electrical conductivity are also observed in both the UV-vis-NIR and FTIR spectra. This radiation-induced conductivity can also be reversed to some extent by further exposing the films to NH 3 vapors, where the oxidized centers are partially reduced (undoped). Several UV/NH 3 /UV cycles can be performed without much loss in conductivity-and/or conductivity-related spectroscopic features. The onset of the photoinduced conductivity both in PVC-only and PVC/PANI composite films is determined to be 300 nm (4.1 eV), which coincides with the first UV absorption band of PVC.
Aqueous solutions of caffeine were treated with ozone and gamma irradiation. The amounts of remai... more Aqueous solutions of caffeine were treated with ozone and gamma irradiation. The amounts of remaining caffeine were determined after solid phase extraction as a function of absorbed dose and ozonation time. In addition to this, some important parameters such as inorganic ions, chemical oxygen demand (COD) dissolved oxygen and total acidity changes were followed. Caffeine (50 ppm) is found to be completely decomposed at 3.0 kGy and 1.2 kGy doses in the absence of H2O2 and in 1.20 mM H2O2 solutions, respectively. In the case of gamma irradiation after ozonation, 50 ppm caffeine was removed at 0.2 kGy when the solution was ozonized for 100 s at a rate of 10 g O3 h–1 in 400 mL 50 ppm paracetamol solution.
Using different types and concentrations of crosslinkers, acrylamide (AAm) hydrogels have been pr... more Using different types and concentrations of crosslinkers, acrylamide (AAm) hydrogels have been prepared with chemical initiation and gamma irradiation techniques. The effects of the preparation method, crosslinkers type and concentration on swelling behavior of AAm hydrogels were investigated. Swelling was performed in distilled water and followed gravimetrically. Swelling parameters such as equilibrium swelling degree, equilibrium water content (EWC), maximum swelling, initial swelling rate, diffusion exponent and coefficient, and network parameters such as molecular mass between crosslinks, crosslink density, mesh size, and porosity were calculated and evaluated. The range of equilibrium swelling degree of AAm hydrogels was varied from 255% to 1450% depending upon the preparation method, crosslinker type, and crosslinker concentration. The diffusion of water into AAm hydrogels was found to be nonFickian.
Electrical conductivity of blends and composites of poly(vinyl chloride) (PVC) with nonconducting... more Electrical conductivity of blends and composites of poly(vinyl chloride) (PVC) with nonconducting polyaniline (PANI) increases when they are subjected to γ-rays or UV radiation. This is attributed to a radiation-induced dehydrochlorination (loss of HCl) of PVC, which in turn oxidizes (dopes) PANI within the PVC matrix causing the increase in electrical conductivity of these films. XPS, UV-vis-NIR and FTIR spectroscopic methods are used to characterize and verify this novel process. After the films are subjected to γ-rays (or UV radiation) the intensities in the XPS spectra of both -N +and Clpeaks increase, confirming the increase in charged species within the PVC matrix. Similar observations attributable to radiation-induced electrical conductivity are also observed in both the UV-vis-NIR and FTIR spectra. This radiation-induced conductivity can also be reversed to some extent by further exposing the films to NH 3 vapors, where the oxidized centers are partially reduced (undoped). Several UV/NH 3 /UV cycles can be performed without much loss in conductivity-and/or conductivity-related spectroscopic features. The onset of the photoinduced conductivity both in PVC-only and PVC/PANI composite films is determined to be 300 nm (4.1 eV), which coincides with the first UV absorption band of PVC.
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Papers by E. Güven
caffeine were determined after solid phase extraction as a function of absorbed dose and ozonation time. In addition
to this, some important parameters such as inorganic ions, chemical oxygen demand (COD) dissolved oxygen and total
acidity changes were followed. Caffeine (50 ppm) is found to be completely decomposed at 3.0 kGy and 1.2 kGy doses
in the absence of H2O2 and in 1.20 mM H2O2 solutions, respectively. In the case of gamma irradiation after ozonation,
50 ppm caffeine was removed at 0.2 kGy when the solution was ozonized for 100 s at a rate of 10 g O3 h–1 in 400 mL
50 ppm paracetamol solution.
caffeine were determined after solid phase extraction as a function of absorbed dose and ozonation time. In addition
to this, some important parameters such as inorganic ions, chemical oxygen demand (COD) dissolved oxygen and total
acidity changes were followed. Caffeine (50 ppm) is found to be completely decomposed at 3.0 kGy and 1.2 kGy doses
in the absence of H2O2 and in 1.20 mM H2O2 solutions, respectively. In the case of gamma irradiation after ozonation,
50 ppm caffeine was removed at 0.2 kGy when the solution was ozonized for 100 s at a rate of 10 g O3 h–1 in 400 mL
50 ppm paracetamol solution.