Dilek Şolpan

Synthesis and characterization of acrylamide–acrylic acid hydrogels and adsorption of some textile dyes

Abstract Acrylamide (AAm)–acrylic acid (AAc) hydrogels have been prepared at AAm initial compositions of 15%, 20% and 30%. AAm–AAc monomer mixtures have been irradiated in a 60 Co-γ source at different doses and percent conversions have been determined gravimetrically. 100% conversion of monomers into hydrogels was achieved at 8 kGy dose. These hydrogels were swollen in distilled water at pH 3.03, 4.18, 4.68, 5.05, 5.30, 6.0, 7.0, 8.0. The results of swelling tests at pH 8.0 indicated that poly(AAm–AAc) hydrogels prepared from solution containing 15% (mol%) AAm showed maximum % swelling as 3000%. Poly(AAm–AAc) hydrogels have been considered for the removal of some textile dyes from aqueous solutions. Among the two common textile dyes tested, Janus Green B (JGB) has showed the highest adsorption capacity while Congo Red (CR) was not adsorbed by these hydrogels. Adsorption isotherms were constructed for JGB and poly(AAm/AAc) gel systems. It is concluded that cross-linked poly(AAm/AAc) hydrogels can be successfully used in the purification of waste water containing certain textile dyes.

Enhancement of transbuccal permeation of morphine sulfate by sodium glycodeoxycholate in vitro

Abstract In this study, enhancement of transbuccal permeation of morphine sulfate was studied in the presence of sodium glycodeoxycholate (GDC). The permeability of the bovine buccal mucosa to morphine sulfate was determined in vitro in the absence and presence of GDC at 10 mM and 100 mM concentrations. Light and electron microscopy studies were performed to determine the histological and ultrastructural changes resulting from transepithelial permeation enhancement. In addition, infrared spectroscopy (IR) was used to investigate the interaction of GDC with the epithelial lipids of bovine buccal mucosa. The permeation of morphine sulfate across the bovine buccal epithelium was enhanced in the presence of 100 mM GDC by a factor of five whereas at lower concentrations, no significant enhancement was obtained. After 4 h treatment with 100 mM (5% w/v) GDC, significant changes were observed in the epithelium at histological and ultrastructural levels which can be defined as formation of vacuoles, swelling of the cells and a possible increase in intercellular space. Furthermore, by means of IR spectroscopy, it was possible to show the effect of GDC on bovine buccal epithelial lipid domains which was in good correlation with the permeation results. In the light of the results obtained by permeation, histological and IR spectroscopy studies, it is concluded that GDC at 100 mM concentration significantly enhances the permeation of MS across the buccal epithelium and the mechanism of this action appears to involve an interaction with the epithelial lipids.

Preservation of beech and spruce wood by allyl alcohol-based copolymers

Abstract Allyl alcohol (AA), acrylonitrile (AN), methyl methacrylate (MMA), monomers and monomer mixtures AA+AN, AA+MMA were used to conserve and consolidate Beech and Spruce. After impregnation, copolymerisation and polymerisation were accomplished by gamma irradiation. The fine structure of wood+polymer(copolymer) composites was investigated by Scanning Electron Microscopy (SEM). It was observed that copolymer obtained from AA+MMA monomer mixture showed the optimum compatibility. The compressional strength and Brinell Hardness Numbers determined for untreated and treated wood samples indicated that the mechanical strength of wood+copolymer composites was increased. It was found that the mechanical strength of the wood samples containing the AA+MMA copolymer was higher than the others. In the presence of P(AA/MMA), at highest conversion, the compressive strength perpendicular to the fibres in Beech and Spruce increased approximately 100 times. The water uptake capacity of wood+copolymer composites was observed to decrease by more than 50% relative to the original samples, and biodegradation did not take place.

Preparation and properties of some wood/(co)polymer composites

Beech and spruce samples which were impregnated with acrylonitrile (AN), methyl methacrylate (MMA), allyl glycidyl ether (AGE), AGE + AN, AGE + MMA monomers and monomer mixtures were subjected to (co)polymerization by gamma radiation. The dimensional stabilization and resistance against biodegradation of wood/(co)polymer composites was investigated. The water uptake capacities of wood/ (co)polymer composites were observed to decrease by more than 70% as compared to untreated samples. There were no noticeable changes in the structure of the wood/(co)polymer composites after treatment with artifical acid rain. It was found that the wood/(co)polymer composites were stable against the biological attacks of microorganisms like mould and bacteria.

Mineralization of paracetamol in aqueous solution with advanced oxidation processes

Paracetamol is a common analgesic drug widely used in all regions of the world more than hundred tonnes per year and it poses a great problem for the aquatic environment. Its phenolic intermediates are classified as persistent organic pollutants and toxic for the environment as well as human beings. In the present study, the irradiation of aqueous solutions of paracetamol with 60Co gamma-rays was examined on a laboratory scale and its degradation path was suggested with detected radiolysis products. The synergic effect of ozone on gamma-irradiation was investigated by preliminary ozonation before irradiation which reduced the irradiation dose from 5 to 3 kGy to completely remove paracetamol and its toxic intermediate hydroquinone from 6 to 4 kGy as well as increasing the radiation chemical yield (Gi values 1.36 and 1.66 in the absence and presence of ozone, respectively). The observed amount of formed hydroquinone was also decreased in the presence of ozone. There is a decrease in pH from 6.4 to 5.2 and dissolved oxygen consumed, which is up to 0.8 mg l−1, to form some peroxyl radicals used for oxidation. Analytical measurements were carried out with gas chromatography/mass spectrometry and ion chromatography (IC) both qualitatively and quantitatively. Amounts of paracetamol and hydroquinone were measured with gas chromatography after trimethylsilane derivatization. Small aliphatic acids, such as acetic acid, formic acid and oxalic acid, were measured quantitatively with IC as well as inorganic ions (nitrite and nitrate) in which their yields increase with irradiation. GRAPHICAL ABSTRACT

Adsorption of Uranyl Ions into Poly(Acrylamide‐co‐Acrylic Acid) Hydrogels Prepared by Gamma Irradiation

Acrylamide (AAm)/Acrylic Acid (AAc) copolymers have been prepared by gamma irradiation of binary mixtures at three different compositions where the acrylamide/acrylic acid mole ratios varied around 15, 20, and 30%. Threshold dose for 100% conversion of monomers into hydrogels was found to be 8.0 kGy. Poly(Acrylamide‐co‐Acrylic Acid) (poly(AAm‐co‐AAc)) hydrogels have been considered for the removal of uranyl ions from aqueous solutions. Swelling behavior of these hydrogels was determined in distilled water at different pH values and in aqueous solutions of uranyl ions. The results of swelling tests at pH 8.0 indicated that poly(AAm‐co‐AAc) hydrogel, containing 15% acrylamide showed maximum % swelling. Diffusion of water and aqueous solutions of uranyl ion into hydrogels was found to be non‐Fickian in character and their diffusion coefficients were calculated. The effect of pH, composition of hydrogel, and concentration of uranyl ions on the adsorption process were studied at room temperature. It was found that one gram of dry poly(AAm‐co‐AAc) hydrogel adsorbed 70–320 mg and 70–400 mg uranyl ions from aqueous solutions of uranyl nitrate and uranyl acetate in the initial concentration range of 50–1500 mg UO2 2+L−, depending on the amount of AAc in the hydrogels, respectively. Adsorption isotherms were constructed for poly(AAm‐co‐AAc)–uranyl ion system indicating an S type of adsorption in the Giles classification system. It is concluded that crosslinked poly(AAm‐co‐AAc) hydrogels can be successfully used for the removal of uranyl ions from their aqueous solutions.

Improvement of mechanical stability of beechwood by radiation-induced in situ copolymerization of allyl glycidyl ether with acrylonitrile and methyl methacrylate

Acrylonitrile (AN), methyl methacrylate (MMA), allyl glycidyl ether (AGE), AGE + AN monomer, AGE + MMA monomer, and monomer mixtures were used to conserve and consolidate beechwood. After the impregnation of these monomer mixtures in the wood, polymerization was accomplished by gamma irradiation. The fine structures of wood + polymer(copolymer) composites were investigated by scanning electron microscopy (SEM). The copolymer obtained from AGE + MMA monomer mixtures showed the optimum compatibility with the wood. The compressive strength and Brinell hardness numbers determined for untreated and treated wood samples indicated that the mechanical strength was greater in wood + polymer(copolymer) composites than in untreated wood and was greatest in the samples containing AGE + AN and AGE + MMA copolymers. All monomer couples used in this study increased the mechanical strength of the wood and protected the samples against aging. AGE + MMA copolymers were the most effective in protecting the wood against various environmental attacks.

Comparison of the dimensional stabilities of oak and cedar wood preserved by in situ copolymerization of allyl glycidyl ether with acrylonitrile and methyl methacrylate

Oak and cedar woods were impregnated with acrylonitrile (AN), methyl methacrylate (MMA), and mixtures of allyl glycidyl ether (AGE) with AN and MMA to conserve and consolidate the wood. After impregnation, these monomer mixtures were polymerized by gamma irradiation. The dimensional stabilities and the resistance against the biodegradation of the wood (oak and cedar)/(co)polymer composites were determined. The water uptake capacity of the wood/(co)polymer composites is up to 50% lower than that of the original wood, for P(AGE/MMA) and P(AGE/AN) copolymers lower than for PAN and PMMA. Artificial raining did not change the structure of wood/(co)polymer composites and no biodegradation occurred. Eichen- und Zedernholz wurde mit Acrylnitril (AN), Methylmethacrylat (MMA) und Mischungen von Allylglycidylether (AGE) mit AN und MMA impragniert, um es zu konservieren und verfestigen. Die Monomeren wurden anschliesend durch Gammastrahlen polymerisiert. Die Formstabilitat und die Verrottungsbestandigkeit wurden untersucht. Die Wasseraufnahmefahigkeit liegt bis zu 50% unter derjenigen der unbehandelten Holzer, mit P(AGE/MMA) und P(AGE/AN) ist sie niedriger als mit PAN und PMMA. Kunstliche Beregnung fuhrte nicht zu einer Anderung der Struktur der Composite, und sie zeigten keine Anzeichen von Verrottung.

Radiation initiated copolymerization of allyl alcohol with acrylonitrile

Copolymerization of allyl alcohol (AA) with acrylonitrile (AN) initiated by γ-rays has been investigated to determine the respective reactivity ratios. Three different experimental techniques, namely Fourier Transform Infrared (FTIR), Ultraviolet (UV/vis) and elemental analysis (EA) have been used for the determination of copolymer compositions. Fineman-Ross (FR), Kelen-Tudos (KT), Non-Linear Least Square (NLLS) Analysis and Q-e methods have been applied to the three sets of experimental data. It has been concluded that data obtained from elemental analysis as applied to the Non-Linear Least Square approach gave the most reliable reactivity ratios as 2.09 and 0.40 for acrylonitrile and allyl alcohol, respectively.

Thermal stability of the copolymers of allyl glycidyl ether with acrylonitrile and methyl methacrylate obtained via gamma irradiation

Abstract Homopolymerization of allyl glycidyl ether (AGE) initiated by gamma rays and the copolymerization of AGE with acrylonitrile (AN) and methyl methacrylate (MMA) were investigated. The thermal characterization of resulting homopolymers and copolymers were realized by Thermal Analysis Techniques and their degradation activation energies were calculated. The copolymers, P(AGE/AN), formed from AGE+AN monomers were more stable thermally than those copolymers, P(AGE/MMA), formed from AGE+MMA monomer mixtures.