Cemal Özeroğlu

Determination of lead, copper and manganese by graphite furnace atomic absorption spectrometry after separation/concentration using a water-soluble polymer

In this study, a water-soluble polymer, polyvinylpyrrolidinone (PVP) having chelating functionalities was used for the preconcentration and separation of traces of Pb, Cu, Ve and Mn prior to their determination by graphite furnace atomic absorption spectrometry. For this purpose, the sample and the PVP solutions were mixed and the metal bound polymer was precipitated by adding the mixture onto acetone. The precipitate was separated by decantation and dissolved with water. By increasing the ratio of the volumes of sample to water used in dissolving the precipitate, the analyte elements were concentrated as needed. The concentration of trace elements was determined using graphite furnace atomic absorption spectrometry. The analyte elements in matrix free aqueous solutions were quantitatively recovered. The validity of the proposed method was checked with a standard reference material (NIST SRM 1577b bovine liver) and spiked fruit juice, sea water and mineral water samples. The analytical results were found to be in good agreement with certified and added values. Detection limits (3delta) were 1.7, 3.6 and 4.1mugl(-1) for Pb, Cu and Mn, respectively, using 10mul of sample volume. The method is novel and can be characterized by rapidity, simplicity, quantitative recovery and high reproducibility.

Kinetic and thermodynamic studies on the adsorption of U(VI) ions on densely crosslinked poly(methacrylic acid) from aqueous solutions

Abstract In this study, densely crosslinked poly(methacrylic acid) was used to adsorb uranium(VI) ions from aqueous solution. For this purpose, the crosslinked copolymer of ethylene glycol dimethacrylate (EGDM) and methacrylic acid (MA) containing 25% (w/w) methacrylic acid (MA) was synthesized by using dibenzoyl peroxide-N,N-dimethylaniline (BPO-DMA) initiator system at room temperature. The adsorption of uranium(VI) ions on the copolymer sample (0.02 g copolymer/5 mL solution of U(VI) ions) was carried out in a batch reactor. The parameters which effect the uranium adsorption process, such as, contact time, pH of solution, initial uranium(VI) concentration and temperature were investigated. It was observed that an increase in these parameters enhanced the removal of U(VI) ions from aqueous solution. The adsorption data were modelled by the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherms. The adsorption capacity of the crosslinked copolymer and free energy change were calculated by using D–R isotherms. Thermodynamic parameters (ΔH°, ΔS° and ΔG°) were determined for the adsorption of U(VI) ions from aqueous solutions by the crosslinked copolymer bearing methacrylic acid functional groups. Experimental adsorption data were analyzed using sorption kinetic models of the pseudo-first order and pseudo-second order kinetic models. It was observed that pseudo-second order kinetic model provided a high goodness of fit with experimental data for the adsorption of U(VI) ions on the crosslinked copolymer bearing methacrylic acid functional groups. The densely crosslinked poly(methacrylic acid) might be of interest in large scale uranium removals from aqueous solution, since it had high uranyl sorption capacities ranging from 0.16 mmol/g to 2.37 mmol/g copolymer at pH 2.7 (293 K).

Low temperature initiation by methylene bis(diethyl malonate)–Ce(IV) redox system in organic solvents

Abstract Methylene bis(diethyl malonate)–cerium ammonium nitrate redox couple serves as initiator in triethyl phosphate for polymerization of methyl methacrylate at room temperature. High polymerization yield (>90%) can be attained at moderate concentration ratios (monomer/initiator ≅70:1) in 4 h reaction periods. Increasing molar ratio of methylene bis(diethyl malonate) to cerium salt causes to low molecular weights which implies possibility of its chain transfer effect through active methylene groups at the same time.

Kinetics of the adsorption of strontium ions by a crosslinked copolymer containing methacrylic acid functional groups

The crosslinked copolymers of ethylene glycol dimethacrylate (EGDM) and methacrylic acid (MA) containing different amounts of MA as weight percentage (MA content = 10.00%, 25.00% and 50.00%) were synthesized by using BPO-DMA initiator system at room temperature. Infrared (FTIR) and thermal gravimetric analysis (TGA) were used to characterize the crosslinked copolymers. The crosslinked copolymer containing 25.00% of MA as weight percentage (w/w) was used as adsorbent for the removal of strontium ions from aqueous solution. The effects of parameters including strontium concentration, agitation time, temperature and pH were examined. Kinetics of the adsorption of strontium ions on the copolymer bearing methacrylic acid functional groups from aqueous solution at various initial strontium concentrations was studied. Goodness of experimental results to the Elovich, fractional powder, pseudo-first order and pseudo-second order models have been examined. The pseudo-second order model provided a high degree of correlation with the experimental data for the adsorption process of strontium ion on the crosslinked copolymer bearing methacrylic acid funtional goups from aqueous solutions.

The synthesis and characterization of acrylamide polymer containing R-(+)-cysteine end groups

Abstract Water soluble polyacrylamides which contain R-(+)-cysteine end groups were synthesized by using R-(+)-cysteine–Ce(IV) sulfate and R-(+)-cysteine–KMnO4 redox systems in acid–aqueous medium. The dependence of polymerization yields and the molecular weight of polymers on the mole ratio of acrylamide to R-(+)-cysteine (nCys=nCe(IV)) at different temperatures, the polymerization time, the temperature, and the concentration of sulfuric acid was investigated. The increase in the mole ratio of acrylamide to R-(+)-cysteine resulted in an increase in the molecular weight but a decrease in the yield. The increase of reaction temperature from 30°C to 60°C resulted in an increase in the molecular weights and slight increase in the yield of polymer. Ce(IV) and Mn(IV) ions are reduced to Ce(III) and Mn(II) respectively in polymerization reaction. The existence of Ce(III) ion in polymer was investigated by UV–Vis spectrometry and fluorescence measurements. The amount of Mn(II) which is incorporated in the polymer was determined. The mechanism of this phenomenon is discussed.

Use of the crosslinked copolymer functionalized with acrylic acid for the removal of strontium ions from aqueous solutions

A crosslinked polyester resin containing acrylic acid as functional groups was synthesized and characterized by using FT-IR method. Adsorption behavior of strontium ions on the synthesized polyester resin was investigated as a function of sorptive concentration, time, temperature, and pH by using ICP-OES measurements. Adsorption data were analyzed by the modified Freundlich, Elovich, pseudo-first order and pseudo-second order kinetic models, by the Freundlich, Langmuir and Dubinin–Radushkevich isotherms and by the thermodynamic parameters such as enthalpy (∆H°), entropy (∆S°) and free energy change (∆G°).

Low Temperature Initiation by 3-Mercaptopropionic Acid-Ce(IV) or -KMnO4 Redox System for Polymerization of Acrylamide Monomer

ABSTRACT Polymerization of acrylamide monomer was performed at low temperatures using 3-mercaptopropionic acid-cerium(IV) sulfate and 3-mercaptopropionic acid-KMnO4 redox systems in acid aqueous medium. Water soluble polyacrylamides containing 3-mercaptopropionic acid end groups were synthesized. The effects of mole ratio of acrylamide to initiator(nMSA= nCe(IV)), polymerization time, temperature, and concentration of sulfuric acid on the yield and molecular weight of polymer were investigated. The decrease in the mole ratio of acrylamide/Ce(IV) at constant monomer concentration resulted in an increase in the yield but a decrease in molecular weight of polymer. The increase of reaction temperature from 20° to 70°C resulted in a decrease in the yield but indicated generally a constant value for the molecular weight of polymer. With increasing of polymerization time, the yield and molecular weight of polymer did not change mainly. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions, respectively in the polymerization reaction. The existence of Ce(III) ion bonded to polymer was investigated by UV-visible spectrometry and fluorescence measurements. The amount of Mn(II) that is incorporated to the polymer was determined using graphite furnace atomic absorption spectrometry. The mechanism of this phenomenon is discussed.

Oxidative Polymerization of Methyl Methacrylate in Acid-Aqueous Medium

Abstract The polymerization of methyl methacrylate monomer initiated by l-methionine-Ce(IV) sulfate redox system in an acid-aqueous medium was investigated. Partially cross-linked methyl methacrylate polymers with limited solubility in known solvents were obtained. The dependence of polymerization yields on the mole ratio of l-methionine to cerium(IV) sulfate and methyl methacrylate monomer to cerium(IV) sulfate (n Ce(IV) = n Meth), polymerization time, acid concentration, temperature, and amount of solvent (acetone and methanol) was investigated. The results of infrared, thermal gravimetric analysis, differantial scanning calorimetry measurements to indicate the thermal oxidative properties of obtained polymers also are given. The possible mechanism for the polymerization reaction is discussed.

Oxidative polymerization of acrylamide in the presence of thioglycolic acid

Chemical polymerization of acrylamide at room temperature was examined by using thioglycolic acid-cerium (IV) sulfate and thioglycolic acid-KMnO4 redox systems in acid aqueous medium. Water soluble polyacrylamides containing thioglycolic acid end groups were synthesized. The effects of the molar ratio of acrylamide to Ce(IV) nAAm/nCe(IV), the polymerization time, the temperature, the monomer concentration, the molar ratio of cerium (IV) sulfate to thioglycolic acid and the concentration of sulfuric acid on the yield and molecular weight of polymer were investigated. Lower molar ratios of acrylamide/Ce(IV) at constant monomer concentration resulted in an increase in the yield but a decrease in molecular weight of polymer. The increase of reaction temperature from 20 to 70°C resulted in a decrease in the yield but generally resulted in a constant value for the molecular weight of polymer. With increasing polymerization time, the yield and molecular weight of polymer did not change substantially. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions respectively in the polymerization reaction. The existence of Ce(III) ion bound to polymer was investigated by UV-visible spectrophotometry and fluoresce measurements. The amount of Mn(II) incorporated into the polymer was determined using graphite furnace atomic absorption spectrometry. The mechanism of this phenomenon is discussed.

The Effect of Tertiary Amines on the Free Radical Copolymerization of Unsaturated Polyester and Styrene

Abstract This article gives a discussion of the accelerating effects of tertiary amines in hardening unsaturated polyester. For this purpose, by using 2-methyl-1,3-propandiol, terephthalic acid, and maleic anhydride, an unsaturated polyester polymer was synthesized in a pilot reactor with a heater control. Stannous oxalate was used as an esterification catalyst. The polymer was dissolved in styrene containing a small part of hydroquinone. Cobalt octoate in toluene (1% m/m of Co) or and tertiary amines such as (DMA), (DMPT), (DHEPT), (PTDEA), and (TMEDA) were evaluated as curing reaction promotors or copromotors for the unsaturated polyester resin by using 1% methyl ethyl ketone peroxide (MEKp, Butanox M60). The increase of cobalt concentration for curing 100 g of unsaturated polyester resin by using 1 mL MEKp reduced gel time and curing time but increased peak exotherm temperature. Tertiary amine promotors, at a constant 1% MEKp and 0.5% cobalt solution catalyst system, were evaluated for efficiency as indicated by decreased gel and cure times: DMPA > DMA ≫ DHEPT > PTDEA ≥ TMEDA.