Şeref Güçer

Photocatalytic degradation of Congo Red by hydrothermally synthesized nanocrystalline TiO2 and identification of degradation products by LC-MS.

Degradation of Congo Red (CR) dye in aqueous solutions was investigated by means of photocatalysis of TiO2 which was hydrothermally synthesized at 200 degrees C in 2 h, in anatase phase with 8 nm crystallite size. Efficiency of TiO2 in photocatalytic degradation under visible irradiation was studied by investigating the effects of amount of TiO2, irradiation time, initial CR concentration and pH. It was found that complete decolorization is achieved within 30 min of irradiation. Effects of nitrate and sulphate ions and humic acid on the degradation were also tested. The results were compared with Degussa P-25 TiO2 at the same degradation conditions. Degradation products were detected using LC-MS technique. The probable pathways for the formation of degradation products were proposed.

Removal of diethyl phthalate from aqueous phase using magnetic poly(EGDMA–VP) beads

The barium hexaferrite (BaFe(12)O(19)) containing magnetic poly(ethylene glycol dimethacrylate-vinyl pyridine), (mag-poly(EGDMA-VP)) beads (average diameter=53-212 μm) were synthesized and characterized. Their use as an adsorbent in the removal of diethyl phthalate (DEP) from an aqueous solution was investigated. The mag-poly(EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly(EGDMA-VP) beads were characterized by N(2) adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM) and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. The maximum DEP adsorption capacity of the mag-poly(EGDMA-VP) beads was determined as 98.9 mg/g at pH 3.0, 25°C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DEP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

Fractionation analysis of magnesium in olive products by atomic absorption spectrometry

A scheme is presented for fractionation of olive components and magnesium determinations in different fractions. The charge of metal species was established using cation exchange with Dowex 50Wx8-40. The resin Amberlite XAD-4 was used for the separation of olive polyphenols in complexes with olive proteins and polysaccharides. The organic and inorganic fraction of magnesium was studied with different solvents as to its bioavailability properties. Flame and electrothermal atomic absorption spectrometry were used off-line for the determinations of magnesium in the different fractions obtained.

Application of factorial design for mercury determination by trapping and graphite furnace atomic absorption spectrometry

Abstract A trapping technique was developed for the determination of mercury traces in blood serum by graphite furnace atomic absorption spectrometry (GFAAS). The mercury was converted to metallic vapour in a reaction cell by tin chloride solution, swept by nitrogen into a gold-plated graphite tube and subsequently atomized. The influence of four experimental factors on the sensitivity of mercury determination was examined using two level factorial designs. It was found that the solution volume is the most significant parameter.

Determination of some phthalate acid esters in artificial saliva by gas chromatography–mass spectrometry after activated carbon enrichment

The determination of six phthalate acid esters was achieved in artificial saliva using gas chromatography-mass spectrometry following activated carbon enrichment of samples. Central composite experimental design was applied to optimize method parameters, such as pH, adsorption time and amount of activated carbon. The best compromise of analytical conditions for the simultaneous determination of analytes from spiked artificial saliva were found to be: pH (3), adsorption time (30 min), activated carbon amount (1.8 g L(-1)) and elution solvent (chloroform). These conditions were applied to study the migration of phthalate acid esters from different childrens toys into saliva. A horizontal agitation method was applied to extract the analytes from plastic toys into saliva for 2h at 37°C. The detection limits of the method were in the range of 1.3-5.1 μg L(-1), while the relative standard deviation (%) values for the analysis of 100 μg L(-1) of the analytes were below 3.0% (n=5). Di-2-ethylhexyl phthalate was the main analyte found in these samples.

DETERMINATION OF CADMIUM, CHROMIUM, LEAD, AND MERCURY IN POLYETHYLENE AND POLYPROPYLENE AFTER XYLENE TREATMENT BY ENERGY DISPERSIVE X-RAY FLUORESCENCE SPECTROMETRY

A convenient organic solvent treatment method was developed for the determination of Cd, Cr, Hg, and Pb in polyethylene and polypropylene matrices by energy dispersive X-ray fluorescence spectrometry. The solvent treatment method had many advantages for the fast, simple, and accurate multi-element analysis of these materials. Calibration curves were prepared using organometallic compounds in xylene in the concentration range of 1–80 mg kg−1. The prepared samples had a homogeneous elemental distribution and good durability. The trueness for the quantification of mentioned elements were checked by using a polyethylene certified reference material. The apparent recoveries of the elements with certified values were in the range of 0.81 (Hg) to 1.14 (Pb). The precision was normally better than 8% RSD, with the exception of Hg (10%). The method detection limits were found to be 12, 24, 12, and 12 mg kg−1 for Cd, Cr, Hg, and Pb, respectively. Polyethylene and polypropylene samples were analyzed by both the XRF method and the reference technique for comparative purposes. Application of analysis of variance (ANOVA) showed no differences between the mean results. The proposed method could be also applied to several different xylene soluble plastics.

Blood lead levels of traffic policemen in Bursa, Turkey

This study was conducted in January 2001, in Bursa, Turkey. Of the 99 traffic policemen who were included in the study, 21 were office workers. Blood lead levels were determined by using an electro-thermal atomic absorption spectrometer (ET-AAS). Average blood lead levels were 9.4 +/- 1.6 micrograms/l and 8.7 +/- 1.7 micrograms/l for policemen working outdoors and indoors, respectively. The difference between the two groups was statistically insignificant (P > 0.05). When policemen less than 15 years on duty were taken into account (n = 48) the difference between the outdoors and indoors working groups was significant (9.3 +/- 1.3 and 8.2 +/- 1.8 micrograms/l, P < 0.05). In order to prevent the negative effects of tetraethyl lead on humans and the environment the use of lead in petrol must be prohibited.

SELECTIVE PRECONCENTRATION AND DETERMINATION OF COBALT(II) USING N,N′-BIS(2-HYDROXY-5-BROMO-BENZYL)-1,2-DIAMINOPROPANE

ABSTRACT The present work describes a selective, rapid, and economical method for the determination of cobalt using N,N′-bis(2-hydroxy-5-bromo-benzyl)-1,2-diaminopropane (HBDAP). The investigation included a study of the characteristics that are essential for solvent extraction and preconcentration of cobalt for determination by FAAS (Flame atomic absorption spectrometry) and also the organic phase loaded with Co(II) from aqueous phase was stripped in one stage by using different mineral acid solutions. It was found that stripping efficiency was quantitative in case of HNO3. Furthermore, a highly sensitive, selective, and rapid spectrophotometric method is described for the determination of trace amounts of Co(II) by HBDAP. This compound reacts with cobalt(II) in the range of pH 6–10 to produce a greenish yellow complex (2 : 3 molar ratio of Co(II)/HBDAP) soluble in chloroform. The complex obeys Beers law from 0.7 to 7.25 µg mL−1 with an optimum range. The relative standard deviations were 0.05% (13 samples, each containing 4.2 µg mL−1 Co(II)). The precision was determined from 25 results obtained for 1 × 10−5 M Co(II); the mean value of a Co(II) was 1.03 × 10−5 M with a standard deviation of 2.35 × 10−7 M Co(II).

Assesment of dimethyl phthalate removal from aqueous phase using barium hexaferrite containing magnetic beads.

The barium hexaferrite (BaFe(12)O(19)) containing magnetic poly (ethylene glycol dimethacrylate-vinyl pyridine; mag-poly [EGDMA-VP]) beads (average diameter=53-212 μm) were synthesized and characterized. Their use as an adsorbent in the removal of dimethyl phthalate (DMP) from an aqueous solution was investigated. The mag-poly (EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly (EGDMA-VP) beads were characterized by N(2) adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM), and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DMP from aqueous solutions such as pH, initial concentration, contact time, and temperature were analyzed. The maximum DMP adsorption capacity of the mag-poly (EGDMA-VP) beads was determined as 96.2 mg/g at pH 3.0, 25 °C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo-first-order, pseudo-second-order, Ritch-second-order, and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DMP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

Interferences in the determination of lithium by flame atomic emission spectrometry with platinum-loop atomizer

Although flame atomic emission spectrometry (AES) is the most popular method for the determination of Li, the method is subject to interference from alkaline and alkaline earth elements. The effects of CaOH and SrO emission bands are particularly severe. The use of a Pt-loop atomizer was found to eliminate interference from Ca and Sr, as salts of these elements remained as solid residues on the loop material. High contents of F–, Cl–, SO42– and PO43– were found to reduce the Li signal, this was largely due to loss of LiCl in the case of Cl–, in the case of F–, SO42– and PO43–, the reduction in the Li signal was due to lithium oxide formation. The accuracy of the Pt-loop technique was shown to be satisfactory in matrices of high Ca and Sr contents. The detection limit obtained with the Pt-loop was at least one order of magnitude better than that of conventional AES. The technique was applied in the determination of Li in several sample types.