Ali Tor

Removal of fluoride from water by using granular red mud: batch and column studies.

This paper describes the removal of fluoride from water using granular red mud (GRM) according to batch and column adsorption techniques. For the batch technique, the experiments demonstrated that maximum fluoride removal was obtained at a pH of 4.7 and it took 6h to attain equilibrium and equilibrium time did not depend upon the initial fluoride concentration. Kinetics data were fitted with pseudo-second-order model. The Redlich-Peterson and Freundlich isotherm models better represented the adsorption data in comparison to the Langmuir model. Column experiments were carried out under a constant influent concentration and bed depth, and different flow rates. The capacities of the breakthrough and exhaustion points decreased with increase of the flow rate. Thomas model was applied to the experimental results. The modelled breakthrough curves were obtained, and they were in agreement with the corresponding experimental data. The column adsorption was reversal and the regeneration operation was accomplished by pumping 0.2M of NaOH through the loaded GRM-column.

Determination of selected polychlorinated biphenyls in water samples by ultrasound-assisted emulsification-microextraction and gas chromatography-mass-selective detection

Ultrasound-assisted emulsification-microextraction (USAEME) procedure was developed for the determination of selected polychlorinated biphenyls (PCBs) in 10 mL of water samples by gas chromatography-mass-selective detection. After determination of the most suitable solvent and extraction time, several other parameters including solvent volume, centrifugation time and ionic strength of the sample were optimized using a 2(3) factorial experimental design. The optimized USAEME procedure used 200 microL of chloroform as extraction solvent, 10 min of extraction with no ionic strength adjustment at 25 degrees C and 5 min of centrifugation at 4000 rpm. The limits of detection ranged from 14 ngL(-1) (for PCB153) to 30 ngL(-1) (for PCB101). Recoveries of PCBs from fortified distilled water are over 80% for three different fortification levels between 0.1 and 5 microgL(-1) and relative standard deviations of the recoveries are below 10%. The performance of the proposed method was compared with those involving traditional liquid-liquid extraction (LLE) and solid phase extraction (SPE) on the real water samples (i.e., tap and well water as well as domestic and industrial wastewaters, etc.) and comparable efficiencies were obtained. The proposed USAEME procedure has been demonstrated to be viable, simple, rapid and easy to use for residue analysis of PCBs in water samples.

Arsenic(V) removal from underground water by magnetic nanoparticles synthesized from waste red mud.

In this study waste red mud (bauxite residue) sample obtained from Seydişehir (Konya, Turkey) was evaluated for the synthesis of Fe(3)O(4) nanoparticles (NPs) in ammonia solution that can be used to remove As(V) from both synthetic and natural underground water samples. The synthesized Fe(3)O(4)-NPs were characterized by using TEM, VSM, XRD, SAXS, TGA and FT-IR spectroscopy. The Fe(3)O(4)-NPs assumed a near-sphere shape with an average size of 9 nm. The results showed that synthesized Fe(3)O(4)-NPs from waste red mud have satisfactory magnetic properties and As(V) sorption capacity, especially at low equilibrium arsenate concentrations.

Application of ultrasound-assisted emulsification-micro-extraction for the analysis of organochlorine pesticides in waters

Ultrasound-assisted emulsification-micro-extraction (USAEME) procedure was developed for the determination of different organochlorine pesticides (OCPs) in water samples by gas chromatography with mu-electron capture detection (GC-microECD). After the determination of the most suitable extraction solvent and its volume, parameters such as extraction time, centrifugation time and ionic strength of the sample were optimized by using a 2(3) factorial experimental design. For 10 mL of water sample, the optimized USAEME procedure used 200 microL of chloroform as extraction solvent, 15 min of extraction without ionic strength adjustment at 25 degrees C and 5 min of centrifugation at 4000 rpm. Limits of detection ranged from 0.002 to 0.016 microg L(-1). Mean recoveries of OCPs from fortified water samples are over 96% for three different fortification levels between 0.5 and 5 microg L(-1) and relative standard deviations of the recoveries are below 9%. The developed procedure was successfully applied for real water samples (i.e., tap water, well water, surface (lake) water, domestic and industrial wastewater). Performance of the procedure was compared with those involving traditional liquid-liquid extraction and solid-phase extraction. The result demonstrates that the USAEME procedure is viable, rapid and easy to use for analysis of OCPs in water samples.

Determination of polycyclic aromatic hydrocarbons in waters by ultrasound-assisted emulsification-microextraction and gas chromatography–mass spectrometry

An ultrasound-assisted emulsification-microextraction (USAEME) procedure was developed for the extraction of US EPA 16 polycyclic aromatic hydrocarbons (PAHs) in 10 mL of water samples, with subsequent determination by gas chromatography-mass spectrometry (GC-MS). After determination of the most suitable solvent and solvent volume, several other parameters (i.e., extraction time, centrifugation time and ionic strength of the sample) were optimized using a 2(3) factorial experimental design. Limits of detection ranged from 0.001 to 0.036 microg L(-1). The developed procedure was applied to fortified distilled water with different fortification levels (0.5, 2 and 5 microg L(-1)). Recoveries were over 92% and relative standard deviations of the recoveries were below 8%. The efficiency of the USAEME was compared with traditional liquid-liquid extraction (LLE) and solid-phase extraction on real water samples (i.e., tap water, well water and surface (lake) water as well as domestic and industrial wastewaters). The USAEME showed comparable efficiencies especially with LLE. The developed USAEME was demonstrated to be robust, viable, simple, rapid and easy to use for the determination of PAHs in water samples by GC-MS.

Transport of hexavalent chromium through anion-exchange membranes

This papers deals with the transport of hexavalent chromium through SB-6407, AFN and ACM anion-exchange membranes in contact with different salt solutions. The effect of salt solutions on the transport of chromium(VI) was investigated. The effect of salt solutions was observed at different sequences and the transport efficiencies of the membranes was found to be in the order SB-6407>AFN>ACM. The transport was found to be highest in a single state.

Surface modification of glass beads with glutaraldehyde: Characterization and their adsorption property for metal ions

In this study, a new material that adsorbs the metal ions was prepared by modification of the glass beads surfaces with glutaraldehyde. First, the glass beads were etched with 4M NaOH solution. Then, they were reacted with 3-aminopropyl-triethoxysilane (APTES). Finally, silanized glass beads were treated with 25% of glutaraldehyde solution. The characterization studies by using Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA), elemental analysis and Scanning Electron Microscopy (SEM) indicated that modification of the glass bead surfaces was successfully performed. The adsorption studies exhibited that the modified glass beads could be efficiently used for the removal of the metal cations and anion (chromate ion) from aqueous solutions via chelation and ion-exchange mechanisms. For both Pb(II) and Cr(VI), selected as model ions, the adsorption equilibrium was achieved in 60 min and adsorption of both ions followed the second-order kinetic model. It was found that the sorption data was better represented by the Freundlich isotherm in comparison to the Langmuir and Redlich-Peterson isotherm models. The maximum adsorption capacities for Pb(II) and Cr(VI) were 9.947 and 11.571 mg/g, respectively. The regeneration studies also showed that modified glass beads could be re-used for the adsorption of Pb(II) and Cr(VI) from aqueous solutions over three cycles.

Application of miniaturised ultrasonic extraction to the analysis of organochlorine pesticides in soil.

A miniaturised ultrasonic extraction procedure was developed for the determination of different organochlorine pesticides (OCPs) in soil by gas chromatography (GC/mu-ECD). For an acetone-petroleum ether (1/1, v/v) as the extractor and a 5-min sonication, parameters such as sample amount, solvent volume and number of extraction steps were optimized by using a 2(3) factorial experimental design. Limits of detection ranged from 0.02 to 1.34 microg kg(-1). The developed procedure was applied to three different real soil samples with different fortification levels (25, 50 and 100 microg kg(-1)) and recoveries were estimated in the 82-106% range with relative standard deviations lower than 15%. Performance of the procedure was compared with those involving traditional shaking flask, Soxhlet extraction and large-scale ultrasonic extraction. The proposed procedure requires small volumes of solvent and sample. It is viable, rapid and easy to use for analysis of OCPs in soils.

Facilitated transport of Cr(III) through activated composite membrane containing di-(2-ethylhexyl)phosphoric acid (DEHPA) as carrier agent

The facilitated transport of chromium(III) through activated composite membrane (ACM) containing di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated. DEHPA was immobilised by interfacial polymerisation on polysulfone layer which was deposited on non-woven fabric by using spin coater. Then, ACM was characterised by using scanning electron microscopy (SEM), contact angle measurements and atomic force microscopy (AFM). Initially, batch experiments of liquid-liquid distribution of Cr(III) and the extractant (DEHPA) were carried out to determine the appropriate pH of the feed phase and the results showed that maximum extraction of Cr(III) was achieved at a pH of 4. It was also found that Cr(III) and DEHPA reacted in 1/1 molar ratio. The effects of Cr(III) (in feed phase), HCl (in stripping phase) and DEHPA (in ACM) concentrations were investigated. DEHPA concentration varies from 0.1 to 1.0M and it was determined that the transport of Cr(III) increased with the carrier concentration up to 0.8M. It was also observed that the transport of Cr(III) through the ACM tended to increase with Cr(III) and HCl concentrations. The stability of ACM was also confirmed with replicate experiments.

Levels of Organochlorine Pesticides and Heavy Metals in Surface Waters of Konya Closed Basin, Turkey

The concentrations of organochlorine pesticides (OCPs), including α-, β-, γ-, and δ-hexachlorocyclohexane (HCH), heptachlor, heptachlor epoxide, dieldrin, aldrin, endrin, endrin aldehyde, endrin ketone, endosulfan I, endosulfan II, endosulfan sulfate, p,p′-DDE, p,p′-DDD, p,p′-DDT, methoxychlor, chlordane I, chlordane II, and heavy metals, such as As, Cr, Cu, Fe, Mn, and Ni in surface water samples from the Konya closed basin were determined to evaluate the level of contamination. Among all HCH isomers, β-HCH is the main isomer with a concentration range of 0.015–0.065 μg/L. DDE, DDD, and DDT were almost determined in all samples, in which DDE isomer had the highest concentration ranged from not detected to 0.037 μg/L. In all studied OCPs, aldrin showed the highest concentration at 0.220 μg/L. The concentrations of heavy metals in water samples were observed with order: Mn < Cu < Ni < As < Cr < Fe. In some samples, As, Fe, and Cr concentrations exceeded the drinking water quality recommended by EU, US EPA, WHO, and Turkish Regulation, while Cu, Ni, and Mn concentrations are below the guideline values. The levels of both OCPs and heavy metals were also compared with other previously published data.