Ulvi Ulusoy

Adsorptive features of polyacrylamide–apatite composite for Pb2+, UO22+ and Th4+

Micro-composite of polyacrylamide (PAA) and apatite (Apt) was prepared by direct polymerization of acrylamide in a suspension of Apt and characterized by means of FT-IR, XRD, SEM and BET analysis. The adsorptive features of PAA-Apt and Apt were then investigated for Pb(2+), UO(2)(2+) and Th(4+) in view of dependency on ion concentration, temperature, kinetics, ion selectivity and reusability. Experimentally obtained isotherms were evaluated with reference to Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. Apt in PAA-Apt had higher adsorption capacity (0.81, 1.27 and 0.69 mol kg(-1)) than bare Apt (0.28, 0.41 and 1.33 mol kg(-1)) for Pb(2+) and Th(4+), but not for UO(2)(2+). The affinity to PAA-Apt increased for Pb(2+) and UO(2)(2+) but not changed for Th(4+). The values of enthalpy and entropy changed were positive for all ions for both Apt and PAA-Apt. Free enthalpy change was DeltaG<0. Well compatibility of adsorption kinetics to the pseudo-second-order model predicated that the rate-controlling step was a chemical sorption. This was consistent with the free energy values derived from DR model. The reusability tests for Pb(2+) for five uses proved that the composite was reusable to provide a mean adsorption of 53.2+/-0.7% from 4x10(-3)M Pb(2+) solution and complete recovery of the adsorbed ion was possible (98+/-1%). The results of this investigation suggested that the use of Apt in the micro-composite form with PAA significantly enhanced the adsorptive features of Apt.

Investigations for Modification of Polyacrylamide-Bentonite by Phytic Acid and its Usability in Fe3+, Zn2+ and UO22+ Adsorption

Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerisation of PAA in a suspension of bentonite (B). Adsorption and thermodynamic features of phytic acid (Phy) adsorption onto B, PAA and PAA-B, and those of Fe3+, Zn2+, UO22+ adsorption onto PAA-B and its modification by Phy (PAA-B-Phy) have been investigated. The reusability, storagability, ion selectivity and recoverability of sorbed ions with 1 M HCl have also been considered.The chemical and physical structure of adsorbents has been characterised by means of FT-IR and XRD. All adsorption isotherms for Phy and the ions were L-type of the Giles classification except, the one which is S type for adsorption of Phy onto PAA. The maximum adsorption capacities for the ions adsorbed were in order of UO22+ > Fe3+ > Zn2+ for PAA-B and Zn2+ > Fe3+ > UO22+ for PAA-B-Phy. Langmuir equilibrium constants for the adsorption of ions onto PAA-B-Phy were significantly higher than those found for PAA-B; the magnitude of increase for UO22+ was about 100. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy.The chemical structure of PAA-B-Phy was not changed at the end of the studies of reusability and storagability. The composite was selective for UO22+ of the ions of interest.The composite of PAA-B and its modification by Phy have been used for the first time in this investigation. It is proposed that the composites can be practically used in the investigations and applications of adsorption.

Polyacrylamide–clinoptilolite/Y-zeolite composites: Characterization and adsorptive features for terbium

The composites of natural (clinoptilolite) and synthetic zeolite (Z and YZ) with polyacrylamide (PAAm) were synthesized and characterized by FT-IR, TGA, XRD, SEM and PZC analysis. The adsorptive features of the minerals and its composites were investigated for Tb analogues to the rare earth elements (REs) by isotopic tracer method, (160)Tb was the radiotracer. The composites were the hybrid formations of PAAm and Z or YZ. Tb adsorption capacities of the composites were higher than those of bare Z and YZ. The compatibility of Tb adsorption kinetics to the second order and Weber-Morris models implied that the sorption process was chemical via ion exchange. The values of enthalpy and entropy changes were positive and the negative free enthalpy change was evidence for the spontaneity of adsorption. The reusability tests for the composites for five uses demonstrated that the adsorbents could be reused after complete recovery of the loaded ion. Unlike PAAm-YZ, PAAm-Z was resistant to acidic environment. The overall results eventually suggested that the composite of Z and PAAm was a potential cost effective adsorbent for Tb(3+) and REs.

Adsorption of UO22+, Tl+, Pb2+, Ra2+ and Ac3+ onto polyacrylamide-bentonite composite

Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerization in a suspension of bentonite (B), the composite was then modified by phytic acid (PAA-B-Phy). The parameters related to adsorption of UO22+ in absence and presence of 0.01M CaCl2 and of natural radionuclides (Tl+, Pb2+, Ra2+ and Ac3+ in a leaching solution) onto PAA-B and PAA-B-Phy, and thermodynamics of the adsorption were investigated. Adsorption isotherms were of L and H types for the adsorption of UO22+ onto PAA-B and PAA-B-Phy, whilst for Tl+, Pb2+, Ra2+ and Ac3+ they were of C type for both adsorbents. Langmuir equilibrium constants for the adsorption of all studied ions onto PAA-B-Phy were significantly higher than those found for PAA-B. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy. The composite of PAA-B and its modification by Phy have been used for the first time in this study. It is concluded that the composites can be practically used for adsorption and applied as adsorbent of radionuclides.

UO22+, Tl+, Pb2+, Ra2+, Bi3+ and Ac3+ adsorption onto polyacrylamide-zeolite composite and its modified composition by phytic acid

The adsorption of naturally occurring radionuclides (UO22+, Tl+, Pb2+, Ra2+, Bi3+ and Ac3+) onto zeolite (Z) and polyacrylamide-zeolite composite (PAA-Z) and its modified composition by phytic acid (Z-Phy and PAA-Z-Phy) were investigated. Adsorption parameters were derived from the Langmuir and Freundlich fits to adsorption isotherms of the ions studied. The adsorption isotherms were of L and H types. The adsorption capacity of Z decreased by PAA inclusion, but the Phy modification of PAA-Z increased the capacity back to that of Z. The Phy modification made the adsorption spontaneity at least ten times better than in the absence of Phy. This investigation showed that the zeolite, as one of the most abundant natural materials and commonly used adsorbent can also be used for the removal of UO22+ and, in the PAA-Z form, of the studied radionuclides. The usage of Z, as PAA-Z and its Phy modification provide research materials which possess adequate practicality and effectiveness in studies of adsorption.

Determination of intestinal uptake of iron and zinc using stable isotopic tracers and rare earth markers

Abstract Determination of trace element absorption using enriched stable isotopic tracers and faecal monitoring has required 5–10 days collection of faecal output. In this study, the possibility of using rare earths as non-absorbable markers for measurement of the intestinal uptake of iron and zinc with single or reduced faecal collection has been investigated. Seven healthy subjects consumed a standard solution labelled with 57 Fe tracer and Sm marker, and a Farina meal labelled with 58 Fe and 70 Zn tracers, and Yb marker. Marker and tracer contents of faecal samples provided after consumption were determined by NAA and ICP-MS after ion-exchange separation. Intestinal uptake was calculated from faecal recoveries of markers and tracers for individual and composites of sequential samples. The uptakes obtained from the first two individual samples were not significantly different from those obtained from composites of the first 2–3 sequential outputs. It should therefore be possible to determine intestinal uptake with single or reduced faecal collection for iron and zinc. Rare earths offer a new opportunity to investigate absorption in unconfined situations.

Profiles of faecal output of rare earth elements and stable isotopic tracers of iron and zinc after oral administration

The objectives of this study were to confirm the non-absorbability and the reproducibility of faecal excretion kinetics of orally administered rare earth elements, and to investigate the excretion profiles of rare earth elements and stable isotopic tracers of Fe and Zn to establish the extent to which rare earth element markers duplicate the behaviour of isotopic tracers. Two investigations were performed: (1) six healthy subjects consumed a solution containing five rare earth elements in amounts varying from 1 to 10 mg; (2) seven healthy subjects were given a standard solution labelled with Sm marker and (57)Fe tracer, and a meal labelled with Yb marker and (58)Fe and (70)Zn tracers. Individual faecal samples were collected and analysed to determine recoveries of rare earth elements and unabsorbed isotopic tracers. The mean values for recoveries were 94.1 (sd 4.5) % for the five rare earth elements, and 103 (sd 3.0) % and 99.8 (sd 2.8) % for Sm and Yb respectively. For Fe consumed with the solution, excretion kinetics of the rare earth element marker and unabsorbed tracers with cumulative collections of the first two and three faecal samples were identical, but endogenous excretion of Fe was significant in stools collected after the third. For Fe and Zn consumed with the meal, the excretion kinetics for the first two individual faecal samples and composites of sequential outputs were identical. Rare earth elements can be used as markers in studies of measurement of absorption. The dose of tracer required for the measurement of absorption would be reduced proportionally to the reduction of the period of faecal sampling, so that studies with stable isotopes would be more economical, thus enabling epidemiological investigations.

Sulfur-Isotope Study of the Ana Yatak Massive Sulfide Deposit, Southeastern Turkey

The Ana Yatak massive sulfide deposit is located in the Ergani-Maden District of southeastern Turkey and has been a major source of copper for more than 4,000 years. The mineralization is hosted by strongly chloritized serpentinite, gabbro, diabase, and mud-stone. The ore body is ∼600 × 250 m in maximum dimension, mainly consists of pyrite and chalcopyrite, and locally contains abundant magnetite, pyrrhotite, and chromite. The gangue contains predominantly chlorite, rarely quartz. This paper is mainly concerned with an investigation of the sulfur-isotope systematics of the Ana Yatak deposit. Pyrite and chalcopyrite from the ore and pyrite from the host rocks were sampled and analyzed to determine their δ34S composition. δ34S values were found to vary within the range from +4.5 to + 9.3‰ for pyrites (mean δ34S = + 6.5 ± 1.8) and from +4.5 to +10.0 for chalcopyrites (mean δ34S = +6.7 ± 1.9) of the ore, and from +5.8 to +8.8 for pyrites (mean δ34S = + 7.3 ± 1.3) of the host rock. The δ34S compositions of all...