Preparation and characterization of chitosan/Fe2O3 nano composite for the adsorption of thorium (IV) ion from aqueous solution.

In this study, novel chitosan/Fe2O3nano composite Ch/Fe-Onc was synthesized and evaluated as an adsorbent for removing thorium (IV) (Th4+) ion from aqueous solution. The Ch/Fe-Onc was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Response surface methodology (RSM) was used in the optimization of Th4+ adsorption for parameters such as pH, the initial metal ion concentration (Th4+ concentration) and contact time. The statistical measures (i.e. analysis of variance, R2, the lack of fit test and the P value) specify that the developed model is proper. Furthermore, the adsorption kinetics was well defined by the pseudo-second-order equation, while the adsorption isotherms were better fitted by the Langmuir model. The adsorption capacity of Ch/Fe-Onc was 430 mg Th4+g-1 composite which leads to 99% removal at 25 °C. Moreover, thermodynamic parameters which state the natural and endothermic nature of the reactions were determined. The loaded Th4+ can be easily regenerated with HNO3 and the Ch/Fe-Onc can be used repeatedly without any significant reduction in its adsorption capacity. The desorption level of Th4+ from the Ch/Fe-Onc by using 0.1 M HNO3, was more than 95%.

High occurrence of potentially-pathogenic free-living amoebae in tap water and recreational water sources in South-West Iran.

The present study was conducted to evaluate the presence of potentially pathogenic free living amoebae in drinking and recreational water sources in south-western Iran. From 75 collected water samples, 40 samples (53.3%) were positive for free living amoebae identified using morphological tools. Interestingly, all recreational waters in Ilam city included in the present study were positive for Acanthamoeba, Vahlkampfidae and Vermamoeba. Thirty percent of tap water samples in Ahvaz city were also positive for potentially pathogenic Free Living Amoebae. Moreover, the three genera identified in the present study have been previously reported as keratitis causative agents in Iran. The present research highlights the need to improve filtration methods for tap waters and to establish awareness in recreational water sources in Iran, in order to prevent Free Living Amoebae related infections. To the best of our knowledge, this is the first report of the isolation of potentially pathogenic free living amoebae including Acanthamoebae, Vermamoebae and Vahlkampfiids in the South-West of Iran.

High occurrence of potentially-pathogenic free-living amoebae in tap water and recreational water sources in South-West Iran

The present study was conducted to evaluate the presence of potentially pathogenic free living amoebae in drinking and recreational water sources in south-western Iran. From 75 collected water samples, 40 samples (53.3%) were positive for free living amoebae identified using morphological tools. Interestingly, all recreational waters in Ilam city included in the present study were positive for Acanthamoeba, Vahlkampfidae and Vermamoeba. Thirty percent of tap water samples in Ahvaz city were also positive for potentially pathogenic Free Living Amoebae. Moreover, the three genera identified in the present study have been previously reported as keratitis causative agents in Iran. The present research highlights the need to improve filtration methods for tap waters and to establish awareness in recreational water sources in Iran, in order to prevent Free Living Amoebae related infections. To the best of our knowledge, this is the first report of the isolation of potentially pathogenic free living amoebae including Acanthamoebae, Vermamoebae and Vahlkampfiids in the South-West of Iran.

Evaluation of PAN-based manganese dioxide composite for the sorptive removal of cesium-137 from aqueous solutions.

Hydrous manganese dioxide-polyacrylonitrile (MnO(2)-PAN) was chemically synthesized and evaluated, as an organic-inorganic composite material, for the removal of radio-contaminant cesium-137 from aqueous solutions. The physico-chemical characterization was carried out by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), CHN elemental analysis, scanning electron microscopy (SEM), nitrogen adsorption-desorption studies and thermogravimetry-differential scanning calorimetry (TGA-DSC). Batch experiments were carried out as a function of contact time, interference of the coexisting ions and initial pH of adsorptive solution applying a radiotracer technique. The effect of temperature on the distribution coefficient of cesium has been utilized in order to evaluate the changes in the standard thermodynamic parameters. The results indicated that Cs(+) ions could be efficiently removed using MnO(2)-PAN composite in the pH range of 4-9 from aqueous solutions and the uptake of cesium is affected to varying degrees by the presence of some diverse co-ions. The equilibrium isotherms have been determined and the sorption data were successfully modeled using Freundlich model.

Studies on the adsorption behavior of trace amounts of 90Sr2+, 140La3+, 60Co2+, Ni2+ and Zr4+ cations on synthesized inorganic ion exchangers.

Three inorganic ion exchangers namely potassium zinc hexacyanoferrate(II) (PZF), magnesium oxide-polyacrylonitrile composite (MgO-PAN) and ammonium molybdophosphate (AMP) were synthesized. The physicochemical properties of these ion exchangers were determined using different techniques including inductively coupled plasma (ICP), CHNSO elemental analysis, infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric (TGA) and pH - titration curve analysis. The solubility of the synthesized ion exchangers in different acidic and alkaline media, their thermal stability and the effect of gamma irradiation were investigated. It was observed that the exchange capacity of the ion exchangers depend upon the pH value of the solution used. Furthermore, the adsorption of (90)Sr(2+), (140)La(3+), (60)Co(2+) and the distribution coefficient of these ion exchangers for Ni(2+)and Zr(4+) were studied. The effect of parameters such as pH and contact time on the adsorption was also investigated and the optimum conditions for separation of these ions were determined.

Preparations of PAN-based adsorbers for separation of cesium and cobalt from radioactive wastes.

Ion-exchange adsorbers are widely used for radioisotope separation, as well as for the removal of hazardous fission products from aqueous waste prior to discharge to the environment. Inorganic exchangers are of particular interest because of their resistance to radiolytic damage and selectivity for specific fission products. Composite inorganic-organic adsorbers represent a group of inorganic ion exchangers modified by using binding organic material, polyacrylonitrile, for preparation of larger size particles with higher granular strength. At the same time, kinetics of ion exchange and sorption capacity of such composite adsorbers are not influenced by the binding polymer. The contents of active component in composite adsorber were varied over a very broad range of 5-95% of the dry weight of the composite adsorber, and tested for separation and concentration of various stimulated wastes. Three different inorganic sorbents, granular hexacyanoferrate-based ion exchanger, were developed for the removal of Cs and Co ions from waste solutions containing different complexing agents as detergents. Radiation and thermal stability studies show that these adsorbents can be used for medium-active waste treatment.