Sorption and desorption of radiostrontium on calcareous soil and its solid components

The effect of different solid components of calcareous soil on the retention of Sr was investigated by using batch technique and selective extraction method. The sorption and desorption isotherms of Sr on the untreated calcareous soil and the three treated soils were determined at 20°C, pH 7.8±0.2 and in the presence of 0.001 M CaCl₂. It was found that all isotherms are linear and that the sorption of Sr on the calcareous soil can be described by a reversible sorption process and the sorption mechanism is mainly ion exchange.     

Effect of pH,ionic strength,fulvic acid and humic acid on sorption of Th(IV) on Na-rectorite

Sorption of Th(IV) on Na-rectorite as a function of pH, ionic strength, soil humic acid (HA) and fulvic acid (FA) are studied under ambient conditions by using a batch technique. The results indicate that the sorption of Th(IV) on Na-rectorite is not only dependent on medium pH values, but also dependent on medium ionic strength and humic substances. Surface complexation and cation competition exchange account for Th(IV) sorption on Na-rectorite. The sorption of Th(IV) on Na-rectorite decreases with the increase on the concentration of NaNO₃, Mg(NO₃)₂ and Ca(NO₃)₂, and increases with the increasing amount of HA/FA in the suspension/adsorbed on rectorite. Soil HA/FA enhances the sorption of Th(IV) on rectorite at medium pH<4 drastically, but the presence of FA reduces the sorption of Th(IV) at medium pH>6, and HA has no effect on Th(IV) sorption at medium pH>6. An interpretation for the results is attempted, considering the occurrence of different sorption mechanisms.     

Sorption and desorption of radioselenium on calcareous soil and its solid components

The effect of different solid soil components of calcareous soils on the retention of SeO₃ has been investigated by a batch technique and selective extraction method. The sorption and desorption isotherms of SeO₃ on the untreated calcareous soil and the three treated soils were determined at 20°C, pH 7.8±0.2 and in the presence of 0.001M CaCl₂. It was found that all isotherms are linear, the sorption-desorption hysteresis for untreated soil and treated soils is obvious and the retention of SeO₃ in calcareous soil is mainly attributed to the oxides.     

Sorption and desorption of radioiodine on calcareous soil and its solid components

The effect of different solid components of calcareous soil on the retention of I was investigated by a batch technique and selective extraction method, and the effect of -irradiation was also investigated. The sorption and desorption isotherms of I on the one untreated, three treated soils and the calcareous soil irradiated with -rays were determined at 30 °C, pH 8.1±0.2 and in the presence of 1.0×10^–4M or 0.67×10^–5M CaCl₂. It was found that the sorption-desorption hysteresis on the calcareous soil actually occurs on the same time scale, that iodine can be easily transported in the calcareous soil and that the exceptionally high contribution of organic matter to the iodine sorption is demonstrated.     

Sorption and desorption of radiocesium on calcareous soil and its solid components

The purpose of this work was to label polyclonal antibodies with^99mTc such as photoactivated IgG and to check the radiochemical and biological behavior of the labeled product. Experiments were carried out to found the formulation of optimal binding of^99mTc to polyclonal IgG. In addition animal studies in normal mice and in mice bearing a promoted inflammation foci were performed. The labeled product was analyzed by size-exclusion HPLC and ITLC. Higher amount than 23μg of tin per 500μg of protein gave between 87% and 93% labeling. Protein concentrations between 1.5 and 5 mg/ml gave 90% labeling yields.     

Sorption and desorption of radioselenium on calcareous soil and its solid components

The effect of different solid soil components of calcareous soils on the retention of SeO₃ has been investigated by a batch technique and selective extraction method. The sorption and desorption isotherms of SeO₃ on the untreated calcareous soil and the three treated soils were determined at 20°C, pH 7.8±0.2 and in the presence of 0.001M CaCl₂. It was found that all isotherms are linear, the sorption-desorption hysteresis for untreated soil and treated soils is obvious and the retention of SeO₃ in calcareous soil is mainly attributed to the oxides.     

Comparative study on sorption of radiocobalt to montmorillonite and its Al-pillared and cross-linked samples: Effect of pH,ionic strength and fulvic acid

Effects of pH, ionic strength and fulvic acid on sorption of radiocobalt on montmorillonite and its Al-pillared and cross-linked samples were studied using batch technique. The results indicate that the sorption of cobalt is strongly dependent on pH values and independent of ionic strength. Fulvic acid enhances the sorption of cobalt slightly at low pH, but has no influence at high pH values. Surface complexation is considered the main mechanism of cobalt sorption to montmorillonite. The sequences of FA/Co²⁺ additions to the system did not affect cobalt sorption.     

Effect of humic acid, pH and ionic strength on the sorption of Eu(III) on red earth and its solid component

Sorption and desorption of radioeuropium on red earth and its solid components to remove organic matter was studied at pH 5.3±0.1 and 4.5±0.1, and in 0.01M and 0.001M NaClO₄ solutions, respectively. Eu(III) sorption showed strong pH and humic acid concentration dependency, and NaClO₄ concentration independency. The sorption increased with increasing pH and amount of HA adsorbed on red earth. The sorption of Eu(III) on red earth was mainly dominated by surface complexation. Humic acid and high pH had a great tendency to immobilize the movement of Eu(III) in red earth. Sorption-desorption hysteresis of Eu(III) on red earth indicated that the sorption was irreversible.     

Effect of humic acid,pH and ionic strength on the sorption of Eu(III) on red earth and its solid component

A highly sensitive separation procedure has been developed to investigate uranium and thorium activities and their isotopic ratios in environmental water samples in Tokushima, Japan. Uranium and thorium isotopes in environmental water samples were simultaneously isolated from interfering elements with extraction chromatography using an Eichrom UTEVA™ resin column. After the chemical separation, activities of U and Th isotopes coprecipitated with samarium fluoride (SmF₃) were measured by α-spectrometry. It has been confirmed that uranium isotopes are isolated successfully from thorium decay chains by analyzing a test aqueous solution as a simulation of an environmental water sample. The separation procedure has been first applicable to the determination of U and Th activities and their isotopic ratios in a drinking well water named “Kurashimizu” in Tokushima City, Japan. The specific activities of ²³⁸U and ²³²Th in “Kurashimizu” were deduced to be within the upper limits of <0.31 and <0.19 mBq/l, respectively.     

Sorption and desorption of radioiodine and radioselenium on calcareous soil and its solid components

This paper is an extension of previous papers^1–3. The breakthrough curves and the displacement curves of¹²⁵I⁻ and⁷⁵SeO₃ on the calcareous soil, the treated soil to remove CaCO₃ and the treated soil to remove organic matter were determined at pH 7.8, at 20°C and in the presence of 1·10⁻³ or 1·10⁻⁴ mol/l CaCl₂. These results from column experiments and from batch experiments in the previous papers^1,2 were mutually complementary. It can be definitely concluded that iodide is retained to a very small degree and tetravalent-selenium is retained to a small degree by calcareous soil and that organic matter in calcareous soil acts as a significant trap of iodide and CaCO₃ acts as a trap of tetravalent selenium. Iodide and tetravalent-selenium would be expected to have relatively high dissemination in calcareous soil.     

A multitracer study on the adsorption of 47 elements on a calcareous soil and its solid components

The distribution coefficients of 47 elements from Na to Bi on untreated calcareous soil, treated soil to remove CaCO₃ and treated soil to remove both CaCO₃ and organic matter, respectively, were determined by using a multitracer technique. The variation of the distribution coefficients of 47 elements was explained in terms of chemical bond formation and hydration. The effect of different solid components of the calcareous soil on the adsorption was investigated.     

Sorption and desorption of radiostrontium on powdered bentonite: Effect of pH and fulvic acid

The effect of pH and fulvic acid on the sorption of Sr on bentonite was investigated by using batch experiments. The sorption and desorption isotherms of Sr on bentonite were determined at room temperature, at pH 6.0±0.2 and in presence of 0.1M NaCl. It was found that the sorption of Sr is independent at pH<8, and then increases slightly with increasing pH. Fulvic acid increases the sorption of Sr significantly on bentonite at low pH, but decreases the sorption of Sr at pH>8. The sorption of Sr on bentonite can be described by a reversible sorption process and the sorption mechanism consists mainly of ion exchange. This revised version was published online in July 2006 with corrections to the Cover Date.     

The sorption of Eu(III) on calcareous soil: effects of pH,ionic strength,temperature, foreign ions and humic acid

The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III) uptake on soil, however at low pH values, the influence of anions was following the order: Cl⁻ ≈ NO₃ ⁻ > ClO₄ ⁻. In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7, the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)₃(s) may play main role above pH ~8.     

Effects of ionic strength and pH on the stability constants of the complex of Co(II) with soil fulvic acid

The stability constants for tracer concentrations of Co(II) complexes with the red earth fulvic acid were determined at pH 3.8–6.8 and ionic strength 0.0010–1.0 mol/l by using the cation exchange equilibrium method and the radiotracer⁶⁰Co. The effects of ionic strength and pH on the stability constants of 1∶1 Co(II) complexes were investigated, and it was found that the stability constants of complexes of humic substances do not vary with ionic strength and pH in a manner similar to that of simple complexes.     

The effects of pH and ionic strength on fulvic acid uptake by chitosan hydrogel beads

The objective of this work is to investigate the effects of pH and ionic strength on the adsorption capacity for fulvic acid (FA) by chitosan hydrogel beads. The results indicated that the sorption amount increased with decreasing pH and increasing ionic strength concentration. The sorption isotherms were well described by using non-linear Langmuir, Freundlich and Redliche–Peterson equation. The adsorption kinetics of FA onto chitosan hydrogel beads could be described by pseudo-second-order rate model. The extent of FA removal in the presence of other ions decreases in the order Ca²⁺ > Mg²⁺ > Na⁺ ≈ K⁺ and Cl⁻ > NO₃⁻ > CO₃²⁻. FTIR along with XPS analyses revealed the amine groups on the beads were involved in the sorption of FA and the organic complex between the protonated amino groups and FA was formed after FA uptake. Sorption mechanisms including electrostatic interaction and surface complexation were found to be involved in the complex sorption of FA on the chitosan hydrogel beads.     

Sorption and desorption of neptunium(V) on calcareous soil and its solid components: A comparative study

The sorption and desorption isotherms of untreated calcareous soil and three treated soils to remove CaCO₃, organic matter (OM) and both CaCO₃ and OM were determined and analyzed with the Freundlich equation at pH 7.8, moderate concentrations of NpO₂ ⁺ (~10^-5mol/l), in the presence of 0.01 mol/l CaCl₂ and under ambient aerobic conditions. The relative contribution of CaCO₃ and OM to the neptunium(V) sorption on calcareous soil and the sorption/desorption hysteresis is discussed. The effects of adding fulvic acid (FA) and carbonate in to the solution on the sorption of neptunium(V) on the soils were also studied. The sorption and desorption characteristics of NpO₂ ⁺, Zn²⁺, Sr²⁺ and Cs⁺ on the soils are compared.     

Effect of fulvic acid on the sorption and desorption of 90Sr2+ on red earth

Summary Sorption and desorption of radiostrontium on the red earth and its solid components in the presence and absence of fulvic acid were investigated by a batch technique under ambient conditions at pH 5.3±0.1 and T = 25±2 °C. The organic matter in the red earth is a significant trap of ⁹⁰Sr²⁺ and the presence of fulvic acid enhances the sorption of ⁹⁰Sr²⁺ on the red earth at pH 5.3. It was found that all the sorption and desorption isotherms are linear and the sorption of ⁹⁰Sr²⁺ on the red earth can be described by a reversible sorption process and the sorption mechanism is mainly ion-exchange. The effect of ionic strength on ⁹⁰Sr²⁺ sorption was also investigated.     

Influence of pH,soil humic acid,ionic strength and temperature on sorption of U(VI) onto attapulgite

The surface property of attapulgite was investigated by N₂-BET surface area and zeta potential analysis in this paper. Solution pH had a remarkable effect on the sorption process, indicated an inner-sphere complexation. Humic acid (HA) in the solution enhanced U(VI) sorption significantly at pH?<?5.0, while decreased U(VI) sorption obviously at pH?>?9.0. The characteristic fluorescence changes of HA indicated that a strong chemical reaction occurred between the functional groups in HA and UO₂²⁺. The sorption was a spontaneous and endothermic process with increased entropy, and the increase in temperature would benefit the sorption.     

pH、富里酸和温度对铀酰在ZrP_2O_7上的吸附影响

采用质量滴定法和静态法分别研究了ZrP2O7的零电荷点(pHPZC)和铀酰离子在ZrP2O7上的吸附及解吸行为.铀酰离子在ZrP2O7上的吸附受体系pH、固液比、电解质种类及富里酸(FA)强烈影响,离子强度对铀酰离子在ZrP2O7上吸附的影响较小;随着固液比(m/V)和pH增大,吸附边界向左偏移;磷酸根与硫酸根对吸附有相反的影响;在低pH下,富里酸(FA)促进铀酰离子在ZrP2O7上吸附;柠檬酸根对吸附有非常大的影响;温度升高有利于吸附.采用Langmuir和Freundlich模型对吸附等温线进行拟合研究,表明Freundlich模型可以更好地拟合铀酰离子在ZrP2O7上的吸附.通过对热力学数据如(△H0,△S0和△G0)的计算可知吸附过程是自发和吸热过程.铀酰离子在ZrP2O7上吸附为不可逆吸附.     

Influence of contact time, pH, soil humic/fulvic acids, ionic strength and temperature on sorption of U(VI) onto MX-80 bentonite

The sorption of U(VI) from aqueous solution on MX-80 bentonite was studied as a function of contact time, pH, ionic strength, solid contents, humic acid (HA), fulvic acid (FA) and temperature under ambient conditions using batch technique. The results indicate that sorption of U(VI) on MX-80 bentonite is strongly dependent on pH and ionic strength. The removal of U(VI) to MX-80 bentonite is rather quick and the kinetic sorption data is simulated well by a pseudo-second-order rate equation. The presence of HA enhances the sorption of U(VI) on MX-80 bentonite obviously, but the influence of FA on U(VI) sorption is not obvious. The thermodynamic parameters (ΔH ⁰, ΔS ⁰, and ΔG ⁰) for the sorption of U(VI) calculated from temperature dependent sorption suggest that the sorption reaction is endothermic and spontaneous.