Adsorption Of Th Research Articles

Study on adsorption of trace thorium(IV) using 6-o-monotosyl-deoxy-β-cyclodextrin inclusion complex of dibenzoyl

The adsorption of thorium(IV) [Th(IV)] was studied using a novel 6-o-monotosyl-deoxy-β-cyclodextrin inclusion complex of dibenzoyl (inclusion complex), which was acquired by the reaction of dibenzoyl and 6-OTs-β-CD with the mole ratio of 1:2. The adsorption of Th(IV) onto inclusion complex were investigated as a function of pH value, contact time, temperature, interfering ions and Th(IV) concentration using batch adsorption technique. The maximum adsorption of Th(IV) and the equilibrium adsorption capacity were found to be 89 ± 1 % and 17.83 mg g−1 respectively at pH 3.0, equilibrium time 20 min and initial Th(IV) concentration 20 mg L−1. Adsorption kinetics, adsorption isotherm and thermodynamics were carried out.

Synthesis of ethylamine-bridged β-cyclodextrins and adsorption properties of thorium

A specialized ethylamine-bridged β-cyclodextrins (EB β-CD) was synthetized. EB β-CD’s adsorption properties of thorium ions were performed. Experimental results show that the adsorption of thorium using the EB β-CD can achieve equilibrium within 60 min at room temperature under the condition of pH 4, the adsorbance is 10.49 mg g−1. The results of SEM and BET nitrogen adsorption show that, EB β-CD is typical mesoporous material. According to pseudo-second-order kinetics, the adsorption of Th(IV) indicating the influence of textural properties of EB β-CD on the rate of adsorption. The thermodynamic parameters obtained showed that the adsorption process is exothermic, spontaneous process.

Kinetic and isotherm analysis for selective thorium(IV) retrieval from aqueous environment using eco-friendly cellulose composite

Thorium reclamation was studied using nano-iron oxide-impregnated cellulose acetate beads to gain insights into the adsorption mechanism, kinetics and thermodynamics. The designed experiments were thoroughly investigated as a function of solution pH, initial thorium(IV) ion concentration, adsorbent dose and nano-iron oxide loading in the cellulose acetate matrix. The batch adsorption of Th(IV) ions revealed the highly pH dependent (pH range 3.0–9.0) behaviour with maximum sorption at pH 6.0 and equilibrium being achieved within 2 h for maximum concentration of 100 mg/L at 298 K. Rapid adsorption of 50 ± 0.2 % was observed within first 10 min. The kinetics data are best described by the pseudo-first-order kinetic model (R 2 = 0.9996) and intraparticle diffusion model. The equilibrium adsorption process was fitted with the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models which yield good fit with Langmuir isotherm equation indicating monolayer adsorption process. The calculated thermodynamics parameter reveals spontaneous and exothermic adsorption process. Further, the desorption was Th(IV) ions that was easily achieved using 0.05 N HNO3 which suggests the reusability of the adsorbent for multiple use.

Adsorption of thorium(IV) on magnetic multi-walled carbon nanotubes

The influences of pH, contact time, solid-liquid ratio, temperature and C60(C(COOH)2) n on Th(IV) adsorption onto the magnetic multi-walled carbon nanotubes (MMWCNTs) were studied by batch technique. The dynamic process showed that the adsorption of Th(IV) onto MMWCNTs could reach equilibrium in 40 h and matched the pseudo-second-order kinetics model. The adsorption of Th(IV) onto MMWCNTs was significantly dependent on pH values, the adsorption ratio increased markedly at pH 3.0–5.0, and then maintained a steady state as pH values increased. At low pH, different C60(C(COOH)2) n content could enhance the adsorption content of Th(IV) onto MMWCNTs, but restrained it at higher pH. Through simulating the adsorption isotherms by Langmuir, Freundlich and Dubini-Radushkevich models, it could be seen respectively that the adsorption pattern of Th(IV) onto MMWCNTs was mainly surface complexation, and that the adsorption process was endothermic and irreversible.

Effect of natural organic matter on the adsorption and fractionation of thorium and protactinium on nanoparticles in seawater

Laboratory experiments were carried out to examine the role of natural organic matter (NOM) in regulating the adsorption and fractionation of 234Th and 233Pa in seawater on inorganic nanoparticles (20nm), including SiO2, CaCO3, Fe2O3, Al2O3 and TiO2. Model macromolecules and natural colloidal organic matter (COM) tested in the present study included dextran with different molecular weights, acid polysaccharides (APS), humic acids (HAs), protein (bovine serum albumin, BSA), and COM isolated from river water and seawater. APS and HAs had comparable affinity and higher partition coefficients (Kd) for 234Th, with logKd values close to 7, while proteins showed weaker binding strength with 234Th and had a logKd value of 5.75. Compared to 234Th, 233Pa showed lower affinity for different organic matters, with logKd values ranging from 4.41 on APS to 5.46 on 6-kDa-dextran. In general, macromolecules and COM preferentially complexed with 234Th over 233Pa, which resulted in a fractionation between 234Th and 233Pa on different NOMs with a fractionation factor (FTh/Pa) following the order of APS>HA≥Dextran>BSA. Results from binary-sorbent experiments (nanoparticles plus NOM) indicated that NOMs evidently affected the adsorption of 234Th and 233Pa on different inorganic nanoparticles likely through the formation of organic coatings. While SiO2 preferentially adsorbed 233Pa over 234Th, the presence of APS could compete the effective sorption sites and thus reduced the adsorption of 233Pa on SiO2 nanoparticles. Based on a two end-member mixing model (Li, 2005), coating extent seemed to depend on the relative abundance and chemical composition of organic matter and inorganic nanoparticles. In addition to organic composition, NOM concentrations also affected the partitioning of 234Th and 233Pa between seawater and particles, showing a strong ‘colloidal concentration effect’. Nevertheless, there was little change in logKd values of 234Th and 233Pa on dextran with a molecular weight between 6–500kDa or 2–10nm in size, indicating negligible NOM size effect from small colloids on the adsorption of Th and Pa in seawater.

Equilibrium, kinetic and thermodynamic studies of adsorption of Th(IV) from aqueous solution onto kaolin

The kinetics and thermodynamics of the adsorption of Th(IV) on the kaolin were studied by using batch method. In addition, the experimental data were studied by dynamic and thermodynamic models. The results showed that the adsorption capacity of the adsorbent increased with increasing temperature and solid liquid ratio, but decreased with increasing initial Th(IV) ion concentration, and the best fit was obtained for the pseudo-second-order kinetics model. The calculated activation energy for adsorption was about 45 kJ/mol, which indicated the adsorption process to be chemisorption. The adsorption isotherm data could be well described by the Langmuir as well as Dubinin–Radushkevich model. The mean free energy (E) of adsorption was calculated to be about 15 kJ/mol. The thermodynamic data calculated showed that the adsorption was spontaneous and enhanced at higher temperature. Considering kinetics and equilibrium studies, the adsorption on the sites was the rate-limiting step and that adsorption was mainly a chemisorption process through cation exchange.

Adsorption of thorium (IV) ions from aqueous solution by magnetic chitosan resins modified with triethylene-tetramine

The triethylene-tetramine modified magnetic chitosan sorbents (TETA-MCS) were synthesized for the adsorption of Th(IV) ions from aqueous solution. FTIR analysis indicated that the amine and hydroxyl groups of TETA-MCS were involved in the adsorption process for the formation of O, N–Th(IV) complex. Th(IV) adsorption was pH dependent and the maximum adsorption was observed at pH 4.0. The adsorption kinetic data could be interpreted by pseudo-second-order kinetic model. The equilibrium data were correlated with the Langmuir, Freundlich and Temkin models, and the maximum monolayer adsorption capacity obtained from the Langmuir model was 133.3 mg Th(IV)/g at 25 °C. Thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of adsorption. The sorbents were successfully regenerated using 0.2 M HNO3−0.1 M EDTA and exhibited good reusability.

An investigation on the behaviors of thorium(IV) adsorption onto chrysotile nanotubes

Prepared chrysotile nanotubes (ChNTs) were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 adsorption•desorption, X-ray photoelectron spectrometer (XPS) and Fourier transform infrared spectroscopy (FTIR). ChNTs were employed to investigate the influence of various experimental parameters on thorium adsorption. Some isotherm and kinetic models were applied to analyze the experimental data among which the Langmuir and pseudo-second-order models were better than others. The pH and ionic strength results indicated that adsorption of Th(IV) on ChNTs was strongly affected by pH values and ionic strength. The possible adsorption mechanism was studied by FTIR and XPS techniques. It was found that both electrostatic interaction and surface complexation mechanisms played important roles in adsorption process.

A chelating resin containing trihydroxybenzoic acid as the functional group: synthesis and adsorption behavior for Th(IV) and U(VI) ions

A novel glycidyl methacrylate chelating resin has been synthesized through copolymerization of glycidyl methacrylate (GMA) in the presence of divinylbenzene (DVB), the resulting resin was immobilized with 3,4,5-trihydroxybenzoic acid (THBA) to give GMA/DVB/THBA chelating resin. The adsorption of Th(IV) and U(VI) on GMA/DVB/THBA adsorbent was studied as a function of initial concentration, pH, shaking time and temperature. The novel chelating resin shows a high capacity for Th(IV) and U(VI), maximum adsorption of Th(IV) and U(VI) were 56 and 83.6 mg/g, respectively. Kinetic studies showed that the adsorption follows the pseudo second order model referring to the influence of the textural properties of the resin on the rate of adsorption. Thermodynamic parameters such as ∆H° and ∆S° were studied and indicated an endothermic process.

Adsorptive removal of U(VI) and Th(IV) from aqueous solutions using polymer-based electrospun PEO/PLLA fibrous membranes

Fibrous membranes based on poly(ethylene oxide) and poly(l-lactide) fabricated by electrospinning were evaluated for the first time as substrates for the adsorption of tetravalent thorium (Th(IV)) and hexavalent uranium (U(VI)) from aqueous media. The membranes consisted of microfibers with diameters of approximately 2 μm as revealed by scanning electron microscopy. The adsorption of Th(IV) and U(VI) on the membrane was investigated as a function of pH, ionic strength and initial metal concentration under normal atmospheric conditions. The experimental data indicated increased affinity of the membrane for Th(IV) and U(VI), which was pH depended and reaches maximum values (>90 %) for Th(IV) and U(VI) at pH 3 and pH 6.5, respectively. The maximum adsorption capacity (qmax) at optimum conditions was evaluated from the Langmuir isotherm and was found to amount 50.08 and 9.3 mmol kg−1 for Th(IV) and U(VI), respectively. In addition, studies on the effect of ionic strength on the adsorption efficiency did not show any significant effect indicating that the adsorption of Th(IV) and U(VI) on the membrane was most probably based on specific interactions and the formation of inner-sphere surface complexes. The significantly higher adsorption efficiency of the membrane for Th(IV) in acidic media (pH ≤ 3) could be utilized for a pH-triggered, selective separation of Th(IV) from U(VI) from aqueous media.

Adsorption characteristics of Th(IV) ions on reduced graphene oxide from aqueous solutions

Reduced graphene oxide (RGO) prepared by the reduction of graphene oxide (GO) using thiourea dioxide (TUD) was examined for the adsorption of Th(IV) from aqueous solutions. The adsorption of Th(IV) on RGO as a function of pH, contact time, adsorbent dosage, the Th(IV) initial concentration and temperature was investigated through batch adsorption experiments. The results showed that the adsorption behavior of Th(IV) on RGO followed the pseudo-second order kinetic and the Langmuir isotherm models. The maximum theoretical adsorption capacity was calculated to be 0.21mmol Th/g RGO at 298.15K. Moreover, the thermodynamic parameters (ΔH0=4.32kJ/mol, ΔS0=69.47J/molK and ΔG0=−16.39kJ/mol at 298.15K) indicated that the adsorption process was a feasible, spontaneous and endothermic in nature.

Th(IV) Adsorption onto Oxidized Multi-Walled Carbon Nanotubes in the Presence of Hydroxylated Fullerene and Carboxylated Fullerene.

The adsorption of Th(IV) onto the surface of oxidized multi-walled carbon nanotubes (oMWCNTs) in the absence and presence of hydroxylated fullerene (C60(OH)n) and carboxylated fullerene (C60(C(COOH)2)n) has been investigated. C60(OH)n, C60(C(COOH)2)n and oMWCNTs have been chosen as model phases because of their representative in carbon nano-materials family. Adsorption experiments were performed by batch procedure as a function of contact time, pH, ionic strength, and temperature. The results demonstrated that the adsorption of Th(IV) was rapidly reached equilibrium and the kinetic process could be described by a pseudo-second-order rate model very well. Th(IV) adsorption on oMWCNTs was dependent on pH but independent on ionic strength. Adsorption isotherms were correlated better with the Langmuir model than with the Freundlich model. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Th(IV) adsorption on oMWCNTs was spontaneous and endothermic. Compared with the adsorption of Th(IV) on the same oMWCNTs free of C60(OH)n or C60(C(COOH)2)n, the study of a ternary system showed the inhibition effect of C60(OH)n at high concentration on the adsorption of Th(IV) in a pH range from neutral to slightly alkaline; whereas the promotion effect of C60(C(COOH)2)n, even at its low concentration, on Th(IV) adsorption was observed in acid medium.

Organo-bentonite-Fe3O4 poly(sodium acrylate) magnetic superabsorbent nanocomposite: Synthesis, characterization, and Thorium(IV) adsorption

Novel magnetic organo-bentonite-Fe3O4 poly(sodium acrylate) (OB-Fe3O4 PSA) superabsorbent nanocomposites were synthesized in aqueous solution through the copolymerization of partially neutralized acrylic acid (SA) on OB-Fe3O4 nanoparticle by using N,N′-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. This new superabsorbent was characterized by FTIR, TGA, FE-SEM and XRD. Its iron content and magnetic properties were studied by using inductively coupled plasma (ICP) and a vibrating sample magnetometer (VSM), respectively. The water retention test of OB-Fe3O4 PSA was also performed. The introduced OB-Fe3O4 could form a loose and coarse surface and improve the water absorbency of OB-Fe3O4 PSA superabsorbent. The effects of pH, ionic strength, and humic substances (HS) on the adsorption of Th(IV) were investigated in detail through batch experiments. The maximum adsorption capacity (Qmax) of Th(IV) on OB-Fe3O4 PSA 3.6 superabsorbent at pH 3.0±0.05 and T=298K was about 6.55mmol/g, higher than any value previously reported. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Th(IV) adsorption on OB-Fe3O4 PSA superabsorbent was an endothermic and spontaneous process. Furthermore, OB-Fe3O4 PSA superabsorbent could be regenerated through the desorption of Th(IV) using 0.1mol/L HCl solution and the adsorption capacity was still higher than 3.6mmol/g after five consecutive adsorption–desorption processes.

Synthesis, characterization, and application of titanate nanotubes for Th(IV) adsorption

Titanate nanotubes (TNTs) have been synthesized by a hydrothermal method using rutile TiO2 powder as titanium source. The determination of the structure and morphology was characterized by XRD, FTIR, SEM and TEM. The results indicate that the TNTs successfully synthesized under hydrothermal conditions of 150 °C. The adsorption of Th(IV) on TNTs was studied as a function of contact time, pH values, ionic strength, initial Th(IV) concentration and temperature under ambient conditions by using batch technique. The results indicate that adsorption of Th(IV) on TNTs is strongly dependent on pH values, but weakly dependent on ionic strength; Adsorption kinetics was better described by the pseudo-second-order model. The adsorption isotherms are simulated by Langmuir and Freundlich models well. ΔG°, ΔH° and ΔS° free energy were calculated from experimental data, The results indicate that the adsorption of Th(IV) on TNTs is an endothermic and a spontaneous process, and increases with increasing temperature. The adsorption of Th(IV) on TNTs is mainly dominated by chemical sorption or surface complexation.

Role of solution chemistry on the trapping of radionuclide Th(IV) using titanate nanotubes as an efficient adsorbent

Titanate nanotubes (TNTs) have attracted great interest in multidisciplinary study since their discovery. The adsorption of thorium [Th(IV)] onto TNTs in the absence and presence of humic acid (HA)/fulvic acid (FA) was studied by batch technique. The influence of pH from 2.0 to 10.0, ionic strength from 0.001 to 0.1 mol L−1 NaClO4, and coexisting electrolyte cations (Li+, Na+, K+) and antions (ClO4 −, NO3 −, Cl−) on the adsorption of Th(IV) onto TNTs was tested. The adsorption isotherms of Th(IV) was determined at pH 3.0 and analyzed with Langmuir and Freundlich adsorption models, respectively. The results demonstrated that the adsorption of Th(IV) onto TNTs increases steeply with increasing pH from 2.0 to 4.0. Generally, HA/FA was showed to enhance Th(IV) adsorption onto TNTs at low pH values, but to reduce Th(IV) adsorption onto TNTs at high pH values. The adsorption of Th(IV) onto TNTs was also dependent on coexisting electrolyte ions in aqueous solution under our experimental conditions. The adsorption of Th(IV) onto TNTs is exothermic and spontaneous. The findings indicating that TNTs can be used as a promising candidate for the enrichment and solidification of Th(IV) or its analogue actinides from large volume solution in real work.

A novel extractant-impregnated resin containing carminic acid for selective separation and pre-concentration of uranium(VI) and thorium(IV)

The present work proposes the use of a novel extractant-impregnated resin (EIR) as an adsorbent in trace separation and pre-concentration of U(VI) and Th(IV) ions. The new EIR was prepared by impregnating carminic acid onto Amberlite XAD-16 resin beads. The morphology of new EIR was studied by BET surface area measurements and SEM micrographs. A column packed with CA/XAD-16 was used for selective separation and pre-concentration of the metal ions. Maximum adsorption of Th(IV) and U(VI) ions occurred at pHs of 3.50–5.75 and 3.75–6.50, respectively. The adsorbed metals could be eluted sequentially using 0.55 mol L−1 HCl for U(VI) and 2.25 mol L−1 HCl for Th(IV). The dynamic capacity of EIR was found to be 0.832 and 0.814 mmol g−1 for Th(IV) and U(VI), respectively. The tolerance limit of some foreign ions was also studied. The proposed method showed a good performance in analyzing geological reference materials and a synthetic seawater sample. Furthermore, the above procedure was successfully employed for the analysis of natural water samples.

Adsorptive removal of thorium (IV) using calcined and flux calcined diatomite from Turkey: Evaluation of equilibrium, kinetic and thermodynamic data

Adsorption experiments were performed under batch process, using Th(IV) initial concentration, pH of solution, contact time and temperature as variables. Th(IV) uptake by calcined (C-D) and flux calcined diatomite (FC-D) was pH dependent (pH range, 3.0–6.0) and maximum sorption was observed at pH 4.0. Sorption capacities for Th(IV) were found to be 0.52 (121.22mg Th/g) and 0.50mmol/g (116.69mg Th/g) for calcined diatomite (C-D) and flux calcined diatomite (FC-D), respectively. Adsorption process is well described by Freundlich and Dubinin–Radushkevich (D-R) isotherms in comparison with Langmuir, Temkin and Flory–Huggins isotherms. Thermodynamic data (ΔH°, ΔS°, ΔG°) were calculated from the temperature-dependent sorption isotherms. Results suggested that the adsorption of Th(IV) on calcined and flux calcined diatomite was a spontaneous and endothermic process. A comparison of kinetic models applied to the adsorption of Th(IV) onto C-D and FC-D was evaluated for the pseudo-first-order, pseudo-second-order, intraparticle diffusion and film diffusion kinetic models. The experimental data fitted very well the pseudo-second-order kinetic model and also followed by intra-particle diffusion model, whereas intraparticle diffusion and film diffusion are both the rate limiting steps for Th(IV) onto calcined and flux calcined diatomite.

Study on adsorption of Th(IV) using surface modified dibenzoylmethane molecular imprinted polymer

The adsorption of Th(IV) was studied using a novel dibenzoylmethane molecular imprinted polymers, which was prepared using acryloyl-β-cyclodextrin as a monomer on surface modified functional silica gel. X-ray photoelectron spectroscopy and FTIR were employed to confirm the reliability of the synthetic polymer. Scanning electron microscope was used to analyze the surface properties of the experimental materials. UV-spectrophotometer was employed to investigate the adsorption property and the concentration of Th(IV). Adsorption kinetics and adsorption isotherm were carried out. In pH 3.5, the adsorption equilibrium could reach a balance in 45 min, the resultant adsorbing capacity was 30.8 mg g−1, and the remove ratio of Th(IV) was 88.1 %.

Adsorption of tetravalent thorium by geomedia

AbstractWe measured the pH-dependent adsorption of Th(IV), an analogue for Pu(IV) and other tetravalent actinides, to two geomedia: goethite (α-FeOOH(s)) and a heterogeneous Fe-containing sand from the southeastern USA. The goal was to examine whether or not the Th(IV)-goethite adsorption data could be used to predict the adsorption of Th(IV) by the heterogeneous sand. In the absence of either geomedia, after forty-eight hours the measured pH-dependent “adsorption” was consistent with the solubility of solid amorphous ThO2(am, aged), despite the fact that ThO2(am, aged) is generally not formed until approximately seventy days. We concluded that ThO2(am, aged) was stabilized by precipitating on the walls of the reaction vessels. Ignoring this phenomenon could lead to experimental artifacts in Th(IV) adsorption studies. Thorium adsorption by both goethite and the sand was strongly pH dependent, with adsorption increasing sharply from pH ∼ 2 to pH ∼ 4. Two methods were utilized to predict the pH-dependent adsorption of Th(IV) by the sand using the Th(IV)-goethite adsorption data. Using the Fe content of the sand and the Th(IV)-goethite adsorption data, we were able to predict the maximum amount of Th(IV) adsorption by the sand within 78% of the actual value (i.e., an error of 22%). In contrast, on a surface-area-normalized basis, we were only able to predict the maximum adsorption of Th(IV) by the sand within a factor of two. These results have important implications to scaling and extrapolating the results of batch-scale tetravalent actinide adsorption studies with pure minerals to predict their field-scale adsorption by and transport in heterogeneous subsurface media.

Magnetic Th(IV)-ion imprinted polymers with salophen schiff base for separation and recognition of Th(IV)

A new complex of N,N′-bis(3-allyl salicylidene)o-phenylenediamine and thorium(IV) (Th(IV)) was synthesized and used as the functional monomer for a novel Th(IV) magnetic ion-imprinted polymer; this polymer was synthesized using a surface imprinting technique that included the modified magnetic Fe3O4 particle and used tetraethyl orthosilicate, 3-Aminopropyltriethoxysilane and maleic anhydride in the process. The magnetic polymer was characterized using FT-IR, and powder- and single crystal-XRD. The behavior of Th(IV) was investigated using batch experiments. At pH 4.5, the uptake capacity of this adsorbent and that of the non-imprinted polymer was 42.54 and 14.10 mg g−1, respectively, and the relative selectivity coefficient values of the synthesized adsorbent for Th(IV)/La(III), Th(IV)/Ce(III), Th(IV)/Nd(III), and Th(IV)/U(VI) were 82.2, 93.1, 21.0 and 62.4 times greater than that of the non-imprinted matrix, respectively. In addition, the Th(IV) adsorption process using Fe3O4@SiO2-IIP follows pseudo-second-order reaction kinetics and the Langmuir adsorption isotherm. The thermodynamic parameters also suggest that the adsorption of Th(IV) onto Fe3O4@SiO2-IIPs was a spontaneous and endothermic process.