Adsorption of cesium (I) from aqueous solution using oxidized multiwall carbon nanotubes

Multiwall carbon nanotubes (MWCNTs) were modified by nitric acid solution and then used to study the adsorption of cesium from aqueous solution using a batch technique under ambient conditions. As produced and oxidized MWCNTs were characterized by nitrogen adsorption/desorption, Boehm’s titration method and Fourier transform infrared spectroscopy. The physical properties of MWCNTs such as functional groups, total number of acid sites and specific surface area were greatly improved after oxidation, and these were responsible for more sorption of cesium from aqueous solution and made them more dispersible in water. The adsorption of cesium ions as a function of contact time, initial concentration of cesium, pH, ionic strength and oxidized MWCNT concentrations was also investigated. The results showed that cesium adsorption percentage strongly depended on the pH value, oxidized MWCNT content and on the solution ionic strength. Kinetic data indicated that the adsorption process achieved equilibrium within 80 min. Equilibrium data for as produced and oxidized MWCNTs was well described by both Freundlich and Langmuir isotherms. The dominant mechanism of cesium adsorption on oxidized MWCNTs may be mainly attributed to ion exchange. This study suggests that oxidized MWCNTs can be a promising candidate for the removal of cesium from nuclear waste solution.     

Selective separation of cesium from simulated high level liquid waste solution using 1,3-dioctyloxy calix[4]arene-benzo-crown-6

The 25,27-di(octyloxy)calix[4]arenebenzocrown-6 (CBC) in 1,3-alternate conformation was synthesized indigenously starting from its intermediates in good yield and purity. The extraction studies of CBC were carried out by using two different phase modifiers namely isodecyl alcohol and ortho-nitrophenyl hexyl ether. Detailed investigations on the effect of various parameters like, concentration of phase modifiers, aqueous phase acidity, ligand concentration, nitrate ion concentration and effect of temperature on extraction of cesium have been carried out. The concentration of phase modifiers was optimized to be 30 % in n-dodecane to ensure optimum extraction of cesium. Stoichiometry of the extracted complex determined by slope analysis method reveals 1:1:1 molar ratio for CsNO₃:CBC:HNO₃. The extraction process was found to be exothermic as determined from the plot of log K _ex versus 1/T. The solvent system with a composition 0.01 M CBC/30 % phase modifier/n-dodecane was found to be effective for selective separation of cesium from simulated high level liquid waste solution.     

Untersuchungen zur adsorptiven anreicherung von elementspuren an adsorberharzen

Summary The mechanisms of the adsorption of neutral compounds, ion associates and metal halogeno-complexes from aqueous solutions on Amberlite XAD-2, XAD-4, XAD-7 and XAD-8 resins are studied in the light of adsorption isotherms and of the pH-dependence of the adsorption. The similarity in the behaviour of adsorption systems to corresponding solvent extraction processes and the regularities of the sorption from aqueous solution on a solid surface are discussed by use of a simple model.

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Herrn Prof. Dr. G. Tölg zum 60. Geburtstag gewidmet

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Teil IV: Fresenius Z Anal Chem (1989) 335:483–488     

Adsorption of cesium on mesoporous SBA-15 material containing embedded copper hexacyanoferrate

In this research, the copper hexacyanoferrate/SBA-15 composite was prepared by embedding method, which was further characterized using scanning electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, transmission electron microscopy and X-ray diffraction. The effects of different factors such as pH, temperature, contact time, initial cesium concentration on adsorption were studied. The pH significantly influenced the adsorption. The pseudo second-order kinetic model fitted the adsorption well, indicating chemisorption. The Langmuir isotherm proved that the adsorption happened on monolayer and the maximum adsorption capacity was determined as 0.123 mmol/g. The result showed that CHCF/SBA-15 could be directly used to adsorb cesium from aqueous solution.

     

Speciation analysis of inorganic Sb(III) and Sb(V) ions by using mini column filled with Amberlite XAD-8 resin

The speciation of inorganic Sb(III) and Sb(V) ions in aqueous solution was studied. The adsorption behavior of Sb(III) and Sb(V) ions were investigated as iodo and ammonium pyrollidine dithiocarbamate (APDC) complexes on a column filled with Amberlite XAD-8 resin. Sb(III) and Sb(V) ions were recovered quantitatively and simultaneously from a solution containing 0.8 M NaI and 0.2 M H₂SO₄ by the XAD-8 column. Sb(III) ions were also adsorbed quantitatively as an APDC complex, but the recovery of the Sb(V)-APDC complex was found to be <10% at pH 5. According to these data, the concentrations of total antimony as Sb(III)+Sb(V) ions and Sb(III) ion were determined with XAD-8/NaI+H₂SO₄ and XAD-8/APDC systems, respectively. The Sb(V) ion concentration was calculated by subtracting the Sb(III) concentration found with XAD-8/APDC system from the total antimony concentration found with XAD-8/NaI+H₂SO₄ system. The developed method was applied to determine Sb(III) and Sb(V) ions in samples of artificial seawater and wastewater.     

Uptake behavior of titanium molybdophosphate for cesium and strontium

This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 °C using column packed with H₃O⁺ form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH₄Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution.     

Diglycolamide functionalized multi-walled carbon nanotubes for removal of uranium from aqueous solution by adsorption

Diglycolamide functionalized multi-walled carbon nanotubes (DGA-MWCNTs) were synthesized by sequential chemical reactions for removal of uranium from aqueous solution. Characterization studies were carried out using FT-IR spectroscopy, XRD and SEM analysis. Adsorption of uranium from aqueous solution on this material was studied as a function of nitric acid concentration, adsorbent dose and initial uranium concentration. The uranium adsorption data on DGA-MWCNTs followed the Langmuir and Freundlich adsorption isotherms. The adsorption capacity of DGA-MWCNTs as well as adsorption isotherms and the effect of temperature on uranium ion adsorption were investigated. The standard enthalpy, entropy, and free energy of adsorption of the uranium with DGA-MWCNTs were calculated to be 6.09 kJ mole⁻¹, 0.106 kJ mole⁻¹ K⁻¹ and −25.51 kJ mole⁻¹ respectively at 298K. The results suggest that DGA-MWCNTs can be used as efficient adsorbent for uranium ion removal.     

Studies on the feasibility of using crystalline silicotitanates for the separation of cesium-137 from fast reactor high-level liquid waste

The commercially available crystalline silicotitanate inorganic ion exchanger, IONSIV IE-911, and its parent precursor, TAM-5, have been evaluated for the removal of ¹³⁷Cs from nitric acid medium and simulated high-level liquid waste. The distribution coefficient (K _d ) of cesium decreased with increasing nitric acid concentration and at 3.0 M nitric acid, a distribution coefficient of 1150 mL/g and 2600 mL/g were obtained for IONSIV IE-911 and TAM-5, respectively. Rapid uptake of cesium followed by the establishment of equilibrium occurring within three hours. Loading of cesium in ion exchangers increased with the increase in the concentration of cesium in aqueous phase and from Langmuir adsorption model the apparent capacity of cesium was 69 mg/g and 82 mg/g for IONSIV IE-911 and TAM-5, respectively. The performance of the sorbent under dynamic conditions was assessed by following a breakthrough (BT) curve up to C/C _o = 1, where C and C _o are the concentrations of cesium in the effluent and feed, respectively.     

Enhanced adsorption of radioactive strontium ions from aqueous solution by H2O2-modified attapulgite

Effective adsorption of Sr(II) onto H₂O₂-modified attapulgite in aqueous solution was investigated about kinetics and isothermal equilibrium adsorption. The adsorption equilibrium process of Sr(II) on adsorbents reached about 8 h at 40 °C. The adsorption kinetics followed the pseudo-second order equation and the isothermal adsorption data were fit well with the Langmuir isotherm model. The enhanced adsorption mechanism of H₂O₂-modified attapulgite for Sr(II) in aqueous solution was expatiated in detail. The H₂O₂ treatment for attapulgite is effective and as-made adsorbents can be applied for removal of Sr(II) in radioactive waste water.

     

Adsorption studies of cesium on potassium copper nickel hexacyanoferrate(II) from aqueous solutions

Adsorption of cesium from aqueous solutions on potassium copper nickel hexacyanoferrate(II) (KCNF) has been investigated in batch experiments and optimized as a function of concentration of acids, salts and adsorbate using a radiotracer technique. The results are presented in terms of distribution coefficient, K_d (ml·g^–1). The uptake of cesium obeys a Freundlich adsorption isotherm over the concentration range of 3.7 to 37 mmol·l^–1 with b values of 0.77, 0.68 and 0.56 at temperatures of 293, 313, 333 K, respectively. The Langmuir adsorption isotherm is followed in the concentration range of 15 to 75 mmol·l^–1 in the same temperature range. The values of limiting adsorption concentration (C_m) have been found to be 2.58, 2.44 and 2.32 mmol·g^–1. The heat of adsorption was calculated as 26.43 kJ·mol^–1. The influence of a number of anions and cations on cesium retention has also been studied. Column experiments have been performed and breakthrough have been obtained under different operating conditions. The low cesium capacity of 1.1 mmol·g^–1 has been obtained under dynamic conditions as compared to batch experiments. Desorption of cesium from the column has been achieved (45.4%) by nitric acid solution of 8M concentration at a flow rate of 0.5 ml·min^–1.     

Uranium removal from aqueous solutions by wood powder and wheat straw

The influence of initial uranium concentration, solution pH, contact time and adsorbent mass was investigated for removal of uranium from aqueous solutions by pine wood powder and wheat straw using a batch technique. The maximum removal efficiency of uranium achieved at pH 8 and 7 for pine wood powder and wheat straw, respectively. Langmuir and Freundlich adsorption isotherms and three kinetic models of adsorption including; Elovich, Lagergren pseudo-first and Lagergren pseudo-second order were used to describe the adsorption mechanisms. The uranium sorption onto wood and wheat straw powders followed a Freundlich isotherm. The kinetic studies showed that the data fitted very well to the pseudo-second order model in the studied concentration range of uranium for both adsorbents. Uranium desorption from loaded adsorbents also studied using batch techniques as a function of desorptive reagent, desorption time and desorptive reagent concentration. The results of the experiment indicated that the optimum desorption efficiency of uranium for wood powder and wheat straw occurred in 5 min shaking time, using 1.5 M HNO₃ and 2 M Na₂CO₃ solutions, respectively.     

Adsorption behaviour of microamounts of cesium on manganese dioxide

The adsorption of cesium on manganese dioxide from aqueous solutions has been studied in relation to pertinent variables such as shaking time, pH, composition of aqueous solutions, mass of adsorbent (10 mg–1 g) and concentration of adsorbate (10^–6–5·10^–3 M), using a radiotracer technique. The influence of various anions and cations on cesium adsorption was examined. The distribution coefficient of a variety of other elements was determined under similar conditions. The adsorption of cesium obeys a Freundlich-type isotherm over the entire concentration range investigated, whereas the Langmuir-type isotherm is followed only at moderate concentrations.     

Studies on synthesis and application of XAD-4-salen chelate resin for separation and determination of trace elements by solid phase extraction

The use of chemically modified XAD-4-salen chelating resin had been studied for the separative concentration of metal ions from an aqueous solution. XAD-4-salen was synthesized by diazonium coupling reaction of salen[N,N′-bis(salicylidene)ethylenediamine] and Amberlite XAD-4 resin. The distribution coefficient at various pH values and adsorption capacities were obtained with respect to Cu(II), Pb(II) and Bi(III). Trace elements were pre-concentrated on the synthesized XAD-4-salen by batch method for atomic absorption spectrometric determination. Some conditions, such as the pH of aqueous solution, amount of XAD-4-salen, kinds and concentration of acids were optimized for the analytical application of XAD-4-salen. For the pre-concentration of metal ions, the pH of the aqueous solution was adjusted to approximately 5.5, and then it was stirred 30 min after the addition of 50 mg of pulverized XAD-4-salen. The adsorbed metal ions were desorbed by 10 mL of 1.0 M HNO₃. The desorption efficiency of Bi(III) was enhanced by the addition of 30 mg/L of Pd(II). The addition of Pd(II) as a matrix modifier could improve the reproducibility and sensitivity in the Atomic Absorption Spectroscopy (AAS) determination of volatile lead and bismuth. In the present study, this procedure has been applied for the determination of Cu(II), Pb(II) and Bi(III) in real samples of five kinds of river water, using a standard calibration curve method. Recoveries of 85–120% were obtained in the spiked samples in which given amount of analytes were added.     

Novel self assembled magnetic Prussian blue graphene based aerogel for highly selective removal of radioactive cesium in water

A novel self-assembled Magnetic Prussian Blue/Reduced Graphene Oxide (3D-MPBRGO) aerogel was prepared by an easy and cost effective process for elimination of radioactive Cesium from contaminated aqueous solution selectively. The 3D-MPBRGO displayed excellent adsorption capability of 3.64 mmol per g or (484.12 mg/g) for Cs (initial 50 mM cesium concentration, pH 7 and 30 °C) and quick separation from solution by applying magnetic field as compared to previously published results for graphene based adsorbents. This excellent removal efficiency of nanocomposite can be ascribed to enlarged adsorbent surface area (402.68 m²/g) and uniform distribution of nanoparticles on RGO which removes aggregation of sheets as well. The thermodynamic analysis displayed exothermic and spontaneous nature of Cs ion adsorption. The experimental data of adsorption isotherm followed the Langmuir isotherm model than that of Tempkin and Freundlich while adsorption kinetics followed pseudo second order.     

Removal of 226Ra from aqueous media and its thermodynamics and kinetics

The composite adsorbent prepared by mixing of polyacrylonitrile and clinoptilolite was used for investigating the adsorption behaviour of ²²⁶Ra in column system. The effective parameters like initial activity concentration, pH of the solution, contact time and temperature for adsorption behaviour of ²²⁶Ra were studied. Adsorption efficiency of ²²⁶Ra on composite adsorbent from aqueous solution was determined to 98.73 ± 0.59 % at pH 5.0 and 30 °C in a short time. The isotherm models were studied to evaluated adsorption characteristics of ²²⁶Ra onto composite adsorbent. The thermodynamic parameters were showing that the processes for ²²⁶Ra were exothermic. Adsorption kinetics of the radium is also studied.

     

Adsorption of cesium on a composite inorganic exchanger zirconium phosphate - ammonium molybdophosphate

The applicability of zirconium phosphate-ammonium molybdophosphate (ZrP-AMP) for the efficient removal of cesium from aqueous acidic solutions by adsorption has been investigated. The adsorption data analysis was carried out using the Freundlich, Dubinin-Raduskevich (D-R) and Langmuir isotherms for the uptake of Cs in the initial concentration range of 3.75^.10^-5-7.52^.10^-3 mol^.dm^-3 on the ZrP-AMP exchanger from nitric acid medium. The mean free energy (E) values for the adsorption of Cs were obtained from the D-R isotherm. Equilibrium adsorption values at different temperatures have been utilized to evaluate the change in enthalpy, entropy and free energy (ΔH°, ΔS°, ΔG°). The adsorption of cesium on the ZrP-AMP exchanger was found to be endothermic. This revised version was published online in August 2006 with corrections to the Cover Date.     

Highly efficient elimination of thorium(IV) from aqueous solution using poly(cyclotriphosphazene-co-melamine) microspheres

Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g^?1 for initial thorium(IV) concentration 50 mg L^?1. When pH?=?0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature.

     

Nanostructured spinel-type M(M = Mg,Co, Zn)Cr2O4 oxides: novel adsorbents for aqueous Congo red removal

Nanostructured spinel-type M(M = Mg, Co, Zn)Cr₂O₄ oxides with novel adsorbents for aqueous Congo red removal were synthesized by a polyacrylamide gel method and studied for their phase structure, microstructure, adsorption performance, and multiferroic behavior. The phase structure and purity analysis revealed that the nanostructured spinel-type M(M = Mg, Co, Zn)Cr₂O₄ oxides presented a spinel-type cubic structure, and the formation of a secondary phase such as Cr₂O₃, MgO, ZnO, or Co₃O₄ was not observed. The microstructure characterization confirmed that the spinel-type MCr₂O₄ oxides grew from fine spherical particles to large rhomboid particles. Adsorption experiments of spinel-type MCr₂O₄ oxides for adsorption of Congo red dye were fitted well with the pseudo-second-order kinetics. The adsorption capacity of the ZnCr₂O₄ oxide (44.038 mg/g, pH 7, temperature 28 °C, initial dye concentration 30 mg/L) was found to be higher than that of MgCr₂O₄ oxide (43.592 mg/g, pH 7, temperature 28 °C) and CoCr₂O₄ oxide (28.718 mg/g, pH 7, temperature 28 °C). The effects of initial adsorbent concentration, initial dye concentration, pH, and temperature between the ZnCr₂O₄ oxide and Congo red dye at which optimal removal occurs, were performed. The thermodynamic studies confirmed that a high temperature favors the adsorption of Congo red dye onto ZnCr₂O₄ oxide studied. The nanostructured spinel-type M(M = Mg, Co, Zn)Cr₂O₄ oxides that exhibited high adsorption performance for adsorption of Congo red dye can be ascribed to the synergistic effect of electrostatic interaction, pore filling, and ion exchange. The present work suggested that the nanostructured spinel-type M(M = Mg, Co, Zn)Cr₂O₄ oxides have excellent adsorption performance and multiferroic behavior, which shows potential applications for removal of the Congo red dye from wastewater, magnetic memory recording media, magnetic sensor, energy collection and conversion device, and read/write memory.     

Synthesis and characterization of CoFe2O4@SiO2-polyethyleneimine magnetic nanoparticle and its application for ultrasonic-assisted removal of disulfine blue dye from aqueous solution

In the present work, a simple synthesis approach was applied for the fabrication of CoFe₂O₄@SiO₂-polyethyleneimine magnetic nanoparticles as an effective sorbent for ultrasonic-assisted removal of disulfine blue dye from an aqueous solution. For identification and characterization of prepared sorbent, different analysis including Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), Vibrating sample magnetometer (VSM), Energy dispersive X-ray analysis (EDX) and Transmission electron microscopy (TEM) were applied. The effect of effective parameters on the removal of disulfine blue such as pH, sorbent mass, ultrasonic time and disulfine blue concentration were also assessed. The optimum values for investigated parameters were achieved to be as follows: pH of 5.0, sorbent mass of 0.015 g, ultrasonic time of 5.0 min and disulfine blue concentration of 10.0 mg L⁻¹. Different isotherm and kinetic models were used for the evaluation of isotherm and kinetic of adsorption. Results showed that the Langmuir isotherm model was better than other isotherm models as well as the second-order equation model was selected as a kinetic model. The maximum adsorption capacity of the proposed magnetic sorbent was achieved to be 110.0 mg g⁻¹ which shows the applicability of proposed sorbent for removal of disulfine blue dye from aqueous solution.     

1-[(2-Hydroxy-phenylimino)-methyl]-naphthalen-2-ol: application in detection and adsorption of aluminum ions

A novel “on–off” Al³⁺ ions fluorescence-enhanced sensor (E)-1-(((2-hydroxyphenyl) imino)methyl)naphthalen-2-ol (AH-2) and its hydrogel hybrid (PAMN) were synthesized. AH-2 showed excellent selectivity and ultrasensitive to Al³⁺ ions; the detection limit was 2.36?×?10^–9 M. The most plausible complexation mechanism was studied by ¹H NMR, FT-IR, HR-MS, Job’s plot and theoretical calculation. And, it was interesting that PAMN could adsorb Al³⁺ ions with a removal rate of over 99%, which also could easily be distinguished by the naked eye in UV lamp (365 nm). Before and after adsorption of Al³⁺ ions, the microstructures of PAMN were analyzed by scanning electron microscope and X-ray energy spectrometer. The silica gel detect plates prepared in this work could rapidly and conveniently detect Al³⁺ ions with a concentration greater than 5?×?10^–6 M (0.13 mg/L) in aqueous solution, and the detection concentration (0.13 mg/L) was lower than the national standard concentration of Al³⁺ ions (0.2 mg/L) in city tap water of china.