Removal Of Cs Ions Research Articles

Effective removal of cesium by ammonium molybdophosphate–polyethylene glycol magnetic nanoparticles

This study synthesizes a new adsorbent composite for the removal of Cs ions from waste effluents. The adsorbent is composed of polyethylene glycol-decorated ammonium molybdophosphate magnetic Fe3O4 nanoparticles (PEG–AMP MNs) and is prepared via coprecipitation by grafting ammonium phosphomolybdate onto the surface of Fe3O4 and coprecipitation with polyethylene glycol. The physical and chemical structure of the PEG–AMP MNs was investigated using various spectroscopic and analytical techniques, revealing that Fe3O4 was tightly bound to the AMP particles and that the composites exhibited superparamagnetic behavior. The Cs+ adsorption behavior of the adsorbent was investigated in a wide range of pH values and temperatures, using multiple Cs+ contact times and initial Cs+ concentration, and with interference from additional ionic species. The adsorbent achieved 99.8% removal of Cs+ in the solution pH range of 1–12 and maintained its stability after adsorption. Interfering ions had little effect on the amount of Cs+ adsorbed. The experimental data were fitted using Langmuir, Freundlich, Redlich-Peterson and Sips isotherms pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption data fitted well with pseudo-second-order kinetics and the Langmuir isotherm model, with a maximum adsorption capacity of 53.89 mg g−1 and equilibrium reached within 20 min. Thermodynamic experiments showed the adsorption process to be inherently endothermic. The mechanism of Cs+ adsorption by PEG–AMP MNs is proposed to primarily be a combination of weak electrostatic attraction and ion exchange between NH4+ and Cs+. More importantly, the encapsulation of a magnetic carrier allows for the efficient separation and recovery of Cs+ after adsorption.

Effective removal of non-radioactive and radioactive cesium from wastewater generated by washing treatment of contaminated steel ash

The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the co-precipitation method was carried out. A simulated liquid waste (133Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (137Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of 137Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of 133Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of 137Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.

The Utilization of Modified Zeolite for the Removal of Cs Ions in an Aqueous Solution: Adsorption Capacity, Isotherms, Kinetics and Microscopic Studies

Nuclear energy is a double-edged technology, which has a significant role in the chemical industry, but may bring about radioactivity and destruction. The 2011 Fukushima nuclear power plant accident caused by a tsunami, which flooded and led to tens of millions of disaster debris and tsunami deposits, severely disrupted the electricity supply in Japan and induced USD 211 billion worth of direct economic losses. Cs+ was easily dissolved in this accident, had a high chemical activity, and thus required an appropriate adsorption method. Zeolite is an effective removal adsorbent, which is suitable to be investigated. The present study uses natural zeolite and three inorganic modified zeolites. Furthermore, the effects of various factors are investigated. Kinetic models and the isothermal adsorption mechanism are also conducted. For microscale studies for the adsorption mechanism, scanning electron microscope (SEM) and X-ray diffraction (XRD) were involved in the study. The results indicate that the optimal dosage is 1.1 g and the maximum adsorption rate is around 80%. An alkaline environment is more conducive to the occurrence of adsorption. As for the isotherm and kinetic studies, the data fits better with the Redlich–Peterson isothermal model and intragranular diffusion model. In this small-scale experiment, the highest adsorption capacity was for Mg-zeolite at 6.53 mg/g. Finally, Mg-Zeolite presents the best adsorption capacity.

Cesium ion-exchange resin using sodium dodecylbenzenesulfonate for binding to Prussian blue.

Radioactive Cs ions are extremely harmful to the human body, causing cancers and other diseases. Treatments were performed on radioactive Cs present in wastewater after use in industrial or medical fields. Prussian blue (PB) has been widely used for the removal of Cs ions from water but its colloidal structure hinders reuse, making it problematic for practical use. To solve this problem, we used a commercial macroporous polymer resin as a PB matrix. To provide an efficient anchor for PB, the surface of the polymer resin was decorated with sodium dodecylbenzenesulfonate to produce a negatively charged surface. The successful chemical binding between the polymer resin and PB prevented leakage of the latter during adsorption and crosslinked structure of the matrix provided regeneration of the adsorbent. The adsorbent maintained its removal efficiency after five repeats of the regeneration process. The PB-based, Cs ion-exchange resin showed excellent selectivity toward Cs ions and good reusability, maintaining its high adsorption capacity.

Permanent disposal of Cs ions in the form of dense pollucite ceramics having low thermal expansion coefficient

Abstract A promising method for removal of Cs ions from water and their incorporation into stable crystal structure ready for safe and permanent disposal was described. Cs-exchanged X zeolite was hot-pressed at temperature ranging from 800 to 950 °C to fabricate dense pollucite ceramics. It was found that the application of external pressure reduced the pollucite formation temperature. The effect of sintering temperature on density, phase composition and mechanical properties was investigated. The highest density of 92.5 %TD and the highest compressive strength of 79 MPa were measured in pollucite hot-pressed at 950 °C for 3 h. Heterogeneity of samples obtained at 950 °C was determined using scanning electron microscopy. The pollucite hot-pressed at 950 °C had low linear thermal expansion coefficient of ∼4.67 × 10−6 K−1 in the temperature range from 100 to 1000 °C.

Synthesis of Prussian blue-embedded porous polymer for detection and removal of Cs ions

A Prussian blue (PB)-embedded coordination polymer (COP) was prepared by simple incorporation of PB into a COP composed of 1,1,2,2-tetrakis(4-carboxyphenyl)ethane and the Zn ion during the synthesis of COP. The PB-COP was prepared as micro-sized particles with green emission (490 nm) from the strongly fluorescent tetraphenylethene group in the solid state through aggregation-induced emission. The PB-COP showed particle shape with sizes ranging from 1 to 6 μm. As the PB in PB-COP efficiently adsorbed Cs ions, the microstructure of PB-COP was degraded to smaller particles, along with a concomitant decrease in the green fluorescence of the PB-COP. Such a decrease in the green emission of PB-COP was used as a signal for the presence of Cs ions, in which the limit of detection for Cs ions was found to be 73.8 ppb. The hybridized material of the PB-COP can be used as both an efficient adsorbent and a sensor for Cs ions, achieving simultaneous removal and detection.

Chemically bound Prussian blue in sodium alginate hydrogel for enhanced removal of Cs ions.

A new approach for efficient removal of radioactive 137Cs was developed using a sodium alginate hydrogel beads-based adsorbent containing chemically bound Prussian blue (PB). Sodium alginate was crosslinked with Fe (III) ions to form hydrogel beads, in which Fe (III) had a dual function; it served as a crosslinking agent and also led to PB formation via reaction with hexacyanoferrate. Fe (III) ions, an unusual crosslinking agent for sodium alginate gel, led to stable, homogeneous distribution of PB inside the beads. The amount of embedded PB in the composite beads was more than two times larger than in the conventional sodium alginate-PB composite beads, resulting in an adsorption capacity for Cs ions that was two to five times higher, mainly because of a higher PB contents and because of the microporosity of the sodium alginate hydrogel.

Adsorptive removal of cesium from aqueous solution using oxidized bamboo charcoal

In this study, the air oxidized bamboo charcoal (BC) was investigated for cesium (Cs) adsorption from aqueous solution. The physicochemical properties of the adsorbent were evaluated systematically using the different techniques including BET, FESEM, FTIR, XPS and also the pHpzc value. Batch adsorption experiments were conducted to determine the effect of contact time, solution pH, initial Cs concentrations, temperature and also the presence of competitive ions on adsorption. The adsorption kinetic parameters confirmed the better fitting of pseudo-second order kinetic model. The isotherm data could be well described by the Langmuir isotherm model and the maximum monolayer adsorption capacity was 55.25 mg g−1. The high specific surface area and the porous structure with some acidic functional groups on the surface were obviously responsible for high Cs adsorption onto oxidized-BC. Thermodynamic parameters such as standard enthalpy, entropy, and Gibbs free energy were evaluated and it had been found that the adsorption process was favorable, spontaneous and endothermic in nature. In the competitive ions study, the presence of Na and K with their concentrations up to 12 mM did not strongly affect the removal of Cs by oxidized-BC. Therefore, the experimental results suggested that the oxidized-BC could be used as an effective adsorbent for significant Cs removal from aqueous solution considering the high adsorption capacity, short adsorption time and selective removal of Cs ions.

Hydrogels Containing Prussian Blue Nanoparticles Toward Removal of Radioactive Cesium Ions.

Recent reports have demonstrated the practical application of Prussian blue (PB) nanoparticles toward environmental clean-up of radionuclide 173Cs. Herein, we prepared a large amount of PB nanoparticles by mixing both iron(III) chloride and sodium ferrocyanide hydrate as starting precursors. The obtained PB nanoparticles show a high surface area (440 m2. g-1) and consequently an excellent uptake ability of Cs ions from aqueous solutions. The uptake ability of Cs ions into poly(N-isopropylacrylamide (PNIPA) hydrogel is drastically increased up to 156.7 m2. g-1 after incorporating our PB nanoparticles, compared to 30.2 m2 . g-1 after using commercially available PB. Thus, our PB-containing PNIPA hydrogel can be considered as an excellent candidate for the removal of Cs ions from aqueous solutions, which will be useful for the remediation of the nuclear waste.

Adsorption kinetic model of alginate gel beads synthesized micro particle-prussian blue to remove cesium ions from water

Prussian blue (PB) impregnated in alginate gel (AG) beads were synthesized in order to test their viability for removing cesium (Cs) ions from wastewater. The impregnation yields PB-AG(syn.) beads containing very fine crystals of PB incorporated into the AG beads. The interaction between PB-AG(syn.) beads and Cs ions was investigated by adsorption experiments and analyzed using Langmuir and adsorption-kinetic models. The adsorption of Cs ions onto PB-AG(syn.) beads reached equilibrium after 12h. The maximum adsorption capacities of the PB-AG(syn.) beads were 0.557mgbead−1 and the kinetic rate was found to be k1=1.72×10−1min−1 at pH 6.0 for the pseudo first order, and 4.65×10−1bead−1mg−1min−1 at pH 6.0 for the pseudo second order. The effects of pH, organic acids and salts such as potassium and sodium ions onto the adsorption of Cs ions by PB-AG(syn.) beads were found insignificant and low. Consequently, the PB-AG(syn.) beads showed a high capacity for the removal of Cs ions from water.

Removal of Cs ions from aqueous solutions by using matrices of natural clinoptilolite and its safe disposal

The possibility to use natural zeolite - clinoptilolite as a host material for radioactive Cs immobilization has been investigated. Cs-exchanged form of clinoptilolite which was prepared by treatment of clinoptilolite powder with 0.25 M CsCl solution was compacted. Both, powder and powder compact of exchanged clinoptilolite were thermally treated at 1200?C. The XRPD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium dodecaoxo-alumopentasilicate in both, powder sample and compact. The newly formed compound showed satisfactory Cs ions retention during leaching test. The sintered compact showed somewhat better resistance to Cs leaching than the thermally treated powder. The compressive strength of sintered compact was close to 200 MPa which is more than enough for easy handling and safe storage.

Development of novel nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric.

A nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric was synthesized for selective removal of Cs ions from contaminated waters by a two-stage synthesis: radiation-induced graft polymerization of acrylic acid monomer onto the nonwoven polypropylene fabric surface with subsequent in situ formation of potassium nickel hexacyanoferrate (KNiHCF) nanoparticles within the grafted chains. Data of scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the formation of KNiHCF homogeneous phase on the fabric surface, which consisted of crystalline cubic-shaped nanoparticles (70 to 100 nm). The efficiency of the synthesized adsorbent for removal of cesium ions was evaluated under various experimental conditions. It has demonstrated a rapid adsorption process, high adsorption capacity over a wide pH range, and selectivity in Cs ion removal from model solutions with high concentration of sodium ions.

Large Cs adsorption capability of nanostructured Prussian Blue particles with high accessible surface areas

Very recently, we have reported preparation of several types of Prussian Blue (PB) particles with varying particle sizes by systematically tuning the synthetic conditions (Angew. Chem., Int. Ed., 2012, 51, 984–988). Here, the obtained PB particles are used for removal of Cs ions from aqueous solutions, which will be useful for remediation of nuclear waste. To evaluate the uptake ability of Cs ions into the PB particles, we utilize quartz crystal microbalance (QCM) for real-time monitoring of uptake behavior of Cs ions into the PB particles. The frequency of the QCM is promptly decreased after injection of Cs ions solution into the QCM cell. Hollow PB nanoparticles of 190 nm in diameter have very high surface area (338 m2 g−1), in comparison with other PB particles, leading to efficient Cs adsorption capability eight times larger than that of the commercial PB particles. The diffusion in terms of dissociation constant (Kd), maximum amount of adsorbed Cs in PB particles (mmax), and the adsorption kinetics (k) of Cs ions into the PB particles are also discussed. Due to the selective uptake for Cs ions based on Kd and k values, the PB particles can be proposed as good candidates in waste management consideration.

Ion exchange of Cs ion in acid solution with potassium cobalt hexacyanoferrate

Potassium cobalt hexacyanoferrate (KCoFC) was synthesized for removal of Cs ions in acid waste solution. The synthesized KCoFC. was stable in nitric acid solution of pH= 1 and showed high selectivity for Cs ion over Sr and Na ions. The Kd,cs for 0.01 N Cs ion solution at pH=2 was about 3.6x 103 mL/g in the presence of the same concentrations of Sr and Na ions, respectively. In the binary ion exchange system, both the Dubinin-Polanyi model and Langmuir model fit the experimental data, although the Dubinin-Polanyi model fit more correctly than the Langmuir model. However, in the multi-component system, only the modified Dubinin-Polanyi model, which is a semiempirical equation, fit the experimental data accurately. The ion exchange capacity of KCoFC. for Cs ion obtained by the Dubinin-Polanyi equation was 1.72 meq/g.