Adsorption Of Gd Research Articles

Displacement chromatography of gadolinium isotopes with strong cation exchange resin using 1,2-cyclohexanedinitrilotetraacetic acid (CDTA)

Adsorptive separation of Gd3+ ions was evaluated using DOWEX-50×8 ion exchange resin. It has shown a maximum adsorption capacity of 228.50 mg/g at optimum pH 5 and room temperature. Separation of Gd isotopes was investigated using packed bed columns of the resin in displacement chromatographic techniques where 1,2-cyclohexanedinitrilotetraacetic acid was used as displacer in the mobile phase. Isotopic analysis data by using MC‒ICP‒MS confirmed that the front end of the Gd adsorption band exhibited enrichment of the heavier isotope (160Gd), while the lighter isotopes (157Gd and 155Gd) were concentrated at the rear end of the stationary phase.

Preparation of imprinted bacterial cellulose aerogel with intelligent modulation of thermal response stimulation for selective adsorption of Gd(III) from wastewater.

Research on recycling of used rare earth elements has been of great interest. Adsorption is one of the advantageous methods to recover gadolinium with high value. In the process of adsorption and separation of gadolinium from materials, the selectivity of materials for gadolinium can be significantly improved by using ion imprinting technique. However, gadolinium elution process is a traditional pickling process, which may affect the construction of imprinting sites. In this study, bacterial cellulose with three-dimensional spatial structure was used as the base material of aerogel material, and functional materials containing a large number of carboxyl groups were introduced by chemical grafting method. In combination with ion imprinting technology and N-polyacrylamide as intelligent temperature control valve, intelligent imprinting aerogel (PNBC-IIPS) with specific selectivity to gadolinium was prepared. The properties of aerogel materials were analyzed by SEM, FT-IR, and BET characterization. The experimental analysis shows that the desorption of gadolinium can be achieved by controlling the temperature change. The adsorption experiments show that PNBC-IIPS can selectively adsorb gadolinium ions from aqueous solution. The maximum adsorption capacity reached 95.51mgg-1. Compared with unimprinted aerogel, the maximum adsorption capacity of gadolinium ion is significantly increased, which proves that the introduced ion imprinting technique plays a key role in the adsorption process. Cyclic experiments show that the adsorption capacity of PNBC-IIPS can still maintain 88% of the original adsorption capacity after 5 times of adsorption and desorption. In conclusion, PNBC-IIPS is a green adsorbent for selective recovery of gadolinium ions.

Selective recovery of Gd(III) by benzimidazole- and benzoxazole-linked 3D porous polymers

Three-dimensional porous benzimidazole- and benzoxazole- linked polymers were successfully prepared through a one-pot method using benzol-1,2,4,5-tetramintetrahydrochlorid (BTD) and 2,5-diamino-1,4-benzediol dihydrochloride (DBD) to react with 4-[tris(4-formyl phenyl)methyl]benzaldehyde (TFPM), respectively. According to nitrogen sorption analysis, TFPM-BTD and TFPM-DBD possessed specific surface areas of 612.60 and 524.90 m2/g, and the total pore volumes (Vtot) of 1.44 and 1.15 cm3/g, respectively. Batch adsorption experiments demonstrated that Gd(III) adsorption processes by TFPM-BTD and TFPM-DBD fit well with the Langmuir isotherm and the pseudo-second-order kinetic model. At 25 °C and pH level of 6, TFPM-BTD showed a much higher adsorption capacity for Gd(III), detected at 173 mg/g, as opposed to TFPM-DBD at 82 mg/g. Associated spectra of N 1s via high-resolution X-ray photoelectron spectroscopy (XPS) revealed the generation of coordination bonds between Gd(III) and (-NH-) of TFPM-BTD polymer during Gd(III) adsorption, while Energy-dispersive X-ray spectroscopy (EDS) analysis proved the uniform adsorption of Gd(III) on TFPM-BTD. TFPM-BTD showed high selectivity toward the adsorption of heavy rare earth ions, in a high-to-low order of Gd3+>Ce3+>Er3+>La3+>Ni2+>Mg2+>Zn2+. Furthermore, TFPM-BTD exhibited excellent cycling stability and regeneration performance. Gd(III) adsorption capacity of TFPM-BTD after five adsorption/elution cycles was retained at 63.9 %. The elution efficiency was extremely high when using 0.1 mol/L hydrochloric acid as the eluent, showing an average five-cycle desorption efficiency over 95 %. The outcomes will provide theoretical and practical guidance to develop high-performance and selective adsorbents for efficient removal of heavy rare earth ions from water.

Rational fabrication of a new ionic imprinted carboxymethyl chitosan-based sponge for efficient selective adsorption of Gd(iii).

The selective recovery of Gd(iii) from wastewater is very meaningful for the prospective development of economics and the environment. To overcome disadvantages of poor adsorption capacity, low selectivity and complex preparation process in conventional adsorbents, herein a new ionic imprinted carboxymethyl chitosan (CMC) sponge functionalized by hyperbranched polyethyleneimine (PEI) with a 3D network structure (PEI-CMC-IIS) was successfully prepared and applied in the selective adsorption of Gd(iii). The PEI-CMC-IIS is endowed with lots of amino groups due to the combination of biomass CMC with highly branched PEI, which is helpful for the adsorption of Gd(iii). The imprinting sites are located at the surface of channels in PEI-CMC-IIS, which can achieve the adsorption specificity to Gd(iii) and improve adsorption capacity. It is found that the maximum adsorption capacity of PEI-CMC-IIS is 38.64 mg g−1 at pH = 7. Meanwhile, the selectivity tests suggest that the PEI-CMC-IIS presents preferential adsorption for Gd(iii) with a distribution coefficient of 437.5 mL g−1. Furthermore, the PEI-CMC-IIS displays excellent reusing and regeneration ability. Our findings will bring about potential application in fabrication of other high-efficiency adsorbents for selective adsorption of Gd(iii).

Optical chemical sensor of Gd(iii) based on 5-(2'-bromophenyl- azo)-6-hydroxypyrimidine-2,4-dione immobilized on poly(methyl methacrylate) and 2-nitrophenyloctylether matrix.

A novel optical chemical sensor (optode) was fabricated for the determination of Gadolinium ions. The optical sensor was prepared by incorporating a recently synthesized ionophore, 5-(2′-bromophenylazo)-6-hydroxy pyrimidine-2,4-dione (BPAHPD), and 2-nitrophenyloctylether (NPOE) as a plasticizer in poly(methyl methacrylate) (PMMA) membrane. The color of the sensing membrane in contact with Gd(iii) ions changed from yellow to red-orange due to the adsorption of Gd(iii) with the maximum absorbance (λmax) at 563 nm. The chemical sensor responds optimally towards Gd(iii) ions at the optimum conditions of pH 7.5, contact time 10 min, 150 ng mL−1 Gd(iii), and 5.0 mL solution. The linear regression equation achieved was A = 4.36C (μg mL−1) – 0.15 (r = 0.9976). A linear Gd(iii) calibration curve can be established in the concentration range of 5.0–250 ng mL−1 with R2 = 0.9976. Detection and quantification limits are 1.47 and 4.75 ng mL−1, respectively. The molar absorptivity and Sandell sensitivity are found to be 6.86 × 107 L mol−1 cm−1 and 0.023 ng cm−2, respectively. In addition to its stability and reproducibility, the optode revealed a great selectivity toward Gd(iii) ions as compared to other coexisting ions in real samples. The recovery of Gd(iii) ions from the sensor material was achieved using 0.4 M HNO3. The offered optode sensor membrane has been employed to monitor Gd(iii) in soil, sediments, river water, and urine with an internal standard addition method and compared statistically with the ICP-OES method. The results revealed calculated t-values between 1.11–1.85, whereas F values were in the range of 2.46–3.77 which did not exceed the theoretical values, indicating no significant difference at 95% confidence level. The observed percent recovery is in the range of 97.24–102.52%.

Ionic imprinted CNTs-chitosan hybrid sponge with 3D network structure for selective and effective adsorption of Gd(III)

From economical and environmental standpoint, it is very meaningful for selective recovery of Gd(III) via adsorption from the real waste solution. At present, conventional adsorbents are impeded by poor adsorption capacity, low selectivity, complicated preparation and eco-pollution. To this end, a novel imprinted CNTs-chitosan hybrid sponge (COOH-CNTs/CS-IIS) with 3D network structure was fabricated via easy polymerization-lyophilization method for selective adsorption of Gd(III). The imprinting sites dispersing on the surface of channels in COOH-CNTs/CS-IIS can achieve the selective adsorption to Gd(III) and improve adsorption capacity. The combining of biomass chitosan sponge with oxidized CNTs not only further enhances the adsorption capacity and mechanical strength of COOH-CNTs/CS-IIS but also actualizes its rapid retrieval by the squeeze of elastic sponge. Systematic adsorption tests indicate that COOH-CNTs/CS-IIS has a maximum adsorption capacity of 71.95 mg g−1, and can adsorb 88.9% of the ultimate adsorption within 60 min. The selectivity tests show that COOH-CNTs/CS-IIS exhibits preferential adsorption for Gd(III) with a distribution coefficient of 0.656 L g−1. Furthermore, COOH-CNTs/CS-IIS has excellent regeneration performance. Considering its cost-effectiveness, eco-friendliness, user-friendliness, easy preparation and favorable adsorption performance, COOH-CNTs/CS-IIS holds great promise in selective recovery of Gd(III) from the real waste solution.

Preparation of an ion imprinted chitosan-based porous film with an interpenetrating network structure for efficient selective adsorption of Gd(iii)

In this work, a new Gd(III) ion imprinted CS-based porous film with interpenetrating network structure was fabricated by a simple polymerization–evaporation approach for the efficient selective adsorption of Gd(III) from aqueous solution.

Electronic Structure of Double-Layer Epitaxial Graphene on SiC(0001) Modified by Gd Intercalation

We systematically study the effects of Gd adsorption and intercalation on the electronic band structure of double-layer epitaxial graphene on Si-terminated SiC(0001) by first-principles calculations. We show that Gd adsorption and intercalation exhibit strong effects on the coupling between the graphene layers and between the buffer layer and substrate. Different adsorption/intercalation geometries can result in very different electron band structures. The number of Dirac cones and the positions of the Dirac cones relative to the Fermi level can be effectively manipulated through controlling the Gd adsorption/intercalation geometries. Our calculations provide useful insights to guide the experimental design of graphene-based materials with desirable functionalities for applications.

Extraction Chromatography Materials Prepared with HDEHP on Different Inorganic Supports for the Separation of Gadolinium and Terbium

Bis(2-ethylhexyl)phosphoric acid (HDEHP) is frequently used as an extractant in the separation and recovery of lanthanides by solvent extraction and extraction chromatography, where HDEHP (stationary phase) is fixed on an inert support and the mobile phase is an aqueous solution. Because the results of extraction chromatography strongly depend on the support material, in this study, we aim to prepare solid extractants (extraction chromatography materials) with different inorganic supports impregnated with HDEHP for the adsorption of Gd and Tb from HCl solutions, putting emphasis on the effect of the supports on the solid extractant behavior. Gd and Tb partition data were determined in HCl solutions from the prepared extraction chromatography materials using elution analysis. Solid extractants were characterized by X-Ray diffraction, electron microscopy, and infrared spectroscopy in order to determine their properties and to explain their extraction behavior. The characterization of the solid extractants showed a heterogeneous distribution of the HDEHP on the surfaces of the different supports studied. The irregular shape of the support particles produces discontinuous and heterogenous silanization and HDEHP coatings on the support surface, affecting the retention performance of the solid extractant and the chromatographic resolution.

Biosorption of Rare-Earth Elements From Aqueous Solutions Using Walnut Shell

Agricultural wastes are considered as green adsorbents that can work as an alternative to recover critical and scarce metals from secondary sources. Critical elements as rare earth elements (REEs) can be obtained from electronic wastes or tailings and could be recovered using these green alternatives. In this study, walnut shell (WS) was tested to determine whether several REEs can be efficiently retained by this green adsorbent. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetry and Differential scanning calorimetry (TG-DSC) were used to characterize WS before and after REE adsorption. Analytical performance of REE quantification was evaluated, besides of adsorption capacity and isotherms that were calculated in order to determine the model that fit well to REE adsorption. ICP-OES results indicated the lowest limit of detection and quantification (LOD and LOQ) with Eu (0.08 and 0.23ppb, respectively), nevertheless, quantification of other elements was also at the ppb level. In order to obtain the highest adsorption of metals, 75 and 2,000 µm particle sizes were studied, reaching >80% of adsorption with both sizes. Additionally, several pH values were tested in order to determine the optimum condition for maximal adsorption and adsorption capacity, noticing that pH 4 showed the best adsorption percentage (>85%, qe = 6.5 - 8mg/g). Langmuir isotherm model fitted well for Eu, La, Sm and Gd adsorption equilibrium. Characterization of WS was done using FTIR, TG-DSC and SEM. FTIR analysis showed several changes in the spectra after adsorption of REE tested but major changes were observed at the OH group, which shifted up to 31 cm-1 of wavelength. Additionally, TG-DSC showed that WS pyrolysis was divided in three stages: vaporization of moisture (about 10% of weight loss), thermal decomposition of hemicellulose, cellulose and lignin (higher than 60% of weight loss), and high-temperature calcination of residues (<25%). Finally, SEM characterization showed empty and filled pores of different sizes in WS after metal adsorption, and more rugged aspect was observed. This study reveals that WS is an efficient low-cost adsorbent for REEs and can be used for future recovery of these elements from secondary sources.

Construction of ion-imprinted nanofiber chitosan films using low-temperature thermal phase separation for selective and efficiency adsorption of Gd(III)

Rare earth elements are a treasure trove of new materials in the twenty-first century, however, the similar radii of the lanthanide metals make it difficult for the ionic rare earth elements to be selectively separated. Ion-imprinted technology can help to selectively separate rare earth elements, nevertheless, most materials used for ion-imprinted are expensive. Chitosan has a wide range of sources, low cost, and a large quantity of amino and hydroxyl groups, which is advantageous for adsorbing heavy metals. Most scholars have made chitosan into a shape such as microspheres, which does not exert the great value of chitosan and is difficult to recycle, which greatly affects the adsorption rate. There are few studies on increasing the specific surface area of chitosan, so there is still much room for improvement in the adsorption capacity of chitosan. In order to improve the performance of chitosan-based materials, this research reports the preparation of imprinted nanofiber chitosan films (INFCF) by ion-imprinted technique and low-temperature thermal phase separation. These methods not only make the material have a high BET surface area, but also enable the material to have selective adsorption capacity. The BET surface area of the film is 203.6 m2 g−1. The maximum adsorption capacity of INFCF for Gd(III) was 71.00 mg g−1 at pH 7.0. The adsorption mechanism is summarized as a single layer of chemical adsorption. The excellent selectivity and repeatability of INFCF make it a high-quality material for the selective recovery of rare earth ions in industrial production.

A facile solvent-free and one-step route to prepare amino-phosphonic acid functionalized hollow mesoporous silica nanospheres for efficient Gd(III) removal

Abstract Gadolinium is known to be a most widely used but toxic rare-earth element, and Gd(III) ions exist in aqueous media will bring about serious damage to the ecosystem. However, few work on the application of adsorption strategy with enough high Gd(III) uptake is reported. Since the hollow mesoporous silica nanospheres (HMSNs) and amino-phosphonic acid (APA) compounds have shown inherent advantage for being used as effective adsorbent and chelating ligand in toxic metals adsorption due to their remarkable properties. Herein, we follow the cleaner production philosophy, proposing for the first time to modify the HMSNs nanomaterial with APA group by reacting phosphorous acid with cyano-functionalized hollow mesoporous SiO2 (CFHMSNs) via one-step reaction under solvent-free conditions, and apply to remove Gd(III) form wastewater. The obtained materials are characterized by a variety of techniques. Characterization results show that the APA-functionalized material (AFHMSNs) has ordered mesoporous structure, high stability and large surface area (825.3 m2/g). The maximum uptake of Gd(III) for AFHMSNs (387.3 mg/g) is much higher than those of the reported adsorbents because of the high surface area, and multifunctional chelating interactions of the adsorbent with Gd(III) ions. Gd(III) adsorption onto AFHMSNs can be well described by the Langmuir isotherm and pseudo second order kinetics model. The adsorption is chemical complexation mechanism which is proposed based on FTIR and XPS analysis. It is found for the first time that the adsorption of Gd(III) onto AFHMSNs slightly enhanced with the coexistence of Al3+ in the relatively lower concentrations, which may be due to the synergistic effect of pseudo-boehmite. This work provides a favorable strategy to design and synthesis of hollow mesoporous nanomaterial with superior adsorption performances and potential for the cleanup of toxic metals from wastewater.

ELECTRONIC AND STRUCTURAL PROPERTIES OF Si–Gd–O ELECTRON EMITTER

Rare earth metals, when deposited and oxidized on semiconductor surfaces, can be an alternative to unstable compounds of alkali metals while creating stable and effective emitters with a low work function. A procedure giving rise to the adsorption of Gd and O atoms on the Si(100) surface and the formation of a Si–Gd–O film with a work function of about 1 eV in the near-surface region is described. The films have been studied using the Auger electron and photoelectron spectroscopy, as well as X-ray diffraction, atomic force and Kelvin probe force microscopy techniques. Information about their electronic properties, structure, surface morphology, and surface distribution of potential was obtained. The main component of the film formed on the Si surface is a polycrystalline Gd2O3phase, which plays the role of a matrix containing textured microcrystallites of one of the following phases: SiO2, GdO2, or GdSi2. The film surface consists of salient clusters 20[Formula: see text]nm to 80[Formula: see text]nm in diameter and up to 20[Formula: see text]nm in height, as well as craters up to 90[Formula: see text]nm in depth. The surface relief inhomogeneities correlate with the surface distribution of the local work function. This correlation can also be a result of the piezoelectric effect in the strained crystallites of the textured phase located in the bulk of the film. The obtained system was stable in time under vacuum conditions and heating up to [Formula: see text]C. The method proposed for the formation of surfaces with a low work function making use of rare earth metals can be applied to create effective and stable electron emitters.

Highly efficient removal of Gd(III) using hybrid hydrosols of carbon nanotubes/graphene oxide in dialysis bags and synergistic enhancement effect

The spontaneous stacking of graphene oxide (GO) nanosheets for the adsorptive remediation of wastewater has been severely restricting their inherent adsorption ability from being brought into full play. Herein, hydrosols of carbon nanotubes/graphene oxide (CNTs/GO) sealed in dialysis bags were utilized for the highly efficient and re-pollution-free removal of trace Gd(III) from water for the first time. The effects of mass ratio between CNTs and GO (MCNTs: MGO), pH value and contact time on Gd(III) adsorption of CNTs/GO hybrid hydrosol (MCNTs: MGO = 1:6) as well as its adsorption kinetics and thermodynamics were studied by comparison with GO hydrosol. The pH-dependent desorption and regeneration of the CNTs/GO hybrid hydrosol were also investigated. The results showed that CNTs/GO hybrid hydrosols with MCNTs: MGO from 1:8 to 1:2 exhibited the remarkable synergistic enhancement effect. The CNTs/GO hybrid hydrosol with MCNTs: MGO = 1:6 had the theoretical maximum Gd(III) adsorption capacity of 534.76 mg·g−1 (pH = 5.9, t = 60 min, T = 303 K) with a leap of 86.42% compared to GO and remained the sorption capacity of 347.83 mg·g−1 at the fourth cycle, showing the excellent regeneration performance. Moreover, the adsorption of Gd(III) on CNTs/GO hybrid hydrosols agreed well with the pseudo-second-order model and Langmuir isotherm adsorption model. In prospect, CNTs/GO hybrid hydrosols in dialysis bags promises of extensive application in the highly efficient and re-pollution free elimination of metal ions from water.

Studies on adsorption of rare earth elements from nitric acid solution with macroporous silica-based bis(2-ethylhexyl)phosphoric acid impregnated polymeric adsorbent

For the adsorption and recovery of rare earth elements from aqueous nitric acid, solid-phase extraction resins were prepared by impregnating and immobilizing of bis(2-ethylhexyl)phosphoric acid extractant into the macroporous silica-based polymeric (SiO2-P) particles. It was found that bis(2-ethylhexyl)phosphoric acid/SiO2-P had higher adsorption distribution coefficient for heavy rare earth elements than for light rare earth elements. The adsorption capacity of Gd(III) was observed to be 0.315 mmol g−1 by bis(2-ethylhexyl)phosphoric acid/SiO2-P in 0.1 M HNO3 at 298 K, which increased slightly when increasing temperature from 298 to 323 K. The adsorption isotherms of Gd(III) matched well with the Langmuir and Freundlich models. The obtained thermodynamic parameters (ΔHo and ΔGo) showed that the adsorption of Gd(III) by bis(2-ethylhexyl)phosphoric acid/SiO2-P was a spontaneous and exothermic process. This study also evaluated the chemical stability of bis(2-ethylhexyl)phosphoric acid/SiO2-P treated with nitric acid at different temperatures and demonstrated that bis(2-ethylhexyl)phosphoric acid/SiO2-P had considerable stability against nitric acid and heat.

ADSORPTION BEHAVIOR OF GADOLINIUM(III) FROM AQUEOUS SOLUTION BY D418 RESIN

Adsorption, desorption, and kinetics behavior of Gd(III) ion on chelating resin were investigated in this paper. Batch adsorption studies were carried out with different pH, contact time, and temperature. The adsorption of Gd(III) follows the Langmuir model better than the Freundlich model. The apparent activation energy Ea and adsorption rate constant are k308 4.16 kJ/mol and 6.01 105 s-1, respectively. Thermodynamic parameters such as .H, .S and .G indicated that Gd(III) ion adsorption by D418 resin was an endothermic and spontaneous process in nature. Column adsorption experiments indicated the maximum dynamically adsorption capacity of 281mg/g for Gd(III). The desorption rate of Gd(III) was 98.3% when the elution agent is 2.0 mol/L HCl solution and the chelating resin can be regenerated and reused. Analysis of IR spectroscopy for D418 resin before and after adsorption of Gd(III) ions and after desorption indicated the attendance of coordination and good regenerative ability of resin. Thermo gravimetric analysis for D418 resin before and after adsorption of Gd(III) ions proved the adsorption of Gd(III) ions.

Impregnated activated carbon for the adsorption of Gd(III) radionuclides from aqueous solutions

ABSTRACTActivated carbons (ACs) impregnated by FeCl3, SnCl4 and ZnCl2 are used as adsorbents for the removal of Gd(III) radionuclides from aqueous solutions. Adsorption of Gd(III) is investigated as a function of pH, concentration of adsorbate, contact time, ionic strength and temperature. Gadolinium is efficiently removed (R% > 95%) at pH values ≥4.8 (for FeAC and SnAC) and 2.9 (for ZnAC). The pseudo-first-order, the pseudo-second-order and Elovich kinetic models are used to analyze the kinetic data of Gd(III), at the studied concentrations (30, 100 and 200 mg/L) onto the employed materials. Of these models, Elovich is the only one that well-fitted the experimental kinetics onto the applied materials at all of the studied Gd(III) concentrations. Equilibrium data of Gd(III) are analyzed by the Freundlich, Temkin, Dubnin–Radushkevich (D-R) and Redlich–Petrson isotherm models. The adsorption efficiency of Gd(III) onto FeAC and SnAC is deleteriously affected by increasing the ionic strength, while adsorption onto ZnAC is unaffected. The thermodynamic parameters are calculated and it is revealed that the adsorption of Gd(III) onto the employed materials is an endothermic process. Desorption studies of Gd(III)-loaded ACs are performed using different desorbing agents (HCl, ZnCl2, FeCl3 and SnCl4) at various concentrations (0.0005, 0.0025, 0.01 and 0.025 M).

Radiation-induced grafting copolymerization of resin onto the surface of silica extracted from rice husk ash for adsorption of gadolinium

Abstract In this study, novel adsorbents were prepared, characterized and investigated for adsorption of gadolinium as one of rare earth elements. The first adsorbent is rice husk ash (RHA), the second is poly(acrylamide/acrylic acid/sodium styrene sulfonate) resin (P), the third and fourth adsorbents were the prepared resin grafted on the surface of the silica powder (poly(acrylamide/acrylic acid/sodium styrene sulfonate/silica powder) (P-SP) and gel form (poly(acrylamide/acrylic acid/sodium styrene sulfonate/silica in gel form) (P-SG) extracted from the first adsorbent (RHA) using alkaline treatment. These grafted resins as novel adsorbents were prepared by 60Co gamma-rays irradiation of 25 kGy. Characterization of the new prepared adsorbents were investigated; swelling kinetics, ash content, FTIR, TGA & DTA, BET surface area and their ability for adsorption of some organic compound (Methylene Blue and P-Nitro-phenol from aqueous solution. It was found that: the swelling ratios take the following order: 28.55, 24.08 and 20.46% for P-SG, P and P-SP, respectively. The P-SP has the highest value of ash content 9.5%, and the BET surface areas were 8.5, 4.3 and 2.815 m2/g for P-SG, P-SP and P, respectively. For the adsorption of MB, the maximum capacity (qm) was 277, 171.5 and 174.2 (mg/g), but for adsorption of P-NP it was 51.1, 38.6 and 52.99 (mg/g) for P, P-SP and P-SG. Finally, the new prepared four adsorbents were investigated for adsorption of Gd(III). The results showed high adsorption capacity; 229.36, 206.61, 184.84 and 133.33 for P-SG, P-SP, P and RHA, respectively. From this study we can conclude that the prepared four adsorbents can be used for sorption of Gd(III) as well as some organic compounds from aqueous solution.

Molecular modeling guided isotope separation of gadolinium with strong cation exchange resin using displacement chromatography

ABSTRACTMolecular modeling was carried out using DFT to identify the suitable displacing agent for carrying out Gd isotope separation using displacement chromatography. EDTA was identified as the best eluting agent among EDTA, malic acid and citric acid. Displacement chromatography of Gd adsorption band in cation exchange resin was performed to observe the isotope effects in the Gd ion exchange processes involving complex forming reagent – EDTA. The heavier isotope of 160Gd was found to be enriched at the front boundary of Gd adsorption band, while the lighter isotopes of 155Gd and 157Gd were enriched at the rear boundary.

Ultrafast and high-capacity adsorption of Gd(III) onto inorganic phosphorous acid modified mesoporous SBA-15

The development of rare earth adsorbent with high adsorption capacity and rapid adsorption rate is one of the most important issues for enriching and recovering rare earth ions. In the present work, an inorganic phosphorous acid-modified mesoporous SBA-15 (P-SBA-15) was facilely synthesized by a simple and cost-effective post-grafting approach, and its adsorption behavior towards the rare earth ion Gd(III) was investigated. Benefiting from high specific surface area (669.7m2·g−1), large pore size (9.1nm), and the presence of abundant phosphorous acid groups (1.4mmol·g−1) on the surface, the P-SBA-15 exhibited an excellent performance in terms of capacity and kinetics on adsorption of Gd(III). Under optimized conditions, the adsorption capacity of P-SBA-15 towards Gd(III) was up to 1.3mmol·g−1 at 30°C, which is the second highest value as compared with previously reported Gd(III) adsorbents. Moreover, the adsorption of Gd(III) onto P-SBA-15 was ultrafast, achieving adsorption equilibrium within only 2min. Test of reusability revealed that this mesoporous adsorbent could be repeatedly used several times without significant loss in binding capacity. This work not only provides a new insight into the fabrication of phosphorous acid-functionalized mesoporous silica, but also demonstrates its prospective application in adsorptive removal and/or recovery of rare earth ions.