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There is a need for developing new sorbents that incorporate renewable resources for the treatment of metal-containing solutions. Algal-polyethyleneimine beads (APEI) (reinforced with alginate) are functionalized by grafting amidoxime groups (AO-APEI). Physicochemical characteristics of the new material are characterized using FTIR, XPS, TGA, SEM, SEM-EDX, and BET. AO-APEI beads are tested for the recovery of Sr(II) from synthetic solutions after pH optimization (&asymp, pH 6). Uptake kinetics is fast (equilibrium &asymp, 60&ndash, 90 min). Sorption isotherm (fitted by the Langmuir equation) shows remarkable sorption capacity (&asymp, 189 mg Sr g&minus, 1). Sr(II) is desorbed using 0.2 M HCl/0.5 M CaCl2 solution, sorbent recycling over five cycles shows high stability in terms of sorption/desorption performances. The presence of competitor cations is studied in relation to the pH, the selectivity for Sr(II) is correlated to the softness parameter. Finally, the recovery of Sr(II) is carried out in complex solutions (seawater samples): AO-APEI is remarkably selective over highly concentrated metal cations such as Na(I), K(I), Mg(II), and Ca(II), with weaker selectivity over B(I) and As(V). AO-APEI appears to be a promising material for selective recovery of strontium from complex solutions (including seawater).

ZnAl layered double hydroxides (LDHs) film was prepared on the pure Al by an in-situ growth method. In-situ observation of the growth behavior of ZnAl-LDHs-NO3 film was studied by electrochemical quartz crystal microbalance (EQCM) and open circuit potential (OCP). The characteristics of the ZnAl-LDHs-NO3 film was analyzed through the X-ray diffraction, X-ray photoelectron spectroscopy and scanning electronic microscope. The corrosion behavior of the LDHs film was investigated by the electrochemical impedance spectroscopy and polarization curves. The results indicate that the growth process of the ZnAl-LDHs-NO3 film can be divided into the dissolution of Al substrate stage, the formation of Al(OH)3 stage, the nucleation of ZnAl-LDHs-NO3 stage and the growth of ZnAl-LDHs stage. The growth mechanism of each stage is explained in detail. The ZnAl-LDHs film is composed of the interconnected two-dimensional nano-sheets, and the microcrystals grow perpendicular to the Al substrate and cover the entire Al substrate surface. The size and thickness of the ZnAl-LDHs nano-sheets gradually increase with the increasing of the growth time, meantime, the [Zn2+]/[Al3+] content ratio in the ZnAl-LDHs also increases. The ZnAl-LDHs film can significantly improve the corrosion resistance of the Al substrate. Keywords: ZnAl-LDHs, EQCM, Growth behavior, Corrosion

Waste green tuff powder produced by cutting Towada stone has been utilized to eliminate formaldehyde related to greenhouse gases. The green tuff contains TiO2 on zeolite as observed by scanning electron microscope (SEM)t. The green tuff is a natural catalyst that can produce hydrogen peroxide with moisture and oxygen with light. The optimum temperature for calcination of the green tuff powder has been investigated in order to produce hydroxyl radicals from the decomposition of hydrogen peroxide using ultraviolet light (UV) and no light. The green tuff calcined at 800 &deg, C showed a high decomposition rate of hydrogen peroxide with no UV light under high alkaline conditions when measured by using ESR. With UV light, the optimum temperature for calcination of green tuff powder in order to reduce the hydroxyl radical was also 800 &deg, C. Next, the powder calcined at 800 &deg, C was used to produce the tile by compression and heating, and then the formaldehyde adsorption rate was measured. The green tuff powder calcined at 800 &deg, C showed a high adsorption rate, similar to that of the activated carbon. The tiles formed at 40 MPa and heated at 1100 &deg, C were the strongest and also showed adsorption with respect to formaldehyde. The adsorbed formaldehyde on the green tuff tile and powder was possibility decomposed by the hydroxyl radical produced by photocatalysis.

Wasted Green tuff powder produced by cutting Towada stone is recycled as environmental cleaning material. The optimum temperature for green tuff powder calcination to reduce the hydroxyl radical produced in hydrogen peroxide decomposition with ultraviolet light (UV) and no light. The green tuff calcined at 800 °C shows the large decomposition rate of hydrogen peroxide with no UV light when measured by using ESR. With UV light, the optimum temperature for calcinating the green tuff powder in order to reduce hydroxyl radical is also 800 °C. Next, the powder calcined at 800 °C is used to produce the tile by compression and heating, and then the formaldehyde adsorption rate was measured. The green tuff powder calcined at 800 °C showed a high adsorption rate, similar to that of the activated carbon. The tiles formed at 40 MPa and heated st 1100 °C were the strongest and also adsorbed formaldehyde. The adsorbed formaldehyde on the green tuff tile and powder might have a possibility to decompose by photocatalytic.

The adsorption and separation of hazard metal ions, radioactive nuclides, or minor actinides from wastewater and high-level radioactive waste liquids using functional silica-based nano/micro-particles modified with various inorganic materials or organic groups, has attracted significant attention since the discovery of ordered mesoporous silica-based substrates. Focusing on inorganic and organic modified materials, the synthesis methods and sorption performances for specific ions in aqueous solutions are summarized in this review. Three modification methods for silica-based particles, the direct synthesis method, wetness impregnation method, and layer-by-layer (LBL) deposition, are usually adopted to load inorganic material onto silica-based particles, while the wetness impregnation method is currently used for the preparation of functional silica-based particles modified with organic groups. Generally, the specific synthesis method is employed based on the properties of the loading materials and the silicon-based substrate. Adsorption of specific toxic ions onto modified silica-based particles depends on the properties of the loaded material. The silicon matrix only changes the thermodynamic and mechanical properties of the material, such as the abrasive resistance, dispersibility, and radiation resistance. In this paper, inorganic loads, such as metal phosphates, molybdophosphate, titanate-based materials, and hydrotalcite, in addition to organic loads, such as 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-Calix{4}arene (Calix {4}) arene-R14 and functional 2,6-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-pyridines(BTP) are reviewed. More specifically, we emphasize on the synthesis methods of such materials, their structures in relation to their capacities, their selectivities for trapping specific ions from either single or multi-component aqueous solutions, and the possible retention mechanisms. Potential candidates for remediation uses are selected based on their sorption capacities and distribution coefficients for target cations and the pH window for an optimum cation capture.

To separate minor actinides (MA) from lanthanides from high-level liquid waste (HLLW), a kind of micro-porous silica-polymer (SiO2-P) based N-donor isoBu-BTP/SiO2-P adsorbent was synthesized and characterized. The efficient separation of 241Am(III) over Ln(III) lighter than Dy(III) was achieved in both batch and column experiments in pH 2–NaNO3 medium. The γ-irradiation stability of isoBu-BTP/SiO2-P was evaluated with the maximum absorption dose reaching to 207 kGy followed by TOC, UV, and UPLC/Q-TOF-MS analysis, which revealed good γ-irradiation stability of isoBu-BTP/SiO2-P. Furthermore, the adsorption mechanism was studied using XPS and EXAFS, which revealed that the interaction between Eu(III) and isoBu-BTP/SiO2-P mainly happened to the N atoms in isoBu-BTP. In a word, isoBu-BTP/SiO2-P is a very promising candidate for separating MA(III) from Ln(III) in pH 2–NaNO3 medium.

International audience; The copolymerization of styrene with divinylbenzene (DVB) in the presence of silica particles produces a commercial silica-supported polymer (SiO2-P) that was chemically reacted with acrylonitrile to synthesize silica-supported polyacrylonitrile (PAN/SiO2). PAN/SiO2 was functionalized by grafting amidoxime moieties to produce PAO/SiO2 sorbent (silica-supported polyacrylamidoxime). The sorbent (PAO/SiO2) was characterized by XPS, TGA, FTIR, pHpzc, elemental and SEM-EDX analyses and tested for Ga(III) recovery from aqueous solutions. The sorption performance was investigated through the study of pH effect, sorption isotherms at different temperatures, and uptake kinetics under slightly acidic conditions (around pH 4) and at pH close to 13.7 (similar to Bayer liquor). The equilibrium was reached within 60 min; the kinetic profiles can be fitted by the pseudo-second order rate equation (PSORE) and the resistance to intraparticle diffusion equation (RIDE). The maximum sorption capacity reaches 1.34 mmol Ga g−1 at 25 °C (1.76 mmol Ga g−1 at 55 °C): the sorption process is endothermic for solutions prepared by alkaline dissolving of Ga2O3. The sorption capacities are higher for solutions prepared with Ga(NO3)3 salt: the maximum sorption capacity increased up to 2.1–2.6 mmol Ga g−1 (from 25 to 55 °C). Langmuir and Sips equations were used for fitting sorption isotherms. Metal desorption and sorbent recycling were performed using 1.5 M HCl solution. Forty-five minutes were sufficient for achieving complete desorption of Ga(III). Sorption and desorption performances remain stable for a minimum of 5 cycles. Sorbent selectivity for gallium recovery was demonstrated in the presence of an excess of competitor cations. The sorbent was successfully applied for Ga(III) recovery from Bayer liquor at high pH values (around 13): combining relatively high efficiency and selectivity compared with LSC-600 amidoxime resin.

The sorption properties of a functionalized magnetic chitosan sorbent have been investigated for the recovery of Ni(II) and Pb(II) from aqueous solutions. This material was prepared by one-pot co-precipitation of chitosan with formation of magnetic core, followed by a series of grafting steps to immobilize hydrazinyl amine derivative at the surface of chitosan layer. The physico-chemical characteristics of this composite material were investigated using FTIR, XRD, XPS, thermogravimetric, titration, elemental analyses. In a second step, the sorbent was tested for heavy metal sorption on synthetic solutions through the study of pH effect, sorption isotherms and uptake kinetics, selective sorption (in function of pH), metal desorption and sorbent recycling. Sorption isotherms were modeled using the Sips equation while the uptake kinetics was fitted by the pseudo-second order rate equation. The sorption capacity reached 4.3 mmol Ni g−1 and 2.5 mmol Pb g−1 but the sorbent was more selective to Pb(II) over Ni(II), especially in acidic conditions. The decrease in sorption capacity at the fifth cycle does not exceed 8%. In the final step of the study, the sorbents were successfully applied for metal recovery from multi-metal synthetic solution and from a contaminated stormwater collected in a local mining area.

In this work, ZnLaAl layered double hydroxides (LDHs) were prepared by the co-precipitation method, and the ZnLaAl-LDHs nanosheets were embedded in sol-gel coating for the corrosion protection of 6061 aluminum alloys. The structure, morphology, and long-term anti-corrosion performance of sol-gel coating modified with ZnLaAl-LDHs were investigated. The structure and morphology analysis showed that nanosheets of ZnLaAl-LDHs are finer than those of ZnAl-LDHs, with the results suggesting that the La can refine the size of LDHs’ nanosheets and improve their nucleation rate. The results of long-term corrosion tests showed that the sol-gel coating with ZnLaAl-LDHs exhibits higher corrosion resistance and better stability compared with the sol-gel coating with ZnAl-LDHs, which indicates that the addition of La enhances the anti-corrosion performance of the LDHs and improves the stability of sol-gel coating with LDHs. Finally, the formation mechanism of ZnLaAl-LDHs and the corrosion mechanism of sol-gel coating with ZnLaAl-LDHs on 6061 aluminum alloys are both discussed in detail.

The composite of zirconium phosphate (ZrP) loaded on mesoporous silica pellet (MSP) was typically prepared by one-pot liquid phase grafting method to develop an effective inorganic adsorbent for strontium (Sr) ion removal from the contaminated water. The as-synthesized product was well characterized by energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), N2 adsorption–desorption isotherms and FT–IR. The adsorption of Sr2+ on ZrP/MSP composite was systematically investigated as the functions of pH, contact time, ionic strength, and various ions interference. It showed that Sr adsorption on ZrP/MSP was highly dependent on pH and the concentration of metal ion, achieving larger adsorption capacity, faster adsorption equilibrium, and higher ion selectivity than those of bare ZrP under batch reaction conditions. The Langmuir model and the pseudo-second-order model separately fitted the adsorption isotherm and kinetic data better than the Freundlich and pseudo-first-order ones. These results suggested that our present methodology may provide a general synthesis of silica supported zirconium phosphate with mesoporous structure in large surface areas which could be used as inorganic composite adsorbent for effective removal of strontium ions from the contaminated solutions.

This research investigates the influences of different contents of Sc on the microstructure, mechanical, electrical conductivities and corrosion resistance properties of 7055 alloy. The effect of Sc can increase the non-uniform nucleation of the alloy and significantly refine the casting structure of the alloy. In addition, the addition of Sc not only inhibits grain coarsening, pins GBs and restrains recovery and recrystallisation, but also maintains the effect of fibre structure during the formation of high-density nano-Al3 (Sc, Zr) phase precipitation. Compared with pure 7055 alloys, the hardness, tensile strength, elongation, electrical conductivity and corrosion resistance of 7055 alloys with Sc are improved remarkably. After adding a little Sc, the grain size of the alloy is refined from 80um to 40um, and the properties of the alloy are improved. When Sc content is 0.25%, the tensile strength of the alloy increases from 623.1mpa to 685.9mpa, and the self-etching current density decreases from 1.56 × 10−5 to 8.74 × 10−7, and the corrosion resistance is also greatly improved.

The development of new materials is needed to address the environmental challenges of wastewater treatment. The phosphorylation of guar gum combined with its association to chitosan allows preparing an efficient sorbent for the removal of U(VI) from slightly acidic solutions. The incorporation of magnetite nanoparticles enhances solid/liquid. Functional groups are characterized by FTIR spectroscopy while textural properties are qualified by N2 adsorption. The optimum pH is close to 4 (deprotonation of amine and phosphonate groups). Uptake kinetics are fast (60 min of contact), fitted by a pseudo-first order rate equation. Maximum sorption capacities are close to 1.28 and 1.16 mmol U g−1 (non-magnetic and magnetic, respectively), while the sorption isotherms are fitted by Langmuir equation. Uranyl desorption (using 0.2 M HCl solutions) is achieved within 20–30 min, the sorbents can be recycled for at least five cycles (5–6% loss in sorption performance, complete desorption). In multi-component solutions, the sorbents show marked preference for U(VI) and Nd(III) over alkali-earth metals and Si(IV). The zone of exclusion method shows that magnetic sorbent has antibacterial effects against both Gram+ and Gram- bacteria, contrary to non-magnetic material (only Gram+ bacteria). The magnetic composite is highly promising as antimicrobial support and for recovery of valuable metals.

Herein we report the fabrication of metakaolin/slag-based geopolymer microspheres by dispersion-suspension-solidification technology, and were then transformed into zeolite microspheres by in-situ thermal curing. The rheological properties and mechanical strength of metakaolin/slag-based zeolite microspheres (M/SZMs) were improved by adding slag. The zeolite microspheres were texturally and morphologically characterized by BET, SEM-EDX and XRD techniques. At 20% slag contents of the total mass of M/SZMs, the specific surface area was significantly increased without changing the structure of the zeolite. Rheological properties analysis of slurry revealed pseudoplastic fluid phase and fitted well to Herschel–Bulkley model. The adsorptive removal data of M/SZMs for Cs+ and Sr2+ from wastewater followed pseudo-second-order kinetics. The maximum adsorption capacity of M/SZMs for Cs+ and Sr2+ was 103.74 mg/g and 54.90 mg/g and were best explained by Freundlich and Langmuir isotherm models, respectively. M/SZMs exhibited excellent dynamic separation effect in column-based experimental set up. In addition, M/SZMs also realized outstanding adsorptive removal performance for Cs+ and Sr2+ from different real wastewater samples. Owing to the simplistic fabrication approach, low cost and highly efficacious nature, M/SZMs can be ranked as alternative candidates for the abatement of Cs+ and Sr2+ from wastewater.

To separate palladium (Pd) from electroplating wastewater, a novel mesoporous ion-exchange resin (SiAcyl) was prepared with the loading rate of 27.3 wt% and the cross-linking degree of 10 wt%. It was synthesized by using macroporous silica as inorganic carrier, acrylic acid, and allyl acetoacetate as monomers, EGDMA as cross-linking agent, AIBN as chemical initiator, dimethyl sulfoxide as diluent. The as-prepared SiAcyl resin was characterized by SEM-EDS, TG-DSC, N2-adsorption–desorption isotherm analysis, which revealed its characterization of high loading rate, mesoporous structure, and large specific surface area. It exhibited significant advantages in Pd separation and recovery, such as significant selectivity (SFPd/M > 124 in pH = 1.95 nitric acid solution), remarkable adsorption capacity (92.6 mg·g−1 Pd), and excellent reusability (n > 5). Moreover, the column separation technique was employed to better evaluate the feasibility of separation of Pd from actual electroplating wastewater by SiAcyl resin that a recovery yield about 100% of Pd and complete separation of Pd from other metal ions were obtained. Compared with several traditional commercial resins, SiAcyl resin exhibited great advantages and potential in industrial applications. Furtherly, XPS and FT-IR analysis demonstrated the ion-exchange between H+ (from –COOH) and Pd(II) is the mechanism during the whole adsorption process.

The designing of high adsorption capacity and selective porous materials to adsorb gallium (Ga) is essential for developing breakthrough Ga separation and purify methods based on resin adsorption to replace traditionally used extraction, chemical precipitation, and electrochemical method. Here, an advanced porous resin with the 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) and tributyl phosphate (TBP) attached to the silica-based materials (SiO2–P) has been prepared, which are synthesized by vacuum impregnation followed by drying. At low concentration sulfuric acid solution (PH = 3.3), the synthetic adsorbent that simultaneously exhibits excellent Ga adsorption capacity and high separation ability (excellent adsorption capacity with 64.2 mg/g, and super-high separation ability with the Kd is over 1600). Adsorption and mechanism studies of Ga (III), using the above P507-TBP/SiO2–P resin, were carried out. IR, XPS, and BET, TG analysis were applied to confirm the resin were successful adsorb Ga (III) and the conversion of polymer to resin, respectively. More importantly, the P507-TBP/SiO2–P adsorbent can also be extended to the design of other silica-based materials for the challenging separate and purify other rare precious metals ions, indicating a very appealing application prospect.

A new type of 7055-Y-Sc alloy with high strength and corrosion resistance was prepared. Eutectic Al3Y particles with sizes in the range of 500–600 nm were found in the as-cast structure of the 7055-Y-Sc alloys. The addition of Y significantly accelerated the precipitation of Al3Zr with L12 structure in Al–Zr–Y alloy, and the number density of Al3 (Zr, Y) precipitates was almost a grade higher than that of Al3Zr. In the process of aging at 120 ℃/12 h, the nano scale L12-type Al3 (Sc x Y y ) phase nucleated uniformly within the Al matrix and nonuniformly on the dislocation. The grain size decreased from 100–200 um in 7055-Y-0Sc to 40–50 um in 7055-Y-0.25Sc, the percentage of Sc continued to increase, and the grain size remained unchanged or even increased, thereby decreasing the Vickers hardness of 7055-Y-Sc alloys from 196.4 HV to 187.9 HV. After aging, the hardness and tensile properties of 7055-Y-Sc alloy showed good performance. The effective Sc proportion of the 7055-Y-Sc alloy was 0.25%. Its tensile strength was 398.6 MPa. Its conductivity was 33.8% IACS. The current corrosion density was 6.7 × 10−8 A cm−2, its good strength, corrosion resistance and conductivity make the studied alloy to be a promising material.

A new cerium oxide loaded slag-based geopolymer microspheres (CeO2@SGMs) was prepared by a two-step i.e. dispersion-suspension-solidification and in-situ co-precipitation method. The optimal parameters for the preparation of 0.02CeO2@SGMs were slag (30 g), 1.7 M water glass (12.86 g), water (8 g) and 0.02 mol/L of Ce4+. 0.02CeO2@SGMs was characterized by SEM, XRD, BET, EDX, FTIR, XPS and PSD techniques. The leaching concentration of Ca2+ (95.65 mg/L) was only 1/5 of the SGMs at pH 2 after the modification of CeO2. Adsorption data fitted well with Freundlich isotherm model suggesting multilayer adsorption mechanism with a maximum adsorption capacity for F− by 0.02CeO2@SGMs of 121.77 mg/g at 298 K. The negative values of thermodynamic parameters (ΔH0 and ΔS0) indicated the exothermic nature of the adsorption process with reduced chaos of the whole system. 0.02CeO2@SGMs exhibited excellent dynamic adsorption performance at 4 mL/min F− solution flow rate. The influence of various co-existing anions on adsorption of F− over 0.02CeO2@SGMs followed an order of: Cl− ≈ NO3−

Radiation-induced degradation of the weakly and strongly 4-vinylpyridine basic ion exchange resins by gamma radiolysis was investigated in the presence of air and liquid water. This study is focused on evaluating the radiolytic gases (H2, CO, CO2 and CH4) and liquid products (water-solute TOC and NH4 +). The weakly basic resin yielded lower amounts of H2 and CO and higher amounts of CO2 than those of the strongly basic resin. Moreover, the strong basic resin tended to yield greater amounts of NH4 +. Resins were characterized by the FTIR spectroscopy technique and the results showed that the resins structures are relatively stable.

Two-dimensional coordination polymers Zn2L2 (1) and Cd2L2·DMF·2H2O (2) (DMF = dimethylformamide) were synthesized under solvothermal conditions by the reactions between rigid dicarboxylate ligand containing two phosphine oxide groups, (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl (H2L), and the Zinc(II) and Cadmium(II) salts. The complexes were characterized by single-crystal X-ray diffraction, infrared spectra (IR), elemental analyses, thermogravimetric analyses (TGA), and photoluminescent studies. Complexes 1 and 2 are isomorphous, while 2 contains different guest molecules with one DMF and two waters. Luminescent properties investigation shows that complexes 1 and 2 have red-shifted 14 nm and 11 nm, respectively, and the luminescence efficiency is also different compared with the free ligand H2L.

This paper describes uranium extraction from aqueous phosphoric acid medium using a silica/polymer based D2EHPA-TOPO adsorbent. The mixture of di-2-ethyl-hexylphosphoric acid (D2EHPA) and tri- n -octylphosphine oxide (TOPO) was impregnated and immobilized into the pores of SiO 2 -P particles. The various experimental parameters such as the synergistic mixture ratio of extractants, phosphoric acid concentration, the contact time and the temperature were investigated. The results showed that 95% uranium extraction was achieved after 10 min contacting time using D2EHPA-TOPO/SiO 2 -P (mass ratio = 3:1 w/w) adsorbent from 1 M phosphoric acid solution containing 165 ppm U (VI), 5000 ppm Fe (III), 1000 ppm Ca (II) and 1000 ppm Al(III) at 25 °C. Also, the obtained results displayed the high adsorption capacity for Uranium as high as 48 mg g − 1 at the mentioned conditions. The rate constant (1.62 g mg − 1 min − 1 ) was calculated by the pseudo-second order equation and it shows that reaction rate was controlled by the chemical adsorption of uranium. Furthermore, D2EHPA-TOPO (3:1)/SiO 2 -P has a good selectivity for U(VI) among the co-existing elements (Fe, Al and Ca). The adsorption isotherms were well described by the Redlich–Peterson equation, closely followed by the Langmuir equation which confirms the mechanism is chemical monolayer adsorption. Obtained thermodynamic parameters (∆ H ° . ∆ S ° and ∆ G ° ) reveal that the U(VI) adsorption to be an exothermic and spontaneous process.

The 4-vinylpyridine-based porous resins (4VP–DVB and 4VP–DVBQ) were synthesized to adsorb 99Tc from radioactive waste. The radiation stability of the synthesized resins were investigated in air, water, HCl, and HNO3 mediums. The radiolytic degradation of resins was evaluated by the total organic carbon analysis. The weakly basic resin (4VP–DVB) and strongly basic resin (4VP–DVBQ) showed a remarkable resistance to radiation in HCl and HNO3 solutions respectively. Moreover, adsorption behavior of irradiated 4VP–DVB and 4VP–DVBQ resins toward 99Tc was studied by the batch experimental method.

A porous Me2-CA-BTP/SiO2-P adsorbent was prepared to separate MA(III) from Ln(III) in high level liquid waste (HLLW). The adsorption behavior of Me2-CA-BTP/SiO2-P toward 241Am(III) and Ln(III) in 0.01 M HNO3-NaNO3 solution was studied. Me2-CA-BTP/SiO2-P showed high adsorption and selectivity toward 241Am(III) over Ln(III) fission products with the separation factor (SF) reaching to 557, 2355, 1952, 1082, 214, 105, 86, 14 for Y, La, Ce, Nd, Sm, Eu, Gd and Dy respectively in 0.01 M HNO3-0.99 M NaNO3 solution. The adsorption kinetics of both Dy(III) and Eu(III) on Me2-CA-BTP/SiO2-P was studied and followed pseudo-second-order rate equation indicating chemical sorption as the rate-limiting step of the adsorption, and the adsorption isotherm of Dy(III) and Eu(III) matched better with the Langmuir isotherm than the Freundlich isotherm with the adsorption amount around 0.22 and 0.20 mmol/g respectively. Thermodynamic study revealed that the adsorption of both Dy(III) and Eu(III) on Me2-CA-BTP/SiO2-P was spontaneous and endothermic processes with a positive entropy at 298, 308, 313 K.

In this study, simultaneous separation and recovery of Cs(I) and Sr(II) from nitric acid solution was investigated using a silica-based hybrid adsorbent. The adsorbent was prepared by successive impregnation and fixing of two supramolecular recognition agents namely, 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-Calix[4]-arene(Calix[4]arene-R14) and 4',4' (5")-di(tert-butylcyclohexano)-18-crown-6, onto a silica-based polymer support(SiO2-P). Uptake properties, characterization, equilibrium kinetics, and dynamic adsorption properties of Cs(I) and Sr(II) were then assessed. Distribution coefficients (Kd) higher than 102 cm3/g for Cs(I) and Sr(II) were obtained using 3 M HNO3 at 298 K, and the Kd values decreased with increasing temperature. Adsorption kinetics and equilibrium studies fitted well with pseudo-second-order model and Redlich–Peterson isotherm model, respectively. The constant total organic carbon values in the aqueous phase were obtained after adding 10−3 ∼ 4 M HNO3. Results of the dyn...

Silica based ammonium molybdophosphate (AMP/SiO2) adsorbent was used to remove Cs(I) from HNO3 solution. The adsorbent with different absorbed dose (0–300 kGy) was characteristed by X-ray power diffraction. The adsorption data against different γ-ray absorbed doses were analyzed by the Langmuir isotherm. The adsorption capacity decreased slightly from 23.22 to 22.37 mg/g with the increase of the absorbed dose. The breakthrough properties of Cs(I) were conducted using column packed with AMP/SiO2 before and after irradiation. The chemical stability of AMP/SiO2 at 300 kGy absorbed dose in 3 mol/L (M) HNO3 was excellent.

A novel macroporous silica-based hexagonal tungsten oxide (h-WO3/SiO2) with exchangeable sodium cations located in hexagonal tunnel structure was synthesized by a facile hydrothermal treatment of sodium tungstate dihydrate with 1 mol/L HCl solution. Utilization of the h-WO3/SiO2 adsorbent to remove aqueous strontium was investigated under the condition of various pH values, contact time, the initial concentration of metal ions, salt ion concentration, and coexisting ions. According to the experimental data, Sr2+ adsorption equilibrium was achieved within 15 min in acidic solution, and the maximum removal capacity of Sr2+ occurred at pH 4. The kinetic adsorption of Sr2+ on h-WO3/SiO2 was controlled by pseudo second-order model, and the saturated adsorption of Sr2+ on h-WO3/SiO2 was better described by Langmuir and Redlich-Peterson isotherm models compared with the Freundlich isotherm model. The distribution coefficient of Sr2+ was more than 2000 cm3/g in the presence of Ca2+, Mg2+, La3+, and Eu3+, indicating that the h-WO3/SiO2 showed excellent selectivity towards Sr2+ in pH 4.

2,6-Bis(5,6-diisohexyl-1,2,4-triazin-3-yl)pyridine (isoHexyl-BTP) is a nitrogen-donor chelating ligand which shows high extraction selectivity for minor actinides (MA) over lanthanides (Ln). We synthesized a macroporous sillica/polymer-based isoHexyl-BTP adsorbent (isoHexyl-BTP/SiO2-P) for the separation of MA(III) from Ln(III) in high-level liquid waste. The work focused on the isoHexyl-BTP/SiO2-P adsorption mechanism towards Ln(III) in nitric acid solution and the coordination chemistry between Ln(III) and isoHexyl-BTP/SiO2-P through batch adsorption experiments, extended X-ray absorption fine spectroscopy, acid-base titration and ion chromatography. It was found that both H+ and NO3− directly participated in the adsorption reaction. For the middle and heavy Ln(III), Ln(isoHexyl-BTP/SiO2-P)3(NO3)3·3HNO3 was supposed as the main product of the adsorption. The Ln(III)-N (Ln(isoHexyl-BTP/SiO2-P)33+) bond length of the first coordination layer decreased as the atomic number of Ln(III) increased, whi...

Porous isobutyl-BTP/SiO2-P adorbent was prepared to separate MA(III) from HLLW. The adsorption behavior of isobutyl-BTP/SiO2-P toward 241Am(III), Y(III) and Ln(III) in 0.01 M HNO3–NaNO3 solution was studied. Isobutyl-BTP/SiO2-P showed high adsorption selectivity toward 241Am(III) over Y(III) and Ln(III) fission products. Adsorption kinetics of Dy(III) followed pseudo-second-order rate equation, and its adsorption isotherm matched the Langmuir isotherm equation well. Moreover, the adsorption product of Dy(III) on isobutyl-BTP/SiO2-P was studied using extended X-ray absorption fine structure (EAXFS) method and Dy(isobutyl-BTP/SiO2-P)3 3+ was supposed as the main adsorption species.

Bauxite residue, as an important source of scandium, is an alkaline industrial waste generated during the Bayer process for alumina production. A novel method for selective extraction of scandium from bauxite residue was proposed by ammonium sulfate roasting and water leaching. During the roasting process, ammonium sulfate could selectively react with Sc, Al and Fe in the bauxite residue to produce respective metal ammonium sulfates, and then which were completely decomposed to their respective metal sulfates at 550 °C. The sulfates of iron (III) and aluminum were decomposed to their respective metal oxides at about 700 °C, whereas the scandium sulfate remained stable. In the leaching process, the scandium sulfate could be selectively leached with water from roasted residues while other elements mainly remained in the leaching residue. The extraction efficiency of scandium reached above 90% under the optimum conditions.

The measurement of 210Pb is significant in environmental studies. Lead separation in HCl solution is a vital procedure but suffers from poor efficiency with high labor and time costs. To overcome this problem, a novel anion exchange resin was synthesized and characterized by different techniques followed by studies on the adsorption behaviors towards lead in HCl solution. The results suggest that SiPS-N(CH3)3Cl was successfully prepared with small particle size, low water swelling rate, and large specific surface area. The maximum anion exchange capacity resulted from quaternary amine groups was determined to be 1.0 mmol (Cl−)/g. The adsorption activities reached equilibrium within 5 min under selected conditions offering extremely fast adsorption kinetics. The synergistic adsorption mechanism and the competition from co-existing chloride anions were found to be responsible for the lead adsorption performance of SiPS-N(CH3)3Cl. Column experiments showed that the feeding volume of lead and HCl had impact on the chemical yield regardless of the co-existence of high concentrations of FeCl3 (90 mM) and a high flow speed (4.0 mL/min). Based on these results, a separation process integrating SiPS-N(CH3)3Cl and the matched parameters was finally developed and tested. Our work greatly raised the lead separation efficiency in HCl solutions with implications for measuring 210Pb in environmental samples.

Scandium (Sc), a rare earth element, generally lacks independent large-scale deposits and is mainly recovered as a by-product in mineral processing. Herein, we systematically investigated the extraction of Sc by trialkyl phosphine oxide (TRPO) from both a scandium sulfate solution and leaching solution of Sc concentrate generated from titanium white waste acid in the sulfuric medium. The results showed that the optimum extraction conditions of Sc from scandium sulfate by TRPO were as follows: 10% TRPO, 5 mol/L H2SO4, and an A/O ratio of 1 for 20 min. The equation of scandium extraction by TRPO was calculated based on the log[c(TRPO)] - log[D] fitting results coupled with Fourier transform infrared spectroscopy (FT-IR) analysis, to which the extracted complex was deduced to be HSc(SO4)2•2TRPO. Furthermore, for Sc extraction from leaching solution of its concentrate from titanium white waste acid, a relatively high extraction rate of up to 95.5% was obtained on the conditions of 20% TRPO, 7 mol/L H2SO4, 0.5% of H2O2, and at an A/O ratio of 10. Stripping with H2C2O4 produced a high stripping rate of 99.9%, and the extraction and stripping system still presented excellent extraction performances even after five treatment cycles. Through the subsequent calcination of the stripped Sc2(C2O4)3 at 1000 °C for 2 h, we obtained the final product of Sc2O3 with a high purity of over 99.34% with a total recovery yield of Sc as high as 95% in the whole process. Our findings contribute novel insights into the extraction and purification of Sc for its recovery from the secondary wastes.

To separate ruthenium(III) from simulated electroplating wastewater, a kind of porous material, TRPO/SiO2–P, was used. TRPO/SiO2–P exhibited unique advantages compared with other materials, such as high selectivity (SFRu/other metals >35), large adsorption capacity (54.6 mg g−1), and fast adsorption kinetics ( =O) and ruthenium(III) during the whole adsorption process and meantime anion groups (NO3− and NO2−) were involved to maintain charge balance. In brief, TRPO/SiO2–P has significant potential in the recovery of ruthenium from electroplating wastewater.

The electrochemical redox behavior of gallium (Ga) in alkaline solution was investigated using the combination of electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV). The electrodeposition morphology and elemental composition were observed using the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results indicate that during the reduction process, the reduction of gallium anion (GaO2−) begins at high negative values of the potential (−1.42 V, vs. Hg/HgO), and the reduction product (Ga2O) is transformed into Ga2O3 and Ga via the disproportionation reaction; the electrodeposition potential of Ga is −1.76 V (vs. Hg/HgO). The oxidation process of Ga can be divided into four stages with the increasing of potential: (i) the oxidation of Ga to form Ga2O, (ii) the electrodissolution of Ga to form GaO2−, (iii) the formation of passivation films (GaO(OH)) on the Ga surface, and (iv) the destruction of passivation films and the continuous dissolution of Ga.

Uranium (Ⅵ) exists as many species in natural water systems. In the recent years, its contamination to groundwater has been reported more frequently. To investigate the effects of speciation on the removal of uranium, this work investigated the uranium adsorption behaviors of a polyamine-grafted silica composite named SAER at the concentration level of μg/L in the alkaline carbonate solutions with other four resins. Results suggested that the change of uranium speciation had minor effect on the adsorption efficiencies of SAER, except the addition of calcium. This was resulted from that the protonated tetraethylenepentamine had a much higher affinity to the electronegative uranyl-carbonate species, leading to the complete removal of uranium through the simultaneous anion exchange and chemical transformation mechanisms; Column experiments confirmed that merely a small portion of calcium while no magnesium cations were involved in the uranium adsorption in the simulated groundwater. Finally, the integrated removal mechanisms were proposed. Overall, this work demonstrated the feasibility of a novel adsorbent for the effective removal of uranium from different water matrices as well as the mechanisms underlying the interaction of uranium and the functional groups on the adsorbents. Furthermore, it enhanced the understanding of uranium removal under environmentally relevant conditions.

The development of the Cs stable immobilization method contributes to the treatment of insoluble ferrocyanide sludge containing radioactive Cs (Cs–CuFC) generated by the Fukushima nuclear accident. Cs–CuFC begins to decompose at 200 °C, and Cs in Cs–CuFC volatilizes after being oxidized to Cs2O in air at high temperature. Therefore, Cs has an immobilization ratio of less than 4% at 1000 °C. Meanwhile, Cs–CuFC generates poisonous gases, such as HCN, NO, and NH3, and the release of HCN is suppressed in active atmosphere. For the stable immobilization of Cs, a pressing/sintering method that used allophane as an additive was examined. Allophane was mixed uniformly with Cs–CuFC in a mass ratio of 1:1, and the mixture was sintered at different temperatures to obtain solidified bodies. A stable crystal called pollucite was formed after sintering above 900 °C, and the immobilization ratio of Cs was approximately 100%. Part of pollucite was concentrated on some spots on the surface of solidified bodies. These bodies had good mechanical properties for geological storage. The leaching percentage of Cs for the solidified bodies sintered at 1100 °C in distilled water was less than 0.01% and 0.4% at 25 °C and 90 °C, respectively, thereby indicating that the solidified bodies had excellent immobilization properties and chemical stability.

A macro porous silica-based nickel hexacyanoferrate (KNiHC/SiO2) adsorbent was synthesized for separation of palladium (Pd(II)) from high-level liquid waste (HLLW). Based on XPS analysis, the Pd 3d5/2 spectrum at 344.4 eV corresponds to metallic palladium Pd(0), indicating that ion-exchange and redox reactions occur in the adsorption of Pd. Mercury intrusion porosimeter (MIP) test results show that the average pore size of KNiHC/SiO2 is 37.6 nm. The adsorption of KNiHC/SiO2 for Pd(II) reaches the equilibrium state within 1 h and follows the pseudo-second-order kinetic model, which indicates chemical adsorption. The maximum adsorption capacity of the adsorbent for Pd(II) in the mixture of 1 M NaNO3 and 3 M HNO3 is 46.09 mg/g. The experimental data fit well with the Langmuir and Redlich-Peterson isotherm models. Furthermore, KNiHC/SiO2 exhibits high selectivity toward Pd(II) over co-existing noble metals, namely, Rh(III) and Ru(III) within a wide range of HNO3 concentrations. The sharp S-shaped breakthrough curves in different feed flow rates suggest the excellent dynamic adsorption performance of the adsorbent in column systems.

The separation of fission products Ru, Rh, and Pd will benefit both the nuclear fuel cycle and enlarge the platinum group metals source. A silica-based isoBu-BTP/SiO2-P adsorbent was used to separate Ru, Rh, and Pd from nitrate solution. It exhibited good adsorption towards Ru, Rh, and Pd with the uptake rates over 95% at 55 °C in 0.1 M HNO3–3 M NaNO3 solution and no adsorption towards 238U(VI). The adsorption towards Ru, Rh, and Pd matched well with pseudo-second-order model with the equilibrium obtained within 24 h, 24 h and 0.5 h and Langmuir adsorption isotherm model with the saturation adsorption amounts as high as 0.37 mmol/g, 0.34 mmol/g and 0.71 mmol/g respectively. The adsorbed Pd, Rh, and Ru can be desorbed by 0.1 M HNO3–0.1 M thiourea, 2 M HCl and NaClO solution (CP) which is expected to realize their mutual separation in desorption stage using the above-mentioned eluents successively. Both FT-IR and XPS revealed that C N C played key role during adsorption and the adsorption needed the participation of NO3− to keep charge balance. In a word, isoBu-BTP/SiO2-P is a promising adsorbent for separation and recovery Ru, Rh, and Pd, especially in the case of separating them from other fission products and actinides from high level liquid waste.

This study reports the fabrication of slag-based Fe2O3-modified porous geopolymer microspheres composites (Fe2O3@PGMs) having uniform particle size distribution (75–300 μm) and good sphericity by in-situ co-precipitation process. The concentration of Fe3+ as modifier (in Fe2O3) significantly enhanced the resistance of Fe2O3@PGMs against corrosion (leaching concentration of Ca2+ decreased from 95.65 to 30.76 mg/L in 120 min) and adsorption capacity towards F− of pristine PGMs while 0.2 mol/L (0.2Fe2O3@PGMs) exhibited the best performance. The adsorption data were best fitted with pseudo-second kinetic model and Langmuir isotherm model, indicating the involvement of both, ion exchange and monolayer phenomena during adsorption. 0.2Fe2O3@PGMs delivered outstanding adsorption capacity (59.55 mg/g) and faster reaction kinetics (k2 = 98.11 × 10−4 g mg−1 min−1) for F− as determined by bath and dynamic experiments. 0.2Fe2O3@PGMs possessed good separation efficiency even at a flow rate of 4 mL/min. The competitive adsorption capabilities of coexisted anions in real seawater, tap water and natural surface water followed an order of: Cl−

ZnAl-LDHs and ZnLaAl-LDHs films were fabricated on the surface of 6061 aluminum alloys using in-situ growth method. The microstructures of LDHs films were investigated through the X-ray diffraction (XRD), scanning electronic microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that ZnAl-LDHs and ZnLaAl-LDHs nanosheets grow up perpendicular to the surface of the aluminum substrate. It is noteworthy that, the nanosheet of ZnLaAl-LDHs is more fine and dense than that of ZnAl-LDHs under the same growth condition. On the other hand, addition of lanthanum ions inhibit the growth rate of the ZnAl-LDHs nanosheet. The corrosion performance of the ZnAl-LDHs and ZnLaAl-LDHs films were analyzed through the polarization curves and electrochemical impedance spectroscopy (EIS). LDHs films enhance the corrosion resistance of 6061 aluminum alloys, and the corrosion protection performance of LDHs films are improved as the growth time increase. Furthermore, lanthanum addition enhances the anti-corrosion performance of the ZnAl-LDHs film. Comparison of the corrosion resistance properties of both films; it was found that ZnLaAl-LDH film has high ratio than ZnAl-LDHs by 24%, 42%, 160% and 210% for the growth time 15 min, 1 h, 4 h and 8 h, respectively. Finally, the formation and corrosion mechanism of ZnLaAl-LDHs film on 6061 aluminum alloys are discussed in detail.

K2Ti6O13/SiO2 adsorbents were prepared by sol–gel method and good microcrystalline K2Ti6O13 phases were formed at 500 °C. From EDS of the adsorbents before and after adsorption of Sr2+ it showed that there was ion-exchange reaction between K+ and Sr2+. Experimental data on adsorption isotherms were best fit by the Freundlich and Langmuir–Freundlich model. The experimental data indicated that the pseudo-second order kinetic equation was best fit for both single Sr2+ solution and simulated Fukushima wastewater. The pH approaching to neutral displayed a better adsorption behavior for Sr2+ solution. The breakthrough capacity for treatment of Fukushima wastewater increased with decreasing flow rate and increasing bed diameter.

In order to predict · OH and · H radicals initiated degradation of proton exchange membrane (PEM) based on polymers obtained by radiation-induced grafting of styrene or α-methylstyrene on different polyolefin, isopropyl benzene sulfonic acid (IPBS) and tert-butyl benzene sulfonic acid (TBBS) were taken as model compounds for PEM with and without α-H, respectively. Results indicated that · OH radicals played a vital role in PEM degradation. Eighty-nine percent of · OH radicals reacted with IPBS to form benzylic radicals by electron transfer and subsequent deprotonation reactions. Benzylic radicals can react with O2 to form peroxyl radicals, which leads to PEM degradation. TBBS, without α-H, reacted with · OH or · H radicals, benzylic radicals would not be generated, and only adducts were formed. Adducts have less influence on the stability of TBBS than benzylic radicals. In this work, we elucidated that PEM, without α-H, with similar structures to TBBS, had a stronger resistance to oxidative degradation than PEM with α-H, with similar structures to IPBS.

A silica/polymer-based CA-BTP/SiO2–P adsorbent was prepared to separate minor actinides and some key radionuclides from HLLW. The adsorption properties of CA-BTP/SiO2–P toward 238U(VI), 239Pu(IV), 241Am(III), 99Tc(VII), 152Eu(III), and some typical fission products were studied. CA-BTP/SiO2–P stability against γ-radiation was also evaluated. It found CA-BTP/SiO2–P showed very poor adsorption abilities toward U(VI) and most experimental FPs, while CA-BTP/SiO2–P exhibited higher adsorption abilities toward 241Am(III), 239Pu(IV), and 99Tc(VII) in 0.5–1 M HNO3 solution. Moreover, dry CA-BTP/SiO2–P demonstrated no instability when the radiation dose was up to 161 kGy. CA-BTP/SiO2–P adsorbent is a potential candidate for separating 241Am(III), 239Pu(IV), and 99Tc(VII) from HLLW.

The extraction chromatography–electrodeposition (EC–ED) process was proposed for the quantitative recovery of palladium from high-level liquid waste (HLLW) in this study. The process coupled the extraction chromatography method to obtain the decontamination of Pd(II) from HLLW with the electrochemical method to recover metallic palladium from the concentrated solution. Separation of Pd(II) from a nitric acid medium by extraction chromatography using isoBu-BTP/SiO2-P adsorbent and the electrochemical behavior of Pd(II) in nitric acid solution in the presence of thiourea (TU) were investigated. isoBu-BTP/SiO2-P exhibited a high selectivity for Pd(II) over other fission products (FPs), and Pd(II) could be desorbed by TU from loaded BTP/SiO2-P. The adsorbent performed good stability against HNO3 because the adsorption performance kept Pd(II) after extended contact with HNO3 solution. The column experiment achieved the separation of Pd(II) from simulated HLLW successfully. The electrochemical behavior of Pd(II) in palladium desorption solution containing TU and nitric acid was investigated at a platinum electrode by cyclic voltammetry. A weak reduction wave at − 0.4 V was due to the reduction in Pd(II) to Pd(0), and the deposition process was irreversible. In electrowinning experiments, a maximum of 92% palladium could be obtained.

Directly separating minor actinides (MA: Am, Cm, etc.) from high level liquid waste (HLLW) containing lanthanides and other fission products is of great significance for the whole nuclear fuel cycle, especially in the aspects of reducing long-term radioactivity and simplifying the post-processing separation process. Herein, a novel silica-based adsorbent Me2-CA-BTP/SiO2-P was prepared by impregnating Me2-CA-BTP (2,6-bis(5,6,7,8-tetrahydro-5,8,9,9-tetramethyl-5,8-methano-1,2,4-benzotriazin-3-yl)pyridine) into porous silica/polymer support particles (SiO2-P) under reduced pressure. It was found Me2-CA-BTP/SiO2-P exhibited good adsorption selectivity towards 241Am(III) over 152Eu(III) in a wide nitric acid range, acceptable adsorption kinetic, adequate stability against γ irradiation in 1 and 3 M HNO3 solutions, and successfully separated 241Am(III) from simulated 3 M HNO3 HLLW. In sum, considering the good overall performance of Me2-CA-BTP/SiO2-P adsorbent, it has great application potential for directly separating MA from HLLW, and is expected to establish an advanced simplified MA separation process, which is very meaningful for the development of nuclear energy.

A silica-based ammonium molybdophosphate (AMP/SiO2) was successfully applied to remove Cs(I) from radioactive waste water in our previous study. The structure characterization of irradiated AMP/SiO2 was carried out by X-ray diffraction (XRD). The effect of the initial concentration of metal ions and acidity concentration for removal Cs(I) by irradiated AMP/SiO2 were investigated. No obvious difference was observed for AMP/SiO2 with 300 kGy absorbed dose from the XRD patterns, except the slightly shift of (110) peak toward a small angle. Relatively large distribution coefficient (8×103cm3/g) of Cs(I) was obtained in 3M HNO3 by irradiated AMP/SiO2. The maximum adsorption capacity of AMP/SiO2 irradiated at 300 kGy was estimated as 22.4 mg/g. The loss of molybdenum from AMP/SiO2 in 3 M HNO3 with 200 kGy absorbed dose is less than 5%.

Technetium (99Tc), a major fission product in nuclear reactors, of high yield, long-half-life and high mobility in the environment must be removed in nuclear fuel reprocessing. Considering rhenium (Re) and Tc are both VIIB elements, Re is a good chemical analogue to 99Tc. Herein, we use Re as a substitution of 99Tc to study adsorption and desorption behavior. Porous 4-vinylpyridine–divinylbenzene-based (4VP–DVB) adsorbent containing tertiary amine groups is synthesized by suspension polymerization and characterized by BET, TGA, SEM and laser particle size analyzer. The adsorbent has high adsorption efficiency toward Re(VII) in 0.1 mol/L nitric acid solution, and the adsorption equilibrium can be achieved in 30 min. The adsorption kinetics of Re(VII) follows pseudo-second-order rate equation, the adsorption isotherm matches well with the Langmuir isotherm, and the adsorption capacity of Re(VII) on 4VP–DVB adsorbent is 352.1 mg/g at 298 K. Thermodynamic study reveals that the adsorption process is exothermic. This adsorbent is of separation convenience when a fixed-bed column is used, compared to the batch adsorption treatment.

1,3-[(2,4-Diethylheptylethoxy)oxy]-2,4-crown-6-Calix[4]arene(Calix[4]arene-R14), used as an extractant of Cs(I) from nitric acid, modified by dodecanol and dodecyl benzenesulfonic acid (DBS), was loaded into the pores of macroporous silica-based polymer support (SiO 2 -P) particles. To evaluate the stability of the adsorbent, the adsorption data at different temperatures (298–323 K) and γ-ray absorbed doses (10–200 kGy) were analyzed by the Langmuir isotherm. The minimum adsorbed amount was calculated to be 0.121 mmol g −1 at 323 K, approximately 23% reduction compared to 298 K. The maximum adsorbed amount of not-irradiated adsorbent with 0.156 mmol g −1 decreased by 20% than that irradiated in 0.5 M HNO 3 . The thermodynamic parameters have revealed that this adsorption reaction is an exothermic and spontaneous process. The reduction in 3 M HNO 3 was about 45% by the comparison between the before- and after-irradiation. It was found that both the concentrations of HNO 3 and DBS have significant influence on the degradation of the adsorbents.

Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water (HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive cesium, three kinds of novel porous silica gels loaded with insoluble ferrocyanides (SLFC) were prepared using a successive impregnation/precipitation method. Based on the results of previous research, the SLFC composites have relatively large uptake ratio above 95%, distribution coefficients (K d) above 103 cm3/g, and excellent adsorption kinetics even in seawater. The solidification results also indicate that zeolites have an excellent Cs immobilization characteristic, gas-trapping and self-sintering abilities, and low leachability. We chose three kinds of SLFC composites to achieve the optimization of solidification by mixing with nine kinds of additives at high temperatures (up to 1200 °C). The Cs contents in the three composites were estimated to be below 30% of the initial contents and decreased with the three stages at calcination temperatures ranging from 25 to 1200 °C. By contrast, the Cs immobilization ratio was markedly lowered by mixing with additives: of those, allophane had the best immobilization result. By increasing the additive ratio to 50 wt%, the Cs immobilization ratio became almost 100% and no volatilization of Cs was detected even after calcination at 1200 °C. This result indicates that calcination of the mixture of SLFC composites after adsorbing Cs+ ions and specific additives under appropriate ratio is effective for stable solidification.

The silica/polymer-based isoHex-BTP adsorbent (isoHex-BTP/SiO2-P) was prepared for partitioning Am(III) and Cm(III) from HLLW. Batch adsorption results showed that isoHex-BTP/SiO2-P exhibited high affinity and selectivity for Am(III) and Pu(IV) over U(VI), Ln(III) and other typical fission products in 3 mol dm(-3) nitric acid. The effects of contact time, initial Dy(III) concentration and temperature on the adsorption of Dy(III) [as a simulated element of MA(III) and a representative element of Ln(III)] by isoHex-BTP/SiO2-P in 3 mol dm(-3) nitric acid were investigated. The adsorption of Dy(III) fitted well to the pseudo-second-order kinetic model and the Langmuir isotherm model. The adsorption thermodynamic parameters revealed that the adsorption was a spontaneous, endothermic and entropy-driving process.

Studying the bonding nature of uranyl ion and graphene oxide (GO) is very important for understanding the mechanism of the removal of uranium from radioactive wastewater with GO-based materials. We have optimized 22 complexes between uranyl ion and GO applying density functional theory (DFT) combined with quasi-relativistic small-core pseudopotentials. The studied oxygen-containing functional groups include hydroxyl, carboxyl, amido, and dimethylformamide. It is observed that the distances between uranium atoms and oxygen atoms of GO (U-OG) are shorter in the anionic GO complexes (uranyl/GO(-/2-)) compared to the neutral GO ones (uranyl/GO). The formation of hydrogen bonds in the uranyl/GO(-/2-) complexes can enhance the binding ability of anionic GO toward uranyl ions. Furthermore, the thermodynamic calculations show that the changes of the Gibbs free energies in solution are relatively more negative for complexation reactions concerning the hydroxyl and carboxyl functionalized anionic GO complexes. Therefore, both the geometries and thermodynamic energies indicate that the binding abilities of uranyl ions toward GO modified by hydroxyl and carboxyl groups are much stronger compared to those by amido and dimethylformamide groups. This study can provide insights for designing new nanomaterials that can efficiently remove radionuclides from radioactive wastewater.