Ceramic immobilization is one of the good strategies for disposal of high-level radioactive waste, but suffers from high temperature and low immobilization capacity. Herein, green spark plasma sintering (SPS) technology was reported to prepare zircon-based multiphase ceramics (x-Z) for enhanced simulated trivalent actinide (Nd3+) immobilization. The effect of Nd3+ content on the phase and microstructure evolutions of the obtained x-Z ceramics was investigated. The x-Z ceramics were prepared by SPS at low sintering temperature (1350 degrees C) and short time (10 min), and their Nd3+ immobilization capacity was up to 20 at% owing to the low sintering temperature and short sintering time reduced the decomposition of ZrSiO4 phase. In addition, the obtained x-Z ceramics exhibited superior aqueous stability due to the high density achieved by SPS. The green and efficient SPS technology could play a significant role in promoting the industrialization of ceramics immobilization of high-level radioactive waste.

The development of adsorbents capable of simultaneous adsorption of methyl iodide (CH3I) and iodine (I2) is meaningful but remains challenging. In this work, a novel Bi/Bi2O2SiO3 composite was prepared by one step method and employed for the simultaneous adsorption of gaseous CH3I and I2. In the single CH3I or I2 system, the Bi/Bi2O2SiO3 composite exhibited excellent adsorption capacities, reaching capacities of 1293 mg/g (CH3I) and 452 mg/g (I2). In the CH3I + I2 coexistent system, the total adsorption capacity was up to 1336 mg/g, which can be attributed to a synergistic effect between Bi and Bi2O2SiO3. The results indicated that the adsorption of both CH3I and I2 was chemical, and the adsorption product was BiI3. Furthermore, the adsorption mechanism of CH3I by Bi2O2SiO3 was catalytic cleavage reaction. Owing to its outstanding performance for simultaneous adsorption of CH3I and I2, the Bi/Bi2O2SiO3 composite could be considered as a promising candidate for the practical decontamination of radioactive iodine species in off-gas streams.

Tin-based materials are expected to be excellent iodine adsorbent, but the stability of the adsorption product (SnI4) poses challenge. Herein, a novel strategy based on the in-situ reconstruction of hydrophobic environment was presented for efficient iodine adsorption and storage. Stannous sulfide@mesoporous silica (SnS@SBA-15) was developed and employed for the adsorption of I2 gas. The optimal material, SnS@SBA-15-50wt%, exhibited an excellent iodine uptake of 2062 mg/g. The adsorption was attributed to a chemical reaction (SnS + 2I2 = SnI4 + S). Notably, the retention rate of SnI4 was as high as 76.5% after storage in air for 90 days due to the in-situ reconstructed hydrophobic environment. The obtained SnS@SBA-15 exhibited efficient iodine adsorption and excellent storage ability. This work presents a novel strategy to design iodine adsorbents, aimed at addressing the storage challenges of iodine adsorption products susceptible to hydrolysis.

The treatment of radioactive iodine vapor faces challenges due to the development of new adsorbents and efficient capture technologies. Here, rice husk-derived carbon/nanosilver (Ag@RC) composites were synthesized using rice husk-derived carbon (RC) as support and developed to efficiently adsorb iodine vapor. The effects of the Ag content, iodine concentration, adsorption temperature and time on the iodine adsorption performance of the obtained Ag@RC materials were investigated. Furthermore, the cooperative interaction between Ag and C components on iodine adsorption were also studied. The obtained Ag@RC materials exhibited a record-breaking iodine vapor adsorption capacity attributed to the synergistic adsorption effect of Ag and C. Particularly, the adsorption capacity of 1292 mg/g was achieved by the 15 %Ag@RC material. The results of adsorption kinetics, XRD, EDS and XPS analyses confirmed the existence of chemical adsorption. The chemical adsorption process involved the reaction of I2 with Ag to form AgI. The results indicated that the resulting Ag@RC materials may be potential adsorbent for iodine vapor capture.

The development of cost-effective and reusable adsorbents for radioactive iodine capture remains an interesting challenge. Herein, a cuprous oxide-silica composite (Cu2O@SiO2) was obtained by a simple reduction method, and the influence of temperature, contact time and iodine concentration on the adsorption performance of Cu2O@SiO2 material were systematically evaluated. The results demonstrated that the Cu2O@SiO2 material exhibited excellent adsorption capacity (897 mg/g) within a short period of time (60 min), and the final product of the adsorption process eventually existed in the stable form of CuI (Cu2O+I2-*2CuI+1/2O2). Moreover, the adsorbed material (I2-Cu2O@SiO2) could be effectively regenerated through a simple reduction process. The regenerated material exhibited outstanding reusability, maintaining over 91% of its initial capacity across ten consecutive cycles. These findings demonstrated that the Cu2O@SiO2 material exhibited significant potential for the safe management of radioactive iodine, offering a promising solution for environmental protection.

The adsorption of iodine and methyl iodide is a challenging topic that has attracted the attention of many researchers. In this article, a N-rich amino functionalized mesoporous SBA-15 (NH2@FS) was prepared by a simple impregnation method and applied for the adsorption of I2 and CH3I gas. The adsorption of I2 and CH3I gas was conducted under conditions close to real spent fuel reprocessing (150 degrees C), and the adsorption capacity of the obtained NH2@FS sample for I2 and CH3I can reach 1778 and 656 mg/g, respectively. It can be found that the N atom of amino group provided a lone pair of electrons, which combined with I to form protonated nitrogen species (N+). Meanwhile, the adsorbed I was presented as polyiodide in the I2-NH2@FS (I3- and I5- ) and CH3INH2@FS (I3- ) samples. These findings suggested that the obtained NH2@FS sample could be considerable potential adsorbent for the adsorption of I2 and CH3I gas.

Tin-based materials are promising for iodine capture. However, they suffer from the instability of adsorption product SnI4 that is easily hydrolyzed even in atmospheric environment due to the presence of moisture. Herein, we report a strategy of constructing the hydrophobic microenvironment on Sn0@SBA-15 materials, which isolates moisture and subsequently stabilizes SnI4. Hydrophobic Sn0@SBA-15 materials (P-Sn0@SBA-15) were fabricated by polymethylhydrosiloxane (PHMS) modification and applied for iodine capture. The obtained P-Sn0@SBA-15 exhibited a record high iodine adsorption capacity (2599mg/g) among inorganic adsorbents. The dominant adsorption mechanism was found that Sn0 reacted with I2 to form SnI4. Remarkably, SnI4 in P-Sn0@SBA-15 was stable up to 3 months exposure to humid atmosphere, while almost all SnI4 in Sn0@SBA-15 was hydrolyzed. The obtained P-Sn0@SBA-15 could be added to the list of iodine adsorbents due to its excellent adsorption capacity and stability. Moreover, the facile strategy could provide reference for the development of other functional materials.

Silicon carbide reticulated porous filters are widely used in steel and alloy smelting industries. However, the hollow voids and microcracks in the ceramic skeletons, caused by the burnout of polymer templates, negatively impact the strength, thermal shock resistance, and corrosion resistance of the filters. In this study, the replica template method was employed with slurries containing novel carbon-silicon microspheres to reconstruct the microstructure of the silicon carbide skeleton and enhance the performance of the filters. The incorporation of carbon-silicon microspheres significantly improved the flowability and structural reconstruction ability of the slurry, resulting in a more homogeneous coating layer within the template. After sintering at 1550 degrees C, silicon carbide whiskers were in-situ generated within the hollow voids, microcracks, and on the surface of the silicon carbide skeleton, thereby improving compressive strength and thermal shock resistance. Additionally, the poor wettability between the sample and molten copper enhances the fluidity of the copper solution within the filter, effectively preventing it from adhering to the ceramic filter. This reduces the risk of blockage and minimizes the potential for corrosion of the ceramic filter by the molten copper.

Developing new matrix for efficient actinides immobilization is of great significance for the sustainable development of nuclear energy. Herein, novel ZrSiO4-borosilicate glass-ceramics (Z-B) were prepared for immobilization of cerium (Ce) as the simulated tetravalent actinides. The effect of Ce content on the phase transformation and microstructure of the obtained Z-B was investigated, and the loading capacity limit of Ce was evaluated. The results demonstrated that Z-B glass-ceramics with high ZrSiO4 phase (91 wt%) was obtained. Owing to the synergistic effect of ZrSiO4 and borosilicate glass phases, the loading capacity limit of Ce in the obtained Z-B reached up to 12 at%. Furthermore, the obtained Z-B waste forms exhibited excellent aqueous durability. The results of this work demonstrated that the Z-B is potential matrix for immobilization of tetravalent actinides due to their good loading capacity and aqueous durability.

Carbon refractory bricks are critical materials for blast furnace hearths, where they must withstand increasingly harsh operating conditions due to the continuous intensification of the furnace environment. To meet the growing performance demands, optimizing the microstructure of these bricks has become essential. In this work, graphitic carbon microspheres were synthesized through hydrothermal carbonization and catalytic graphitization of sucrose wastewater (industrial waste). The rheology of the wastewater was optimized by adding a dispersant, and the influence of dispersant content on the rheological behavior of the wastewater was investigated. The study also explored the relationship between the rheology of wastewater and the structure and size of the resulting graphitic carbon microspheres. These microspheres were then used to replace calcined anthracite coal as raw materials for the preparation of carbon refractory bricks. The effects of the microsphere particle size on the phase composition, microstructure, bulk density, compressive strength, and thermal conductivity of the carbon refractory bricks were analyzed. The results show that an increase in the dispersant content consistently increases the viscosity of the wastewater, which correspondingly leads to a continuous decrease in the particle size of the microspheres. Compared to carbon refractory bricks made with calcined anthracite coal, those prepared with graphitic carbon microspheres demonstrated significant improvements in bulk density, compressive strength, thermal conductivity, and resistance to hot melt corrosion. Furthermore, as the particle size of the graphitic carbon microspheres was reduced from 5.8 mu m to 3.8 mu m, the bulk density, compressive strength, and thermal conductivity of the carbon refractory bricks improved, reaching 1.76 g/cm3, 64.1 MPa, and 11.2 W/m center dot K, respectively, compared to the initial values of 1.74 g/cm3, 60.6 MPa, and 10.9 W/m center dot K. In addition, their resistance to hot melt corrosion improved. However, when the particle size of the graphitic carbon microspheres decreased further, the performance of the carbon refractory bricks began to deteriorate.

In this study, the microporous structure of carbon refractory bricks was enhanced through the incorporation of innovative graphitic-silica microspheres with high chemical reactivity. These microspheres were synthesized via hydrothermal carbonization and catalytic graphitization, using silica sol and sucrose wastewater as raw materials. The elemental distribution and morphology of the products obtained through hydrothermal carbonization and catalytic graphitization were analyzed. Building on these findings, the effects of varying graphitic-silica microsphere contents on the phase composition, microstructure, physical properties, molten iron corrosion resistance, and high-temperature carbon dioxide corrosion resistance of the samples were investigated. Compared to samples without graphitic-silica microspheres, those containing the microspheres exhibited in-situ formation of SiC whiskers within the pores, creating a network structure that effectively subdivided the macropores and increased microporosity. Furthermore, these samples demonstrated significant improvements in density, compressive strength, thermal conductivity, and resistance to both molten iron corrosion and high-temperature carbon dioxide corrosion. As the microsphere content increased from 2 wt% to 8 wt%, the sample properties initially improved and then declined. At the optimal microsphere content of 4 wt%, the samples achieved a porosity of 7.5 %, a density of 1.78 g/cm3 , a compressive strength of 69.4 MPa, a thermal conductivity of 11.53 W/m & sdot;K, and excellent resistance to molten iron and carbon dioxide corrosion. This study offers an effective approach to improving the performance of carbon refractory bricks.

This study prepared gradient pore structure ceramics from silica fume through direct foaming. The rheological behavior of the slurry was improved by varying the solids content. Physical and mathematical models were developed to describe the longitudinal movement of foam in the ceramic slurry and the mechanism of gradient pore formation. These models were used to predict the pore sizes at different heights within the ceramic. Insulation and mechanical properties were enhanced by optimizing the gradient pore structure. The gradient pore structure resulted in significant directional differences in specimen properties. Additionally, suitable sintering-temperatures for gradient pore structure ceramics are discussed. The results indicate that gradient pore structure ceramics were prepared when the solid content ranged from 55 wt% to 62.5 wt%. After sintering at 900 degrees C, the shrinkage was 2.06 %. The apparent porosity and bulk density were 70.82 % and 0.59 g/cm3 . The Flexural strength in the two directions is 0.89 MPa and 1.22 MPa, while the compressive strengths were 2.07 MPa and 4.10 MPa. The thermal conductivity of the ceramics showed a gradient variation from 0.13 to 0.117 W/(m & sdot;K) from the top to the bottom. The coefficient of thermal expansion reached a maximum value of 5.565 x 10- 6 & sdot;1/degrees C at 200 degrees C.

Developing new matrices capable of simultaneous immobilization of lanthanides and actinides are challenging. Herein, this paper reported the ZrSiO4-based borosilicate glass-ceramics with excellent immobilization capabilities of lanthanides and actinides. The phase evolution and microstructure transformation affected by the (Nd, Ce)-co-doping content were investigated systematically. The results indicated that the solubility limits of Nd and Ce in the obtained glass-ceramics decreased with increasing temperature, which were up to 18, 16 and 10 at% at 1400 degrees C, 1450 degrees C and 1500 degrees C, respectively. The formation rate of ZrSiO4 increased with the increase of the (Nd, Ce)-co-doping content and temperature, which reached the highest value of 96.43 wt% with Nd and Ce content of 10 at% at 1500 degrees C. The densification of the obtained glass-ceramics also increased with the increase of the content of Nd and Ce. In addition, it was found that the immobilization mechanism of the resulting glass-ceramics was the synergistic immobilization effect of the ceramic crystal and glass network. This work indicated that the ZrSiO4-based borosilicate glass-ceramics might be promising matrices for immobilizing high-level radioactive wastes containing lanthanides and actinides.

Zirconolite and pyrochlore have been considered as the potential immobilization matrix materials of minor actinides due to their high solubility, radiation tolerance and chemical durability. In this work, a series of xHo2xZr1-xTi2O7 (0.1 <= x <= 1.0) ceramics were prepared by solid state synthesis and sintering at 1400 degrees C for twice. Powder X-ray Diffraction (XRD), Backscattered Scanning Electron Microscopy with Energy-Dispersive ray spectroscopy (BSEM-EDX), Transmission Electron Microscopy (TEM) were employed to investigate the phase evolution, solubility, and substitution mechanism of Ho. The results displayed that zirconolite-2M would transformed to zirconolite-4M and then to pyrochlore with increasing Ho concentration. The initial phase transformation of zirconolite-2M to zirconolite-4M, subsequently zirconolite-4M to pyrochlore were observed x = 0.2 and 0.4 samples, respectively. Zirconolite-4M could be synthesised at x = 0.38 sample with trace perovskite. Moreover, the semi-quantitively solubility limits of Ho in zirconolite-2M and zirconolite-4M were determined to be 27 and 41.5 at.%, respectively. Single-phase pyrochlore were fabricated after 70 at.%. addition, the novel substitution mechanism was revealed by Rietveld refinement with Ho preferentially replacing the Ca of zirconolite-2M so that some replaced Ca occupied vacant Zr site. For pyrochlore, Ho, Ca and occupied A site (16d) and Ti entered in B site (16c). The findings would provide more insights into zirconolite-pyrochlore ceramic system.

The low thermal conductivity and high chemical stability of corundum-mullite refractories have garnered attention for high-temperature insulation and acid-corrosion-resistant applications. A 3D extrusion-based method (direct ink writing) utilizing clay-alumina-silica fume foaming inks was employed to create corundum-mullite refractories with controllable structures (non-porous surface, porous interior). The rheology and printing ability of the inks were modified by adjusting the additives (dispersant and foaming agent) content. Printing parameters, specifically pressure and nozzle moving speed, were adjusted to enhance the precision of the printed construction. The impact of extrusion pressure in the ink on the surface structure of printed products was also investigated. The properties of the corundum-mullite refractory were evaluated by heating it from 1200oC to 1500oC, resulting in improvements in acid corrosion rate (from 1.9% to 14.7%), thermal conductivity (from 0.35 to 1.65W/m·K), and compressive strength (from 20.1 to 45.5MPa), respectively. The Ashby-Glicksman model (closed pore) was employed to forecast the thermal conductivity of the porous refractory with complex pore structures, proving to be a beneficial choice. After acid corrosion for 12h, there were minimal microcracks and pores on the surface of the refractory prepared at 1500oC, and the acid corrosion rates were less than 3.4%. This study illustrates the effectiveness of optimizing printing parameters to adjust pore structure and enhance refractory properties.

In this study, we successfully applied an external magnetic field for the first time in preparing oriented steel fiber reinforced mullite castable (OSFRMC). The impact of the castable's rheology, duration of exposure to the magnetic field and strength of the magnetic field on the orientation of steel fibers and the properties of the refractory castable was investigated. When the duration of exposure to the magnetic field was set at 60 seconds and the strength of the magnetic field was 2.5 mT, an orientation index of steel fibers in the refractory castable of 0.96 was achieved. This specific castable contained 6 wt% of microsilica. Moreover, the castable with a high orientation index (0.96) of steel fibers exhibited significant improvement in mechanical strength and thermal shock resistance compared to the untreated castable. In order to investigate the fracture behavior of steel fiberreinforced refractory castables with different fiber orientations, a comparative study was conducted using forcedisplacement curves and digital image correlation techniques. The primary factor behind this improvement is the directional alignment of steel fibers, which enhances the bridging effect and crack deflection toughness within the material.

The development of matrix with high capacity and stability immobilization of nuclear waste is highly desirable. Herein, new type of zircon-based borosilicate glass-ceramics (ZBGC) with high immobilization capacity and excellent aqueous stability was prepared and applied to immobilize simulated trivalent actinide (Nd). The effects of Nd doping and sintering temperature on the microstructure and phase composition of the obtained ZBGC were researched. The experimental suggested that high ZrSiO4 formation rate (97.49 wt%) was obtained by tuning the Nd content and sintering temperature. The record high immobilization capacity of Nd in ZGBC (18 at%) was achieved owing to the synergistic effect between the crystal lattice and glass network immobilization. Additionally, the obtained Nd-doped ZBGC exhibited excellent aqueous stability (similar to 10(-6) g m(-2) d(-1)) due to the high compactness. The results demonstrated that ZBGC with high immobilization capacity and aqueous stability could be potential matrix for actinides immobilization.

During the traditional preparation of zircon, higher sintering temperatures and longer holding times are inevitable. A novel hydrothermal-assisted sol-gel process and microwave sintering (HM, microwave sintering precursors derived from hydrothermal-assisted sol-gel process) were provided to prepare zircon ceramics hereof. The influences of sintering temperature and holding time on the phase composition, microstructure, and compactness of ceramics were investigated. Data display that the properties of the obtained ceramics were highly dependent on the temperature and time, and the ZrSiO4 formation efficiency can be improved by increasing these two factors. The sample prepared by the HM process has the formation efficiency of ZrSiO4 up to 91.74 wt% (HM-1350-300), which far exceeds that of conventional microwave sintering (M-1350-300, 45.02 wt%). The results demonstrate that the HM process can be employed to obtain ZrSiO4 ceramics rapidly at low temperatures.

Fe-Si3N4 was introduced to improve the service performance of corundum-based dry vibratable refractories in the casting industry, specifically enhancing their thermal shock resistance and resistance to slag corrosion. The study analyzed the effects of Fe-Si3N4 powder content on the refractories' mechanical properties, phase compositions, slag corrosion resistance, and microstructures. The addition of Fe-Si3N4 facilitated the production of magnesium aluminate spinel in the refractory matrix, while also decreasing the wettability between the molten slag and refractory. Increasing the Fe-Si3N4 content resulted in accelerating the replacing Mg2+ (0.072 nm) with Al3+ (0.053 nm) in the spinel. Simultaneously, Fe3+ (0.055 nm) was effectively dissolved into the alumina crystals. The bulk density, compressive strength, and slag corrosion resistance of the refractories were improved. However, the thermal shock resistance initially increased but then decreased. In industrial tests, a corundum-based dry vibratable refractory with a 1 wt.% Fe-Si3N4 content effectively prolonged the lifespan of an induction melting furnace when used as a lining refractory. Importantly, the refractory did not spall or generate cracks in the matrix after induction melt furnace industrial test.