Pub Date : 2024-03-12DOI: 10.1016/j.jre.2024.03.006
Saeid Taghavi Fardood, Fateme Yekke Zare, Farzaneh Moradnia, Ali Ramazani
The characterization of MgFeO@CeO superparamagnetic nanocomposites was thoroughly investigated using powder X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), dispersive X-ray analysis (EDX), elemental mapping (MAP), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and UV–Vis diffuse reflectance spectroscopy (DRS) analyses. The photocatalytic activity of the synthesized samples was evaluated as a novel magnetic nanocatalyst for degrading Congo red (CR) dye in an aqueous solution under visible light at room conditions. The results demonstrate that the efficiency of photocatalytic degradation is higher than that of absorbance and photolysis. The degradation efficiency of photodegradation is 93% within 49% of total organic carbon removal performance. The prepared MgFeO@CeO magnetic nanocomposites (MNCs) can be easily recovered and recycled for five repeated cycles, demonstrating potential extensive efficiency in magnetic nanocomposites in wastewater and water treatment. The nanoscale morphology of MgFeO@CeO MNCs was characterized as spherical, with a size range of 35–40 nm, utilizing SEM and TEM techniques. The saturation magnetization () of the resulting nanocomposites was analyzed by VSM, revealing a value of 3.58 emu/g. Furthermore, the surface area was determined to be 27.194 m/g using BET analysis, and the band gap was identified as 2.85 eV through DRS analysis.
利用粉末 X 射线衍射 (XRD)、振动样品磁力计 (VSM)、扫描电子显微镜 (SEM)、色散 X 射线分析 (EDX)、元素图谱 (MAP)、透射电子显微镜 (TEM)、布鲁诺-艾美特-泰勒 (BET) 和紫外-可见漫反射光谱 (DRS) 分析，对 MgFeO@CeO 超顺磁性纳米复合材料的特性进行了深入研究。评估了合成样品作为新型磁性纳米催化剂在室内可见光条件下降解水溶液中刚果红（CR）染料的光催化活性。结果表明，光催化降解效率高于吸光和光解效率。光降解的降解效率为 93%，总有机碳去除率为 49%。所制备的 MgFeO@CeO 磁性纳米复合材料（MNCs）可轻松回收并循环使用五次，表明磁性纳米复合材料在废水和水处理中具有潜在的广泛效率。利用 SEM 和 TEM 技术，MgFeO@CeO MNCs 的纳米级形貌特征为球形，尺寸范围为 35-40 nm。利用 VSM 分析了所得纳米复合材料的饱和磁化率（），结果显示其值为 3.58 emu/g。此外，利用 BET 分析确定的表面积为 27.194 m/g，通过 DRS 分析确定的带隙为 2.85 eV。
{"title":"Preparation, characterization and photocatalysis performances of superparamagnetic MgFe2O4@CeO2 nanocomposites: Synthesized via an easy and green sol–gel method","authors":"Saeid Taghavi Fardood, Fateme Yekke Zare, Farzaneh Moradnia, Ali Ramazani","doi":"10.1016/j.jre.2024.03.006","DOIUrl":"https://doi.org/10.1016/j.jre.2024.03.006","url":null,"abstract":"The characterization of MgFeO@CeO superparamagnetic nanocomposites was thoroughly investigated using powder X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), dispersive X-ray analysis (EDX), elemental mapping (MAP), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and UV–Vis diffuse reflectance spectroscopy (DRS) analyses. The photocatalytic activity of the synthesized samples was evaluated as a novel magnetic nanocatalyst for degrading Congo red (CR) dye in an aqueous solution under visible light at room conditions. The results demonstrate that the efficiency of photocatalytic degradation is higher than that of absorbance and photolysis. The degradation efficiency of photodegradation is 93% within 49% of total organic carbon removal performance. The prepared MgFeO@CeO magnetic nanocomposites (MNCs) can be easily recovered and recycled for five repeated cycles, demonstrating potential extensive efficiency in magnetic nanocomposites in wastewater and water treatment. The nanoscale morphology of MgFeO@CeO MNCs was characterized as spherical, with a size range of 35–40 nm, utilizing SEM and TEM techniques. The saturation magnetization () of the resulting nanocomposites was analyzed by VSM, revealing a value of 3.58 emu/g. Furthermore, the surface area was determined to be 27.194 m/g using BET analysis, and the band gap was identified as 2.85 eV through DRS analysis.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"28 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-12DOI: 10.1016/j.jre.2024.03.007
N.S. Al-Bassami
Copper-zinc-nickel (Cu–Zn–Ni) ferrite nanoparticles are used for wastewater treatment technology. However, low degradation efficiency and stability are two main issues that make them unsuitable for actual production needs. In this paper, the citrate-nitrate auto-combustion method was applied for the formation of CuZnNiLaFeO; (0≤≤0.1; step 0.02) (CZNL) nanoferrites. Although the substitution process entails the replacement of a small ion with a larger one, the lattice constant and crystallite size does not exhibit a consistent incremental pattern. This behavior is justified and discussed. The size of all the CZNL ferrite nanoparticles is in the range of 8–12 nm, and the lattice constant is in the range of 8.6230 to 8.4865 nm. The morphological analysis conducted using field emission-scanning electron microscopy (FE-SEM) reveals that the CZNL exhibits agglomerated spherical morphology. The energy dispersive X-ray spectrameter (EDAX) analysis was employed to confirm the elemental composition of CZNL nanoferrites. Since the process entails the substitution of Fe magnetic ions with non-magnetic ions La, the magnetic parameters of CZNL nanoferrites show a general decreasing trend as predicted. At 20 K, saturation magnetization shows an overall drop in its values from 59.302 emu/g at = 0.0–41.295 emu/g at = 0.1, the smallest value of 37.87 emu/g is recorded at = 0.06. the highest coercivity ( = 125.9 Oe) and remanence ( = 13.32 emu/g) are recorded for = 0.08 and = 0.04 nanoferrite, respectvely. The band gap of all the CZNL nanoferrites was determined using the Kubelka–Munk function and Tauc plot for direct permitted transitions. La doping modifies the band gap (within 1.86–1.75 eV), increases light absorption, induces efficient e/h separation and charge migration to CuZnNiLaFeO surfaces. The nanoferrite CuZnNiLaFeO achieves a degradation efficiency of 97.3% for methylene blue (MB) dye removal after just 60 min. After five recycling processes, the nanocatalyst CuZnNiLaFeO is degraded by 95.83%, resulting in a negligible 1.51% decrease in photocatalytic activity efficiency. The new CuZnNiLaFeO has exceptional photocatalytic activity and remarkable stability, making it a promising candidate for applications in wastewater treatment.
{"title":"La3+ substitution-adjusted magnetic and optical properties with enhanced photocatalytic activity and stability of copper zinc nickel ferrites for wastewater treatment applications","authors":"N.S. Al-Bassami","doi":"10.1016/j.jre.2024.03.007","DOIUrl":"https://doi.org/10.1016/j.jre.2024.03.007","url":null,"abstract":"Copper-zinc-nickel (Cu–Zn–Ni) ferrite nanoparticles are used for wastewater treatment technology. However, low degradation efficiency and stability are two main issues that make them unsuitable for actual production needs. In this paper, the citrate-nitrate auto-combustion method was applied for the formation of CuZnNiLaFeO; (0≤≤0.1; step 0.02) (CZNL) nanoferrites. Although the substitution process entails the replacement of a small ion with a larger one, the lattice constant and crystallite size does not exhibit a consistent incremental pattern. This behavior is justified and discussed. The size of all the CZNL ferrite nanoparticles is in the range of 8–12 nm, and the lattice constant is in the range of 8.6230 to 8.4865 nm. The morphological analysis conducted using field emission-scanning electron microscopy (FE-SEM) reveals that the CZNL exhibits agglomerated spherical morphology. The energy dispersive X-ray spectrameter (EDAX) analysis was employed to confirm the elemental composition of CZNL nanoferrites. Since the process entails the substitution of Fe magnetic ions with non-magnetic ions La, the magnetic parameters of CZNL nanoferrites show a general decreasing trend as predicted. At 20 K, saturation magnetization shows an overall drop in its values from 59.302 emu/g at = 0.0–41.295 emu/g at = 0.1, the smallest value of 37.87 emu/g is recorded at = 0.06. the highest coercivity ( = 125.9 Oe) and remanence ( = 13.32 emu/g) are recorded for = 0.08 and = 0.04 nanoferrite, respectvely. The band gap of all the CZNL nanoferrites was determined using the Kubelka–Munk function and Tauc plot for direct permitted transitions. La doping modifies the band gap (within 1.86–1.75 eV), increases light absorption, induces efficient e/h separation and charge migration to CuZnNiLaFeO surfaces. The nanoferrite CuZnNiLaFeO achieves a degradation efficiency of 97.3% for methylene blue (MB) dye removal after just 60 min. After five recycling processes, the nanocatalyst CuZnNiLaFeO is degraded by 95.83%, resulting in a negligible 1.51% decrease in photocatalytic activity efficiency. The new CuZnNiLaFeO has exceptional photocatalytic activity and remarkable stability, making it a promising candidate for applications in wastewater treatment.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"36 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-11DOI: 10.1016/j.jre.2024.03.003
Wei Quan, Longfei Ma, Yanbai Chen, Niuniu Wang, Hubin Luo, Qiang Zheng, Juan Du
In recent years, nanocrystalline magnets based on the critical single domain size theory have received increasing attention. However, nanocrystalline magnets are difficult to enhance the remanent magnetization by forming textures with conventional magnetic field orientation. Texturing of nanocrystalline magnets is usually done using the hot pressing and hot deformation technique, but there are some difficulties in applying this technique to form texture in SmCo systems. To discover and solve the difficulties of obtaining texturized nanocrystalline SmCo-based magnets during the deformation process, samarium cobalt magnets with different degrees of deformation were first experimentally prepared by low strain rate hot deformation method. Then, molecular dynamics simulations were utilized to study the microstructural changes and the multi-phase formation process during hot deformation. The process of deformation together with the reason why it is difficult to form textures in SmCo systems by low-temperature hot deformation is discussed, and the strain energy densities of SmCo multiphase in multiple directions were calculated, which gives a feasible method to form low-temperature hot deformation textures in SmCo systems experimentally.
{"title":"Deformation behavior of SmCo compounds via amorphization and recrystallization","authors":"Wei Quan, Longfei Ma, Yanbai Chen, Niuniu Wang, Hubin Luo, Qiang Zheng, Juan Du","doi":"10.1016/j.jre.2024.03.003","DOIUrl":"https://doi.org/10.1016/j.jre.2024.03.003","url":null,"abstract":"In recent years, nanocrystalline magnets based on the critical single domain size theory have received increasing attention. However, nanocrystalline magnets are difficult to enhance the remanent magnetization by forming textures with conventional magnetic field orientation. Texturing of nanocrystalline magnets is usually done using the hot pressing and hot deformation technique, but there are some difficulties in applying this technique to form texture in SmCo systems. To discover and solve the difficulties of obtaining texturized nanocrystalline SmCo-based magnets during the deformation process, samarium cobalt magnets with different degrees of deformation were first experimentally prepared by low strain rate hot deformation method. Then, molecular dynamics simulations were utilized to study the microstructural changes and the multi-phase formation process during hot deformation. The process of deformation together with the reason why it is difficult to form textures in SmCo systems by low-temperature hot deformation is discussed, and the strain energy densities of SmCo multiphase in multiple directions were calculated, which gives a feasible method to form low-temperature hot deformation textures in SmCo systems experimentally.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"11 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1016/j.jre.2024.02.021
Essam A. Elkelany, Hesham Y. Amin, A. Samir, M.M. EL-Hady, H.H. El-Bahnasawy, Moukhtar A. Hassan
Lanthanum-bearing iron lithium borate glass is a quaternary system for oxide glasses and was prepared via the melt-quenching method. The present article correlates the structure, optical, ligand field and Mössbauer data on iron lithium borate glass containing . The density was measured, while the molar volume was calculated. Other physical parameters are well-described. With increasing the content within the glass network, infrared spectra analysis reveals structural modifications such as the increase in units and the decline in both units and NBO bonds content. Furthermore, optical absorption spectra were measured. The absorption spectra disclose a plethora of electronic transitions that are related to in tetrahedral and octahedral sites, however, phase is not observed in optical spectra, but it has a clear signature in Mössbauer spectra. Besides, the glass absorption edges undergo a clear blue shift, reflecting an increased band gap energy (1.96–2.28 eV). The decline in NBO bonds justifies this trend. Bewitchingly, the values of crystal field splitting are increased, while the values of Racah parameters are decreased. This trend is justified by the decline in NBO bonds and increases electron localization around Fe cations. Mössbauer spectra confirm the existence of in tetrahedral and octahedral sites, while exists in only a tetrahedral state. With increasing content, the isomer shift of in tetrahedral sites changes to be 0.312–0.329 mm/s, while the isomer shift of octahedral is 0.424–0.456 mm/s. These findings coincide with optical data. While the isomer shift of tetrahedral is 0.902–0.911 mm/s. Our results of structural, optical and ligand field associated with Mössbauer spectra open more vistas toward the utility of these samples in the optics realm.
{"title":"Mössbauer, optical and structural properties of [formula omitted] ion in borate glass","authors":"Essam A. Elkelany, Hesham Y. Amin, A. Samir, M.M. EL-Hady, H.H. El-Bahnasawy, Moukhtar A. Hassan","doi":"10.1016/j.jre.2024.02.021","DOIUrl":"https://doi.org/10.1016/j.jre.2024.02.021","url":null,"abstract":"Lanthanum-bearing iron lithium borate glass is a quaternary system for oxide glasses and was prepared via the melt-quenching method. The present article correlates the structure, optical, ligand field and Mössbauer data on iron lithium borate glass containing . The density was measured, while the molar volume was calculated. Other physical parameters are well-described. With increasing the content within the glass network, infrared spectra analysis reveals structural modifications such as the increase in units and the decline in both units and NBO bonds content. Furthermore, optical absorption spectra were measured. The absorption spectra disclose a plethora of electronic transitions that are related to in tetrahedral and octahedral sites, however, phase is not observed in optical spectra, but it has a clear signature in Mössbauer spectra. Besides, the glass absorption edges undergo a clear blue shift, reflecting an increased band gap energy (1.96–2.28 eV). The decline in NBO bonds justifies this trend. Bewitchingly, the values of crystal field splitting are increased, while the values of Racah parameters are decreased. This trend is justified by the decline in NBO bonds and increases electron localization around Fe cations. Mössbauer spectra confirm the existence of in tetrahedral and octahedral sites, while exists in only a tetrahedral state. With increasing content, the isomer shift of in tetrahedral sites changes to be 0.312–0.329 mm/s, while the isomer shift of octahedral is 0.424–0.456 mm/s. These findings coincide with optical data. While the isomer shift of tetrahedral is 0.902–0.911 mm/s. Our results of structural, optical and ligand field associated with Mössbauer spectra open more vistas toward the utility of these samples in the optics realm.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-07DOI: 10.1016/j.jre.2024.02.019
Venkata Lakshmi Borra, Prasanta Jana, P.P. Sahoo, Prakash Venkatesan, Mehmet Ali Recai Önal, Chenna Rao Borra
Rare earth elements (REEs) play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars. Permanent magnets account for a quarter of total global REEs production and have high recycling value. In this study, smelting process was used to selectively oxidize REEs in the permanent magnets by adding FeO. This separates REEs into a slag phase from an iron-rich metallic phase. BO was also added to the system as a flux to lower the slag melting temperature. This minimizes REEs loss to the metallic phase and allows a more efficient phase separation. The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB (NdCeFeB) magnets. At 1350 °C and for 1 h, the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of FeO and 40 wt% of BO. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron. After the selective removal of iron into the metallic phase, REEs are recovered from the slag phase through an acid leaching process allowing >99% of REEs recovery. Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique. The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.
{"title":"Selective recovery of rare earth elements by smelting of magnets","authors":"Venkata Lakshmi Borra, Prasanta Jana, P.P. Sahoo, Prakash Venkatesan, Mehmet Ali Recai Önal, Chenna Rao Borra","doi":"10.1016/j.jre.2024.02.019","DOIUrl":"https://doi.org/10.1016/j.jre.2024.02.019","url":null,"abstract":"Rare earth elements (REEs) play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars. Permanent magnets account for a quarter of total global REEs production and have high recycling value. In this study, smelting process was used to selectively oxidize REEs in the permanent magnets by adding FeO. This separates REEs into a slag phase from an iron-rich metallic phase. BO was also added to the system as a flux to lower the slag melting temperature. This minimizes REEs loss to the metallic phase and allows a more efficient phase separation. The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB (NdCeFeB) magnets. At 1350 °C and for 1 h, the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of FeO and 40 wt% of BO. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron. After the selective removal of iron into the metallic phase, REEs are recovered from the slag phase through an acid leaching process allowing >99% of REEs recovery. Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique. The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"121 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.1016/j.jre.2024.02.020
Hao Qin, Hui Wan, Guofeng Guan
Hydroisomerization of n-alkanes plays an important role in fuel and lubricants processing. Bifunctional catalysts with ultralow platinum loading have recently been reported successively for hydroisomerisation. Herein, the catalysts were prepared successfully with different methods to improve the catalytic performance. The conversion of 0.01%Pt1@CeOx/SAPO-11 prepared by co-calcination method (0.01%Pt1@CS-c) is 71.4%, 25% higher than the other prepared by precipitation method. The turnover frequency per active surface platinum site (TOFPt) of 0.01%Pt1@CS-c is as high as 13115 h–1. Revealed by the X-ray photoelectron spectroscopy (XPS) results, the quality of phase boundary/intersurface between ceria and zeolite is found significantly different. The conjunction quality of phase boundary directly affects the spillover rate of intermediate species, which further leads to an apparent activity difference. In addition, the possible role of ceria in the reaction is discussed, rather than just as a carrier for the active metal atoms.
{"title":"Unusual roles of ceria as the support of a single-atom catalyst in hydroisomerization of n-heptane: Phase boundary acts as transport channels between different active centers","authors":"Hao Qin, Hui Wan, Guofeng Guan","doi":"10.1016/j.jre.2024.02.020","DOIUrl":"https://doi.org/10.1016/j.jre.2024.02.020","url":null,"abstract":"Hydroisomerization of n-alkanes plays an important role in fuel and lubricants processing. Bifunctional catalysts with ultralow platinum loading have recently been reported successively for hydroisomerisation. Herein, the catalysts were prepared successfully with different methods to improve the catalytic performance. The conversion of 0.01%Pt1@CeOx/SAPO-11 prepared by co-calcination method (0.01%Pt1@CS-c) is 71.4%, 25% higher than the other prepared by precipitation method. The turnover frequency per active surface platinum site (TOFPt) of 0.01%Pt1@CS-c is as high as 13115 h–1. Revealed by the X-ray photoelectron spectroscopy (XPS) results, the quality of phase boundary/intersurface between ceria and zeolite is found significantly different. The conjunction quality of phase boundary directly affects the spillover rate of intermediate species, which further leads to an apparent activity difference. In addition, the possible role of ceria in the reaction is discussed, rather than just as a carrier for the active metal atoms.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"104 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140046233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on the previous findings that the presence of hydroxyl groups on the outer surface is crucial for maintaining skeletal stability, we propose a strategy modified Cu/SAPO-34 using Pr ions in this study. Therefore, we conducted several measurements to investigate the effect of Pr ions on the low-temperature hydrothermal stability of Cu/SAPO-34. We find that Pr exists only on the surface of Cu/SAPO-34 as ions and oxides, with Pr ions playing a protective role in occupying surface acidic sites. The addition of small amounts of Pr leads to the re-dispersion of Cu, resulting in improved low-temperature selective catalytic reduction (SCR) activity in the as-synthesized samples. Furthermore, it enhances the resistance to decomposition of the Si–(OH)–Al framework during low-temperature hydrothermal aging, thereby preserving the framework structure and allowing detached active Cu species to return to exchangeable positions, ultimately restoring SCR activity. However, as the Pr content increases, the enhanced acidity causes some structural damage, gradually weakening the protective effect. Our work demonstrates that Pr modification is a simple and effective solution to the issue of poor low-temperature hydrothermal stability in Cu/SAPO-34, providing a promising way for the application of light rare earth elements.
{"title":"Praseodymium effects on great improving low-temperature hydrothermal stability of Cu/SAPO-34 NH3-SCR catalysts","authors":"Xiaojie Yu, Xinyu Li, Chen Wang, Jianqiang Wang, Meiqing Shen, M.D. Tarikul Islam, Gurong Shen","doi":"10.1016/j.jre.2024.02.009","DOIUrl":"https://doi.org/10.1016/j.jre.2024.02.009","url":null,"abstract":"Based on the previous findings that the presence of hydroxyl groups on the outer surface is crucial for maintaining skeletal stability, we propose a strategy modified Cu/SAPO-34 using Pr ions in this study. Therefore, we conducted several measurements to investigate the effect of Pr ions on the low-temperature hydrothermal stability of Cu/SAPO-34. We find that Pr exists only on the surface of Cu/SAPO-34 as ions and oxides, with Pr ions playing a protective role in occupying surface acidic sites. The addition of small amounts of Pr leads to the re-dispersion of Cu, resulting in improved low-temperature selective catalytic reduction (SCR) activity in the as-synthesized samples. Furthermore, it enhances the resistance to decomposition of the Si–(OH)–Al framework during low-temperature hydrothermal aging, thereby preserving the framework structure and allowing detached active Cu species to return to exchangeable positions, ultimately restoring SCR activity. However, as the Pr content increases, the enhanced acidity causes some structural damage, gradually weakening the protective effect. Our work demonstrates that Pr modification is a simple and effective solution to the issue of poor low-temperature hydrothermal stability in Cu/SAPO-34, providing a promising way for the application of light rare earth elements.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"28 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140047826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-01DOI: 10.1016/j.jre.2024.02.017
Sc and Y are key rare earth elements and are widely used in lamp phosphors, lasers and high-performance alloys. However, highly efficient extraction and separation of Sc3+ and Y3+ is laborious, harmful, slow, and costly, strongly necessitating more efficient extraction and separation techniques. Here, we produced hydrated Sc3+- and hydrated Y3+-controlled graphene oxide (GO) membranes and find that both hydrated cations were completely self-rejected by the membrane. By combining this self-rejection effect of the larger hydrated Y3+-controlled GO membrane and the rapid passage of the membrane through the smaller hydrated Sc3+, we proposed a strategy to separate Sc3+ and Y3+ by using a hydrated Y3+-controlled GO membrane. The experimental results show that the permeation rate of Sc3+ exceeds that of Y3+ when the separation factor reaches 4.02, which can be attributed to the interlayer sieving effects of the GO membrane. Our finding illustrates the use of a forward osmosis process with a GO membrane for the efficient separation of Sc3+ and Y3+ by interlayer sieving, which provides a new effective and eco-friendly method for the separation of rare earth elements.
钪和钇是关键的稀土元素，被广泛应用于荧光灯、激光器和高性能合金中。然而，Sc 和 Y 的高效萃取和分离费力、有害、缓慢且成本高昂，因此迫切需要更高效的萃取和分离技术。在这里，我们制备了水合 Sc 和水合 Y 控制的氧化石墨烯（GO）膜，并发现这两种水合阳离子都能被膜完全自排斥。通过将较大的水合 Y 控制 GO 膜的这种自排斥效应与膜快速通过较小的水合 Sc 的效应相结合，我们提出了一种利用水合 Y 控制 GO 膜分离 Sc 和 Y 的策略。实验结果表明，当分离因子达到 4.02 时，Sc 的渗透率超过 Y 的渗透率，这可归因于 GO 膜的层间筛分效应。我们的研究结果表明，使用带有 GO 膜的正渗透过程可以通过层间筛分高效分离 Sc 和 Y，为稀土元素的分离提供了一种新的有效且环保的方法。
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Pub Date : 2024-03-01DOI: 10.1016/j.jre.2024.02.015
Na Jiang, Weiwei Wang, Haoxin Liu, Meiyao Wu, Chunjiang Jia
The activation of CO molecules is a fundamental step for their effective utilization. Constructing high-density oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO. In this work, we prepared a series of 0.5PtCe/AlO ( = 1, 5, 10, or 20) catalysts with varying Ce loading and 0.5 wt% of Pt for the reverse water gas shift (RWGS) reaction. The size of CeO particle increases with Ce loading. Remarkably, the 0.5Pt5Ce/AlO catalyst with an average CeO particle size of 5.5 nm exhibits a very high CO conversion rate (116.4 × 10 mol/(g·s)) and CO selectivity (96.1%) at 600 °C. Our experimental findings reveal that the small-size CeO in 0.5Pt5Ce/AlO possesses a greater capacity to generate reactive oxygen vacancies, promoting the adsorption and activation of CO. In addition, the oxygen vacancies are cyclically generated and consumed during the reaction, which contributes to the elevated catalytic performance of the catalyst. This work provides a general strategy to construct rich oxygen vacancies on CeO for designing high-performance catalysts in C chemistry.
一氧化碳分子的活化是其有效利用的基本步骤。在可还原氧化物表面构建高密度氧空位是活化 CO 的关键。在这项工作中，我们制备了一系列 0.5PtCe/AlO ( = 1、5、10 或 20) 催化剂，这些催化剂中 Ce 的含量和 0.5 wt% 的 Pt 的含量各不相同，用于反向水煤气变换（RWGS）反应。CeO 颗粒的尺寸随 Ce 用量的增加而增大。值得注意的是，平均 CeO 粒径为 5.5 nm 的 0.5Pt5Ce/AlO 催化剂在 600 °C 时表现出极高的 CO 转化率（116.4 × 10 mol/（g-s））和 CO 选择性（96.1%）。我们的实验结果表明，0.5Pt5Ce/AlO 中的小尺寸 CeO 具有更强的生成活性氧空位的能力，从而促进了 CO 的吸附和活化。此外，氧空位在反应过程中循环生成和消耗，这有助于提高催化剂的催化性能。这项工作提供了一种在 CeO 上构建富氧空位的通用策略，用于设计高性能的 C 化学催化剂。
{"title":"Alumina supported platinum-ceria catalyst for reverse water gas shift reaction","authors":"Na Jiang, Weiwei Wang, Haoxin Liu, Meiyao Wu, Chunjiang Jia","doi":"10.1016/j.jre.2024.02.015","DOIUrl":"https://doi.org/10.1016/j.jre.2024.02.015","url":null,"abstract":"The activation of CO molecules is a fundamental step for their effective utilization. Constructing high-density oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO. In this work, we prepared a series of 0.5PtCe/AlO ( = 1, 5, 10, or 20) catalysts with varying Ce loading and 0.5 wt% of Pt for the reverse water gas shift (RWGS) reaction. The size of CeO particle increases with Ce loading. Remarkably, the 0.5Pt5Ce/AlO catalyst with an average CeO particle size of 5.5 nm exhibits a very high CO conversion rate (116.4 × 10 mol/(g·s)) and CO selectivity (96.1%) at 600 °C. Our experimental findings reveal that the small-size CeO in 0.5Pt5Ce/AlO possesses a greater capacity to generate reactive oxygen vacancies, promoting the adsorption and activation of CO. In addition, the oxygen vacancies are cyclically generated and consumed during the reaction, which contributes to the elevated catalytic performance of the catalyst. This work provides a general strategy to construct rich oxygen vacancies on CeO for designing high-performance catalysts in C chemistry.","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"28 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140046232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-29DOI: 10.1016/j.jre.2024.02.008
Jianmin Luo , Wenqin Li , Xinglei Wang , Eric Lichtfouse , Donglan Huang , Xiaoyuan Chen , Yi Zhang , Lejie Zhu , Chuanyi Wang
Reactive oxygen species are essential in photocatalytic water treatment. In this paper, Gd doped carbon nitride (CN) photocatalysts were prepared by simple thermal polymerization for the photocatalytic degradation of tetracycline under visible light irradiation. The photodegradation rate of 1.0GdCN is as high as 95% in 18 min, and the photocatalytic performance is much higher than that of CN. The improvement of photocatalytic performance is mainly attributed to the fact that Gd ion implantation directly provides active sites for oxygen activation and induces the formation of N vacancies. The results of characterizations show that the introduction of Gd in CN can improve the conversion ability of activated oxygen, carrier separation and energy band structure adjustment. Therefore, 1.0GdCN photocatalyst can be employed for efficient photocatalytic synthesis of tetracycline. Furthermore, three ways of photocatalytic degradation of tetracycline were revealed by high performance liquid chromatography-mass spectrometry. This work provides insights into the doping strategy of CN to improve the production of reactive oxygen species for environmental remediation.
{"title":"Linker gadolinium as charge channel and singlet oxygen activation site in graphitic carbon nitride for enhancing photocatalytic decomposition of tetracycline","authors":"Jianmin Luo , Wenqin Li , Xinglei Wang , Eric Lichtfouse , Donglan Huang , Xiaoyuan Chen , Yi Zhang , Lejie Zhu , Chuanyi Wang","doi":"10.1016/j.jre.2024.02.008","DOIUrl":"10.1016/j.jre.2024.02.008","url":null,"abstract":"<div><p>Reactive oxygen species are essential in photocatalytic water treatment. In this paper, Gd doped carbon nitride (CN) photocatalysts were prepared by simple thermal polymerization for the photocatalytic degradation of tetracycline under visible light irradiation. The photodegradation rate of 1.0GdCN is as high as 95% in 18 min, and the photocatalytic performance is much higher than that of CN. The improvement of photocatalytic performance is mainly attributed to the fact that Gd ion implantation directly provides active sites for oxygen activation and induces the formation of N vacancies. The results of characterizations show that the introduction of Gd in CN can improve the conversion ability of activated oxygen, carrier separation and energy band structure adjustment. Therefore, 1.0GdCN photocatalyst can be employed for efficient photocatalytic synthesis of tetracycline. Furthermore, three ways of photocatalytic degradation of tetracycline were revealed by high performance liquid chromatography-mass spectrometry. This work provides insights into the doping strategy of CN to improve the production of reactive oxygen species for environmental remediation.</p></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 5","pages":"Pages 827-837"},"PeriodicalIF":4.9,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140045962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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