The Yen Phu (YP) rare‐earth mine, located in Yen Bai, Vietnam, currently reserves 28,000 tons of ... more The Yen Phu (YP) rare‐earth mine, located in Yen Bai, Vietnam, currently reserves 28,000 tons of total rare earth oxides (TREO) with a TREO grade of about 1.16%. A mineralogy study shows the dominance of iron‐oxide‐ and silicate‐bearing minerals in YP ore, whereas xenotime presents as the major rare‐earth metal (REM) bearing mineral. Chemical analyses also exhibit a relatively high proportion of heavy rare earth metals (HREMs) at 41.2%, which suggests the high economic value of YP ores. The factors influencing the flotation involving the pH, the depressant, and the collector dosage were first assessed. Then, a beneficiation flowsheet including grinding, wet magnetic separation, and flotation was recommended and practically conducted to enrich the TREO. The proposed process successfully promoted the TREO grade from 1.16% to 29.70% with a high recovery of 80.31% in the REM concentrates, while a tiny loss of TREO was exhibited in the tailing. The chemical analysis of REM concentrates a...
Nanocapsule composites of C/Ce-co-doped ZnO supported on graphene synthesized by a one-pot hydrot... more Nanocapsule composites of C/Ce-co-doped ZnO supported on graphene synthesized by a one-pot hydrothermal method with a band gap of 2.72 eV were used to enhance the photodegradation of methylene blue under various conditions.
In this study, the CeO2-Fe2O3 mixed oxide catalysts have been prepared by combustion method using... more In this study, the CeO2-Fe2O3 mixed oxide catalysts have been prepared by combustion method using gel-created tartaric acid. The ability of effective carbon monoxide (CO) oxidation to carbon dioxide (CO2) by CeO2-Fe2O3 catalyst under low-temperature conditions was also demonstrated. The calcined CeO2-Fe2O3 material has a porous honeycomb structure and good gaseous absorption-desorption ability. The solid solution of CeO2-Fe2O3 mixed oxides was formed by the substitution of Fe+3 ions at some Ce4+ ion sites within the CeO2 crystal lattice. The results also showed that the calcination temperature and the molar ratio of Ce3+ ions to Fe3+ ions (CF) affected the formation of the structural phase and the catalytic efficiency. The catalytic properties of the CeO2-Fe2O3 mixed oxide were good at the CF ratio of 1 : 1, the average crystal size was near 70 nm, and the specific surface area was about 20.22 m2.g-1. The full conversion of CO into CO2 has been accomplished at a relatively low tempe...
Polyurethane (PU) coating degrades quickly under the irradiation of ultraviolet (UV). Thus, incre... more Polyurethane (PU) coating degrades quickly under the irradiation of ultraviolet (UV). Thus, increasing the durability of the coating is necessary. In this study, porous CeO2-SiO2 nanocomposites (CS-NCs) were used to disperse into the PU matrix. The CS-NCs were prepared by a sol-gel combustion method using polyvinyl alcohol as precursors. Prepared nanocomposites were characterized by x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) as well as Energy dispersive x-ray (EDX) mapping analysis. Next, the prepared nanocomposites were employed for the preparation of PU coatings. The loading of nanoparticles was varied between 0.1% and 2.0%. These coating properties were investigated by using FTIR and UV–vis spectroscopy. As also in this study, these coatings were subjected to UV exposure with accelerated weather testing. The structural changes were characterized by applying FTIR analysis and measuring gloss and color deviat...
Ce doped ZnO nano-catalysts were synthesized by two different methods i.e., hydrothermal and poly... more Ce doped ZnO nano-catalysts were synthesized by two different methods i.e., hydrothermal and polymer gel combustion method, to compare their photodegradation efficiency.
In this study, CeO 2 -Fe 2 O 3 coated SiO 2 nanoparticles were prepared by a sol–gel process. One... more In this study, CeO 2 -Fe 2 O 3 coated SiO 2 nanoparticles were prepared by a sol–gel process. One of the prepared nanoparticles was applied in a formulation of polyurethane film for automotive applications. The loading of nanoparticle was varied between 0.1% and 2.0%. First, these films' properties were investigated by using FTIR and thermal gravimetric analysis. Next, these films were subjected to UV exposure testing. The structural changes were characterized by applying FTIR analysis and measuring water contact angle, gloss, and colour deviation. The results indicate that incorporating nanoparticles into the polymer matrix improves the UV-resistance properties of the polymer matrix. Additionally, the nanoparticles enhanced the polymer film's thermal stability until the temperature was 320 °C. Above this temperature, nanoparticles were catalytically active, which accelerated polymer's decomposition giving residue of lower weight percentage. Overall, polyurethane films with nanoparticle loading levels from 0.1 to 1.0 wt% gave the best UV-resistance performance.
BiTaO4 nanoparticles were successfully synthesized by the gel-combustion method using polyvinyl a... more BiTaO4 nanoparticles were successfully synthesized by the gel-combustion method using polyvinyl alcohol and freshly prepared precursor Ta2O5.nH2O. Materials were characterized by x-ray diffraction and transmission electron microscopy (TEM). With an average grain size of 30 nm, the prepared particle was used to investigate the photocatalytic capacity under the visible light irradiation. The photodegradation process of methyl orange occurred following the pseudo-first order reaction mechanism on the surface of the materials. BiTaO4 nanoparticles which calcined at 750°C presented the best catalytic capacity with the highest rate constant to degrade methyl orange about 5.43 × 10−2 mg l−1 min−1. Besides, the intermediates coming from the photocatalytic degradation of methyl orange were evaluated by liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry (LC/MS). The results showed that the intermediates of degradation reactions of methyl orange were not more toxic than the initial methyl orange. BiTaO4 nanoparticles can mineralize the methyl orange after 60 min of illumination.
The Yen Phu (YP) rare‐earth mine, located in Yen Bai, Vietnam, currently reserves 28,000 tons of ... more The Yen Phu (YP) rare‐earth mine, located in Yen Bai, Vietnam, currently reserves 28,000 tons of total rare earth oxides (TREO) with a TREO grade of about 1.16%. A mineralogy study shows the dominance of iron‐oxide‐ and silicate‐bearing minerals in YP ore, whereas xenotime presents as the major rare‐earth metal (REM) bearing mineral. Chemical analyses also exhibit a relatively high proportion of heavy rare earth metals (HREMs) at 41.2%, which suggests the high economic value of YP ores. The factors influencing the flotation involving the pH, the depressant, and the collector dosage were first assessed. Then, a beneficiation flowsheet including grinding, wet magnetic separation, and flotation was recommended and practically conducted to enrich the TREO. The proposed process successfully promoted the TREO grade from 1.16% to 29.70% with a high recovery of 80.31% in the REM concentrates, while a tiny loss of TREO was exhibited in the tailing. The chemical analysis of REM concentrates a...
Nanocapsule composites of C/Ce-co-doped ZnO supported on graphene synthesized by a one-pot hydrot... more Nanocapsule composites of C/Ce-co-doped ZnO supported on graphene synthesized by a one-pot hydrothermal method with a band gap of 2.72 eV were used to enhance the photodegradation of methylene blue under various conditions.
In this study, the CeO2-Fe2O3 mixed oxide catalysts have been prepared by combustion method using... more In this study, the CeO2-Fe2O3 mixed oxide catalysts have been prepared by combustion method using gel-created tartaric acid. The ability of effective carbon monoxide (CO) oxidation to carbon dioxide (CO2) by CeO2-Fe2O3 catalyst under low-temperature conditions was also demonstrated. The calcined CeO2-Fe2O3 material has a porous honeycomb structure and good gaseous absorption-desorption ability. The solid solution of CeO2-Fe2O3 mixed oxides was formed by the substitution of Fe+3 ions at some Ce4+ ion sites within the CeO2 crystal lattice. The results also showed that the calcination temperature and the molar ratio of Ce3+ ions to Fe3+ ions (CF) affected the formation of the structural phase and the catalytic efficiency. The catalytic properties of the CeO2-Fe2O3 mixed oxide were good at the CF ratio of 1 : 1, the average crystal size was near 70 nm, and the specific surface area was about 20.22 m2.g-1. The full conversion of CO into CO2 has been accomplished at a relatively low tempe...
Polyurethane (PU) coating degrades quickly under the irradiation of ultraviolet (UV). Thus, incre... more Polyurethane (PU) coating degrades quickly under the irradiation of ultraviolet (UV). Thus, increasing the durability of the coating is necessary. In this study, porous CeO2-SiO2 nanocomposites (CS-NCs) were used to disperse into the PU matrix. The CS-NCs were prepared by a sol-gel combustion method using polyvinyl alcohol as precursors. Prepared nanocomposites were characterized by x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) as well as Energy dispersive x-ray (EDX) mapping analysis. Next, the prepared nanocomposites were employed for the preparation of PU coatings. The loading of nanoparticles was varied between 0.1% and 2.0%. These coating properties were investigated by using FTIR and UV–vis spectroscopy. As also in this study, these coatings were subjected to UV exposure with accelerated weather testing. The structural changes were characterized by applying FTIR analysis and measuring gloss and color deviat...
Ce doped ZnO nano-catalysts were synthesized by two different methods i.e., hydrothermal and poly... more Ce doped ZnO nano-catalysts were synthesized by two different methods i.e., hydrothermal and polymer gel combustion method, to compare their photodegradation efficiency.
In this study, CeO 2 -Fe 2 O 3 coated SiO 2 nanoparticles were prepared by a sol–gel process. One... more In this study, CeO 2 -Fe 2 O 3 coated SiO 2 nanoparticles were prepared by a sol–gel process. One of the prepared nanoparticles was applied in a formulation of polyurethane film for automotive applications. The loading of nanoparticle was varied between 0.1% and 2.0%. First, these films' properties were investigated by using FTIR and thermal gravimetric analysis. Next, these films were subjected to UV exposure testing. The structural changes were characterized by applying FTIR analysis and measuring water contact angle, gloss, and colour deviation. The results indicate that incorporating nanoparticles into the polymer matrix improves the UV-resistance properties of the polymer matrix. Additionally, the nanoparticles enhanced the polymer film's thermal stability until the temperature was 320 °C. Above this temperature, nanoparticles were catalytically active, which accelerated polymer's decomposition giving residue of lower weight percentage. Overall, polyurethane films with nanoparticle loading levels from 0.1 to 1.0 wt% gave the best UV-resistance performance.
BiTaO4 nanoparticles were successfully synthesized by the gel-combustion method using polyvinyl a... more BiTaO4 nanoparticles were successfully synthesized by the gel-combustion method using polyvinyl alcohol and freshly prepared precursor Ta2O5.nH2O. Materials were characterized by x-ray diffraction and transmission electron microscopy (TEM). With an average grain size of 30 nm, the prepared particle was used to investigate the photocatalytic capacity under the visible light irradiation. The photodegradation process of methyl orange occurred following the pseudo-first order reaction mechanism on the surface of the materials. BiTaO4 nanoparticles which calcined at 750°C presented the best catalytic capacity with the highest rate constant to degrade methyl orange about 5.43 × 10−2 mg l−1 min−1. Besides, the intermediates coming from the photocatalytic degradation of methyl orange were evaluated by liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry (LC/MS). The results showed that the intermediates of degradation reactions of methyl orange were not more toxic than the initial methyl orange. BiTaO4 nanoparticles can mineralize the methyl orange after 60 min of illumination.
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