Hydrothermal synthesis and luminescent properties of Y2O3:Eu3+ from waste phosphors

Europium-doped yttrium oxide (Y2O3:Eu3+) phosphors were successful synthesized by hydrothermal method from waste phosphors in the presence of sodium citrate. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. The experimental results showed that the morphology and photoluminescent properties of the obtained samples had a strong dependence on the concentrate of sodium citrate, the addition amount of NaOH and Eu in the hydrothermal process. Well-dispersed Y2O3:Eu3+ hexagonal microdisk with average diameter of 2 μm were synthesized in the presence of 6 mol% Eu, 37.5 mmol NaOH, molar ratios of Cit3−:Y3+ = 1:1. The photoluminescence properties measurement reveled that Y2O3:Eu3+ phosphors showed a strong red emission corresponding to 5D0–7F2 (613 nm), suggesting promising application in optoelectronics. Keywords: Hydrothermal synthesis, Y2O3:Eu3+, Morphology, Photoluminescence, Waste phosphor

Effect and mechanism of surface pretreatment on desulfurization and desilication from low-grade high-sulfur bauxite using flotation

Surface pretreatment using a hot alkaline solution was carried out to improve the effect of desulfurization and desilication on low-grade bauxite with high sulfur content. The results demonstrated that, after surface pretreatment, a maximum grade and recovery of 66.17% and 87.27%, respectively, were achieved, and the sulfur content and ratio of A/S were 0.19% and 7.09, respectively. The surface pretreatment mechanism was further analysed by XRD and SEM analyses. The improved results of desulfurization and desilication were attributed to the selective corrosion of aluminosilicate minerals in coarse particles, reducing the active silicon sites on the surface of coarse particles as well as enhancing the cation exchange between the collector and aluminosilicate minerals

Recycling Y and Eu from Waste Fluorescent Powder and High Temperature Solid-State Synthesis of Y2O3:Eu Phosphors

Y2O3:Eu were prepared through precursors synthesized by leaching tests, removing impurities, enrichment of Y and Eu from residual purified liquors, annealing treatment, and high temperature solid-state reaction method, which is the most suitable for large-scale production. The analysis of product shows that the purity is 99.42%. The resultant powders were characterized by X-ray diffraction (XRD), differential thermal analysis (TG-DTA), scanning electron microscope (SEM), and photoluminescence (PL). Compared with the commercial phosphors, the XRD spectrum of the product samples revealed the synthesized particles to have a pure cubic Y2O3:Eu structure without any impurities in the crystalline phase. On the morphology, the Y2O3:Eu particles synthesized by a combustion and high temperature solid state process with sintering aids, were large and uniform. For luminescence property, the emission intensity of Y2O3:Eu phosphors synthesized by combustion process and high temperature solid state process with sintering aids were higher than those without sintering aids, at 1400 °C

Reverse anionic flotation of dolomitic collophanite using a mixed fatty acid collector : adsorption behavior and mechanism

Collophanite in south China generally has a high MgO level, which negatively impacts wet-process phosphoric acid production and cannot be utilized directly. A novel mixed fatty acid soap (GSWF01) was employed as a collector for dolomite. A single reverse flotation experiment was performed on a dolomitic collophanite from Guizhou, China under different pH and collector dosages. A phosphate concentrate with P2O5 grade of 33.73%, MgO content of 1.07%, MER value (ω(MgO+Al2O3+Fe2O3)/ω(P2O5)) of 4.86% and phosphorus recovery of 91.06% was obtained. The beneficiation indexes of GSWF01 were better than that of sodium oleate (NaOL). The adsorption behavior and mechanism of GSWF01 on dolomite surface were investigated using quartz crystal microbalance with dissipation (QCM-D), atomic force microscope (AFM), infrared spectrometer (IR), and zeta potentiometer. The results revealed that GSWF01 chemically reacted with metal ions (Ca2+, Mg2+, etc.) on the surface of dolomite to generate fatty acid salt precipitation (chemisorption). The adsorbed layer transitioned from dense to loose in two stages, resulting in a stable double-layer adsorption structure. Moreover, in a weak acidic solution environment, physical adsorption of fatty acid molecules (RCOOH ((aq)) and fatty acid ion-molecular association compounds (RCOOH• RCOO-) generated by hydrolysis can also occur on the dolomite surface. These are the main reasons for the hydrophobic floating of dolomite. This is of great significance to the development of a novel high-efficiency dolomite collector and the enhancement of flotation process for carbonate collophanite

Recovering Y and Eu from Waste Phosphors Using Chlorination Roasting—Water Leaching Process

Recovering Y and Eu from waste phosphors using chlorination roasting followed by a water leaching process was investigated in this study. Firstly, by chlorination roasting and water leaching, Y and Eu elements present in waste phosphors were efficiently extracted into a leach solution. Secondly, the majority of the impurities in the solution can be removed by adjusting the pH to 4.5 using a Na2S and NH3·H2O solution. Thirdly, the rare earths can be precipitated afterwards by adding a H2C2O4 solution and adjusting the pH to 2.0. Then rare earth oxides (REOs) can be obtained after calcining at 800 °C for 1 h. The characterization study of the waste phosphors and the rare earth oxide products was performed by XRD, XRF, and SEM-EDS analysis to determine the phase and morphological features. Influences of the factors, such as roasting temperatures and time, the addition of ammonium chloride on the roasting of waste phosphors, as well as the pH and the amount of oxalates on the precipitation of Y and Eu, were investigated. The maximum grade (99.84%) of mixed rare earth oxides and recovery rate (87.35%) of Y and Eu were obtained at the optimized conditions

The mechanism study on aryl-substituted aromatic acid ionic liquid as the collector for quartz flotation

An aryl-substituted aromatic acid ionic liquid (M-X) was synthesized through hexadecyl trimethyl ammonium bromide and sodium salicylate, and it was employed as a flotation collector for the separation of quartz from magnetite. Laboratory flotation studies of magnetite and quartz were conducted using the M-X and dodecylamine (DDA) as collector. The results showed that the M-X has a stronger collecting ability and selectivity for quartz without starch. The adsorption mechanism of M-X on quartz and magnetite surfaces was studied by Fourier transform infrared spectroscopy (FTIR), zeta potential and X-ray photoelectron spectroscopy (XPS) analysis. Results indicated that the adsorption of M-X on the quartz surface was more efficient than that on the magnetite surface. And the salicylate anion in M-X was found to have depression effect to magnetite

XRCC1 Arg194Trp and Arg280His Polymorphisms in Bladder Cancer Susceptibility: A Meta-Analysis

The XRCC1 Arg194Trp and Arg280His polymorphisms were likely to be involved with the development of bladder cancer. However, there had been inconsistent reports of association. This meta-analysis of literatures was performed to draw a more precise estimation of the relationship. We systematically searched PubMed, Embase, and Web of Science for relevant articles with a time limit of April 25, 2013. Summary odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association between the two polymorphisms and bladder cancer susceptibility using a random-effects model. This meta-analysis including 14 case-control studies evaluated the associations between the two XRCC1 polymorphisms and bladder cancer susceptibility. Overall, for Arg194Trp, significant associations were found in TT versus CC (OR = 1.78, 95% CI = 1.12-2.82) and the recessive model (OR = 1.71, 95% CI = 1.11-2.65); for Arg280His, significant associations were also found in AG versus GG (OR = 1.63, 95% CI =1.24-2.13) and the dominant model (OR =1.39, 95% CI = 1.07-1.82). When stratified by ethnicity, in Asian population, significant associations were found for Arg194Trp polymorphism in TT versus CC (OR = 2.99, 95% CI = 1.48-6.06), the dominant model (OR = 1.33, 95% CI = 1.03-1.72) and the recessive model (OR = 2.72, 95% CI = 1.36-5.45), and for Arg280His in GA versus GG (OR = 2.13, 95% CI = 1.63-2.97), but no significant associations were found in no-Asian population. This meta-analysis suggested that XRCC1 Arg194Trp and Arg280His polymorphisms were risk factors for increasing bladder cancer in Asian population.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000327166800006&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Biotechnology & Applied MicrobiologyGenetics & HereditySCI(E)8ARTICLE4339-3542

Flotation separation of quartz from phosphorite using an imidazole ionic liquid collector and its adsorption mechanism

In this study, an imidazole ionic liquid (dodecyl-tri-methylimidazolium chloride) was employed as a collector to separate quartz from phosphorite. The micro-flotation experiments of a single mineral found that it had selective collecting ability for quartz than phosphorite. Mixed mineral flotation experiments confirmed that efficient separation results could be obtained using the imidazole ionic liquid as the collector. A concentrate with a 31.44% grade of phosphorite could be obtained with a 0.285 kg/Mg collector dosage at neutral pH, which was much better than the traditional collector dodecylamine. The adsorption mechanism of the imidazole ionic liquid on the surface of phosphorite and quartz was investigated by contact angle and zeta potential measurements, Fourier transform infrared and X-ray photoelectron spectroscopy analyses. These results showed that the adsorption of imidazole ionic liquid at the quartz surface was stronger than that of phosphorite, and the collector adsorbability difference between quartz and phosphorite resulted in the efficient flotation separation. Consequently, the dodecyl-tri-methylimidazolium chloride salt is an effective collector for reverse flotation of quartz from phosphorite

The mechanism study on deep eutectic solvent for desilication of magnetite by reverse flotation

Magnetite reverse flotation using a new deep eutectic solvent synthesized by lactic acid and CTAC as the collector has been investigated in this work. The flotation test results were compared with dodecylamine. The CTAC/lactic acid DES increased the grade of total iron to 66.69%, and the reduce quartz content to 6.67%, which were preferable to dodecylamine (the grade of Fe in the concentrate is 63.47%, and the grade of quartz in the concentrate is 9.13%). The depression performance and adsorption mechanism of CTAC/lactic acid DES on surface of magnetite and quartz are investigated by FT-IR, zeta potential and XPS. The results show that the adsorption of CTAC/lactic acid DES on quartz surface is more effective than that of magnetite. Therefore, deep eutectic solvent is an effective reagent for reverse flotation of magnetite as collector