Treatment of engineering waste slurries by microbially induced struvite precipitation mechanisms

With societal development, the growing scale of engineering construction, and the increase in environmental protection requirements, the necessity of engineering waste mud disposal is becoming increasingly prominent. In this study, microbially induced struvite precipitation (MISP) was introduced to treat engineering waste mud. The study mainly focused on: i) the optimal mineralization scheme for microbially induced struvite precipitation, ii) the feasibility of the process and the effect of reaction parameters on treating engineering waste mud with microbially induced struvite precipitation, and iii) the mechanism of microbially induced struvite precipitation in treating engineering waste mud. The results showed that the waste mud could be well treated with 8.36×106 cell⋅mL−1 bacteria, 10 mM urea, 20 mM phosphate buffer, and 25 mM MgCl2 at pH 7. The kaolin suspension could be effectively flocculated. The flocculation rate reached approximately 87.2% under the optimum mineralization conditions. The flocculation effect was mainly affected by the concentrations of reactants and heavy metals and the suspension pH. The X-ray diffraction (XRD) patterns showed a strong struvite (MAP) diffraction peak. Scanning electron microscopy (SEM) images indicated that under the optimal mineralization conditions, the crystals were large and showed prismatic shapes tilted at both ends with adhered kaolin particles. In summary, this manuscript provides an effective way to treat engineering waste mud, and the findings should have a positive effect on enhancing soil fertility and preventing secondary pollution

Specific trends in phosphate glass crystallization

This paper focusses on investigating and comparing the congruent crystallization of phosphate glasses with different degrees of polymerization. The study was performed both on powders, with different size fractions, and coarse particles which can be assimilated to bulk. From DSC experiments, corroborated by SEM analysis, it was demonstrated that LiPO3 crystallizes from surface whereas LiGe2(PO4)3 crystallizes in the whole volume. Sn2P2O7 presented both phenomena, the nucleation time lag being short enough to observe internal crystallization at the laboratory time scale. Using the non-isothermal Ozawa method, the kinetic parameters of the overall devitrification process were determined in terms of the Avrami exponent and of the activation energy for crystallization. The temperature of the maximum nucleation rate was calculated by using the nucleation adiabatic theory. For the achievement of this calculation, the heat capacity temperature dependence up to melting was determined from DSC experiments. The results were found in a good agreement with the SEM observation and the results of the non-isothermal crystallization study.acceptedVersionPeer reviewe

Matériaux hybrides verres inorganiques / molécules organiques pour des applications light-emmitting electrochemical cells

The light-emitting electrochemical cell (LEC) is a planar layered device, which is comprised of an electroluminescent organic semiconductor (OSC) and mobile ions as the active material sandwiched between an anode and a cathode. Electrolyte is one of the “short slab” of LEC technology. The main objective of this work is developing a new LEC device based on organophosphorus molecule doped organic-inorganic hybrid glass electrolyte. This hybrid glass cannot be synthesized by using classic melt-quenching technique because the melting temperature of glass is always much higher than the degradation temperature of organic molecule. Thus, in this work, we devote to that how to dope the organophosphorus molecule into the glass with high ionic conductivity. In first chapter, the background and mechanism of LEC were introduced. In the second chapter, we attempted to dope the organophosphorus molecule into silicate glass containing high lithium content by sol-gel method. In third chapter, we are working to obtain organophosphorus molecule doped phosphate glass with high ionic conductivity through spark plasm sintering (SPS). A hybrid phosphate glass with ionic conductivity of around 10 -7 S/cm was obtained, and strong photoluminescence was observed. Besides, the electrochemical properties were investigated as well. Moreover, during the process of preparing the LEC by SPS, an interesting phenomenon was found. A broadband blue emission was observed in rare-earth free zinc phosphate oxynitride glass. The fourth chapter is focus on this interesting phenomenon.La cellule électrochimique électroluminescente (LEC) est un dispositif à couches minces, composé d’un semi-conducteur organique électroluminescent (OSC) et d’ions mobiles en tant que matériau actif intercalé entre une anode et une cathode. Dans le premier chapitre, le contexte et le mécanisme de la LEC ont été introduits. Dans le deuxième chapitre, nous avons dopé la molécule organophosphorée dans un verre de silicate contenant une teneur élevée en lithium par la méthode sol-gel. Dans le troisième chapitre, nous avons travaillé à l’obtention d’un verre de phosphate dopé à une molécule organophosphorée avec une conductivité ionique élevée par frittage Spark Plasma Sintering (SPS). Un verre de phosphate hybride ayant une conductivité ionique d'environ 10 -7 S / cm a été obtenu et une forte photoluminescence a été observée. En outre, les propriétés électrochimiques ont également été étudiées. De plus, lors du processus de préparation de la LEC par SPS, un phénomène intéressant a été découvert. Une émission bleue à large bande a été observée dans le verre d’oxynitrure de phosphate de zinc exempt de terres rares. Le quatrième chapitre est consacré à ce phénomène

Enhanced luminescence of manganese in singly doped white light zinc phosphate glass

International audienceOn the basis of a kind of zinc phosphate oxynitride glass matrix with a broadband blue light, a series of manganese single-doped glasses were obtained. A broader red emission with the higher intensity belonging to the Mn2+ ion was observed in this glass matrix. The mechanism of the emission from Mn2+ ions was clarified through Mn3+ as an "energy acquisition probe" to replace complex dynamic luminescence discussion, which was a fit explanation for the differences in luminescence behavior of Mn ions in prepared glasses at different degrees of redox. The research results indicated that the prepared manganese-doped glass was a potential candidate as phosphor-converted white-light-emitting diodes. An encapsulated white-light-emitting diode device based on this glass with 276 nm ultraviolet chip was achieved. It showed the CIE values of (0.33, 0.35), high CRI (Ra = 86), and low color temperature (5228 K)

Novel ultra-wideband fluorescence material: Defect state control based on nickel-doped semiconductor QDs embedded in inorganic glasses

In recent years, the development of an environmentally friendly quantum dots (QDs) embedded luminous solid by a simple method has attracted considerable attention. In this study, semiconductor ZnS QDs were successfully prepared in an inorganic matrix of amorphous glass, which yielded beneficial broad-band emission in the long-wavelength region of the visible range. The strong red emission belonged to the defect state energy level of the ZnS QDs, which could be enhanced by incorporation of nickel ions into the fixed matrix to regulate the defects state. The novel material had a small self-absorption, wide excitation and emission ranges, and thus potential applications in light-conversion devices, luminescent solar concentrators, and solar cell cover glasses

Highly Efficient 2.84-mu m Emission in Ho3+/Yb3+ Co-Doped Tellurite-Germanate Glass for Mid-Infrared Laser Materials

International audienceThe use of Yb3+ co-doping with Ho3+ to enhance the Ho3+: I-5(6) -> I-5(7) similar to 2.84-mu m emissions is investigated in the tellurite-germanate glasses. An intense similar to 2.84-mu m emission with a full width at half maximum (FWHM) of 132 nm is achieved in the Ho3+/Yb3+ co-doped tellurite-germanate glass upon excitation at 980 nm. The glass not only possesses considerably low OH-absorption coefficient (0.206 cm(-1)), but also exhibits 2.84-mu m large emission cross section (14.6 x 10(-21) cm(2)). Moreover, the measured lifetime of Ho3+: I-5(6) level is as high as 0.283 ms. Results reveal that Ho3+/Yb3+ co-doped Tellurite-germanate glass is an attractive host for developing a mid-infrared 3-mu m solid-state laser

Tm3+-doped lead silicate glass sensitized by Er3+ for efficient similar to 2 mu m mid-infrared laser material

International audienceEr3+/Tm3+ co-doped lead silicate glasses with low phonon (953 cm(-1)) and good thermal stability were synthesized. The similar to 2 mu m mid-infrared emission resulting from the F-3(4) -> H-3(6) transition of Tm3+ sensitized by Er3+ has been observed by 808 nm LD pumping. The optimal luminescence intensity was obtained in the sample with 1Tm(2)O(3)/2.5Er(2)O(3) co-doped. Moreover, the energy transfer mechanism from Er3+ to Tm3+ ion was analyzed. Absorption and emission cross section have been calculated. The calculated maximum emission cross section of Tm3+ is 2.689 x 10(-21) cm(2) at 1863 nm. Microparameters of energy transfer between Er3+ and Tm3+ ions have also been analyzed. These results ensure that the prepared Er3+/Tm3+ co-doped lead silicate glasses have excellent spectroscopic properties in mid-infrared region and provide a beneficial guide for mid-infrared laser material. (C) 2018 Elsevier B.V. All rights reserved

2.8 μm emission and OH quenching analysis in Ho3+ doped fluorotellurite-germanate glasses sensitized by Yb3+ and Er3+

Abstract The use of Yb3+ and Er3+ co-doping with Ho3+ to enhance and broaden the Ho3+: 5I6 → 5I7 ~2.8 μm emissions are investigated in the fluorotellurite-germanate glasses. An intense ~3 μm emission with a full width at half maximum (FWHM) of 245 nm is achieved in the Er3+/Ho3+/Yb3+ triply-doped fluorotellurite-germanate glass upon excitation at 980 nm. The glass not only possesses considerably low OH− absorption coefficient (0.189 cm−1), but also exhibits low phonon energy (704 cm−1). Moreover, the measured lifetime of Ho3+: 5I6 level is as high as 0.218 ms. In addition, the energy transfer rate to hydroxyl groups and quantum efficiency (η) of 5I6 level were calculated in detail by fitting the variations of lifetimes vs. the OH− concentrations. The formation ability and thermal stability of glasses have been improved by introducing GeO2 into fluorotellurite glasses. Results reveal that Er3+/Ho3+/Yb3+ triply-doped fluorotellurite-germanate glass is a potential kind of laser glass for efficient 3 μm laser

Tunable white light in trivalent europium single doped tin fluorophosphates ultra-low melting glass

International audienceIn recent years, low melting temperature glasses have received wide attention as the hosts of phosphor-converted light emitting diodes (pc-WLED). In this work, a series of trivalent europium doped tin fluorophosphates glasses were prepared by conventional melting method. Under ultraviolet excitation, the blue-green broadband emission from Sn 2+ activation centers in the glass matrix and the red emission of Eu 3+ ions together constituted a cool white luminescence. The spectra analysis was used to demonstrate the energy transfer between Sn 2+ centers and Eu 3+ ions. The results showed that Sn 2+ and Eu 3+ possessed independent intrinsic emission and mutual energy transfer simultaneously. The 5 D 4 and 5 G 2 excited states of Eu 3+ ion favored the energy transfer to Sn 2+ center, the 5 L 6 excited state of Eu 3+ ion would absorb more of the energy by the Sn 2+ ground state excitation to contribute on red emission. Therefore, the fluorescent glass can transform cool white light to warm white light by changing the excitation wavelength. The tunable white light is obtained in the WLED devices built with the glass and commercial UV chips

Investigation of Tm3+/Yb3+ co-doped germanate-tellurite glasses for efficient 2 µm mid-infrared laser materials

International audienceThe Tm3+/Yb3+ co-doped germanate-tellurite glasses with good thermal properties were prepared. Based on the absorption spectra and the Judd-Ofelt theory, the J-O intensity parameters (Omega), radiative transition probability (276.78 s(-1)), fluorescence lifetime (3.89 ms), absorption and emission cross sections (sigma(e)=1.35 x 10(-20) cm(2)) were calculated. The similar to 2 mu m mid-infrared emission resulting from the F-3(4) -> H-3(6) transition of Tm3+ sensitized by Yb3+ was observed pumped by 980 nm LD. Besides, the energy transfer mechanism between Yb3+ and Tm3+ was thoroughly discussed. The measured similar to 2 mu m emission lifetime of Tm3+/Yb3+ co-doped glass can reach as high as 2.38 ms. The above results showed that Tm3+/Yb3+ co-doping glass could be expected to be a promising material to achieve high efficient similar to 2 mu m lasing with a 980 nm LD pumping