Jean Claude Jumas

Local structure of glasses in the As2S3Sb2S3 system

The local structure of glasses of composition As 2(1-x) Sb 2x S 3 with x = 0-0.8 is studied by different techniques : 121 Sb Mossbauer spectroscopy, infrared and optical absorption experiments. The results are consistent with a model of the glasses formed by a random distribution of AsS 3 and SbS 3 trigonal pyramidal units connected by sulphur atoms. The variations in the experimental data with Sb 2 S 3 concentration can be correlated with the substitution of Sb atoms for As atoms.

X-ray spectroscopy investigation of the electronic structure of SnSx and Li0.57SnS2 compounds

Abstract Photoemission spectroscopy and X-ray emission spectroscopy have been used to investigate the role of the chemical environment on the electronic structure of SnS, SnS2, Sn2S3 and Li0.57SnS2 compounds. For this purpose, we have studied the Sn 3d5/2 and S 2p1/2,3/2 inner levels and the valence band by photoemission spectroscopy and the S 3p electronic distributions by X-ray emission spectroscopy. We have established fingerprints of the SnII and SnIV valencies in the compounds SnS and SnS2 and have shown that these are observed in Sn2S3 where it is known that both II and IV valencies are present. By comparing the data for Li0.57SnS2 with those for the other compounds, we have demonstrated that the SnII and SnIV signatures are also found in this compound. We have thus ascertained experimentally that Sn is partially reduced in SnS2 upon Li intercalation. In addition, the data have been found to be in excellent agreement with recent densities of electronic states calculations performed in the framework of the density functional theory for the same compounds.

Mössbauer investigation of tin-containing chalcogenide glasses and glass-ceramics

Abstract The parameters of Mossbauer spectra, namely isomer shift, quadrupole splitting and linewidth were obtained before and after crystallization of glass samples of composition xSn0.5Se0.5 (100x) (As0.1Ge0.3Se0.6) with x = 5 ∼ 30 mol.%. It is demonstrated that the higher the crystallinity, the more the isomer shift decreases, this is probably due to the variation of average SnSe bond length. An electric field imbalance in the Sn nucleus caused by distortion of (Sn Se6) octahedra in glasses showed a greater quadrupole splitting as compared with glass-ceramics of the same tin content.

Improvement of the Sorption Characteristics of Diatomite by Heat Treatment

In this paper, the adsorption of Orange Bezaktiv (SRL-150), onto Diatomite treated at 100°C (Dt-100) and at 300°C (Dt-300) was investigated in aqueous solution. The crystalline phases and surface study of Dt-100 and Dt-300 was investigated using respectively XRD, SEM, FTIR, and BET. The effect of operational parameters such as pH, contact time and, initial dye concentration was studied. From the obtained results there is not drastic difference in the crystalline phases between the obtained materials Dt-100 and Dt-300. The treatment at 300°C increases slightly the specific surface area from 11.09 to 16.12 m2/g, and pores volume. The results of adsorption tests show, that the most suitable pH and equilibrium time were respectively 2 and 30 min, at an adsorbent dosage of 2 g/L. The kinetic studies revealed that the adsorption results fitted very well with pseudo-second order model (R2 = 0.99 for both adsorbents). Adsorption isotherms results were in accordance with Freundlich.

Characterization and Recycling of a Low-Coast Derivative Iron Hydroxide Adsorbent

This work presents the possible recovery and reuse, after treatment, of an iron-based sludge from wastewater treatment station in the removal of cadmium in aqueous solution. The sludge sustained a heat treatment (100 and 500°C) and was characterized by XRD, FTIR, BET and SEM witch shown an evolution in the morphology and the structure of the materials indicating the effect of the heat temperature. The material was then applied to remove cadmium in aqueous solution. The results show that the raw material gives the best results with a maximal adsorption capacity of 70.92 mg/g at pH=5.This study has shown us that it is possible to recover and reuse effectively sludge, from wastewater treatment plant, considered as a solid waste, in the removal of a pollutant such as cadmium in aqueous solution.

Bio-Waste Recovery for the Removal of Cr (VI) in Aqueous Solution: Case of the Green Alga Ulva lactuca

This work is in addition to the various works undertaken by the researchers, using biomass as adsorbent. However, the aim of this study is the recovery of a marine material alga: Ulva lactuca) that we were able to transform into adsorbent with treatment under physical carbonization and chemical activation. The ability of treated and untreated Ulvala ctuca, to remove hexavalent chromium Cr (VI) ions in aqueous solutions was investigated. The influence of pH, sorbent dose, initial concentration, temperature, and contact time has been studied in batch process. The materials are characterized by FTIR and SEM analysis. The highest Cr (VI) removals (100%) were achieved at pH of 3, particle size of less than 250μm, dose of 1 g/L, and equilibrium time of 180 minutes. Thermodynamic results indicated that the Cr (VI) adsorption process was spontaneous and exothermic. The adsorption data fit well with Langmuir isotherm model with a maximum adsorption capacities (qmax) of untreated and treated Ulva lactuca were between 0.6 and 2 mg/g. Higher Cr (VI) removal revealed the practical applicability of Ulva lactuca in water and wastewater treatment systems.

Synthesis of New Fluorosulphate Materials Using Different Approaches

Searching for possible new cathode materials with the ability to outperform LiFePO4, our group has recently discovered LiFeSO4F, a novel metal fluorosulphate compound. Needing no further optimization, it delivers excellent reversible capacity (~140 mAh/g) involving a 3.6 V FeII/III redox plateau. This parent fluorosulphate phase has been synthesized by three different routes, namely ionothermal synthesis, solid-state synthesis and polyol-assisted synthesis. These low temperature processing routes are described focusing on synthesis of LiFeSO4F. Furthermore, these methods were successfully employed to unravel other LiMSO4F compounds (M = Co/Ni/Mn/Zn) as well as sodium-based metal fluorosulphate NaMSO4F compounds (M = Fe/Co/Ni/Mn). These syntheses were realized at temperature not exceeding 300°C. We have discovered many interesting and at times intriguing structural, electrochemical and transport properties in these fluorosulphate materials. A few of these findings are illustrated to show the richness of the metal fluorosulphate chemistry.