Advantages and Limitations of Using FTIR Spectroscopy for Assessing the Maturity of Sewage Sludge and Olive Oil Waste Co-composts

Composts prepared using different solid and liquid organic wastes from various sources can be used as growing media when these materials present adequate proprieties for plant development. The stability and maturity are among the main characteristics of composts. The purpose of this study is to recommend specific bands of the IR spectrum recorded on different composts to enable qualitative and rapid monitoring of the stages of biodegradation during composting. At the beginning of humification, the significant decrease in the intensity of the band located at 1735 cm–1 shows that lignin is affected at the first stage of the composting process. At the end of the humification, the band located toward 3450–3420 cm–1 at the beginning of the process undergoes a systematic shift (Δν of the order of 10 cm–1) toward lower wave numbers. The band located at 1660–1650 cm–1 on the Fourier transform infrared spectroscopy (FTIR) spectra before composting shifts systematically toward 1640 cm–1 at the end of humification. This phenomenon can be used as index of compost maturity. Measuring the band at 1035 cm–1 as an internal standard, it is possible to quantify the degradation rate of organic matter

Contribution a l'etude structurale de la dickite et de la kaolinite par spectrometrie d'absorption infrarouge

SIGLET 55433 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

A study on structural properties, conductivity and FT-IR spectroscopy of Cu–Al doubly substituted Bi4V2O11

The double-substituted solid solutions Bi4V2-xCux/2Alx/2O11-5x/4, with identical quantitative compositions of Cu2+ and Al3+ ions, can occur for a substitution rate 0.1 ​≤ ​x ​≤ ​0.6. The compound with x ​= ​0.1 is found to be a monoclinic α-form of Bi4V2O11, whereas compounds with 0.2 ​≤ ​x ​≤ ​0.6 are found to be tetragonal γ and γ’ polymorphs. We used electrochemical impedance spectroscopy to measure the electrical conductivity of doped samples in the temperature range of 250–700 ​°C. The slope changes observed in the Arrhenius plots might be related to the microstructural transitions occurring in these compounds. The sample with x ​= ​0.2 shows the highest ionic conductivity values

Extraction chimique des métaux lourds des argiles de la décharge finale d’Agoè-Nyivé au Togo

A sufficiently thick layer of clay, continuous and homogeneous under a deposit of waste constitutes a barrier preventing pollution of the water table if the leachates are well drained on its surface and then properly treated.Since the exploitation of the landfill of Agoè-Nyivé (Lomé), very few studies have been carried out on the state of pollution, especially of heavy metals, of the base layer of the clay-filled landfill.The objective of this work, is to evaluate the content of heavy metals (Pb, Cd, Ni, Cu and Zn) in the base layer samples of the final discharge Agoè-Nyivé and evaluate their potential migration to the depths.The qualitative analysis of the clay samples through X-ray diffraction shows the existence of quartz, carbonate and kaolinite with varying proportions from one sample to another. Complementary analysis of the infrared spectroscopy shows spectra that reveal the presence of a kaolinite with bands observed in the vibrational region of the hydroxyls located at 3698, 3652 and 3622 cm-1.The heavy metal contents in the clay samples show that lead and nickel have a strong propensity to bind respectively to the reducible and residual fraction. On the other hand, cadmium has an almost equal distribution in the four fractions while zinc is more present in the exchangeable and acid-soluble fraction with percentages ranging from 18.75 to 76.67 %.The strong presence of heavy metals found in soil fractions where they can be easily mobilized shows the risk of their migration to the depths.Une couche d’argile suffisamment épaisse, continue et homogène sous un dépôt de déchets constitue une barrière empêchant la pollution de la nappe phréatique si les lixiviats sont bien drainés à sa surface puis correctement traités. Depuis l’exploitation de la décharge d’Agoè-Nyivé (Lomé), très peu d’études, ont été réalisées sur l’état de pollution notamment en métaux lourds de la couche de base de la décharge composée d’argile.L’objectif de ce travail est d’évaluer la teneur de certains métaux (Pb, Cd, Ni, Cu et Zn) dans les échantillons de couches de base de la décharge finale d’Agoè-Nyivé afin d’évaluer leur potentielle migration vers la nappe.L’analyse qualitative des échantillons d’argile à travers la diffraction des rayons X, montre l’existence de quartz, de carbonates et de kaolinite avec des proportions variables d’un échantillon à l'autre. Une analyse complémentaire notamment la spectroscopie infrarouge montre la présence d’une kaolinite avec des bandes observées dans la région de vibration des hydroxyles situées à 3698, 3652 et 3622 cm-1.Les teneurs en métaux lourds analysées après extractions sélectives montrent que le plomb et le nickel ont une forte propension à se lier respectivement à la fraction réductible et résiduelle. Par contre, le cadmium a une répartition quasi-égale dans les quatre fractions alors que le zinc est plus présent dans la fraction échangeable et acido-soluble avec des pourcentages variant de 18,75 à 76,67 %.La forte présence des métaux lourds constatée dans les fractions de sol où ils peuvent être facilement mobilisables montre le risque de leur migration vers les profondeurs

MONITORING OF ORGANIC POLLUTION AND MATURITY OF ORGANIC MATTER FROM SLUDGE LANDFILLING

The biotransformation during the 3 years of sludge landfilling was evaluated by physicochemical analysis and phytotoxicity test. The final product exhibited a high degree of decomposition rate (51.06 %) than the controls as shown by a decrease of C/N ratio of about 19.67. The results showed that the lipid, surfactant and polyphenol as main compound of the sludge were breakdown over time. The concentrations decreased from 29.9 to 11.8 mg·g-1 and 3.4 to 0.6 mg·g-1, respectively for surfactant and polyphenols after 3 years of landfilling. This corresponds to a reduction of 80.2 % for polyphenols and 60.4 % for surfactant, due to the microorganisms activity. Total lipids decrease from 16.5 to 6.27 mg·g-1 of dry matter, representing an abatement rate of about 62 %. The evolution of organic matter reflects the progress of the humification process, which judging by the increase in the polymerization degree, is about 20 %. The landfilling efficiency to reduce phytotoxicity of sludge was confirmed by the germination index, which reached 52 and 59 %, respectively for alfalfa and cress after 3 years of landfilling. These results are promising and pave the way for agricultural spreading of sludge

Effect of the doping element on the structure and UV–visible properties in the system Bi4V1.7(Si,Me)0.3O11-δ (Me = Si, P, Cu, and Co)

While BIMEVOX systems have attracted the attention of researchers for their electrical conductivity by O2− oxide ions at relatively low temperatures, there is only a limited number of works concerning their local structure. In this work, the Bi4V1.7(Si.Me)0.3O11-δ (Me = Si, P, Cu, and Co) system is studied using X-ray powder diffraction (XRD), Raman spectroscopy, IR spectroscopy, SEM–EDX, UV–visible spectrophotometry, and differential scanning calorimetry (DSC). The three main polymorphs α, β, and γ are obtained at room temperature. In the case of the Bi4Si0.15P0.15V1.70O11-δ compound, two successive structural transitions were observed, while only one structural transition was observed for the Bi4Si0.30V1.70O11-δ compound. The UV–vis diffuse reflectance spectroscopy (DRS) indicates that the double-doped Bi4V1.7(Si.Me)0.3O11-δ compounds present a band gap energy in the range 1.76 ≤ Eg ≤ 2.36 eV and Bi4Si0.15Co0.15V1.70O11-δ presents the narrowest band gap

New silicon substituted BiMeVOx: synthesis and study of structural properties in relation to ionic conductivity

Partial substitution of vanadium with silicon in the compound Bi4V2O11, which belongs to the Aurivillius family, leads to the creation of a solid solution Bi4V2−xSixO11−δ (0 ≤ x ≤ 0.4). The compound with x = 0.1 turns out to be a monoclinic α-form of Bi4V2O11, while the compounds with x = 0.2 and x = 0.3 are orthorhombic β-polymorphs, and the compound with x = 0.35 is of tetrahedral γ-polymorph. Electrochemical Impedance Spectroscopy has been used to measure the ionic conductivity of doped samples. The ceramic sample with x = 0.1 has the highest ionic conductivity values

High-conducting Bi4V1.8Cu0.2-xSbxO10.7+3x/2 ceramics: Structural, microstructural, electrical and optical properties

The partial substitution of copper by antimony in Bi4V1.8Cu0.2O10.7 compounds leds to the solid solution Bi4V1.8Cu0.2-xSbxO10.7+3x/2 (0.00 ≤ x ≤ 0.20). X-ray diffraction and thermal analysis showed that for all compositions, the obtained phases are isotype to the tetragonal γ or γ′ form of Bi4V2O11. The effect of Sb5+ doping on electrical conductivity was studied using electrochemical impedance spectroscopy in the temperature range 200–700 °C. The changes in slope observed in the Arrhenius plots correspond to the structural transitions that occur within the material. The band gap was determined by DRS spectra, BiCuSbVOx materials have a very low gap band (1.77–1.80 eV) compared to parent phase Bi4V2O11 and the most of BIMEVOX semiconductor materials. The band located around 860 cm−1 in Raman spectroscopy is attributed to V–O bond and more especially to V–O2 bond

Structural study and ionic conductivity of Bi4V2−xSix/2Px/2O11−δ (0.0 ≤ x ≤ 0.5) compounds

The solid solution of general formula Bi4V2−xSix/2Px/2O11−δ (0.0 ≤x≤ 0.5) has been synthesized and characterized by XRD, SEM, FTIR, ATD, Raman spectroscopy and Electrochemical Impedance Spectroscopy. The present study showed that compounds with x ​≤ ​0.3 are isostructural with the monoclinic α polymorph, while the compound with x ​= ​0.4 is crystallize with the β polymorph. In the temperature range from 25 to 700 ​°C, the electrical conductivity of the substituted samples has been measured as a function of composition. In the low temperature range, the conductivity of the doped compounds is higher than that of the parent compound Bi4V2O11. The highest conductivity was obtained for x ​= ​0.1

Effect of simultaneous Cu and Nb doping Bi4V2O11 on structural and electrical properties of Bi4V2−xCux/2Nbx/2O11−3x/4

BiMeVOx compounds Bi4V2-xCux/2Nbx/2O11-3x/4 doubly substituted solid solution, with identical compositions of Cu2+ and Nb5+ ions, show an area of existence from x ​= ​0 to 0.5. X-ray diffraction measurements and thermal analysis have shown that, depending on the composition, the three main Bi4V2O11 polymorphs α, β and (γ/γ′) are observed at room temperature. The evolution of the electrical conductivity with the rate of substitution has been investigated by electrochemical impedance spectroscopy (EIS) in the temperature range 120–720 ​°C. The highest values of conductivity are observed for samples with x ​= ​0.2. Scanning electron microscopy (SEM) shows an important grain growth and the presence of micro-cracks in the ceramics with x ​= ​0.5 composition