Removal of a food dye on two solid supports by adsorption

Activated carbon and natural clay are extremely promising for the removal of dyes in a water solution. Natural clay and activated carbon were characterized using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) techniques, and the food dye was characterized by UV-Visible. The effects of various experimental parameters, such as initial carmine concentration, contact time, temperature and pH were studied. The removal of the dye increases with the decrease in the initial concentration of carmine and the contact time of the solution. The percentage of carmine removal increases accordingly, reaching 97% for activated carbon and 67% for natural clay. Langmuir and Freundlich adsorption models were used for the adsorption equilibrium descriptions. The data was very well corrected with these models. Monolayer adsorption capacities were equal to 31 mgg-1 at pH 8.0 and 27°C. Adsorption measurements show that the adsorption process is very fast and physical in nature. Thermodynamic parameters such as enthalpy ∆H°, ∆S° entropy and ∆G° free enthalpy were also evaluated to reveal the nature of adsorption. The results explain that the adsorption process is an exothermic, spontaneous physisorption

EEffet de P2O5 sur les propriétés diélectriques et piézoélectriques de la solution solide Pb0.98Ca0.02[(Zr0.52Ti0.48)0.98(Cr3+ 0.5, Ta5+ 0.5)0.02]O3

Notre travail a pour objectif, d'étudier l'influence de P2O5 sur les propriétés diélectriques et piézoélectriques d'un matériau en céramique de formule générale: Pb0.98Ca0.02[(Zr0.52Ti0.48)0.98(Cr3+ 0.5, Ta5+ 0.5)0.02]O3 et de structure pérovskite. Les échantillons choisis pour cette étude ont été préparés par la méthode de synthèse à voie solide, un traitement thermique à été appliqué sur ces échantillons à différentes températures (1000 oc, 1050 oc, 1100 oc, 1150 oc, 1180 oc). Différentes techniques de caractérisation ont été utilisées pour cette étude telles que, la diffraction des rayons X, la microscopie électronique à balayage et les mesures électriques. On peut constater que la temperature d’agglomeration du piezoelectrique Pb0.98Ca0.02[(Zr0.52Ti0.48)0.98(Cr3+ 0.5, Ta5+ 0.5)0.02]O3 peut être réduite après l'addition du phosphore sans compromettre les propriétés diélectriques. La densité agglomérée de 96% de la densité théorique a été obtenue pour l’addition de 4% de P2O5 après l’agglomération à 1050 oc pendant 2h. Au-dessus ou en dessous de 4%, montres une densification inférieure

Etude des proprietes dielectriques et piezoelectriques dans le systeme ternaire: Pb0.98Ca0.02(Zr0.52Ti0.48)0.98(Cr3.5,Ta5.5)0.02O3 effet du dopage

In this work, we studied the influence of P2O5 on the crystal structure, the microstructure and the dielectric and piezoelectric properties of a new ceramic material of the general formula: Pb0.98Ca0.02(Zr0.52Ti0.48)0.98(Cr3+ 0.5, Ta5+ 0.5)0.02O3 and of structure perovskite. The samples chosen for this study were prepared by a conventional oxide mixing technique. A thermal treatment was applied on these samples at different temperatures (1000, 1050, 1100, 1150 and 1180 °C). Various techniques of characterization were used for this study such as the X-ray diffraction, the scanning electron microscopy, the atomic force microscopy and electrical measurements. The results indicate that all the ceramics have a perovskite phase of tetragonal and rhombohedral symmetry. The sintering temperature of piezoelectric PZT-CTC can be reduced after the addition of phosphorus without compromising the dielectric properties. The density agglomerated of 94 \% of the theoretical density to been gotten for the addition of 4 wt. \% of P2O5 after the agglomeration to 1050 oC. Above or below 4 wt. \%, show a lower densification. Ceramics sintered at 1050 °C with 4 wt. \% P2O5 achieve excellent properties, which are as follows: kp = 0.73, $\rho$ = 0.09 � 10 (�. cm), $\epsilon$r = 18800, tan$\delta$ = 0.0094 and Tc = 390°C

Microstructural, Dielectric, and Piezoelectric Properties of SFN-modified PZT Ceramics

AbstractThis study described the structural, dielectric, and piezoelectric behavior of (1-x)Pb(Zr0.51 Ti0.49)O3-xSm(Fe0.5, Nb0.5)O3 ceramics (PZT-SFN, x = 0.02, 0.04, 0.06, 0.08 and 0.10), prepared by a high-temperature solid-state reaction technique. X-ray diffraction, dielectric, and piezoelectric investigations were carried out to analyze the crystal structure. Preliminary X-ray structural analysis of the materials at room temperature has confirmed their formation in single-phase with tetragonal crystal structure. SFN-doping increased the sintered density and the average grain size of lead zirconate titanate ceramics. The room temperature dielectric permittivity ɛr, tangent loss tan δ, piezoelectric coefficient d31, electromechanical coupling factor kp, and mechanical quality factor Qm of 0.92PZT–0.08SFN ceramics are 940, 1.43%, 119 pC/N, 67.10%, 326, respectively, which mean it has a great promise for actuator applications

Sintering and Properties of Pb0.98Ca0.02 [(Zr0.52Ti0.48)0,98(Cr3+0.5, Ta5+0.5)0,02] O3 Ferroelectric Ceramics Doped with P2O5

AbstractThe effect of phosphorus additions on the structure, microstructure and dielectrics properties of the Pb0.98Ca0.02[(Zr0.52Ti0.48)0,98(Cr3+0.5, Ta5+0.5)0,02]1-xPx O3 (x ranged from 0.01 to 0.12) ceramics have been investigated. All of the samples were prepared by a high-temperature solid-state reaction technique. AFM analysis of the compounds suggests that the average grain size increases with increasing sintering temperature which is characteristic of a ceramic material. Until that it reaches maximum values for the simple doped with 4 Wt. % of P2O5 at a sintering temperature of 1050°C. Dielectric studies of the compounds as a function of frequency (from 1 to 200 KHz) sintered at different sintering temperatures (1000, 1050, 1100, 1150 and 1180° C) show that the compounds undergo a phase transition of diffuse type. The transition temperature shifts towards higher side with increase in frequency a typical characteristic of a relaxor material

The Influence of Zr/Ti Content on the Morphotropic Phase Boundary and on the Properties of PZT–SFN Piezoelectric Ceramics

AbstractThe polycrystalline samples of (1-x)Pb (Zry Ti1-y)O3-xSm(Fe3+0.5, Nb5+0.5)O3 [PZT–SFN] (where x = 0.02 and 0.41 ≤ y ≤ 0.57) were prepared by a high-temperature solid-state reaction technique. All samples were sintered at a temperature of 1150 oC for 2h. The crystallographic phase and microstructure of the ceramics were examined by using X-ray diffraction (XRD) and atomic force microscopy (AFM). The experimental result shows that the samples consist of a mixture of tetragonal and rhombohedral phases (morphotropic phase boundary MPB) in the range of 0.53 ≤ y ≤ 0.55, grains grow up homogeneously and the minimum value of Curie temperature was obtained with y = 0.53 and 0.55. Main piezoelectric parameters are optimized at around y = 0.53-0.55 with a high piezoelectric coefficient (d31 = 106- 117 pC/N), a planar electromechanical coefficient (kp = 61.7- 61.8%), a high dielectric constant (ɛr = 798- 974) and a low dissipation factor (tan δ = 1.405% - 1.356%) measured at 1kHz room temperature, which indicates that the PZT–SFN ceramics are promising for practical applications

The Effect of Nb2O5 Addition on the Structural, Dielectric and Piezoelectric Properties of Pb0,98 Ba0,02 [(Zr0.52Ti0.48)0,98(Cr3+0.5, Ta5+0.5)0,02] Ceramics

AbstractSpecimens of Pb0,98 Ba0,02[((Zr0.52Ti0.48)0,98(Cr3+0.5, Ta5+0.5)0,02)] + x wt.% Nb2O5 (x = 0, 0.1, 0.2, 0.3 and 0.4wt.%) ceramics were prepared by a conventional mixed-oxide route. In the present study, the effect of Nb doping was investigated on the structural, microstructural, dielectric and piezoelectric properties of the ceramics. X-ray diffraction analysis indicated that the phase of the material changed from an rhombohedral structure to a MPB structure and then a tetragonal structure when the Nb2O5 content was increased from 0.00 to 0.40wt.%. The PBZT–PBCT ceramics doped with 0.20wt. % of Nb2O5 exhibited denser and finer microstructures, which produced a high relative density of ≥ 97%. Scanning electron microscopy (SEM) observations revealed that Nb2O5 (x) addition enhanced the sintering density through the formation of a liquid phase. The maximum dielectric constant (ɛr = 17100) and the piezoelectric charge coefficient (d31 = 203 pC/N) were observed for 0.20wt.% of Nb2O5. It has been observed that the dielectric and piezoelectric constants increased gradually with increasing x up to 0.20 and was found optimum, which could be ideal for electromechanical and energy harvesting applications