Adsorptive removal of anionic and non‐ionic surfactants from aqueous phase using Posidonia oceanica (L.) marine biomass

BACKGROUND: In this study, the capability of low‐cost, renewable and abundant marine biomass Posidonia oceanica (L.) for adsorptive removal of anionic and non‐ionic surfactants from aqueous solutions have been carried out in batch mode. Several experimental key parameters were investigated including exposure time, pH, temperature and initial surfactant concentration. RESULTS: It was found that the highest surfactant adsorption capacities reached at 30 °C were determined as 2.77 mg g^?1 for anionic NaDBS and as 1.81 mg g^?1 for non‐ionic TX‐100, both at pH 2. The biosorption process was revealed as a thermo‐dependent phenomenon. Equilibrium data were well described by the Langmuir isotherm model, suggesting therefore a homogeneous sorption surface with active sites of similar affinities. The thermodynamic constants of the adsorption process (i.e. ΔG°, ΔH° and ΔS°) were respectively evaluated as ? 8.28 kJ mol^?1, 48.07 kJ mol^?1 and ? 42.38 J mol^?1 K^?1 for NaDBS and ? 9.67 kJ mol^?1, 95.13 kJ mol^?1 and ? 174.09 J mol^?1 K^?1 for TX‐100. CONCLUSION: Based on this research, valorization of highly available Posidonia oceanica biomass, as biological adsorbent to remove anionic and non‐ionic surfactants, seems to be a promising technique, since the sorption systems studied were found to be favourable, endothermic and spontaneous. Copyright © 2007 Society of Chemical Industry     

Etude par conductivite electrique et par spectrometrie d'absorption infra-rouge de la precipitation d'hematite a partir de ferrites lacunaires

The hematite precipitation from zinc or cobalt-substituted defective spinels of type $\text{(M}{}_{\mathrm{x}}{}^{\mathrm{2+}}\text{Fe}{}^{\mathrm{3+}}{}_{\mathrm{<mtext>(8?2x)</mtext><mtext>3</mtext>}}\text{■}{}_{\mathrm{<mtext>(1?x)</mtext><mtext>3</mtext>}}\text{)O}{}_4{}^{\mathrm{2?}}$ has been investigated using electrical conductivity and infrared spectrometry. The experimental data show that the temperature and kinetic of hematite precipitation depend of substitution extent x and might be closely associated with the cation vacancy in the spinel lattice. Stabilization of spinel solid solution by the cation is more pronounced for zinc than for cobalt and the effect of the cation is interpreted in terms of cation distribution in the spinel lattice.     

Studies on the recovery of aflatoxin b1 injected into frozen beef at different intervals of storage.

Beef stored at --18 degrees C for 20,25,32,153, and 183 days showed a diminution in the recovery of injected aflatoxin B1. An unusual passing of aflatoxin in ether and hexane fractions of silica gel column was noted. Ether fraction contained aflatoxin B1-like substance from stored beef samples. Probable occlusion of aflaton B1 to meat constituents due to physico-chemical changes associated with muscle during storage was discussed.     

Iron(III) and Cobalt(III) Complexes with Oxalate and Phenanthroline: Synthesis,Crystal Structure,Spectroscopy Properties and Magnetic Properties

We report herein the synthesis and physicochemical characterization of two mixed-ligand complexes of the following stoichiometric formulae: [Fe(phen)₂(ox)](NO₃)?2H₂O (1) and [Co(phen)₂(ox)](NO₃)?4H₂O (2) (as phen: 1,10-orthophenanthroline; ox: oxalate dianion). Both compounds have been prepared by slow evaporation at room temperature and characterized by single-crystal X-ray diffraction. They have been characterized by IR and UV–Vis spectra and thermoanalysis (TG and DTA) The structures of these compounds are highly symmetric. Indeed, the two compounds are isomorphous and crystallize in the orthorhombic space group Ibca. In each material, the M^III ion has a slightly distorted square bipyramidal environment, coordinated by one oxalate ion and two 1,10-orthophenanthroline ligands. Structural cohesion is established essentially by π–π interactions between the rings of phen groups and intermolecular O–H…O hydrogen bonds connecting the ionic entities and uncoordinated water molecules. Magnetic susceptibility measurements of (1) in the range 5–300 K exhibit paramagnetic behavior at high temperature. However, at low temperature, the magnetic data show the occurrence of weak antiferromagnetic intermolecular interactions between the local spins.     

Experimental Investigation of the Isothermal Section at 800 °C of the Nd-Fe-Co Ternary System

The phase equilibrium of the ternary Nd-Fe-Co system at 800 °C was investigated by means of powder x-ray diffraction and scanning electron microscopy–energy dispersive x-ray spectroscopy. Seven binary compounds, i.e., Nd₂Co₁₇, NdCo₅, Nd₅Co₁₉, Nd₂Co₇, NdCo₃, NdCo₂, Nd₂Fe₁₇ were identified to exist at this isothermal section. This isothermal section consists of ten single-phase, ten two-phase and six three-phase regions. All measured compositions and unit-cell refinements were performed at room temperature from quenched samples annealed at 800 °C for one week. The maximum solubility at 800 °C of Fe in NdCo_2?x Fe _x (MgCu₂-type structure, Fd-3 m), NdCo_3?x Fe _x (PuNi₃-type structure, R-3 m space group), Nd₂Co_7?x Fe _x (Ce₂Ni₇-type structure, R-3 m), Nd₅Co_19?x Fe _x (CeCo₁₉-type structure, R-3 m space group), NdCo_5?x Fe _x (CaCu₅-type structure, P6/mmm), Nd₂Co_17?x Fe _x (Th₂Zn₁₇ type structure, R-3 m) and Nd₂Fe_17?x Co _x (Th₂Zn₁₇ type structure, R-3 m) are about 31.6 at.% Fe, 47.9 at.% Fe, 13.3 at.% Fe, 8.6 at.% Fe, 10.37 at.%, 36.35 at.% Fe, and 58.23 at.% Fe respectively. The solid solubility range of Co in Nd₂Fe₁₇ form discontinuous series of 2 ranges is about 0-30.14 at.% Co, and 51.9-100 at.% Co and the solid solubility range of Fe in Nd₂Co₁₇ is about 0-48.1 at.% Fe, and 69.86-100 at.% Fe.     

Homogenization of a heat transfer problem in a highly heterogeneous periodic medium

We consider the homogenization of a heat transfer problem in a periodic media made of two connected components having comparable conductivities separated by a third medium (insulating layer), the thickness of which is of the same order ? than the basic periodicity cell, and such that its conductance λ becomes infinitely small at the same time as ?, following a rate λ=λ(?). In the case where ?²/λ remains bounded, we identify the homogenized problem. Otherwise, we have to assume moreover that there are no sources in the third medium.     

Surveys on the possible presence of aflatoxin and ochratoxin in corn harvested in France in 1973 and 1974

0,1 and 1,9 p. 100 of French corn samples harvested in 1973 and 1974 contain respectively 4 to 42 ppb aflatoxin and 15 to 200 ppb ochratoxin A. Because the dilution of this product in the feed, such amounts could not be considered causing acute or chronic mycotoxicosis. In case of corn contamination by ochratoxin A, the analysis of technologic parameters conclude to question the drying corn with ears in cribs and the delayed drying after the reception of corn in storage corporation.     

Design,Manufacture, and Characterization of a Carbon Fiber‐Reinforced Silicon Carbide Nozzle Extension

Nozzle extensions made of ceramic matrix composites (CMCs) have shown the potential to replace heavy superalloy nozzles and improve the performance of future upper‐stage and orbital rocket engines. Gas permeability has been reported to be a critical issue during the manufacture for CMC nozzles. This work shows the manufacture of a dense radiation‐cooled C/C‐SiC nozzle demonstrator. A multi‐angle fiber architecture was applied using filament winding technique to reduce the incidence of delaminations during the manufacturing process under high temperatures. Additional efforts were made to improve the final gas tightness and reduce the amount of residual silicon by means of an adapted liquid silicon infiltration process. The manufacture, the material, and structural characterization as well as a finite element analysis of a performed internal pressure test are presented.     

Phenolics extraction from Agave americana (L.) leaves using high-temperature, high-pressure reactor

The Agave americana plant has been largely used in traditional medicine. The setting up of efficient methods for phenolics extraction from A. americana leaves is one of great interest. With the aim of optimizing phenolics extraction from this material, the effects of temperature (from 25 to 150 °C) and extraction time (from 15 to 240 min) were investigated using a high-temperature, high-pressure (PARR) reactor, under either air or nitrogen atmosphere. Total polyphenols and flavonoids were determined, and their antioxidant activity was measured by the DPPH radical method. The use of PARR reactor for phenolics extraction proved to be more efficient compared to the conventional solid-liquid extraction at room temperature. The results of this work demonstrated that an increase in both temperature and extraction time led to a corresponding increase in the amount of phenolic compounds extracted and suggested that, after process optimization, this material could be used as an interesting alternative source of polyphenols.     

Long-term bond performance of GFRP bars in concrete under temperature ranging from 20 °C to 80 °C

Eighty pull-out specimens were used to study the effect of temperature ranging from 20 °C to 80 °C in dry environment on bond properties between Glass Fiber Reinforced Polymer (GFRP) bars and concrete. The pullout-test specimens were subjected during 4 and 8 months to high temperatures up to 80 °C and then compared to untreated specimens (20 °C). Experimental results showed no significant reduction on bond strength for temperatures up to 60 °C. However, a maximum of 14% reduction of the bond strength was observed for 80 °C temperature after 8 months of thermal loading. For treated specimens, the coefficient β in the CMR model, which predicts the bond–stress–displacement behavior, seems to be dependant with the temperature.