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Our work concerns the feasibility of certain models based on approach of a capillary type, and applied before in ultrafiltration process, for the prediction of the divalent salts retention by a nanofiltration membrane. The model solutions that we chose are those of cadmium and copper salts - whose cations constitute toxic elements introduced into the environment by the effluents coming from industries like those of surface treatment - calcium salt solutions, used within the framework of the nanofiltration softening of the aqueous solutions. The study of the bibliography on the salts retention through a membrane enabled us to formulate some observations: The flow of solvent depends on the membrane permeability; the aqueous solution flow depends on the solvent nature and membrane structure. On this basis, we also could highlight the existence of two mechanisms observed during the filtration of salts: the first, of type solubilization diffusion with the Donnan effect which does not take account of the membrane porosity; the second, electrokinetic who takes account of the membrane porosity. The mathematical models chosen, which seem quite suitable and which derive from this second type of mechanism are: TREMBLAY model; VERNIORY model; NAKAO model. The application of these mathematical models (for the study of the retention evolution of bivalent salts according to volumic flow) requires the development of a data-processing program which finally led to software simulation. We confronted this modeling with experimental results allowing to estimate the principal parameters of transport: the optimal pore radius, reflection coefficient a and membrane permeability for solute Ps. Apparently, the comparison carried out between the experimental results and numerically results obtained (VERNIORY model in particular) gave a good correspondence for a pore radius close to that evaluated by porosimetry method [1]. Moreover, this confrontation authorized us to underline the essential role of certain parameters influencing the retention such as: pH, transmembrane pressure, temperature, concentration of solution treatment and components nature in the solution.

A mathematical model is proposed as a contribution to the modelling of the concentration polarization phenomenon occurring during increasing transmembrane pressure in membrane processes. The developed model is based on the extended Nernst–Planck equation (to describe the transport in membrane pores) and film theory equation (to describe the transfer mechanism in the polarization layer). It is characterized by two transfer parameters: solute permeability, Ps, and reflection coefficient, σ, and which allows the estimation of the thickness of the boundary layer, δ. Solute concentration at the membrane surface, Cm, and concentration profiles in the polarization layer are also estimated. The model is applied for the prediction of Ca(NO3)2, Cu(NO3)2 and Cd(NO3)2; ZnCl2 retention in nanofiltration and the influence of feed concentration on concentration polarization phenomenon were studied. The validation of the established models was obtained by the analysis of the experimental results resulting from treatment by nanofiltration of a synthetic solution with and without concentration polarization which determined the three principal parameters: reflexion coefficient σ; the solute membrane permeability, PS; and the layer polarization thickness, δ.

The periodic disappearance of fish from the marshes of Reghaia (Algiers) caused by industrial waste alarmed responsible personnel at the Department of the Environment to pollution that threatens one of the most significant wet sites of Algeria. An anti-pollution plan was developed and put in action. This plan aims to provide an overall basis for evaluating the pollution generated by the various units in the industrial park of Rouiba – Reghaia, in order to reduce or to stop pollution affecting the marshes of Reghaia. Our work presents a complementary study on the effluent of a leather processing unit at Rouiba [1] , [2] , [3] , [4] . Our study was based on the effluent of liming baths which contain a great quantity of sulfides. To reduce the pollution generated by sulfides in the effluent, we were interested in the use of nanofiltration in order to refine post-processing such as precipitation.

This study deals with a subject that has recently been developed in our laboratory and whose aim is to reduce fouling of tangential membranes. In the work reported here, we show that, thanks to the resistance model, the effects of instabilities generated by a double-phase gas–liquid flow in the presence of a turbulence promoter lead to a more efficient hydrodynamics in terms of reducing deposited material on the membrane surface. The use of such a process to filtrate sodium alginate leads to very encouraging results allowing flux improvements by a factor of 2.3.

Cet article propose une étude de la rétention du nitrate d'ammonium par une membrane commerciale de nanofiltration (Nanomax 50). Les effets de la pression, de la concentration et de la vitesse d'écoulement tangentiel ont été étudiés avec le souci d'une meilleure compréhension du mécanisme de transport des ions nitrate et en vue d'une optimisation de la rétention. Le taux de rétention des ions nitrate augmente dans un premier temps avec la pression, atteint un maximum puis diminue. La rétention, pour des pressions élevées, peut cependant être améliorée en augmentant la vitesse d'écoulement tangentiel. La séparation résulterait d'un rapport de différentes forces : une force d'entraînement radial dans le pore (illustrée par l'effet de la pression transmembranaire), une force d'entraînement tangentiel vers le rétentat (illustrée par l'effet de la vitesse d'écoulement tangentiel) et une force de surface traduisant les interactions membrane-soluté (illustrée par l'effet de la concentration). L'équation de Spiegler et Kedem est proposée en première approche de modélisation pour une valeur limite de pression., Many water sources deal with the problem of increasing nitrate concentrations above authorised levels for drinking water. In order to minimise this amount of pollution and to achieve high quality of water and reused water in the distribution system, membrane processes are becoming a promising technology. Indeed, they present the major advantages of a small land area requirement, low temperature operation, continuous separation, better effluent quality, little or no sludge production and a large reduction in the quantities of chemical additives. Reverse osmosis has already been used to remove most of the nitrates together with the other solutes, but the disadvantage is that this technique induces a total demineralisation of the treated water. Another possible filtration process, nanofiltration, has been investigated in this study while no extensive research has been carried out on its nitrate removal potential. Theories cannot adequately predict the influence of operating parameters on membrane performance. Consequently, new membranes and modules must be experimentally evaluated for each new application. The main objective of this study was to provide fundamental data for designing an operation of nanofiltration under various operating conditions such as transmembrane pressure, cross-flow velocity and initial feed concentration for drinking water and water reuse purposes.The retention rate rises with an increase of the applied pressure, reaches a maximum and then decreases. Such a result is quite different from those usually mentioned in the literature where the retention increases and reaches a plateau when the pressure grows. The singular decrease of the retention rate observed in this study could be explained in terms of a concentration polarization phenomenon. However, since the volumetric flux increased linearly with the pressure and remained close to the pure water flux, it might be thought that such an assumption is not valid in the case of this work. Therefore, another hypothesis has to be provided to explain the variation of the retention with transmembrane pressure. As the size of NH4+ ion (ionic radius=0.148 nm) is lower than that of the pore of membrane (diameter=1 nm), cations can enter the pores where they are partially retained due to surface forces (electrostatic and friction forces). When the pressure increases, these forces remain constant while drag forces increase due to the flux in the pore. At low pressure (∆P < 5 bars), the surface forces are stronger than the drag forces. Therefore, the solute flux remains low while the solvent flux increases with the pressure, leading to an increase in the solute retention. Above a given pressure (≅ 5 bars), the drag forces become higher than the surface forces. Consequently, the retention rate decreases.As can be observed in the obtained results, the retention rate decreased when the feed concentration was increased regardless of the operating pressure. This effect is mainly attributed to the cation shielding of the effective charge of the membrane. This characteristic can be explained by the fact that the electric repulsion becomes less efficient at higher concentration. It has been recognized that the effective charge density of the membrane decreases with an increase in the feed concentration of an ionic solution. Consequently, the retention rate of the co-ion due to charge effect is reduced. It follows that a greater amount of nitrate ions could permeate when feed solutions of higher concentration are applied.The effect of cross-flow velocity on the fluxes is insignificant since the permeate flux depends only on transmembrane pressure. However, the retention performance increases with velocity. The lower the cross-flow velocity, the higher the interaction between the solute and the membrane. Therefore, at low cross-flow rate, the solute amount that enters the membrane pores is high. When the drag forces become stronger than the surface forces, as explained above, the retention sharply decreases. At high cross-flow velocity, the feed circulation transports a large solute amount and therefore, the solute amount that enters the pores is reduced and is less sensitive to operating pressure. In consequence, the sensitivity of the retention to transmembrane pressure is not so marked. It might be thought that for a very high cross-flow velocity, the retention increases and then remains constant.It was demonstrated in this work that nanofiltration can be successfully used to remove nitrates from water. The retention was shown to depend strongly on operating parameters such as feed solution concentration, applied pressure and circulation cross-flow rate. In fact, the retention is mainly determined by the intensity of the solute / membrane interaction. This interaction comes from two main forces: a tangential one due to the feed solute flow (illustrated by the cross-flow velocity effect) and a radial one in the pores due to drag forces (illustrated by the transmembrane pressure effect). Moreover, it was observed that the valence of the associated ions is an important factor that can affect nitrate retention. It can be expected that the optimization of the separation performance will result of the best combination of all these parameters. Therefore, with a view to a future industrial application, it will be necessary to take into consideration the chemical composition of the resource and to adapt the operating conditions to the desired objectives.

In dairy plants the process waters generated during the starting, equilibrating, interrupting and rinsing steps contribute to the production of effluents. They correspond to milk products (milk, whey, cream) diluted with water without chemicals. The treatment of these dairy process waters by nanofiltration (NF) or reverse osmosis (RO) operations was proposed to concentrate dairy matter and to produce purified water for reuse in the dairy plant. The study reports one-stage and two-stage (NF + RO and RO + RO) spiral-wound membrane treatments with five model process waters representative of the main composition variations observed in dairies. Performances (permeate flux, milk components rejection, purified water characteristics) of the different operations were compared. Discussion was focused on the comparison between quality of produced waters and vapour condensates (from product drying and evaporation processes) reused in dairy plants. Accordingly, both total organic carbon (TOC) and conductivity of water treated by a single RO or NF + RO operations were convenient for reuse as heating, cooling, cleaning and boiler feed water. With the two-stage RO + RO process, a more purified water complying with the TOC drinking water limit was achieved.

The paper presents results of a study investigating softening by nanofiltration of the Hamma underground waterresource. The Hamma wells supply the City of Constantine with hard drinking water containing calcium bicarbonate. The main parameters investigated were pressure, cross-flow velocity and water temperature. Nanofiltration was found to be a very efficient process for partial reduction of the temporary hardness, within the pressure limits considered, the calcium and bicarbonates retentions reaching 34% and 30%, respectively. Experiments were also conducted to modify the furring capacity of the water by doping the Hamma water with metal cations. Addition of Zn2+ and Cu2+ induced some inhibition, but no effect was observed in the cases of Fe2+ and Mn2+.

The treatment of a rejection of tannery effluent was carried out on an organic nanofiltration membrane. The rejection was recovered from a leather manufacturing plant in the area of Algiers (Rouiba). The effluent of the bath of tanning and liming charged with chromium ions was the subject of this study. In the case of synthetic solutions, the experimental variations of the retention ranged from 94–99.9% depending on initial feed concentration. For the tanning bath, the results indicated that chromium retentions of 60 and 30% were observed respectively in acid and basic medium. In acid medium, the rejection of the bath of liming has generated a retention of 15%. The use of the model of Nakao et al. [1] based on the extended modified Nernst Planck equation enabled us to compare the theoretical retention of chromium ions with the experimental results and to calculate the membrane pore radius.

A mathematical model is proposed to predict the transfer mechanism of calcium salts through a nanofiltration membrane. The model is a combination of Nernst-Planck and film theory equations and it is characterized by three transport parameters: solute permeability P s , reflection coefficient σ and film thickness δ. In the present work, the influence of including concentration polarization phenomena on salt rejection is studied and the thickness of the boundary layer formed at the feed side adjacent to the membrane, δ, is estimated. Model results were shown to be in good agreement with experimental data at various operating conditions of pressure, temperature and initial concentration. The results show that including concentration, polarization has not a great effect on salt rejection for the present operating conditions. Estimated thickness of boundary layer formed near the membrane surface was too small and ranged between 10 −13 and 10 −12 m. In later work, we plan to perform some experiments at different operating conditions as higher initial concentration of calcium salts or lower tangential flow to bring the system in polarization concentration and then to apply, verify and validate the model proposed.

In this study, the retention of nitrate ions by a commercial nanofiltration membrane is investigated to highlight their transport mechanism. The influence of the operating pressure and the ionic composition (nature of the associated ion, feed concentration, pH and solution complexity) are studied. The separation performance should be the result of dual forces: a global surface force (friction, electrostatic) which retains the solute in the pore and a global convective force directed towards the retentate which depends on the applied pressure. In binary solutions, surface force depends on the hydration energy of the associated cation as well as membrane–solute electrostatic interactions. In ternary mixtures, we underscored the influence of solute–solute interactions (Donnan effect). The observations made with simple nitrated solutions (binary and ternary) were extrapolated and confirmed in experiments made on polluted or nitrates doped waters.

This study was developed to highlight the influence of the nature of the water to be treated on the efficiency of nitrate elimination by a commercial membrane. By modifying the pH and gradually increasing the complexity of the treated solutions (binary, ternary and then natural waters), we identified phenomena which govern the ion transfer across the membrane. We underline the influence on membrane selectivity of the hydration energy as well as the membrane–solute and the solute–solute interactions. The observations made with simple nitrated solutions (binary and ternary) were extrapolated and confirmed in experiments made on polluted or nitrates-doped waters.

This study is focused on the influence of the nature of the water to be treated on the efficiency of nitrate elimination by a commercial membrane. By gradually increasing the complexity of the treated solutions (binary, ternary mixtures and then natural waters), we identified the physical, chemical and electric phenomena, which govern the ion transfer. We highlighted the influence on the membrane selectivity of the hydration energy of the solute, of the membrane-solute and solute-solute interactions. The observations made with simple nitrated solutions (binary and ternary) were extrapolated and confirmed in experiments on the water doped out of nitrates.

Mechanism specificity of ion separations in drinking water is necessary for the study of modeling transfer of calcium salt through nanofiltration membrane. In the present work, we have investigated a mathematical model which can specify the transfer phenomena of solute through a nanofiltration membrane and to predict its reject. The proposed model is based on the extended equation of Nernst-Planck. It is characterized by constants called transfer parameters, which have been determined according to the composition of the initial solution as a binary or a ternary mixture. The established model permitted us to predict the retention of calcium salt. The result of the application of the model has shown that there is a good agreement between the theoretical and experimental curves.

Based on the model initially proposed for nanofiltration combining the modified equation of Nernst–Plank and the film theory, expressions were developed to allow accurate characterization of solute transports during nanofiltration. In nanofiltration, the solute concentration in the feed solution is one of the factors which have an effect on solute rejection. So, it was important to study the effect of solute concentration on these transport parameters. In this approach, the model transport parameters, K eff and Φ have been related to the feed solution concentration. While serving to us as the equilibrium equations of Donnan and that of Kirianov, we have established relations between these parameters of transport to the concentration of the feed aqueous solutions. Both the effective transfer coefficient and the transmittance increase when concentration increases. The relations describe our experimental results satisfactorily. They have also allowed us the determination of the order of the charge density of the membrane. It was found to be 8.57×10 −4 and 49.5×10 −4 equivalent mol l −1 which correspond to −33 and −191 mC m −2 , respectively for a 0.4 μm membrane thickness.

In the present work, we were interested in the treatment by nanofiltration of synthetic solutions containing chromium salts. Two types of solutions (CrCl3  K2Cr2O7) were treated according to the experimental parameters such as pH, pressure and concentration. With the aim of studying the influence of possible ionic interactions, we have carried out tests on solutions containing the trivalent and hexavalent chromium ions in the presence of various salts (NaCl, KCl, NaNO3, Na2SO4, K2SO4) for different concentrations. The results have shown a total chromium retention which varies from 38 to 99% relating to the composition of the solution and operating conditions. For Cr(III), a better retention was obtained in acid medium and for an optimal pressure of 5 bar. The influence of the ionic strength as well as the concentration were found weak. The retention of the Cr(III) ions was not affected by the presence of salts solution. The results for bichromate solutions were strongly dependant of the form in which the Cr(VI) ions were present. The form of HCrO4− has given a better retention at low concentrations. When the concentration increases, the phenomenon of repulsion becomes less significant and consequently the ions were less and less retained. The influence of the salt addition on the retention of the Cr(VI) ions have revealed the effect of the interactions of the membrane/solute and solute/solute on the selectivity of the membrane.

Carbon prepared from peanut husks (PHC) has been used for the adsorption of Pb2+, Zn2+, Ni2+ and Cd2+, over a range of initial metal ion concentration (0.15 mM). Chemical and physical characteristics of PHC were determined. The effects of particle size and of carbon doses were evaluated by batch experiments. The kinetics of sorption were followed, based on the amounts of metal sorbed at various time intervals. The modeling of kinetic and isotherm curves has also been investigated. The rate constant and the reaction order have been calculated. The results show that Pb2+ has best affinity to PHC than Cd2+, Ni2+, Zn2+. From these results an order of the sorption capacity of metal ions sorbed was derived.

The aim of this work was to determine mass transfer coefficients in the cases of ultrasonically-assisted and classical stirred dead-end ultrafiltration. A comparative study was then performed, and mass transfer coefficients obtained under ultrasonic conditions are described by an empirical model. This correlation results from an analogy with what is observed using a stirred cell and involves the ultrasonic power as the main parameter. The hydrodynamics are assumed to depend on the intensity of the ultrasound effects illustrated by the agitation arising within the cell. This agitation is due to convective currents as well as physical effects due to cavitation. The concentration polarization phenomenon is therefore affected by this action of ultrasonic waves.

A new process which helps to reduce membrane fouling during ultrafiltration by a deposit of particles has been developed in our laboratory. It consists of injecting air in such a way as to obtain a two-phase gas-liquid flow that passes through a turbulence promoter (sulzer), placed upstream of the membrane, which creates a strong shearing stress on the surface of the membrane. Experiments have been performed with a polymer, sodium alginate. Various speed values of the gas, liquid and polymer concentrations have been examined, as well as the influence of the molecular weight cut-off of the membrane. The process of air injection in the presence of the turbulence promoter leads to a 180% improvement of the permeate flux. The shear stress exerted by the turbulent gas-liquid mixture prevents particles from depositing on the surface of the membrane and/or facilitates the detachment of the deposited polymer and thus improves mass transfer.

Mixed solutions containing copper salts were separated using a nanofiltration membrane. For mixed electrolyte solutions with the same co-ion, the rejection of copper was shown to depend strongly on the nature of the second counter-ion. In the presence of H3O+ or at low concentration of Na+, copper ions are completely rejected, while in the presence of Ca2+, their transfer is slightly improved. The extended Nernst Planck equation was applied to modelize experimental results using specific calculated transfer parameters. The variations of the concentration and the electrostatic potential were considered to be linear through the membrane. Moreover, the solute concentration near the membrane was assumed to be equal to the feed solution concentration. Calculated copper rejections are in good agreement with experimental results.

Low-frequency ultrasound (20 kHz) has been used to facilitate dead-end ultrafiltration of polymer solutions. The influence of ultrasonic irradiation on permeate fluxes and retention ratios was investigated and compared with conventional stirred and unstirred operations. In addition, the effect of the ultrasonic field on the membrane permeability and on the polymer solution was examined. The efficiency of ultrasound in enhancing ultrafiltration performance was demonstrated. This improvement is due to a decrease of the boundary layer resistance against permeation flow, which may be attributed to disturbance induced within the cell and at the membrane surface by physical effects associated with ultrasonic waves propagation.

Primary cultures of Pecten maximus heart cells, isolated by an enzymatic procedure, were routinely obtained with a high level of reproducibility in a simple medium based on sterile seawater. Cells attached to the plastic substratum without the need to add a special factor. The number of adhering cells gradually increased with the time of culture. Two types of adhering cells were observed: epitheliallike cells and fibroblastlike cells, which were more numerous. The latter cells were identified as myocytes by electron microscopy and immunofluorescent staining. Results obtained by autoradiography, after incorporation of [14C]leucine, [3H]thymidine, and [14C]acetate, confirmed functional activity of the cells. These cultures were maintained viable in vitro during at least 1 mo.

This paper reports the influence of anion nature, applied pressure and pH on the retention of copper and cadmium salts by nanofiltration. The retention of cations is shown to depend strongly on hydration energy and charge valency of the permeating co-ion. At more than 5 bars, the ion retention is independent of the applied pressure. At pH

A dissociation protocol for Pecten maximus heart has been established that makes it possible to obtain functional primary cultures routinely (9, 10); freezing assays of isolated cells were performed with the aim of making it possible to cultivate these cells in vitro after thawing to provide a constant standardized source of cells for applied research. Various parameters such as the nature and the concentration of the cryoprotectant, the cooling rate, and the incubation time of cells with the cryoprotective agent were evaluated. Best results were obtained by freezing cells in 12% dimethyl sulfoxide (Me2SO) in Leibovitz L15 medium at a cooling rate of approximately 2-3 degreesC/min. Thawed cells in culture attached to the substrate and survived for at least 3 weeks. They exhibited similar morphology and synthesised proteins, DNA, and lipids in vitro at levels close to those observed in fresh cells. To our knowledge, it is the first time that cultures have been obtained from cryopreserved marine invertebrate cells. Copyright 1998 Academic Press.

This article discusses the transport mechanism of cadmium salts (CdCl2, Cd(NO3)2) through a nanofiltration membrane. A model based on the extended Nernst-Planck and the film theory equations is reported. This model is characterized by three transport parameters: the water permeability Lp, the ion transmittance Φ and the effective transfer coefficient Keff. The knowledge of the feed and permeate concentrations and the permeate flux enable the calculation of these parameters. The model was used to predict cadmium salt solution rejection by a NANOMAX 50 membrane. The experimental values and calculated predictions are in good agreement.

The problems involved in the environment for a surface treatment are especially at the level of water and even dangerous often toxic waste for the environment. The purpose of the surface treatments is to make acquire on metal or plastic surfaces new properties by a surface dressing of material. In this search for the respect of the environment, of the standards, and the laws in strengths; the application of the membrane techniques in industry of surface treatment often require less energy and offer low fresh working assets compared to much of conventional systems of treatment. The coupling of the membrane techniques such as the nanofiltration with traditional methods of treatment physicochemical seems the promising solution to reduce volumes of industrial wastes considerably. The inorganic and organic pollutants present in its effluents can be removed simultaneously by using this kind of system of treatment. The removal of copper from effluent by a negatively charged microporous nanofiltration (NF) membrane called Nanomax50 was investigated. The difficulty encountered during the treatment of the synthetic solutions filtration and the effluent, suggested the investigation one of the limiting nanofiltration factors in fact the concentration polarization. In this context and in order to understand the bivalent ions transfer phenomenon through a nanofiltration membrane we will try to develop the coupling of the hydrodynamic approach and the model of film.

The aim of the present work is to propose a model for predicting the transfer mechanism of divalent ions through NF membranes by including the concentration polarization phenomenon and to study its influence on salt rejection. The proposed model is a combination of two transport models: the first one is based on the extended Nemst-Planck equation while the second is based on the film theory. This model is characterized by two transfer parameters: reflection coefficient a and solute permeability P s which are estimated numerically. The thickness of the boundary layer, 6, solute concentration at the membrane surface, C m , and concentration profile in the polarization layer have also been estimated. The model is applied for predicting cadmium, calcium, copper and zinc salts rejection at a various concentrations and a comparison, between estimated results with and without considering concentration polarization. J i =-C i ·D i,p d(lnγ ι ) dx-C i ·D i,p R·TV i dp dx-D i,p dC i dx-z i ·C i ·D i,p R·T·F·dψ dx+K i,c ·C i ·V and a film theory (C m -C p ) (C 0 -C p )=e Jvδ D 1 It is characterized by two transfer parameters: solute permeability P s and reflection coefficient a, and permits us to estimate the thickness of the boundary layer, 6. Solute concentration at the membrane surface, C m , and concentration profiles in the polarization layer are also estimated. The solution is C m1 =(1-a Exp[(1-σ)J v /P s ])C p1 1-σ.

Tacrolimus is an immunosuppressant drug currently used for the treatment of atopic dermatitis and pruritus. This topical therapy is effective and safe, but transient burning, stinging and itch are frequently reported.To understand the mechanisms underlying these burning sensations.We examined the impact of tacrolimus on substance P (SP) release in an in vitro model of cutaneous neurogenic inflammation. Because phosphorylation of TRPV1 (transient receptor potential subtype vanilloid 1) plays a role in the induction of pain, we investigated whether tacrolimus regulates the phosphorylation state of TRPV1. Finally, we used a macropatch to evaluate the impact of tacrolimus on voltage-gated calcium currents of sensory neurons.Tacrolimus was able to induce initial SP release by extracellular calcium influx and inhibited SP release induced by capsaicin after 1, 24 and 72 h of pretreatment. Analysis of TRPV1 phosphorylation by Western blot confirmed the capacity of tacrolimus to favour phosphorylation. An electrophysiological study showed inhibitory effects on calcium currents.The efficacy of tacrolimus in pruritus, as well as the sensory side-effects, could be explained by a direct effect on neurons through an effect on calcineurin, possibly by a desensitization of TRPV1 and calcium currents through the PIP(2) regulation pathway.

The comet assay is a single cell gel electrophoresis test currently used as a qualitative and quantitative genotoxicity test. However, some of the results from this comet assay and current knowledge on apoptosis lead us to suspect the presence of some false positive results. The aim of this study was to ascertain if apoptotic cells can yield comet images that might distort the interpretation of the results. Using Jurkat cells, that hardly express Fas antigen, and apoptosis induction with anti-Fas antibody, it was possible to show that apoptosis can generate typical comet pictures as soon as the cells enter the apoptosis process. Therefore, comet images cannot be interpreted as a genotoxicity indicator when an apoptosis risk is present. Yopro-1 staining, that is also nearly immediate after apoptosis induction, can be used to balance comet assay results.

We propose in this study the effectiveness of an organic membrane Nanomax50 charged negatively on complex solution tanneries. Our choice was made on the solutions of tanning and liming of the tannery tawing of Rouiba/Algiers because of the nature of the substances which they contain, namely chromium and sulphides. Initially, of the pretreatments by precipitation and coagulation flocculation respectively with the solutions of tanning and liming are planned in order to avoid the filling of the membrane. The products used at these stages are FeSO 4 –HCl–Ca(OH) 2 . After each stage of pretreatment, the Nanofiltration is used in order to study the behavior of the membrane with respect to the composition of the solution with various stages. The parameters of studies under consideration in this study are as follows: pH, electric conductivity, turbidity, concentration chromium plate some by atomic absorption.

Malformations in shellfish have been reported by many authors. They attributed the cause of the deformity to the presence in water of organotin compounds used in the formulation of antifouling paints, for example bis(tributyltin) oxide (TBTO) and tributyltin chloride (TBTC). The behaviour of these compounds has been examined under abiotic laboratory conditions. The influence of many parameters such as sunlight, pH, oxygen, salinity have been examined. The degradation compounds obtained have been identified: (1) In the gas phase two major products, butene-1 and buetene-2, are observed with consumption of oxygen; (2) In the liquid phase, three main products are obtained, butanol-1, butanol-2 and butanone 2. The identified products represent a small part of the total concentration, suggesting a competing process such as formation of butyltin polymers; (3) In fresh water an amorphous solid phase is observed while in seawater a white cristalline precipitate appears.

Les valeurs du produit de solubilité de la calcite et des constantes de dissociation de CaHCO3+ et CaCO30, notées K3 et K4, ont été déterminées à différentes températures comprises entre 5 et 75 °C (la calcite est instable aux températures plus élevées) à partir des mesures [(Ca2+)T, pH] de solubilité de ce sel dans l'eau carboniquement pure. Les résultats obtenus ont permis d'établir les relations empiriques suivantes :pKs= 7,8156 + 0,03111 T + (1 502/T) - 5,518 log TpK3= 6,2447 + 0,00437 T + (864,479/T) - 0,363 log TpK4= 2,89636 + 0,00707 T + (102,87/T) - 0,44176 log Texpressions dans lesquelles T désigne la température absolue (K) et log le logarithme décimal.Des variations de pKS avec la température nous avons déduit, à 25 °C, les grandeurs thermodynamiques relatives à la dissolution de la calcite :∆H0 = -2510 cal. mol-1, ∆S0 = -47,2 cal. mol-1. K-1et ∆C∘p = -73,9 cal. mol-1. K-1, The values of the solubility product of calcite and dissociation constants of CaHCO3+ and CaCO30, K3 and K4 respectively, were determined at several temperatures between 5 and 75 °C (calcite becomes unstable at higher temperatures) from measurements [(Ca2+)T, pH] of calcite solubility using carbonically pure water. The results obtained lead to the following empirical expressions for the dependence of equilibrium constants on the temperature :pKs= 7,8156 + 0,03111 T + (1 502/T) - 5,518 log TpK3= 6,2447 + 0,00437 T + (864,479/T) - 0,363 log TpK4= 2,89636 + 0,00707 T + (102,87/T) - 0,44176 log Twhere log T is the common logarithm of the absolute temperature T(K).Using this expression of pKS, the calculated thermodynamic properties of the calcite dissolution reaction at 25 °C are :∆H0 = -2510 cal. mol-1, ∆S0 = -47,2 cal. mol-1. K-1et ∆C∘p = -73,9 cal. mol-1. K-1

Depuis quelques années la pollution par les métaux lourds et devenue un problème important pour la protection de l'environnement et de nombreuses méthodes ont été développées pour éliminer les métaux toxiques présents dans l'eau.Parmi les différents procédés utilisés, la complexation-ultrafiltration est bien connue et de nombreuses études sur ce sujet sont décrites dans la littérature. Cependant, le choix de nouveaux macroligands hydrosolubles demeure important pour développer cette technologie.L'un des objectifs de ce travail était de montrer que dans ce procédé un biopolymère peut remplacer un macroligand de synthèse. Les expériences ont été menées avec de l'alginate de sodium, polysaccharide extrait des algues brunes, et porteur de groupements carboxyliques et hydroxydes capables de complexer les cations.Notre étude se divise en trois parties. Après avoir décrit, dans la première, le matériau et les méthodes utilisées, nous étudions dans la seconde les conditions de l'ultrafiltration (seuil de coupure, pression appliquée, pH, concentration ), avant de discuter dans la troisième les résultats obtenus dans le traitement de solutions contenant Cd2+, Cu2+, Mn2+ and Pb2+., For some years past, pollution by heavy metals has become one of the main problems for environmental protection. A number of methods have been developed to remove toxic metals from water. Among the various processes used, complexation-ultrafiltration is well known and numerous studies on this subject are described in the literature. However, the choice of new water-soluble macroligands remains important for developing this technology.One aim of the present work was to prove that biopolymers can replace synthetic macroligands in the process. The experiments have been conducted with sodium alginate, a polysaccharide extracted from brown seaweeds and containing carboxylic and hydroxyl groups able to complex heavy cations. Filtration experiments were performed with a frontal system, equipped with a polysulfone membrane with a 20000 Daltons cut-off . The solutions studied were prepared by diluting in demineralized water either sodium alginate or "Titrisol Merck" for cations. Before filtration the two solutions were mixed and stirred for 20 min. The pH of the feed solutions was adjusted with HCl (or HNO3 for Pb) or NaOH and determined accurately using a calibrated probe.The molecular weight of sodium alginate was determined by liquid chromatography and the viscosity was measured with either a viscosimeter for low values or a capillary method for concentrated solutions. Cation concentrations were measured by atomic absorption spectrophotometryBoth permeate and retentate macroligands concentrations were estimated from measurements of total organic carbon (TOC). Following each experiment, chemical cleaning was performed by filtration of HCl, NaOH and water. This procedure was followed by demineralized water filtration, to ensure that the initial permeability was restored.In the first part of the work the ultrafiltration of sodium alginate solutions for different concentrations and various pressures was studied. Experimental results for macroligand retention, deduced from the TOC values, show a total rejection. All the curves, permeate flux versus time, present the same profile which indicates a significant concentration polarization. According to the obtained results we chose the value of 5 10-2 g L-1 for the ligand concentration and one bar for the applied pressure.In the second part of the study, the retention of cations (Cd2+, Cu2+, Mn2+ and Pb2+) was investigated. The observed results show that the removal rates are close to 100%. These values depend both on the total concentration of cation and on the pH value. The retention of cations is shown to depend strongly on pH: a variation of pH between 3 and 5 leads to changes in retention efficiency from 0 to 100%. This can be explained by the dissociation of alginic acid as a function of pH. For lower pH values the macroligand is in a molecular form and the metallic cation remains free; for higher values metal complexation is possible, increasing the rejection. If coordination number, rejection rate and pH are known, the various association constants can be determined using a graphical method. It can be seen from the results that the stability of the complexes formed decreases in the sequence Pb>Cu>Mn>Cd.In order to investigate the retention of these cations in a fresh water, the influence of calcium hardness was studied. The results indicate that cation removal decreases when the calcium concentration increases. This observation is an important restriction for fresh water treatment but does not affect the elimination of metals from a solution or an industrial waste containing cations.