[Show abstract][Hide abstract] ABSTRACT: The aims of this study were to determine the phosphorus (P) adsorption capacity of the semi-arid soils from Tunisian Sahel and to generate that relates these capacities to soil properties. Air-dried samples soils collected at four depths from three sites in the Sahel region of Tunisia (Chott-Mariem, Enfidha and Kondar). Soil chemical, physical and mineralogical properties were analyzed. 0,5g of each soil samples were shaken with increasing concentrations of solution P for 36 hr at 20 °C. The maximum of P adsorption were greatly influenced by soil organic matter, calcium, magnesium and clay content. Moreover, the data obtained was fitted using Langmuir and Freundlich isotherm functions. P adsorption data revealed that Langmuir equation (R2= 0.98) showed a better describe the adsorption phenomena over the Freundlich equation (R2 =0. 96) in all the three series.
[Show abstract][Hide abstract] ABSTRACT: To optimise recovery of phenolics from Vitex agnus-castus Linn., a non-conventional high-pressure (2-24 bar) and temperature (100-180°C) extraction method was used under nitrogen atmosphere with methanol as a solvent. Optimal temperature was between 100 and 140°C, and optimal extraction time was about one half that of conventional solid/liquid extraction at room temperature. Final yields of total polyphenols, total flavonoids, o-diphenols and anthocyanins extraction were 2.0, 3.0, 2.5 and 11-fold those obtained by conventional extraction.
Natural product research 01/2014; 28(1):67-9. DOI:10.1080/14786419.2013.832678 · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Kinetics sorption study was carried out with varying pH, concentration, and temperature to determine the potential of Agave americana fiber for the removal of methylene blue. The thermodynamic properties (ΔG°, ΔH° and ΔS°) were determined. In order to investigate the sorption mechanisms, kinetic parameters were determined using the Lagergren, the pseudo-second order and the recently established fractal kinetic equations. The experimental kinetics data have been fitted with the non linear form of the new Brouers Sotolongo kinetic model. Fractal kinetic equation gives higher correlation coefficients, indicating that this model can be considered accurate for describing the sorption methylene blue kinetics.
[Show abstract][Hide abstract] ABSTRACT: Increasing concentrations of in surface water and groundwater can cause ecological and public health effects and has come under increased scrutiny by both environmental scientists and regulatory agencies. For many regions though, including the Sahel of Tunisia, little is known about the sorption capacity of soils. In this project we measured sorption by a profile of an iso-humic soil from Chott Meriem, Tunisia. Soil samples were collected from four soil depths (0–25, 25–60, 60–90, and 90–120 cm) on 1 June 2011, and their sorption capacity was determined using batch experiments under laboratory conditions. The effects of contact time, the initial concentration, and the soil-solution ratio on sorption were investigated. In general, the results suggested that was weakly retained by the Chott Meriem soil profile. The quantity of sorption increased with depth, contact time, initial concentration, and soil-solution ratios. To evaluate the sorption capacities of the soil samples at concentrations ranging between 25 and 150 mg L−1 experimental data were fitted to both Freundlich and Langmuir isotherm sorption models. The results indicated that Freundlich model was better for describing sorption in this soil profile.
Applied and Environmental Soil Science 07/2013; 2013(5). DOI:10.1155/2013/597824
[Show abstract][Hide abstract] ABSTRACT: The primary objective of this study was to valorized Vitex agnus-castus residues in terms of phenolic compounds. The effects of extraction time (30–360 min), solid to liquid ratio (0.1–0.3 gDryBiomass/mlSolvent), type of solvent and different tissue types (leave, roots and seeds) on total polyphenols, o-diphenols, total flavonoids and anthocyanins were evaluated. The highest total polyphenol (31.5 mgCaffeicAcidEquivalent/gDryBiomass) and o-diphenol (12.4 mgCaffeicAcidEquivalent/gDryBiomass) contents were obtained from methanolic extract of leaves after 180 min using a solid/liquid ratio of 0.1 gDryBiomass/mlSolvent, while total flavonoids, reached a maximum value of 19.4 mgCatechinEquivalent/gDryBiomass after 360 min under the same conditions. Roots of V. agnus-castus were found to be a good source of anthocyanins with the highest yield of 0.62 mgMalvidinEquivalent/gDryBiomass using ethanol as a solvent (180 min and 0.2 gDryBiomass/mlSolvent). The maximum antiradical power (178.5 μlextract/μgDPPH) was exhibited by the methanolic leave extract obtained after 360 min at solid/liquid ratio of 0.3 gDryBiomass/mlSolvent.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: The potential of Agave americana fibers as biosorbent was investigated in batch Pb(II) and Cd(II) removal as a function of pH, initial metal concentration and temperature. Metal sorption followed pseudo-second-order kinetics with excellent correlation. The Langmuir model was successfully applied to describe the sorption isotherms. Under optimum conditions (20 °C, pH 5.0, contact time of 30–60 min and 5 g L−1 biomass concentration), the maximum sorption capacity of A. americana fibers was 40.0 mg g−1 for Pb and 12.5 mg g−1 for Cd, respectively. The results obtained at different temperatures allowed estimating the thermodynamic parameters (ΔG°, ΔH° and ΔS°) from the sorption equilibrium constants. The positive ΔH° value obtained for sorption of both metals indicates the endothermic nature of the process. A. americana fibers were also analyzed by IR-FT spectroscopy and scanning electron and metallographic microscopy, with the aim of investigating the interactions of biomass functional groups with cations and evaluating the mechanisms involved in metal sorption.
Chemical Engineering Journal 05/2010; 159(1-3-159):67-74. DOI:10.1016/j.cej.2010.02.036 · 4.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This research deals with the utilization of highly available and renewable marine biomass, Posidonia oceanica (L.) fibres as low cost biosorbent for the removal of toxic hexavalent chromium from aqueous solutions and the investigation of the probably involved physiochemical mechanisms in such sorption system throughout a kinetic modelling study. Experiments were carried out in batch reactor. Firstly, the adsorption process was studied as a function of contact time under different initial chromium concentration and initial solution pH. The highest Cr(VI) adsorption capacity determined within the equilibrium time (3 h) was found at pH 2, under a constant temperature of 30 °C. Secondly, several adsorption kinetic models were applied to fit the experimental data, namely Lagergren irreversible first-order, reversible first-order, pseudo-second-order, Elovich and Brouers–Sotolongo models using both the linear and nonlinear regression analyses. The proposed explanations were deduced from the theoretical assumptions behind the most appropriate model(s), which could satisfactorily describe the present biosorption phenomenon.The interpretation of the related results have shown, although some error estimation ambiguities, that the Brouers–Sotolongo “BS” model is the most suitable dynamic theory describing the biosorption of hexavalent chromium onto P. oceanica fibres, predicting therefore a chemisorption process and providing the time necessary to adsorbed half the maximum quantity (τ1/2), a convenient tool to measure the speed of the reaction.
[Show abstract][Hide abstract] ABSTRACT: The leaf sheath fibres of the Mediterranean seagrass Posidonia oceanica (L.) were used as low cost, available and renewable biological adsorbent for the removal of a metal complex textile dye from aqueous solutions. Batch experiments were carried out for sorption kinetics and isotherms. Operating variables studied were exposure time, pH and biomass dosage. Maximum color removal was observed at pH 2. Biosorption capacity was enhanced by increasing biomass quantity up to 10 g/L. Experimental sorption kinetic data were fitted to Lagergren irreversible first-order, reversible first-order, pseudo-second-order and Elovich models and rate constants were estimated. The related data were found to follow the pseudo-second-order and Elovich equations, thereby predicting a chemisorption process. Besides, equilibrium data were well represented by both Redlich–Peterson and Langmuir isotherm models, suggesting a monolayer coverage of dye molecules onto the marine biomass surface and adsorption active sites of quite similar affinities toward the experimental textile pollutant.
[Show abstract][Hide abstract] ABSTRACT: Batch biosorption experiments were carried out for the removal of methylene blue, a basic dye, from aqueous solution using raw and dried Enteromorpha spp., Mediterranean green alga. A series of assays were undertaken to assess the effect of the system variables, i.e. contact time, solution pH and sorbent amount. The results had showed that sorption capacity was optimal using 6-10 solution pH range (i.e. maximum adsorption capacity of 274 mg/g). The minimum sorbent concentration experimentally found to be sufficient to reach the total removal of the dye molecules from the aqueous solution was 5 g/L. Besides, equilibrium data were fitted using five linearisable isotherm models. The related results showed that the experimental data were very well represented by the Langmuir model for the linear regression analysis and both the Langmuir and Redlich-Peterson isotherm models for the non-linear analysis. In both cases, such modelling behaviour confirms the monolayer coverage of methylene blue molecules onto energetically homogenous Enteromopha surface. In addition, an exhaustive comparative study was done to situate this marine biomass among other proposed sorbents.
[Show abstract][Hide abstract] ABSTRACT: A new isotherm equation, the Brouers–Sotolongo isotherm (BSI), a deformed (Weibull) exponential equation was used to describe adsorption equilibrium of phenol and methylene blue (MB), respectively onto a non-porous adsorbent, Posidonia oceanica fibres and two porous adsorbents, chemically and physically activated carbons (ACs) prepared from vetiver roots. The adsorption characteristic parameters obtained were also calculated using classical adsorption isotherm, i.e. the Langmuir isotherm (LI), Freundlich isotherm (FI) and Redlich–Peterson isotherm (RPI). Using only R2 to determine the best-fitting model was not sufficient, calculation of the error deviation using both the Marquardt's percent standard error (MPSE) and the average relative error (ARE) was also done. For the case of phenol, and among all studied models, the BSI involving adsorption on a heterogeneous surface is definitely the most suitable one to satisfactorily describe biosorption of phenol on posidonia, but as well adsorption of phenol on the ACs giving the highest squared correlation coefficients and the lowest MPSE. For posidonia and as well for the ACs, when MB is the adsorbate, the RPI is the best-fitting model.
Chemical Engineering Journal 12/2008; 145(2):196-202. DOI:10.1016/j.cej.2008.04.001 · 4.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Industrial valorisation of low cost and renewable biomass as raw precursor of activated carbon for environmental applications is an interesting alternative to costly commercial activated carbons. In this study, the possible use of Mediterranean, Posidonia oceanica fibrous biomass, as a precursor for chars and physically activated carbons, is investigated. Firstly, the raw marine material was chemically and biochemically characterised throughout dry-basis elemental, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis. Then, several P. oceanica chars were prepared and characterised under different pyrolysis times and temperatures. In addition, physically activated carbons (PACs) were produced via water steam flow under various activation periods. The results showed that the pyrolysis induces the creation of pores at different levels with respect to the involved temperature. Thereafter, the physical activation tends to enhance the development of the porous structure. In that issue, the performed Brunauer-Emmett-Teller (BET) and Barrett-Joiner-Halenda (BJH) analysis revealed that the prepared PACs have a mainly mesoporous inner morphology with a varying fraction of micropores.
[Show abstract][Hide abstract] ABSTRACT: Les ægagropiles du végétal marin Posidonia oceanica (L.) ont été utilisées comme un adsorbant biologique renouvelable et bon marché pour l’élimination de colorant textile métallifère à partir de solutions aqueuses. Les expériences en batch ont été effectuées aussi bien pour les cinétiques que pour les isothermes d’adsorption. Les variables expérimentales étudiées étaient le pH, le temps de contact à différentes concentrations initiales et la quantité de fibres. La capacité d’adsorption s’est avérée maximale à un pH de 2. De plus, elle semble être optimisée par une augmentation de la concentration initiale de colorant et la quantité d’adsorbant jusqu’à 20 g/L. La modélisation des données expérimentales relatives aux cinétiques a montré que le modèle de pseudo-second ordre décrit d’une façon satisfaisante l’adsorption sur fibres brutes, suggérant ainsi une « chimiosorption ». De plus, les données à l'équilibre ont été modélisées en utilisant les équations de Langmuir, Freundlich, Temkin et Redlich-Peterson. L’analyse statistique des constantes relatives à chaque modèle par plusieurs méthodes de calcul de l’erreur a montré que les modèles de Langmuir et de Redlich-Peterson semblent être les plus appropriés pour décrire le présent phénomène d’adsorption avec une probable adsorption en monocouche sur des sites actifs d’affinités similaires.
Journal of Environmental Engineering and Science 10/2008; 7(6):645-650. DOI:10.1139/S08-040 · 0.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This research deals with the exploitation of highly available and renewable marine biomass, Posidonia oceanica (L.) fibres as low cost biosorbent for the removal of metal-complexed textile dyestuff from aqueous medium, and the investigation of the probably involved physiochemical mechanisms. Experiments were carried out in batch reactor. Firstly, the adsorption process was studied as a function of initial solution pH and contact time under different initial dye concentration. The results showed that the highest dye adsorption capacity was found at pH 2 under a constant temperature of 30 degrees C, and the equilibrium state was reached within 48 h of exposure time. Secondly, several adsorption kinetic models were applied to fit the experimental data, namely Lagergren irreversible first-order, Reversible first-order, Pseudo-second-order, Elovich, Ritchie and intraparticle diffusion models. The proposed explanations were deduced from the theoretical assumptions behind the most appropriate model(s), which could satisfactorily describe the present biosorption phenomenon. The interpretation of the related results have shown that, with R(2) of about 99%, the pseudo-second order model is the most suitable dynamic theory describing the biosorption of metal complex dye onto P. oceanica fibres, predicting therefore a chemisorption process.
[Show abstract][Hide abstract] ABSTRACT: In this research, a new low cost and abundant biosorbent; Agave americna (L.) fibres has been investigated in order to remove metal dye (Alpacide yellow) from aqueous solutions. In order to optimize the biosorption process, the effect of pH, temperature, contact time and initial solution concentration was investigated in batch system. The results indicated that acidic pH=2 was favourable for metal dye removal. The increase of temperature increases the velocity of the biosorption reaction. The biosorption kinetics of alpacide yellow were closer to the pseudo-second order than to the first order model for all concentrations and temperature. The calculated thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 indicated a spontaneous and endothermic biosorption process of metal dye onto Agave americana fibres. The equilibrium data were analysed using the Langmuir and Freundlich isotherms and showed a good fit with Langmuir model at lower temperatures and with Freundlich model at 50 °C.
International journal of Environmental Science and Technology 09/2008; 5(4). DOI:10.1007/BF03326047 · 2.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this research, the biosorption of phenol using the fibres of a Mediterranean seagrass Posidonia oceanica (L.) was studied. Batch experimental procedures were made to investigate the ability of this novel marine biomass to remove phenol from aqueous phase. The influences of pH and contact time at different initial concentrations were evaluated. The results showed that biosorption capacity was enhanced using solution pH equal to 5.2. The modelling results showed that pseudo-second-order and Redlich-Peterson models were found to be the most suitable to satisfactory describe the kinetic and equilibrium adsorption data, respectively.Dans cette recherche, on a étudié la biosorption du phénol à l'aide de fibres d'une algue méditerranéenne, Posidonia oceanica (L .). Des essais expérimentaux discontinus ont été menés pour étudier la capacité de cette nouvelle biomasse marine à retirer le phénol de la phase aqueuse. Les influences du pH et du temps de contact à différentes concentrations initiales ont été évaluées. Les résultats montrent que la capacité de biosorption est améliorée avec une solution d'un pH égal à 5,2. Les résultats de modélisation montrent que les modèles de pseudo second ordre et de Redlich-Peterson s'avèrent les plus adaptés pour décrire de manière satisfaisante les données d'adsorption pour la cinétique et l'équilibre, respectivement.
The Canadian Journal of Chemical Engineering 08/2008; 84(4):495 - 500. DOI:10.1002/cjce.5450840411 · 1.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present paper, a review of the production methods of activated carbons from various kinds of precursors and their industrial use is presented, based on recently developed patents. The main discussion is divided into two major parts: (i) the activated carbons fabrication industry starting from the choice of the precursor to the activation of the carbonaceous materials and (ii) their diverse applications. Dealing with the activated carbons precursors, recent patents pointed out the beneficial use of several bioresources, agro-industrial wastes, used tires and newspapers for example. In addition, inventors proposed different kinds of fabrication process, with respect to the field in which the activated carbon
will be used including wastewater and air treatment, fuel purification and gold recovery. Besides, to enhance the overall economical benefit in using activated carbons, other researchers developed some innovative techniques to regenerate hose costly materials, for further utilization of the carbon itself or the recovery of the already sorbed precious compounds.
Hence, this review article summarizes recent and important patents relating to the chemical engineering of activated carbons.
[Show abstract][Hide abstract] ABSTRACT: Three isotherm models were used to describe adsorption equilibrium of a toxic chemical compound, phenol, onto a non porous adsorbent (Mediterranean Posidonia oceanica fibres) and a porous adsorbent, activated carbon prepared from Caribbean Vetiveria zizanoides roots. The adsorption characteristic parameters obtained were calculated using classical adsorption isotherm, i.e. the Langmuir (LI), Freundlich (FI) and Redlich-Peterson (RPI) isotherms. Calculation of the error deviation was performed using both R² and the average relative error (ARE). Thus, among the studied models, the Langmuir equation involving adsorption on a homogeneous actives site is definitely the most suitable modelling tool to satisfactorily describe biosorption of phenol on Posidonia and vetiver-derived activated carbon, by providing the highest squared correlation coefficients and the lowest ARE.
Twelfth International Water Technology Conference; 03/2008
[Show abstract][Hide abstract] ABSTRACT: Les fibres du végétal marin Posidonia oceanica (L.) ont été utilisées en tant que matrice adsorbante d'un colorant textile réactif (Cibacron Red) pour son élimination des solutions aqueuses. Des essais en batch ont été réalisés pour déterminer les cinétiques et les isothermes d'adsorption. Les variables expérimentales étudiées sont la taille des particules, la quantité de fibres, la température, le pH et les prétraitements chimiques. L'état d'équilibre est atteint au bout de 48 h. La capacité de biosorption semble être maximisée par une augmentation de la quantité de support. La température a également un effet stimulant sur la biosorption du colorant. Le maximum de biosorption a été observé à un pH de 5,5. Le prétraitement préalable des fibres à l'acide phosphorique et nitrique permet d'augmenter considérablement leur capacité d'adsorption. La modélisation des données expérimentales a montré que les modèles du pseudo-second ordre et de Freundlich décrivent, respectivement, les cinétiques et les isothermes d'adsorption d'une façon satisfaisante. L'étude des aspects thermodynamiques a montré que l'adsorption du colorant par la biomasse P. oceanica est un phénomène favorable, endothermique et spontané.
The marine biomaterial Posidonia oceanica (L.) fibres were used as a novel low-cost biological adsorbent for the removal of reactive textile dye (Cibacron Red) from aqueous solutions. Batch experiments were carried out for sorption kinetics and isotherms. Operating variables studied were contact time, fibres quantity, temperature, pH, and chemical pre-treatment. The equilibrium state was reached within 48 h. Biosorption capacity seems to be enhanced by increasing the biosorbent mass. Rising the temperature has also a positive effect on dye removal rate. Maximum colour removal was observed at pH 5.5. Pre-treating fibres with H3PO4 and HNO3 solutions increased considerably the adsorption capacity. Kinetic and equilibrium data for raw fibres were well described by the pseudo-second order and Freundlich models, respectively. Besides, the thermodynamic study has showed that the dye-adsorption phenomenon onto P. oceanica biomass was favourable, endothermic and spontaneous.
The Canadian Journal of Chemical Engineering 02/2008; 86(1):23 - 29. DOI:10.1002/cjce.20005 · 1.23 Impact Factor