CONGO RED REMOVAL FROM AQUEOUS EFFLUENTS BY ADSORPTION ON CHERRY STONES ACTIVATED CARBON

International audienceSoluble dyes are intensively used in various industrial activities. They represent an important class of water pollutants from which they are rather difficult to remove. This paper focusses on the elimination of Congo Red (CR) ionic azo dye by adsorption on a low cost material. Cherry stones were used for activated carbon preparation by carbonization method. A temperature of 600 degrees C and a time of 4 h were found as adequate parameters for the physical activation and led to a final white powder with fine particles. The obtained product was put in contact with CR aqueous solutions having concentrations ranging between 200 mg/L and 1000 mg/L and pH values between 2 and 12 and the mixtures were magnetically agitated for periods of 10 to 180 minutes. The best results were recorded at acidic and neutral pH where the CR removal percentage was over 99 % while in alkaline environment the adsorption was negligible. The applied tests revealed that the process is well described by a pseudo-second-order kinetic model (with correlation coefficients close or equal to unity) and that Freundlich isotherm is suitable to insure a very good fit with the experimental data (with correlation coefficients values higher than 0.99). The acquired results proved that cherry stones (a rarely used waste from food industry) can constitute an interesting and adequate alternative for manufacturing inexpensive materials possessing adsorption properties with high capacity for dye removal from aqueous solutions

Evaluation of Three Operational Parameters in Adsorption Process of Organic Dyes

International audienceThe present research was focused on the synthesis of a new material and on the evaluation of its adsorptive capacity. Powder of cherry stones (waste product of fruit industry) was entrapped on chitosan (a natural polymer). The developed product performance was assessed for the elimination of an organic dye (Acid Red 66). The experimental results reveal that the produced composite can be a viable solution for the treatment of colored aqueous effluents. Under optimized conditions (pH 2, adsorbent concentration: 100 g/L, working temperature: 30 °C), the manufactured adsorbent was able to retain more than 95 % of the target pollutant

Effective Removal of Biebrich Scarlet Dye from Aqueous Solutions by Adsorption on Cherry Stones Powder Coated with Chitosan

International audienceCherry stones powder and chitosan were used to prepare an adsorbent material that served to remove Biebrich Scarlet dye from aqueous matrices. Optimal working parameters were obtained by applying the Response Surface Methodology-Central Composite Design. Hence, at pH 3 and at 30 degrees C with 1 g of adsorbent, more than 90 % of the pollutant was removed from the aqueous solutions with concentrations between 10 mg/L and 50 mg/L after 4 hours of adsorption. Pseudo-2nd order kinetic model and Freundlich isotherm were established as describing with a high degree of confidence (correlation coefficients were above 0.99) the kinetic behavior and the equilibrium isotherm of the conducted process

A new strategy for pentachlorophenol monitoring in water samples using ultra-high performance liquid chromatography - mass spectrometry tandem

International audienceA novel sensitive and rapid anal. approach based on ultra-high performance liq. chromatog. - mass spectrometry (UHPLC/MS/MS) tandem was developed for the monitoring of pentachlorophenol in water samples. Chromatog. sepn. was carried out on Acquity BEH C18 (100 × 2.1 mm, 1.7 μm) column under gradient mode using a mobile phase consisting of acetonitrile/ultrapure water/formic acid. Quantification of pentachlorophenol was performed on a triple-quadrupole tandem mass spectrometer under multiple reaction monitoring (MRM) mode, via a neg. electrospray ionization (ESI-). The limit of quantification of the developed instrumental method was 0.3 μg L-1. The linearity was validated within the concn. range 0.1-100 μg L-1 with a correlation coeff. (R2) of 0.998. Intra-day and inter-day precision values were 99.78 and 99.12%, resp. Moreover, for the application to real water samples, a solid phase extn. method (SPE) was proposed for the extn. and preconcn. of analyte. Some of the main factors involved in the SPE extn. process such solid phase material, elution solvent and sample vol. were investigated and optimized in order to maximize the extn. efficiencies. Oasis HLB cartridges showed the best results in term of extn. recovery. High analyte recoveries (between 98.2% and 100.18%) were achieved with the proposed SPE procedure and the extn. RSD was less than 3.1%. In addn., the whole new anal. strategy (SPE-UHPLC/MS/MS) was then successfully applied for pentachlorophenol quantification in natural waters at low part per trillion levels

Removal of Astrazone Blue from aqueous solutions onto brown peat. Equilibrium and kinetics studies

International audienceThe aim of this study is to characterize and assess the sorption potential of brown peat, in relation to colored pollutants from the textile industry wastewater. The objectives of this paper were: the physicochem., morphol., and mineralogical characterization of brown peat, testing the adsorption capacity of natural and chem. treated peat samples for Astrazone Blue, evaluation of adsorption process from equil. isotherm and kinetic point of view. The characteristics of the peat samples were investigated using elemental anal., SEM and X-​ray diffractometry. Exptl. data indicated that the brown peat tested confirm a high level of adsorption (removal efficiency >93.00​%, adsorption capacity reaching up to 24.27 mg​/g) of Astrazone Blue from aq. soln. The Langmuir and Freundlich adsorption isotherm models were used to find the best equation able to describe the adsorption process. Exptl. adsorption data were successfully described by the Langmuir equil. isotherm model. This fact is supported by the agreement between the q values obtained using the Langmuir equation (26.32 mg​/g)​, and the ones obtained exptl. (24.27 mg​/g)​. The kinetic studies showed that the pseudo-​second-​order model described Astrazone Blue sorption kinetics, as confirmed by the high values of R, which are over 0.99 for the whole investigated concn. range (200 to 800 mg​/L)​. The use of brown peat adsorbent is more advantageous compared with other materials since it does not require a preliminary treatment, is low-​cost and is an eco-​friendly adsorbent. Hence, this peat appears to be a viable material for the decontamination of effluents contg. dyes

PHOTOCATALYTIC OXIDATION OF A HAZARDOUS PHENOLIC COMPOUND OVER TiO2 IN A BATCH SYSTEM

International audienceRecently, environmental scientists have been focused their attention on the occurrence and the elimination of specific organic compounds in water. Among them, chlorophenols are considered to be a public health problem due to their carcinogenic properties. Thus, there is an important need to find new strategies to efficiently transform these compounds to no toxic or inactive by-products. In this work the photocatalytic removal of 2,4-dichlorophenol in water solution was investigated at laboratory scale in a batch photoreactor using a commercial titanium dioxide as catalyst. Effects of different operating parameters such as initial pollutant concentration, catalyst load and UV-light intensities on the photocatalytic elimination efficiency were evaluated in detail for future practical application purposes. Obtained data clearly showed an optimum degradation of the target compound under an initial pollutant concentration of 1.5 mg/L, a titanium dioxide concentration of 1 g/L and for UV-light intensity of 59.6 W/m(2). The total organic carbon removal was also calculated in order to confirm the mineralization of 2,4-dichlorophenol. The obtained data showed a higher mineralization yield under the optimized photocatalytic reaction conditions demonstrating the performance of the photocatalytic oxidation to remove the target molecule at low concentrations from aqueous medium

EFFICIENT DEGRADATION OF CLOFIBRIC ACID BY HETEROGENEOUS PHOTOCATALYTIC OXIDATION PROCESS

International audienceEmerging pollutants such as pharmaceutical active compounds were detected worldwide in different environmental compartments. Nowadays, multiple studies are focused on the investigation of their environmental fate, as well as to find new, efficient and sustainable removal technologies. Several studies demonstrated that heterogeneous photocatalysis is one of the most promising techniques used for water purification. Thus, the aim of our work was to evaluate the photodegradation efficiency of a refractory emergent compound, named clofibric acid, under UV light in aqueous solution. We report that photodegradation and mineralization efficiency are strongly dependent of the catalyst used. Results showed that the photodegradation was enhanced in the presence of TiO2 Aeroxide. The complete elimination was achieved for an initial pollutant concentration of 1.5 mg/L after 30 min of irradiation, the degradation rate following the pseudo-first order kinetics. It was also observed that the rate constant for the photodegradation process is affected by the concentration of catalyst. Process efficiency is enhanced by increasing the light intensity. The simultaneous reduction of pollutant concentration and dissolved organic carbon demonstrates the mineralization of the target molecule. Furthermore, it was demonstrated that the addition of nitrate to the system increases the pollutant degradation rate, while the carbonate reduces its removal, suggesting that this last ion can act as a hydroxyl scavenger. Preliminary phytotoxicity tests were also carried out and showed the capacity of the heterogeneous photocatalysis to reduce the toxicity of reaction intermediates generated during the photocatalytic reaction

Investigation into Biosorption of Pharmaceuticals from Aqueous Solutions by Biocomposite Material Based on Microbial Biomass and Natural Polymer: Process Variables Optimization and Kinetic Studies

International audienceBiosorbtive removal of the antibacterial drug, ethacridine lactate (EL), from aqueous solutions was investigated using as biosorbent Saccharomyces pastorianus residual biomass immobilized in calcium alginate. The aim of this work was to optimize the biosorption process and to evaluate the biosorption capacity in the batch system. Response surface methodology, based on a Box-Behnken design, was used to optimize the EL biosorption parameters. Two response functions (removal efficiency and biosorption capacity) were maximized dependent on three factors: initial concentration of EL solution, contact time, and agitation speed. The highest values for the studied functions (89.49%, 26.04 mg/g) were obtained in the following operational conditions: EL initial concentration: 59.73 mg/L; contact time: 94.26 min; agitation speed: 297.57 rpm. A number of nonlinear kinetic models, including pseudo-first-order, pseudo-second-order, Elovich, and Avrami, were utilized to validate the biosorption kinetic behavior of EL in the optimized conditions. The kinetic data fitted the pseudo-first-order and Avrami models. The experimental results demonstrated that the optimized parameters (especially the agitation speed) significantly affect biosorption and should be considered important in such studies

Successful fodder yeast production from agro-industrial by products through a statistical optimization approach

International audienceThe present work focused on the fodder yeast production, an attractive source of proteins for the livestock nutrition through the efficient growth of microorganisms on inexpensive waste substrates. Two agricultural by-products, sugar beet pulp and barley husks, rich in simple carbohydrates (88 g/L and 31.77 g/L for sugar beet hydrolysate and barley husks hydrolysate, respectively) were mixed after acid hydrolysis and used as a carbon and energy source for the "fodder yeast" Candida utilis production. Various nutritional requirements affecting the yeast growth were considered and investigated through an experimental design approach. The Response Surface Methodology was applied in order to optimize the medium composition aiming to increase on the one hand the yield on biomass rich in protein content and the substrate bioconversion on the other hand. Statistical analysis of the mathematical models developed for the studied response functions revealed a good correlation between the experimental data and the predicted values. In a medium containing 32-34 g/L reducing sugar, 1.022-1.079 g/L nitrogen and 0.406-0.427 g/L phosphorous, 6.47-6.62 g/L biomass were obtained. Under these conditions the final product protein content was of 50.40-51.55% (w/w) for a substrate consumption yield (expressed as monosaccharides content) of 92.94-95.4% (w/w)

Intensification of the photodegradation efficiency of an emergent water pollutant through process conditions optimization by means of response surface methodology

International audienceHeterogeneous photocatalysis has been increasingly investigated during the past years and has been recognized as a promising technique for clean and safe water purification. The current study exploits the advantage of this technique demonstrating that the removal of a biorefractory water pollutant named clofibric acid can be really improved by photocatalysis through a parametric comprehensive investigation and optimization study based on response surface methodology. Its novelty comes from the approach used to enhance the efficiency of the photocatalytic degradation of clofibric acid. A custom central composite design consisting of 49 trials was applied for process modeling and a quadratic robust model was derived based on the analysis of variance for the optimization of the process parameters. The effective removal of the target molecule with about 70% carbon mineralization was achieved under optimal photocatalytic conditions: 1.5 mg/L as the initial concentration of pollutant, 0.61 g/L catalyst, and an irradiation time of 190 min. Further, it was provided that nitrates play a positive role in the removal of this pollutant, while hydrogenocarbonates slow down its elimination. The ecotoxicity evaluation at different trophic levels confirmed the low toxicity of photodegradation by-products. Data analysis demonstrated that response surface methodology is a reliable approach for the optimization of the interactive effects of photocatalytic process parameters and is able to enhance their performance for the complete elimination of this hardly removed water pollutant