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Ben Hamed K.,Center de Biotechnologie de la Technopole de Borj-Cedria | Zorrig W.,Center de Biotechnologie de la Technopole de Borj-Cedria | Hamzaoui A.H.,National Center for Research in Materials science
Computers and Electronics in Agriculture

In order to evaluate the reliability and the practical use of the electrical impedance spectroscopy method applied in the area of salt resistance, electrical impedance spectra were compared in the leaves of halophyte plants cultivated under different growth conditions (biotope versus controlled conditions, hydroponic versus sand system cultures) and different salt stress conditions. The kinetic of impedance parameters was also monitored under short term salinity. The spectra of electrical impedance of leaves under biotope and laboratory conditions showed difference in the electrical response of Cakile maritima in the biotope and laboratory conditions. The response of electrical impedance parameters to salinity was also different in the hydroponic system when compared to the soil one, indicating more stressful conditions in solution culture. The amplitude of the curves of impedance spectrometry decreased when plants were stressed comparatively to their controls, with the highest electrical resistance in the presence of 50 and 100 mM while the lowest value was at 400 mM NaCl. The electrical resistance increased at an early stage after the application of salt stress reaching maximal value 180 min later, before it rapidly declined thereafter. The observed peak can translate a signal, that the plant could have received, which triggers a cascade of metabolic reactions allowing the plant to regain its hydro-ionic balance. In conclusion, electrical impedance spectroscopy can be used to quickly compare different growth conditions as well as different salinity treatments. This method can also separate between the osmotic and the ionic phases of the response to salt stress. © 2016 Elsevier B.V. Source

Bennani C.F.,National Institute of Research and Physico Chemical Analysis | Ousji B.,National Institute of Research and Physico Chemical Analysis | Ennigrou D.J.,National Center for Research in Materials science
Desalination and Water Treatment

Abstract: Large amounts of water are daily used in dairy industries for different parts of their services such as chilling, cooling, steam production, pasteurizing, etc. This consumption generates a huge quantity of wastewaters which could be reused after performed treatment. In the present work, a real sample of dairy wastewater was treated using ultrafiltration (UF) and process efficiency and permeate quality were improved by operating under optimum conditions of transmembrane pressure (TMP) and volume reduction factor (VRF). More than 99% of retention rate were observed for turbidity and the BDO5, more than 80% for suspended matter, and 95% for proteins with an optimal TMP fixed at 2.5 bar. Moreover, a reduction of 40 and 55% was recorded for conductivity and the total dissolved salts, respectively. Rather important retention rates varying from 95 to 99% for the majority of the analyzed parameters were observed for a VRF range varying from 1.11 to 2.5. A recovery of 58% of the dairy effluent is possible after treatment by UF using the PES-5 membrane. The permeate quality obtained in optimal TMP and VRF allows the industry to reject its effluents into the river without risks of contamination (according to Tunisian standard for wastewater discharge NT106-02) and to reuse or recycle them during the process (according to Tunisian standard for reusing treated wastewater NT106-03). © 2014 Balaban Desalination Publications. All rights reserved. Source

Hammami R.,Center for Research and Energy Technologies n | Ahamed Z.,National Center for Research in Materials science | Charradi K.,Center for Research and Energy Technologies n | Beji Z.,Center for Research and Energy Technologies n | And 5 more authors.
International Journal of Hydrogen Energy

Nafion hybrid membrane containing titanium dioxide (TiO2) nano-particles were elaborated by in situ sol-gel technique. Micro wave treatment was used during hybrid elaboration to 2 h. The X-ray diffraction (XRD) shows the crystallization of TiO2 in anatase and rutile phases. The Infrared spectroscopy IR spectrum of hybrid membranes Nafion-TiO2 confirm the presence of bonds Ti-O and Ti-OH which proves that the hybridization of the membrane by sol-gel method is successful. Atomic Force Microscopy AFM confirmed the good dispersion of TiO2 nano-particles. The electrochemical impedance spectroscopy (EIS) and solvent uptake measurements suggest the enhancement of the membrane performance. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Ennigrou D.J.,National Center for Research in Materials science | Ben Sik Ali M.,Desalination and Water Treatment Research Unit | Dhahbi M.,National Center for Research and technology water

Copper and Zinc removal from aqueous solution by polyelectrolyte enhanced ultrafiltration (PEUF) process was investigated using poly(acrylic acid) (PAA) with average molecular weight 100kDa. The ultrafiltration studies were carried out using a tangential cell system, equipped with 10,000 MWCO regenerated cellulose. Several parameters have been studied such as: transmembrane pressure, PAA concentration, pH and ionic strength to improve the retention of the metal ions. The removal of Zn2+ and Cu2+ is respectively more than 70% and 93%. A better retention was observed at 2·10-3molL-1 PAA concentration and 3bar transmembrane pressure. The pH effect on the Zinc and Copper recovery revealed a maximum retention around 75% and 97%, respectively, for pH=5. The study of the ionic strength effect has shown a retention decrease with the salt concentration increase. Selectivity was studied using a solution containing the two metal ions. Zinc retention decreases compared to single metal solutions, and this is more significant in the case of Copper ions. © 2013 Elsevier B.V. Source

Ennigrou D.J.,National Center for Research in Materials science | Sik Ali M.B.,Desalination and Water Treatment Research Unit | Dhahbi M.,Water Researches and Technologies Center | Ferid M.,National Center for Research in Materials science
Desalination and Water Treatment

One of the recently developed water treatment processes is the polyelectrolyte-enhanced ultrafiltration (PEUF). This technique combines a membrane filtration process (ultratfiltration) and a cation–polyectrolyte complexation technique. PEUF is shown to be an efficient technology for the removal of heavy metals from liquid effluents even at low concentrations. In this proposal, the removal of three heavy metals (cadmium, copper and zinc) from aqueous solutions by PEUF process was investigated. The poly(acrylic acid) (PAA) with an average molecular weight 100 kDa was used as complexing agent. The ultrafiltration experiments were performed using a tangential cell system equipped with a polyethersulphone membrane having a 10.000 molecular weight cut-off (MWCO). To improve the retention of the heavy metal ions, the effect of some operating parameters and solution characteristics were studied. For different PAA concentrations, this study showed that all permeate fluxes increased linearly by increasing transmembrane pressure. For the three studied metals, the best retentions were observed at 2 × 10–3 mol L–1 PAA concentration, 3 bar transmembrane pressure and pH above 5. The removal of cadmium, copper and zinc exceeded, respectively, 80, 93 and 70%. © 2014 Balaban Desalination Publications. All rights reserved. Source

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