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Bennajah M.,Chemical Engineering Laboratory | Maalmi M.,Chemical Engineering Laboratory | Touhami M.E.,Université Ibn Tofail
Journal of Urban and Environmental Engineering | Year: 2010

A variable order kinetic (VOK) model derived from the langmuir-freundlish equation was applied to determine the kinetics of fluoride removal reaction by electrocoagulation (EC). Synthetic solutions were employed to elucidate the effects of the initial fluoride concentration, the applied current and the initial acidity on the simulation results of the model. The proposed model successfully describes the fluoride removal in Airlift reactor in comparison with the experimental results. In this study two EC cells with the same capacity (V = 20 L) were used to carry out fluoride removal with aluminum electrodes, the first is a stirred tank reactor (STR) the second is an airlift reactor (ALR). The comparison of energy consumption demonstrates that the (ALR) is advantageous for carrying out the defluoridation removal process. © 2010 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.

Filippidi E.,Materials Research Laboratory | DeMartini D.G.,Cellular and Developmental Biology Laboratory | De Molina P.M.,Chemical Engineering Laboratory | Danner E.W.,University of California at Santa Barbara | And 7 more authors.
Journal of the Royal Society Interface | Year: 2015

Marine mussels of the genusMytilus live in the hostile intertidal zone, attached to rocks, bio-fouled surfaces and each other via collagen-rich threads ending in adhesive pads, the plaques. Plaques adhere in salty, alkaline seawater, withstanding waves and tidal currents. Each plaque requires a force of several newtons to detach. Although the molecular composition of the plaques has been well studied, a complete understanding of supra-molecular plaque architecture and its role in maintaining adhesive strength remains elusive. Here, electron microscopy and neutron scattering studies of plaques harvested from Mytilus californianus and Mytilus galloprovincialis reveal a complex network structure reminiscent of structural foams. Two characteristic length scales are observed characterizing a dense meshwork (approx. 100 nm) with large interpenetrating pores (approx. 1 mm). The network withstands chemical denaturation, indicating significant cross-linking. Plaques formed at lower temperatures have finer network struts, from which we hypothesize a kinetically controlled formation mechanism. When mussels are induced to create plaques, the resulting structure lacks awell-defined network architecture, showcasing the importance of processing over self-assembly. Together, these new data provide essential insight into plaque structure and formation and set the foundation to understand the role of plaque structure in stress distribution and toughening in natural and biomimetic materials. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Chemat-Djenni Z.,Chemical Engineering Laboratory | Sakhri A.,Chemical Engineering Laboratory
MATEC Web of Conferences | Year: 2013

The active pharmaceutical substance artemisinin found in Artemisia annua L. remains the most effective remedy against malaria. The objective of this work is the purification of the active ingredient through a natural matrix composed of clay sandwiched by aluminum. The purification process is carried by adsorption of the extracts on sodium type and bridged clay type. The XRD characterization of this material shows an increase in the basal distance of 10 Å to 17 Å. This shows the success of the intercalation of aluminum polycation. We find a better purification of the extract when using aluminum bridged clay compared to sodium clay. The best performance of 80.64% adsorption is obtained at 40 °C for the clay matrix bridged with aluminum complex. © Owned by the authors, published by EDP Sciences, 2013.

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