Nitrate removal from aqueous solutions by γ-Al2O3 ultrafiltration membranes

In the framework of understanding the transport mechanism that governs the filtration of NO3− solution through a γ-Al2O3 membrane with a nominal pore size of 5 nm at low ultrafiltration, a series of various types of nitrate solutions and operating conditions were investigated. The effect of filtration parameters such as pH, applied pressure and NO3− concentration on the selectivity and permeability of the membrane were studied using binary solutions (KNO3, NaNO3, Ca(NO3)2 and Mg(NO3)2) and ternary solutions ((NaNO3 + KNO3), (NaNO3 + Ca(NO3)2) and (Mg(NO3)2 + Ca(NO3)2). The experimental filtration results showed that high NO3− rejection was observed when pH was close to the point of zero charge of the membrane for both binary and ternary solutions. NO3− rejection increased with an increase of applied pressure. The rejection gradually decreased when the initial NO3− concentration increased. It appeared that the valency and hydrated radius of associated cation had a dramatic effect on NO3− rejection, with the divalent cations being more rejected than monovalent cations. In order to get to natural water complexity, three different samples of mineral water doped with NO3− from two different sources were studied at optimized operating conditions (25 ppm of NO3− and 6 bar). Experimental results demonstrated that NO3− rejection strongly depended upon the total mineralization and the presence of divalent anions in solution. In addition, the obtained results showed the potential use of γ-Al2O3 ultrafiltration membrane for denitrificatoin of contaminated water especially in Moroccan agricultural areas

Electrostatic interactions as governing the fouling in protein microfiltration

The influence of pH and electrostatic interactions on the fouling mechanism during protein dead-end microfiltration (MF) has been investigated for two charged membranes. Polyethersulfone acidic membranes (ICE-450), being negatively charged, and basic ones (SB-6407), these positively charged, both from Pall Co., have been used in the investigations. BSA and Lysozyme solutions at different pH values (3.0, 5.0, 7.0, 8.5 and 10.0) were microfiltered through the membranes at a constant applied transmembrane pressure. Results have been analysed in terms of usual blocking filtration laws and a substantial change in the fouling behaviour has been observed when solution pH and/or membrane charge as the pressure was changed, this change being clearly related with the specific membrane-protein and protein-protein interactions

Optimal preparation of low-cost and high-permeation NaA zeolite membrane for effective ethanol dehydration

International audienceIn this work, low-cost and high permeation NaA zeolite membrane was successfully prepared on kaolinite support by in-situ crystallization using secondary growth method. The effect of synthesis conditions including temperature and time of crystallization, and water ratio was studied aiming to improve the quality and the performance of the membrane. The prepared membrane was thoroughly characterized using many techniques such as X-ray diffraction, scanning electron microscopy infrared spectroscopy, Brunauer-Emmett-Teller specific surface area and zeta potential to investigate the layer deposition. The prepared membrane exhibits high permeation flux of 8.49 kg m −2 h−1 and separation factor of 10900 for the dehydration of 90 wt% ethanol by pervaporation at 75 °C. © 2022 Elsevier Inc

Flat ceramic microfiltration membrane based on natural clay and Moroccan phosphate for desalination and industrial wastewater treatment

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Paléorivages, dunes côtières et occupations humaines à l'embouchure de l'Oued Tamri, Maroc Atlantique, au Pléistocène Supérieur (SIM 5)

International audiencel’embouchure de l’oued Tamri, rive gauche, un paléorivage de faciès marin et fluvio-marin (unité U1) culmine aux environs de + 6m a.s.l. Une co-quille marine de Patella sp. prélevée dans cette unité U1 (faciès marin) a été datée 100,02 ± 1,662 ka et 101,188 ± 1,339 ka par la méthode U/Th (SIM 5.3). La dune surincombante (série Sx) a été datée par OSL 84 ± 4 ka (SIM 5.1). A Tighrine Imkssawne, à 200 m au Sud de l’embouchure, ce paléorivage est surmonté d’une séquence de dé-pôts dunaires et colluviaux de plus de 20 m d’épaisseur. Ces derniers renferment plusieurs paléosols rubéfiés interstratifiés et des encroûte-ments, témoins de périodes humides et de ruissel-lements, qui permettent de distinguer trois unités principales (unités U2, U3, U4) :(U2), unité d’accumulation interdunaire inférieure où dominent les faciès détritiques continentaux de colluvionnement/ruissellement. Elle renferme de nombreux Hélicidés et de rares témoins d’outillage lithique.(U3), unité d’accumulation éolienne moyenne, à séries dunaires encroûtées où la série (S5) a été datée par OSL 92 ± 6 ka (SIM 5.3 ou SIM 5.2), et où le paléosol rubéfié (S6) a fourni une industrie à proto-hachereaux.(U4), unité d’accumulation éolienne supérieure à séries friables, séparée de la précédente par une paléo-surface encroûtée (S6/S7) à industrie proba-blement épipaléolithique, et où des coquilles d’oeufs d’Autruche de la série (S8) sont datées par radiocarbone à plus de 30 ka. BPLes analyses géomorphologiques, sédimentolo-giques et pétrographiques aboutissent à un mo-dèle sédimentaire d’accumulation de pied de fa-laise morte qui permet de répondre aux contradic-tions apparentes entre la position de l’industrie lithique et des datations

Résilience entre les occupations humaines préhistoriques et les dépôts de travertins au Maroc.

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