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

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

Elaboration and Characterization of Porous Materials from Moroccan Natural Resources: Application to Industrial Wastewater Treatment

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