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Mahmoud K.A.,Qatar Environment and Energy Research Institute | Mahmoud K.A.,Khalifa University | Abdel-Wahab A.,Texas A&M University at Qatar | Zourob M.,Center Energie | Zourob M.,Cranfield University
Water Science and Technology | Year: 2015

A new versatile electrochemical sensor based on poly(styrene-co-acrylic acid) PSA/SiO2/Fe3O4/AuNPs/lignin (L-MMS) modified glassy carbon electrode (GCE) was developed for the selective detection of trace trinitrotoluene (TNT) from aqueous media with high sensitivity. The fabricated magnetic microspheres were characterized by transmission electron microscopy (TEM), energydispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). L-MMS films were cast on the GCE surface to fabricate the TNT sensing electrode. The limit of detection (LOD) of TNT determined by the amperometric i-t curve reached 35 pM. The lignin film and well packed Fe3O4/AuNPs facilitated the pre-concentration of trace TNT on the electrode surface resulting in a fast amperometric response of 3 seconds near the detection limit. The high sensitivity and excellent catalytic activity of the modified electrode could be attributed to the lignin layer and highly packed Fe3O4/AuNPs on the electrode surface. The total recovery of TNT from tapwater and seawater matrices was 98% and 96%, respectively. The electrode film was highly stable after five repeated adsorption/desorption cycles. The new electrochemical sensing scheme provides a highly selective, sensitive and versatile assay for the in-situ detection of TNT in complex water media. © IWA Publishing 2015 Water Science & Technology. Source


Asbik M.,Moulay Ismai University | Ansari O.,University Med uissi | Bah A.,University Med uissi | Zari N.,Center Energie | And 2 more authors.
Desalination | Year: 2016

The exergy analysis of a passive solar still combined with heat storage system is presented in meteorological conditions taken on 15th of June 2011 at Errachidia city (Latitude: 31°58'N, Longitude: 4°20'W, Morocco), to determine the magnitude of exergy losses during the heat storage/retrieve period. Paraffin wax is used as phase change material (PCM) to store/retrieve energy in the process of changing the aggregate state from solid to liquid. The exergy balance equation for each element of the desalination unit as well as for the PCM is formulated and numerically solved. The variations versus time of temperature within PCM, the exergy destruction of solar still and that of PCM medium, the pure water productivity and exergy efficiency are shown in the obtained results. Effects of the influencing parameters (the thickness of the PCM medium, the ambient air velocity and the brackish water depth) on the exergy destruction (entropy generation) are highlighted. Moreover, the latent heat storage increases the water productivity and reduces the exergy efficiency. © 2015 Elsevier B.V. Source


Mahmoud K.A.,Qatar Environment and Energy Research Institute | Mahmoud K.A.,Center Energie | Zourob M.,Center Energie | Zourob M.,King Saud University
Analyst | Year: 2013

A new lignin modified hybrid microsphere, comprising poly(styrene-co- acrylic acid) core and magnetite (Fe3O4)/Au nanoparticle (NP) shell, was proposed here for the selective and highly sensitive detection and removal of 2,4,6-trinitrotoluene (TNT) explosives based on surface enhanced Raman scattering (SERS) and electrochemical detection methods. The presence of lignin and the highly packed layer of Fe3O4/AuNPs as a magnetic collector and metal enhancer for SERS signals allowed for the detection of TNT below 1 pM. This journal is © 2013 The Royal Society of Chemistry. Source

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