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    Optimization of the activity of Mo7-Zn3/CaO catalyst in the transesterification of waste cooking oil into sustainable biodiesel via response surface methodology
    (2024) Kouider Elouahed, Salima; Asikin-Mijan, Nurul; Alsultan G, Abdulkareem; Kaddour, Omar; Yusop, Muhammad Rahimi; Mimoun, Hadj; Samidin, Salma; Mansir, Nasar; Yap, Taufiq Yun Hin
    An enriched basic site CaO-supported bimetallic Molybdenum-Zinc (Mo7-Zn3) catalyst was successfully synthe- sized via wet-impregnation and evaluated for the transesterification of waste cooking oil into biodiesel. The physicochemical characterization of the Mo7-Zn3/CaO catalyst demonstrated good dispersion of CaMoO4 and ZnO oxides on CaO support, with a mesoporous structure allowing for better mass transfer between reactants. The Mo7-Zn3/CaO catalyst exhibited high transesterification activity (95 ± 0.3 % FAME conversion), owing to the large density of strong Brønsted basic sites (conjugated O2–) generated from simultaneous interaction among Ca2+, Zn2+, and Mo6+ metal species. Response Surface Methodology (RSM) and Box Behnken Design (BBD) were used to optimize the reaction and indeed, the utmost FAME conversion of 95 % is achieved using 3.37 wt% catalyst loading, 12:1 methanol to oil molar ratio within 2.27 h at 62.7 ◦C reaction temperature. The model reliability in predicting the FAME yield using the established catalyst under varying operational conditions was excitedly validated with a reasonable accuracy error of 0.5 %. The catalyst exhibited good stability, maintaining a high FAME conversion (95–85 %) during 5 reusable cycles without significant loss in catalytic activity. A closer look for a detailed approach and a heterogeneous mechanism for the reaction using Mo7-Zn3/CaO catalyst was proposed. The physical and chemical properties of the produced biodiesel were carefully compared with the standard for biodiesel, and were found to majorly comply with ASTM D6751 and EN 14214 biodiesel properties. An investigation into the economic competitiveness and industrial applicability of biodiesel production using Mo7-Zn3/CaO from WCO reveals significant potential for sustainable and efficient biodiesel synthe
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    Total contents of major minerals in the nature yoghurt and in the yoghurts with the date powder of three dry varieties
    (2011) Amellal, Hayet; Benamara, Salem
    In this paper we report on the content of major minerals (calcium, magnesium, sodium, potassium, iron and zinc) in the nature yoghurt (without sugars) and three yoghurts added with date powders. The latter’s were from three dry date varieties (Mech-Degla, Degla-Beida and Frezza). The elements determination was carried out using atomic absorption spectrometry after mineralization processing. Total mineral content showed a great difference between the yoghurt nature and yoghurts enriched by date powder fruits. In the yoghurts added with date powder, following results were found (in mg/Kg): calcium (2213.31-2938.67), sodium (783.37-959.36), potassium (725.68-771.77), magnesium (169.54-267.85), iron (9.6-11.52), zinc (1.29-7.93). Concerning the natural yoghurt the values obtained were (in mg/Kg): calcium (1950.41), Sodium (684.72), potassium (540.58), magnesium (132.16), iron (5.26), zinc (0.35). These results are in positive interrelationship with those of the rheological properties
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    Effect of calcium competition on chromium adsorption by fungi biomass
    (2006) Louhab, K.; Sahmoune, Mohamed Nasser; Addad, J.; Bar, S.
    The kinetics and thermodynamic of adsorption of a mono-solute of chromium ions and of a bi-solute of chromium and calcium ions by fungi biomass (Streptomycine rimosus) was investigated in a batch system. The experimental data were analyzed based by Langmuir isotherm and a Pseudo second order mechanism, in the both the mono-and bi-solute adsorption systems, in order to predict the rate constant of adsorption, the equilibrium capacity. The results indicate that the adsorption mechanism is described by Langmuir isotherm and a Pseudo-second-order. The equilibrium adsorption capacity and the equilibrium rate constant increased with an increase in the initial chromium concentration in both mono-and bi-solute adsorption systems. The adsorption capacity of chromium decreased with an increase in calcium concentration