Browsing by Author "Khireddine, H."

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    Comparative study on the removal of zinc(II) by bovine bone, billy goat bone and synthetic hydroxyapatite
    (Taylor & Francis, 2010) Meski, S.; Khireddine, H.; Ziani, S.; Rengaraj, S.; Sillanpää, Mika
    The objective of this work is to investigate the possibility of using a low cost and naturally avail-able apatite rich adsorbents from animal bones such as bovine bone (BV) and billy goat (BG)bones for the removal of zinc(II) from aqueous solutions. The adsorption studies were compared with synthetic hydroxyapatite (HAPs). The samples were characterized by thermogravimetry(TG), Fourier transform infrared spectroscopy (IR) and X-ray diffraction (XRD). The equilib-rium isotherm data were fitted to the Langmuir, Freundlich, Temkin, Elovich and Dubinin-Redushkevich isotherm equations to obtain the characteristic parameters of each model. The adsorption of Zn(II) on BV and BG fi tted well with the Langmuir isotherm where as HAPs fi tted well with Dubinin Raduskevich isotherm model. The kinetic studies showed that the sorption rates could be described well by a pseudo-second-order kinetic model. Also it was shown that the adsorption of Zn(II) could be fitted to the intraparticle mass-transfer model. The studiesshowed that BG, BV and HAPs can be used as an efficient adsorbent material for the treatment of Zn(II) from water and wastewater. The order of the removal capacity for these adsorbents was determined as HAPs (93%)>BG (90%)>BV (82%)
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    Effect of EDTA (Acid and Salt) on the formation of hydroxyapatite by sol gel processing : a comparative study
    (2009) Khireddine, H.; Saoudi, S.; Ziani, S.; Meski, S.; Meskour, S.
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    Removal of lead Ions by hydroxyapatite prepared from the egg shell
    (ACS publications, 2010) Meski, S.; Ziani, S.; Khireddine, H.
    Carbonate hydroxyapatite (CHAP) was synthesized from domestic hen egg shells. The obtained CHAP was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy and investigated as metal adsorption for Pb2+ from aqueous solutions. The effect of various parameters on the adsorption process such as contact time, solution pH, and temperature was studied to optimize the conditions for maximum adsorption. The results showed that the removal efficiency of Pb2+ by carbonate hydroxyapatite calcined at 600 °C (CHAPF) reached 99.78 %, with an initial Pb2+ concentration of 200 mg·L−1, pH = 3, and a solid/liquid ratio of 1 g·L−1. The equilibrium removal process of lead ions by CHAPF foam at pH = 3 was well described by the Langmuir isotherm model, with a maximum adsorption capacity of 500 mg·g−1 at (25 and 35) °C. The removal mechanism of Pb2+ by the CHAPF varies, depending on the initial concentration of lead in the aqueous solution: the dissolution of CHAPF and precipitation of hydropyromorphite (Pb10(PO4)6(OH)2) is dominant at low concentration [(20 to 200) mg·L−1], and the adsorption mechanism of Pb2+ on the CHAPF surface and ion exchange reaction between Ca2+ of hydroxyapatite and Pb2+ in aqueous solution is dominant at high concentration [(500 to 700) mg·L−1]. The thermodynamics of the immobilization process indicates an exothermic sorption process of Pb2+
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    Study of the antideposit effect of 2-Hydroxy-4-methylbenzylphosphonic acid
    (2009) Ghemmit-Doulache, Naima; Khireddine, H.; Bourouina, M.; Boudissa, N.
    The scale inhibitor, 2-hydroxy-4-methylbenzylphosphonic acid (HMBP) appears efficient for desalination plants of sea water. A concentration of 26.5 ppm (131 μmol/L) prevents the calcareous magnesium deposits. The anti-scale effect of this inhibitor is achieved by chronoamperometry at imposed potential and complex impedance. SEM allows observation of the calcareous magnesium deposits with and without inhibitor 2-hydroxy-4-methylbenzylphosphonic acid (HMBP)
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    Verification of Levich law. determination of hydrogen currents accoring to temperature and polarization potential during calcareous deposition
    (2011) Ghemmit-Doulache, Naima; Khireddine, H.; Si Salah, D.
    The complexity of calcareous deposits processes in a marine environment results in simultaneous effects of the following parameters: temperature, polarization potential, interfacial pH, chemical composition, etc.. The comprehension of these processes implies studies in artificial seawater and a follow-up of the parameters by voltamperometry and chronoamperometry. Calcareous deposits electrochemically are very often used to follow up the evolution of scale deposition in desalination circuits. Again, the scale formation is brought about by electrochemical reduction of dissolved oxygen. The hydroxyl ions formed on the metallic surface engender a rise of interfacial pH which causes calcareous deposition (CaCO3 and Mg(OH)2). This reaction goes with reaction of hydrogen evolution which could disrupt the formed deposit. A study is carried out in a solution of seawater ASTM without calcium and without magnesium (so that the deposit will not be formed) on a titanium rotating disk electrode monitored between 300 and 1000 rpm. Study shows that Levich criterion is checked for the four values of selected potential on the diffusion plateau and a very cathodic polarization potential and a high temperature favors hydrogen current rate