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سؤال الى المهندسين الرجاء الأجابة

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  1. [1]
    cyclone604
    cyclone604 غير متواجد حالياً

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    تاريخ التسجيل: Apr 2009
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    سؤال الى المهندسين الرجاء الأجابة

    فيما يتعلق ب pressure vessels
    ما هي وظيفة packed column

  2. [2]
    General michanics
    General michanics غير متواجد حالياً
    عضو متميز
    الصورة الرمزية General michanics


    تاريخ التسجيل: Jul 2009
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    Packed Column A chromatographic device must contain a distribution system where the solute can exchange between a moving phase and a stationary phase. This distribution system usually takes the form of a cylindrical body (although not necessarily so, e.g. a TLC plate) in which one phase is held stationary and another, immiscible phase, allowed to pass through, or by it. The cylindrical body is called the column and can take two forms depending on how the stationary phase is contained in it. In one form (the capillary column) the stationary phase is held as a thin film adhering to the column walls. In the other form, the column contains an inert supporting material carrying the stationary phase absorbed on it and is called the packed column. The packing usually consists of a very inert porous material such as Celite (a diatomaceous earth made up of the skeletons of diatoms), calcined Celite (in the form of powdered fire brick) or a synthetically prepared support made from Celite. To minimize surface activity the support is often washed with acid to remove traces of iron and other heavy metals, then with water and acetone and dried. The material is then treated with hexachlorodisilazane to block any hydroxyl groups remaining on the support surface. The stationary phase is usually added to the support as a solution in a suitable solvent and ?tumble dried? in a rotating flask. Stationary phase loading can range from about 2% by weight to a maximum of about 15% by weight depending on the nature of the sample, the nature of the stationary phase and the anticipated sample load. In adsorption chromatography the adsorbent itself is packed into the column. The support or adsorbent is normally packed into the column by mechanical vibration. The disadvantage of the packed column over the capillary column is its relatively high flow impedance

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    كل ابن انثى و إن طالت سلامته
    يوماً على آلة حدباء محمول

  3. [3]
    د.محبس
    د.محبس غير متواجد حالياً
    عضو متميز جداً
    الصورة الرمزية د.محبس


    تاريخ التسجيل: Oct 2009
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    اقتباس المشاركة الأصلية كتبت بواسطة General michanics مشاهدة المشاركة
    Packed Column A chromatographic device must contain a distribution system where the solute can exchange between a moving phase and a stationary phase. This distribution system usually takes the form of a cylindrical body (although not necessarily so, e.g. a TLC plate) in which one phase is held stationary and another, immiscible phase, allowed to pass through, or by it. The cylindrical body is called the column and can take two forms depending on how the stationary phase is contained in it. In one form (the capillary column) the stationary phase is held as a thin film adhering to the column walls. In the other form, the column contains an inert supporting material carrying the stationary phase absorbed on it and is called the packed column. The packing usually consists of a very inert porous material such as Celite (a diatomaceous earth made up of the skeletons of diatoms), calcined Celite (in the form of powdered fire brick) or a synthetically prepared support made from Celite. To minimize surface activity the support is often washed with acid to remove traces of iron and other heavy metals, then with water and acetone and dried. The material is then treated with hexachlorodisilazane to block any hydroxyl groups remaining on the support surface. The stationary phase is usually added to the support as a solution in a suitable solvent and ?tumble dried? in a rotating flask. Stationary phase loading can range from about 2% by weight to a maximum of about 15% by weight depending on the nature of the sample, the nature of the stationary phase and the anticipated sample load. In adsorption chromatography the adsorbent itself is packed into the column. The support or adsorbent is normally packed into the column by mechanical vibration. The disadvantage of the packed column over the capillary column is its relatively high flow impedance
    thanks on this info

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    مهندس ميكانيك
    1981

  4. [4]
    cyclone604
    cyclone604 غير متواجد حالياً
    جديد


    تاريخ التسجيل: Apr 2009
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    شكرا لك اخي جزاء الله خيرا

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