I would be extremely grateful if some experts could help translate a passage in organic chemistry. Thank you so much! ! !
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To obtain satisfactory results, the tube must be filled uniformly with the adsorbent; uneven distribution can lead to the formation of cracks and channels as well as significant distortions in the shape of the absorption bands. If there is any doubt regarding the uniformity of the particle size of the adsorbent powder, it should be sifted before use to remove larger particles. Fine particles are removed from the adsorbent using a sedimentation process just before filling the column. In this process, the alumina or silica gel adsorbent is mixed with a volume of solvent or solvent mixture equal to five to ten times its own volume; it is then allowed to settle for five minutes, after which the upper layer of liquid is drained off. This process is repeated until the liquid remaining on top is clear. As a general guideline, the amount of adsorbent used should be 25–50 times the weight of the material to be separated. A slurry of the adsorbent in the solvent (approximately 1:10 ratio) is poured into a clean, dry column that has been positioned vertically, in a place free from drafts or warm air currents from radiators or electric ovens. Gently tapping the tube with a wooden rod helps the adsorbent to settle evenly without any air bubbles. When filling larger columns, it is best to use a separatory funnel to hold the slurry and stir it with a linkage stirrer while it flows into the column. The solvent is removed through the tap located at the end of the column, and more slurry is added until the desired column length is achieved. Some practitioners recommend using a second column on top of the first one, so that all the slurry can be added at once, resulting in a more uniformly distributed layer of adsorbent after settling. Fresh solvent is allowed to flow through the column under the hydrostatic pressure expected during subsequent chromatographic operations, until no further settling occurs. At no point during column preparation or during subsequent use should the liquid level drop below the level of the adsorbent. ] This post was last edited by 050514302 on 2009-2-27 at 10:28
Using: http://translate.google.com. For reference only. Modify it by yourself. To obtain satisfactory results, the tubes must contain uniformly packaged adsorbents; uneven distribution can lead to the formation of cracks and channels, as well as significantly distorting the shape of the adsorption zone. If there are any adsorbent powders with uneven particle sizes, larger particles should be carefully removed before use; the powder should be packaged in a sealed container on the eve of use in the adsorption and sedimentation process. In this process, the alumina or silica adsorbent is mixed with 5 to 10 times its volume of a selected solvent or solvent system, and the mixture is allowed to stand for five minutes; then the supernatant liquid is drained off. This procedure is repeated until the supernatant becomes clear. As a rough guide, the amount of adsorbent should generally be 25-50 times the weight of the material to be separated. The adsorption of the suspension in the solvent (about 10 liters per unit volume) is carried out by pouring it through a funnel into a clean, vertical container; at a location away from drafts or warm air streams coming from radiators or electric heaters, the adsorbent is distributed evenly, free of bubbles, thanks to gentle stirring using a wooden stick. It is best for the Forpacking large-column mud to be contained within a separatory funnel and a stirrer of the mixing-connected type, although flow into the column is allowed. The removal of solvents from tap water is completed through the bar installed on the adapter, and the required length bar for adding it to the slurry is obtained as well. Some workers suggested that the second column should be installed at the top for the first time, so that all the sludge could be added as a component, thereby resulting in a more perfect and uniform arrangement of adsorbents. Fresh solvent allows flow under the hydrostatic pressure of the column, which is evident for future developments in chromatography until further solutions are found. At any time during preparation, the liquid level should not be lower than that of the adsorbent in subsequent use.
Students who have questions should first write down what they are capable of doing, as well as their difficulties and ideas. Only on this basis can others help you better. If you paste such a long paragraph without having any ideas of your own, how can we help you? Classmate on the second floor, the stuff produced by the translation software is probably something even you can’t stand to look at, right? ?