First, how to choose the filter funnel?
According to the purpose and requirements of the experiment, the type of filter funnel was selected, the weight of the frame was selected to select the long-neck funnel, and the corrugated funnel was used for the gelation sedimentation. According to the amount of sediment, the funnel of the corresponding specification is selected, and the amount of the sediment is large. The size of the funnel should be larger. When the amount of sediment is small, the size of the selected funnel is smaller.
Filter funnel filter paper selection
Select the type of filter paper according to the type of precipitated crystal, and select the filter paper of the appropriate size according to the amount of precipitation.
How to use the filter funnel?
Wash the funnel.
Place the selected filter paper at the bottom of the funnel, place it on the bottom of the funnel, press it tightly by hand, and then wet all the filter paper with a small amount of water.
Always use a glass rod to gently press the filter paper, and then remove the bubbles from the filter paper and the wall of the bucket (to avoid the filtration speed), then add water to the edge of the filter paper. At this time, the funnel neck should be filled with water to form the original. When the water on the filter paper is completely drained, the water in the neck of the bucket should still be preserved. Thus, the gravity of the liquid can act as a turbidity, which speeds up the tempering. When placing the male paper, it should be noted that the filter level should not exceed the funnel, and should be lower than the edge of the funnel by 5-10t17117o. (If the water column is not made, use your fingers to block the funnel. Use a small bottle to filter the paper to the filter paper and the funnel. Add water to the air barrier until the funnel neck and a part of the cone are filled with water. Then press the filter paper and slap the finger below the lower neck. Under this time, the water column should be made, if it still cannot form a water column. Or the water column cannot be kept, check whether the funnel, especially the funnel neck, is clean, or if the funnel neck is too large.)
The funnel is placed on the funnel holder, and the filtrate is taken up with a clean beaker below, and the filtrate can be used as a side profile for the other components. The filtrate is sometimes not required, but in view of the possibility of precipitation percolation during filtration or accidental rupture of the filter paper, re-filtration is required, so a washed beaker is used to carry the filtrate. In order to prevent splashing of the filtrate, the long side of the inclined neck outlet is generally attached to the inner wall of the beaker. The height of the funnel is such that the outlet of the filter neck is not connected to the filtrate during the filtration process.
Filtration operation of the filter funnel (dipping method) The cylinder should first emphasize that the filtration and milling can not be interrupted (can not be completed in stages), especially the filtration of the gelatinous precipitate, to prevent the sedimentation and block the filter paper. In this case, you must plan your time in advance. If you don't have enough time, don't rush to filter.