Filtration

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Filtration
By 3A Julia Chan (1) Vivian Chan (4)
Vivian Chan (2) Melody Chan (5)
Haily Chan (3)
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Filtration
In chemistry, filtration is the process of using
a filter to mechanically separate a mixture, to
remove microorganisms from liquid.
- There are many different methods of filtration,
but all aim to attain the separation of two or
more substances. - This is achieved by some form
of interaction between the substance or objects
to be removed and the filter. - The substance
that is to pass through the filter must be a
fluid, i.e. a liquid or gas. The simplest method
of filtration is to pass a solution of a solid
and fluid through a porous interface so that the
solid is trapped, while the fluid passes through.
This principle relies upon the size difference
between the particles making up the fluid, and
the particles making up the solid.
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Gravity Filtration
The filtration we do in the laboratory is called
gravity filtration. - It relies simply on
gravity to effect the filtration. - It is most
useful when removing reasonably large solid
particles from a solution.  - The impurity can
be a drying agent or an undesired side product or
leftover reactant
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Folding filter paper
Fold the round piece of filter paper in half
Folded it again and crease to produce a quarter
circle
Make a crease so it becomes a half circle
Place the conical shaped piece of filter paper
into a glass or plastic funnel
Make one outer layer of the paper be separated
from the other three
Make the opening wider by squeezing slightly
together at the creases
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Procedure for the gravity filtration

• 1) Support the filter funnel by a clamp.
• this helps to avoid having the apparatus tip
  over
• 2) Select the suitable size of filter paper. Fold
  it and put it in the funnel.
• 3) Carefully pour the solution into the funnel
• (be careful not to overfill the funnel, but you
  can keep topping up the funnel)
• 4) Prepare a beaker or container to collect the
  filtrate

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• We can see the result of the filtration
• a clear, colourless solution is collected in the
  beaker
• the black residue (charcoal) is trapped on the
  fluted filter paper in the funnel.
• Note
• Folding the filter paper this way can provide
  more surface area for the solution to be
  filtered.

filter paper
residue
filtrate
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Vacuum filtration

• It is used to collect a desired solid
• It is faster than gravity filtration,
• the solution and air is forced through the filter
  paper by the application of reduced pressure

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• Procedure for vacuum filtration
• Set up an apparatus with a side arm flask, a
  filter paper, an adaptor, a Buchner funnel
• Connect the side arm flask to a vacuum source
  with a thick-walled tubing

Buchner funnel
tubing
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• 3) Wet the paper with a small amount of the
  solvent to be used in the filtration.
• ?this keeps the paper to stick to the plate
• Turn on the water aspirator.
• 4) Filter the solution Pour the mixture to be
  filtered onto the filter paper. The vacuum pull
  the liquid rapidly through the filter into flask.

mixture
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• 5) Rinse the cake with a small amount of fresh,
  cold solvent
• To help remove impurities that were dissolved in
  the filtrate
• 6) Carefully remove the filter paper and solid
  from the funnel. Set the filter cake onto a watch
  glass to air dry.

filter cake
solvent
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References
http//en.wikipedia.org/wiki/Filtration http//or
gchem.colorado.edu/hndbksupport/filt/filtration.ht
ml http//www.chem.ucalgary.ca/courses/350/labora
tory/expt03gf.html http//www.chemistry.sjsu.edu/
straus/FILTRATION20htms/GravFilt.htm http//www.
ipfw.edu/chem/266/266Spring04/266n0407.htm