PASCO ME-6940 Diffusion-Osmosis Apparatus - Manual (Page 3)

M o d e l N o . M E - 6 9 4 0 U s i n g t h e A p p a r a t u s
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• Membranes cannot be reused if they are allowed to dry out. Drying causes unrecoverable collapse of the pore
structure.
• Membranes are resistant to the following groups: halogenated hydrocarbons, alcohols, ketones, esters, oxides
and solvents containing nitrogen.
• Membranes are not resistant to the following: greater than 25% hydrochloric, nitric or perchloric acids; 96%
sulfuric acid; 1 N potassium hydroxide; and 10% phenol.
Maintenance and Care
• Always disassemble the apparatus after an experiment. Empty all fluid from the cylinders and separate the
two cylinders to remove the membrane. Rinse the inside and outside of the cylinders, including the O-rings
and the area around the O-rings, with cool, warm or hot water. Soap may be used, but is not necessary. Dry the
rinsed pieces of the apparatus on a paper towel or drying rack.
• Reassembling the apparatus before long-term storage will help to ensure that all of the pieces stay together.
• The columns are dishwasher-safe but be sure to remove the O-rings first! Do not put the blue caps and plastic
tubing in the dishwasher.
Safety
• Be careful when removing the caps from the columns as pressure may have built up during your experiment.
• Protect your eyes by wearing protective eyewear. Do not lean over the apparatus if pressure has accumulated,
or when removing the caps.
• Pressure in the columns can be as great as 15 pounds per square inch (psi).
Using the Apparatus
1. Soak the membranes: Before using the membrane, soak it in distilled water for at least 30 minutes (at room
temperature) to remove the preservative on the membrane. Then rinse the membrane thoroughly with distilled
water.
2. Prepare your solutions: Prepare the solutions necessary for your experiment. If the solutions have been pre-
pared beforehand and stored in refrigerator, be sure to bring the solutions to room temperature before starting the
experiment.
3. Assemble the apparatus:
• Start with a clean, dry apparatus and a soaked, rinsed membrane. Unscrew the four bolts and place them in a
safe location. Separate the two cylinders.
• Line up two of the four corner holes on the soaked membrane with the two raised pegs on one of the cylinders.
It does not matter which cylinder you put the membrane on.
Specifications
Pore size 40-50 m (micrometers)
Molecular weight cut-off 6,000 daltons
Temperature range 4 °C - 60 °C
pH range 2 - 12