Simplified Procedure for Pulping Plant Materials in the Laboratory (Refer to Manual For

SIMPLIFIED PROCEDURE FOR PULPING PLANT MATERIALS IN THE LABORATORY (REFER TO MANUAL FOR BACKGROUND AND MORE DETAILED AND GENERIC INSTRUCTIONS)

1.  When you arrive in the lab, your 18 % NaOH solution should already be heating in a 1000-ml Erlenmeyer flask. Record your observation as to the color of the liquid.

2.  A cold sample of the 18 % NaOH solution will be available beside the pH meters. Insert the pH probe and record the pH of the starting alkaline solution.

3.  Place a beaker or other container on one of the available balances and press “Tare” to zero its weight out. Weigh out 50 grams of your selected dry plant material (note: this assumes that the material has been properly air-dried. If it has not, then consult your lab instructor).

4.  Using hot gloves, remove the flask from the hot plate (leave the hot plate ON) and remove the small flask from the top. Using a funnel, transfer the 50 grams of your plant material into the flask. You may need to use the plastic rod to push the material down into the flask or loosen material stuck to the sides.

5.  Replace the small flask back into the larger one, then return the larger flask to the hot plate and resume heating on HI. When the liquid starts to boil, pay close attention – you want to maintain a slow, steady, percolating-type boil instead of a violent boil which can come out of the flask. Adjust the heat downward in single-number increments until a steady boil is reached. If the flask starts to boil too violently, you may use a gloved hand to remove it from the heat for a moment.

6.  When the flask starts to boil, record the time, using a watch or the clock. The target boil time is 45 minutes.

7.  Note the change in appearance of both the plant material and the liquid as the boil commences.

8.  Once the boil has stabilized (10-15 minutes), you may leave with your group to go the handsheet making lab. An attendant will watch your setup while you are gone.

9.  After one hour of boiling (refer to your starting time), use a gloved hand to remove the flask from the hot plate and set aside. Turn off the hot plate. Allow the flask to stop all boiling activity, then use a gloved hand to remove the small flask from the larger one.

10.  Record your observations about the appearance of the liquid after the boil has finished.

11.  Using gloves, carefully transfer the flask to the sink. Fill a colander (strainer) with two thicknesses of cheesecloth. Set the colander over a plastic 1-liter beaker in the sink. Open the cold tap water valve until a moderate flow is achieved (going into the sink, not into the colander). Decant some of the hot liquid into into the colander, permitting the liquid to accumulate in the beaker. When about 2-3 inches of liquid have been collected in the beaker, stop decanting and set the flask aside. Carefully remove the colander from the beaker. Take the beaker over to the pH meter and insert the probe into the liquid. Record the pH value obtained. Return the pH probe to the water from which it came.

12.  Replace the colander in the sink, this time without the beaker under it. Resume decanting of the flask. Some of the solid material will come out with the liquid and be caught in the cheesecloth. When all of the liquid has been decanted, shake the flask gently to dislodge any remaining solid material. You may have to fill the flask with cold tap water several times and pour it into the colander in order to remove all the solid material.

13.  Direct the cold tap water over the solid contents of the cheesecloth for several to minutes to wash it thoroughly. Allow the material to drain briefly, then, using latex gloves, bundle up the cheesecloth to contain the solid material. Squeeze the bundle to expel free liquid. Keep squeezing until no more liquid can be expelled.

14.  Open the bundle and examine the contents. Using your bare finger, feel of the material. If there are still large chunks or pieces, roll one between your fingers and see what happens. Record your observations about the color, texture, appearance, and feel of the material.

15.  Transfer all of the material from the cheesecloth into the blender container. Add cold tap water until the level reaches the 600-ml mark. Add three drops of anti-foaming agent. Place the blender on the motor base. Carefully place the lid securely on the blender, with the lip opening pointing away from you. With one hand securely placed on top of the blender, turn on the blender on its lowest setting for two minutes.

16.  Stop the blender. Insert Buchner filtering funnel into the filtering flask and line with two thicknesses of cheesecloth. Turn on the vacuum supply valve to the flask 100 % open. Slowly pour the contents of the blender container into the funnel, allowing liquid to be removed the vacuum into the flask. When no more liquid is observed going into the flask, fill the blender container halfway with cold tap water (making sure that it captures any remaining fiber in the container), the pour this liquid slowly across the fiber mat formed in the funnel

17.  When no more liquid is observed going into the flask, turn off the vacuum. Using your bare finger, feel of the material. Record your observations about the color, texture, appearance, and feel of the material, especially as compared to its state prior to the blender.

18.  Remove a small piece about the size of half of your little finger and place into a small sample bag. Label with your group number and the name of the plant material used (if known!).

19.  Use cold tap water to wash out your boiling flask thoroughly. Fill with cold tap water to about half full. Take a tiny bit (like the head of a pin) of the remaining pulp and drop into the flask. Cover the top with your hand, then shake vigorously until the piece has been dispersed. Hold the flask up to the light. Record your observations about what you see in the water.