2.5 Kitchen synthesis of nanorust  (Page 3/3)

Table 1. Cost comparison of the materials needed for a FAM/rust synthesis of magnetite nanocrystals with a conventional laboratory synthesis. Most of the savings results from the reduction in cost of the iron source. *Cost of the rust is an estimate.

In the kitchen synthesis, the black product that forms can be separated from the solution by simply using a handheld magnet rather than the expensive and large centrifuges used in a conventional laboratory setting.

Experimental Procedure

Caution!! While all of the following chemicals and utensils can be found in a kitchen, this procedure is potentially dangerous (even the soap is caustic). Gloves and goggles must be worn at all times!!

Materials

• vegetable oil
• lye or 100% NaOH drain opener
• wooden spoon
• glass bowl
• 5% vinegar
• cooking pot
• hot plate
• turkey baster or plastic pipette
• rust

Part 1: Soap making process

This step requires a week of advanced preparation and has been done for you

1. In a crystallization dish or a similar container, weigh 100 g. of the liquid oil (if not liquid gently melt it and keep as melted).
2. In a 50 mL vial (or a cup) weigh 15 g. of crystal drain opener (or caustic soda, or sodium hydroxide, or potash).
3. Add 30 mL of tap water and shake (or stir) until all solid is dissolved (CAUTION: solution gets hot!). While still warm pour it into the liquid oil.
4. Stir with a spoon (or a magnetic stir bar) for about 15 minutes (or until tracing occurs – tracing is the visible tracks of stirring).
5. Let it sit open to air in a hood (or ventilated area) to dry and cure for a few weeks. If a shorter time span is allotted, the soap can be dried in an oven. To help the drying process, the excess oil can be decanted after 48 hours. Use caution when decanting the soap as there may be excess unreacted NaOH present.

Part 2: Oleic acid from soap with commercial vinegar

1. Grate the soap given to you and weigh it. You should have approximately 30 grams. If you have extra soap, do not discard it; give it back to your TA.
2. Check the vinegar’s acidity (i.e. 5%).
3. Use 1 mL of acid for every gram of soap (i.e. 30 mL of acid, 600 mL of commercial vinegar with 5% acidity).
4. Combine the vinegar and soap in a cooking pot.
5. Heat on med-high and stir with a wooden spoon until all of the chunks are dissolved (light boiling is preferred). – This takes 15 to 30 minutes.

Caution!! This must be done a hood or other well-ventilated area!!

1. Turn off the heating and cool the solution down.
2. Pour your solution into the 1L beaker provided. You should see two layers separating from each other.
3. Separate the top yellowish layer using a turkey baster or plastic pipette into a 50 mL beaker. Make sure you get as much of the organic layer that as you can out of the vinegar/acid mixture.
4. Separate the organic layer off again into another 50 mL beaker so that you are left with only the organic layer. This is your fatty acid mixture (FAM)
5. Thoroughly clean your cooking pot in the sink with soap and water.

Part 3: Magnetite nanocrystals from rust and fatty acids

1. Carefully measure 0.5 grams of rust. Do not discard excess rust; put it back in the stock container.
2. Mix the rust with the fatty acid mixture in the cooking pot.
3. Cover the top of the container with a loose cap for proper ventilation. The reaction smokes and steams. This method produces 50-90 nm nanocrystals.
4. Start heating and timing. The rust should be heated for roughly 1 hour , until the solution is dark black with little or no smoking. Remember to continue stirring at regular intervals. Do not heat the oil to the point of popping and spattering. Adjust the heat as necessary so that the solution only steams and smokes.

Caution!! This must be done a hood or other well-ventilated area!!

1. If your rust solution looks like it might dry out, notify your TA immediately and they will provide you with extra oleic acid to complete your reaction. DO NOT LET YOUR RUST DRY ONTO THE FRYING PAN!!!!!!!
2. Once the rust solution appears dark black and little to no smoke is being produced, pour the nanorust solution into a 50 mL beaker.
3. Hold a magnet to the side of the beaker and observe what happens. Hold the magnet to the beaker for several minutes.
4. Clean the cooking pot thoroughly again with soap and water. If there is any black or burnt crusting, this needs to be scrubbed away.