THIS PROCEDURE WILL SYNTHESIZE FERROFLUID.  THIS MAGNETIC LIQUID CAN DEFY GRAVITY, CHANGE DENSITY, AND CAN FORM SPIKES WHEN NEAR A MAGNET.

 

 
WARNINGS:  THIS SYNTHESIS INVOLVES FLAMMABLE SUBSTANCES, TOXIC FUMES, AND HEAT.  WEAR SAFETY GOGGLES, AND PERFORM IN A WELL VENTILATED AREA.  FOLLOW EMERGENCY PROCEDURES MARKED ON EACH OF THE CHEMICALS' CONTAINERS.  BEWARE THAT AMMONIA FUMES ARE TOXIC.


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"Dr." Anne Helmenstine from About.com has stolen this content, word-for-word at times.  Please write to Anne Helmenstine here and tell her what you think about her theft for profit.  You can view her version of the site here.

I have written to Anne, and she has flat out refused to acknowledge the obvious plagiarism:

"Yes, your article is one I read when I wrote that tutorial. It was not, however, the only one, and I haven't copied you...

You haven't been plagiarized. You have a one-page recipe for a ferrofluid. I have a 5-page resource, with background information and information on what to do with a fluid. I think it's obvious I didn't lift your text.

Best wishes,
Anne Helmenstine, Ph.D.
About Chemistry"

DESCRIPTION

FERROFLUIDS ARE A STABLE (MEANING INSEPARABLE) SUSPENSION OF NANOMETER SIZED SOLID MAGNETIC PARTICLES IN A CARRIER FLUID.  THE PARTICLES ARE COATED WITH A SURFACTANT; A CHEMICAL WHICH PREVENTS THE PARTICLES FROM CLUMPING TOGETHER AND FORMING A SOLID MASS.  THE MOST COMMON TYPE OF FERROFLUID, PRESENTED HERE, IS AN OIL BASED FLUID CONSISTING OF MAGNETITE AS THE MAGNETIC SOLID, AND OLEIC ACID AS THE SURFACTANT.  THE FINAL COMPONENT IS A CARRIER FLUID, WHICH SUSPENDS THE PARTICLES;  IN THIS EXPERIMENT THE CARRIER WILL BE KEROSENE.  

FERROFLUIDS FIND USE IN HIGH END SPEAKERS, AS WELL AS HIGH PERFORMANCE SHAFT SEALS.  SOME AQUEOUS FORMULATIONS CAN BE USED IN EYE SURGERY.  

OLEIC ACID IS A FATTY ACID, AND IS  HISTORICALLY IMPORTANT FOR IT'S ROLE IN SOME OF THE FIRST SOAPS.  SODIUM OLEATE, A SALT OF OLEIC ACID, IS STILL WIDELY USED IN SOAPS TODAY.  THIS MOLECULE IS INTERESTING BECAUSE HALF OF IT IS SOLUBLE IN WATER AND HALF IS NOT.  THIS MEANS, ESSENTIALLY, THAT ONE END IS 'STICKY' AND ONE IS NOT.  THE MOLECULE'S STICKY END CAN ATTACH ITSELF TO A MAGNETITE PARTICLE AND WHEN THE PARTICLE IS COMPLETELY SURROUNDED, THE ACID MOLECULES KEEP THE MAGNETITE PARTICLES FROM STICKING TOGETHER.  THIS IS THE SAME WAY SOAPS WORK; DIRT IS COATED AND MADE 'SLIPPERY' SO IT CAN BE WASHED AWAY.
 

MATERIALS        

 -OLEIC ACID
-HOUSEHOLD AMMONIA
-PCB ETCHANT (FERRIC CHLORIDE SOLUTION)
-DISTILLED WATER
-STEEL WOOL
-A STRONG MAGNET
-KEROSENE

EQUIPMENT        

-HEAT SOURCE
-2 PYREX BEAKERS (MEASURING CUPS)
-PLASTIC SYRINGE
-COFFEE FILTERS

PROCEDURE

WHY?

THE FIRST PHASE IS TO PRODUCE FERROUS CHLORIDE FROM FERRIC CHLORIDE (PCB ETCHANT), WHICH WILL LATER BE USED TO PRODUCE MAGNETITE.  NOTE THAT COMMERCIAL PCB FLUID IS 1.5M, SO THE AMOUNTS GIVEN BELOW WILL PRODUCE ABOUT 5 G OF MAGNETITE.

1.  WITH THE PLASTIC SYRINGE, MEASURE 10ML OF FERRIC CHLORIDE (PCB ETCHANT) INTO A PYREX CUP.  ADD 10ML OF DISTILLED WATER.

 

THIS PORTION OF FeCl3 WILL BE REDUCED TO FeCl2.  IT MUST BE DILUTED FIRST BECAUSE OF SOME ADDITIVE IN RADIOSHACK PCB FLUID THAT CAUSES SIDE REACTIONS WITH THE IRON. 

2.  ADD A SMALL PIECE OF STEEL WOOL.  STIR OR SWIRL THE SOLUTION UNTIL IT HAS TURNED BRIGHT GREEN.  FILTER WITH A COFFEE FILTER.

 

FeCl2 IS BRIGHT GREEN AFTER FILTERING.  EVEN BEFORE YOU FILTER YOU'LL NOTICE A COLOR CHANGE, BUT THERE WILL BE 'CRUD' FLOATING IN IT.

NOW MAGNETITE WILL BE PRECIPITATED FROM A SOLUTION OF FERRIC AND FERROUS CHLORIDE.
3.  ADD 20ML OF FERRIC CHLORIDE (PCB ETCHANT) TO THE GREEN FERROUS CHLORIDE SOLUTION FeCl3 AND FeCl2 REACT IN A 2:1 RATIO.  THE CONCENTRATION OF FeCl2 IS HALF THAT OF FeCl3 (SINCE WE ADDED WATER), SO EQUAL VOLUMES PRODUCE THE REQUIRED RATIO.
4. WHILE STIRRING, ADD 150ML OF HOUSEHOLD AMMONIA THE AMMONIA PARTICIPATES IN A COMPLEX REACTION WITH THE IRON SALTS TO PRODUCE MAGNETITE, Fe3O4, WHICH FALLS OUT OF SOLUTION.  THE AMMONIA REACTS WITH THE EXCESS CHLORINE, PRODUCING MAGNETITE POWDER IN AMMONIUM CHLORIDE SOLUTION.
THE MAGNETITE WILL NOW BE COATED WITH OLEIC ACID.
5.  IN A WELL VENTILATED AREA, HEAT THE SOLUTION TO NEAR BOILING.  ADD 5ML OF OLEIC ACID, WITH STIRRING.  CONTINUE TO HEAT NEAR BOILING UNTIL THE SMELL OF AMMONIA DISAPPEARS, USUALLY ABOUT AN HOUR. THE OLEIC ACID REACTS WITH THE AMMONIA TO FORM AMMONIUM OLEATE, A SLIGHTLY SOLUBLE SOAP.  THE HEAT CAUSES THE AMMONIUM OLEATE TO BREAK DOWN, AND THE OLEATE ION ENTERS SOLUTION WHILE THE AMMONIA ESCAPES AS A GAS.  THE OLEATE ION ATTACHES TO A MAGNETITE PARTICLE, AND IS RECONVERTED TO OLEIC ACID.
THE COATED MAGNETITE WILL NOW BE SUSPENDED IN A CARRIER FLUID.
6. IN A WELL VENTILATED AREA, ADD 100ML OF KEROSENE TO THE COOLED SOLUTION.  STIR UNTIL MUCH THE BLACK COLOR HAS LEFT THE WATER AND TRANSFERRED TO THE KEROSENE WHILE BOTH MAGNETITE AND OLEIC ACID ARE INSOLUBLE IN WATER, OLEIC ACID IS SOLUBLE IN KEROSENE.  STIRRING ALLOWS THE OLEIC ACID COATED PARTICLES TO LEAVE THE AQUEOUS PHASE AND ENTER THE KEROSENE
7.  POUR OFF AND COLLECT THE KEROSENE LAYER.  DISCARD THE WATER.  VOILA! THE KEROSENE HAS SUSPENDED THE MAGNETIC PARTICLES, AND IS NOW A FERROFLUID.


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