Making Pb Anode
Making PbO2 (lead dioxide) anodes is much cheaper than buying platinum for anodes.
A drawback to PbO2 is that it can only take about 1/3 the current per square centimeter of anode (max 200mA/cm^2)
that platinum can handle (600mA), however since lead dioxide anodes are cheap they can be made larger to compensate.
Another drawback to lead dioxide anodes is that they are a bit less efficient that platinum.
This lower efficiency means that you will need more amperage to produce the same amount of product in equal time.
I read almost all of the info on this page at this website.
An important note about making these anodes is that it uses lead which is very toxic.
Always wear gloves/masks and work outside.
List of things needed to make PbO2 anodes:
------------------------------------
lead dioxide (used with water to form a paste which is put on anode substrate and then electroplated in solution)
alumina oxide (white powder: part #1 of the ceramic substrate)
sodium silicate (almost clear thick liquid: part #2 of the ceramic substrate)
distilled water or clean rainwater (used in the electroplating bath)
lead nitrate (160 to 200g/l in plating bath)
copper nitrate (A few g/l in plating bath)
lead metal or litharge (lead used if making lead nitrate from lead + nitric acid)
copper metal (used if making copper nitrate from copper + nitric acid)
nitric acid (used for making lead nitrate, copper nitrate and it is also used in plating solution too)
heater (used to keep the plating solution at 50 Celcius
glass jar (used to do the electroplating in: one litre of solution per 80 square centimetres to be plated is big enough.
copper cathodes (3 or 4 pieces of copper to surround the anode in the plating solution to help it plate evenly.
galvonmeter (used to measure current when plating)
power supply (powers the electrolysis)
silver paint (optional use to paint on things to make them conductive (good for making connections to anode).
Notes on obtaining necessary items:
-------------------------------
lead dioxide: powder from charged old car battery (brown powder on + lead grid plates) or pyrotechnics store
alumina oxide: pottery supply store
sodium silicate: pottery supply store
lead nitrate: added to solution: stir when plating since it precipitates on anode which causes adherence problems.
copper nitrate: added to solution: plates onto the cathode to save lead ions for the anode
lead: obtain from builders providers: used for roofing (lead from car batteries contains antimony - solder contains tin)
litharge: can obtain litharge from pottery or ceramics supply store (used to make lead nitrate if lead metal wasn't used)
copper: obtain from copper wire
nitric acid: 40% to 70% is ok. It is used for washing milking machines and can be bought from farm stores etc.
heater: use a thermostat controlled ceramic box heater and blow onto jar of wall or use a hotplate or an aquarium heater.
copper cathodes: 14 guage copper wire or similiar
galvonmeter: radioshack analog type or multimeter
power supply: car battery and charger or 5V computer power supply. Use either with resistor to limit current.
silver paint: purchase from car accessory stores. Used to join broken rear window defogger connections.
General process for making lead dioxide anodes:
-------------------------------
1. make a ceramic anode substrate (ie. 8 inch long 1" wide rod) by mixing sodium silicate with alumina oxide
2. put a 1" long stainless steel 1/2" rod into one end of the ceramic and let dry for a couple days then fire.
3. weigh this substrate to later determine how much PbO2 was plated on so that you can replenish the solution easily.
4. make copper nitrate: 6 grams copper reacted with about 13 grams 60% acid is good per litre of plating solution.
5. make lead nitrate Several ways to do this: , easy one is mix lead metal and nitric acid outside/upwind TOXIC
6. construct cathodes: use 4 copper wires with a similiar surface area to the anode.
7. prepare mixture of lead dioxide powder and distilled water into a paste.
8. rub the paste all over the ceramic anode substrate with a cloth and gloves.
9. install prepared anode in center of jar lid
10. put cathodes into insulated holes in the jar's lid around anode with 1 to 2" seperating cathodes from anode.
11. hook up battery supply to anode and cathodes with a switch to turn power on/off.
12. make plating solution by adding copper nitrate and lead nitrate solutions to distilled or rain water.
13. Fill the jar with plating solution up to where you want to plate (some solution may evaporate so have extra)
14. get the solutions temperature to a steady ~50 Celcius with heater. Should stay at this temp without monitoring.
15. turn power on and plate at 4mA/cm^2 for the first four hours, check the current with a galvanometer
16. mixing the solution will keep bubbles from staying on the forming anode which will keep the plated surface smooth
17. turn up the current (change resistance) to 30mA/cm^2 if desired to build up the remaining plate to > 1 mm thickness
18. weight the anode to determine how much PbO2 was plated.
19. optionally cut or break off steel if this isn't going to be used as the anode power connector.
20. use silver paint on top of PbO2 on one end of anode to form a good connection to the power supply
21. put the anode connector on top of this silver paint (silver will still conduct well when oxidized)
22. thats it! This anode should be ready for use in a chlorate/perchlorate cell!
Our Setup:
--------
once we have successfully used the above process to make lead dioxide anodes,
I will put pics and more stuff here.
We may not do this since we are trying to talk a local chrome plating company into giving us some anodes! ;)