Alguns funcionam bastante bem, como por exemplo o Hidroxido de Sodio ( NaOH - mais conhecido por Soda Caustica ) e o Hidroxido de Potassio ( KOH ).
Outros, embora cumpram a sua função, tornam-se demasiado perigosos, seja no seu manuseio no dia-a-dia, ou pelos elementos que libertam durante o processo de electrolise.
Mesmo o NaOH e KOH necessitam de cuidados a manusear e de pelo menos um conhecimento basico das suas propriedades, de forma a que em caso de acidente ( contacto com a pele, olhos, etc ) saibam como neutralizar os seus efeitos.
De futuro sera posto neste texto um link para a secção de segurança, com uma explicação detalhada : Link
Para melhor percebermos quais os elementos a utilizar, foi feita uma comparação por um membro de um forum estrangeiro, que, com a sua autorização, transcrevo para aqui :
Fonte : http://hhoforums.com/
Membro : BoyntonStu
Choice of what “grade” of water to use in a booster
Rainwater, spring water, or tap water contains impurities. A typical analysis will show minerals, suspended solids and more contained in these varieties. These impurities will precipitate out of the water when subjected to electrolysis. These appear in the form of brown, black and green scum in water or any discoloration of the water itself. These impurities has a solid mass which in turn will clog up the electrodes and further impede the operation of the cell overall. Of further concern is the fact that these solids accompany known gases which mix with the hydroxy to go on to create unknown chemical reactions which are toxic to the environment. Therefore ONLY DISTILLED WATER MUST BE USED FOR THIS TASK.
Electrolyte and mixing
There are many different electrolytes that CAN work in an electrolysis process, but does that mean they are suitable? NO. Some common ones considered for hydroxy boost application include:
KOH- Potassium Hydroxide- Used in soap making
NaOH- Sodium Hydroxide- Lye- Used to open drains!
NaCI- Sodium chloride- Table Salt- Raises blood pressure – DO NOT USE!
NaHCO- Baking Soda- Makes bubbles and poisonous gas– DO NOT USE!
H2SO4- Sulfuric acid- Car battery acid- Makes bad gases and burns! – DO NOT USE!
Vinegar ( 5 to 10% solution of acetic acid ) – DO NOT USE!
Sodium sulphate - DO NOT USE!
There are many other electrolytes in the acid, base and salt families, but generally these are the common off the shelf ones considered for use in most hydroxy electrolyzers.
The best choice of electrolyte is judged by its ability to remain unchanged as the reaction takes place. Note first understand what is a catalyst? An electrolyte such as he KOH acts as an ionizer for conduction of the electricity, whereas the nickel in stainless steal acts as the catalyst (hence the finish on the surface of the plates after iron is leached out). Other papers refer to nickel as a catalyst in this electrolysis process. The better the flow of electricity the better the splitting of water to a point, current is the generator of heat. Once most of the free iron has been cleansed from the cells, the KOH or NaOH combines with the nickel (and molybdenum in 316L) to form the catalytic layers. The anode and cathode each take on a slightly different characteristic patina and chemistry.
By using distilled water it must be understood that this water cannot conduct electricity on its own, therefore a catalyst is required in order to aid electrolysis. The ideal catalyst is a substance that enables the reaction to take place without becoming a part of that reaction.
From empirical testing, it has been found that Potassium hydroxide (KOH) and sodium hydroxide (NaOH) are two substances that catalyze efficiently. Tests have shown that when combining distilled water with one of these two catalysts that a cleaner cell bath and more homogeneous hydroxy mix results. This results in a more efficiently operating unit thus an in improved mileage gains, performance and less emissions.
Therefore KOH is what you want to use. It is the most stable, and it is not consumed during the electrolysis. So once you have your cell working at the target amperage you just need to add distilled water as the water is consumed, no more KOH. About once a month you want to use the water from your primary bubbler to replenish your cell. This will put back any of the KOH that may have been carried by pressure or steam to your primary bubbler back into your cell.
Every couple of months you need to check your amp draw to confirm you haven't had any MAJOR Changes. About every 6 months it is a good idea to drain your cell and refill with fresh electrolyte. This is because as you run your booster it should get more efficient and require less KOH to get the same result.
Warning- Potassium hydroxide also known as “caustic potash” is highly caustic. This needs to be handled carefully and kept away from ANY contact with skin, and even more importantly your eyes. If any splashes come in contact with you, by adding water on the effected area will cause it to react and heat up, the use of vinegar will neutralize the burning, then wash it off with allot of rinsing.
Always store it in a sturdy, air-tight container which is clearly labeled "DANGER! - Potassium Hydroxide". Keep the container in a safe place where it can’t be reached by children, pets or people who won't take any notice of the label. When working with dry KOH flakes or granules, wear safety goggles, rubber gloves, a long sleeved shirt, socks and long trousers. Additionally wear a face mask which covers your mouth and nose.
If you are mixing solid KOH with water, always add the KOH to the water, and not the other way round, and use a plastic container for the mixing, preferably one which has double the capacity of the finished mixture. The mixing should be done in a well-ventilated area which is not draughty as air currents can blow the dry KOH around.
When mixing the electrolyte, never use warm water. There results a chemical reaction between the water and the KOH which generates allot of heat. By placing the mixing container in a larger container filled with cold water will help to keep the temperature down, and also prevent any spillage if your mixture should “boil over”. Add only a small amount of KOH (table spoon) at a time, stirring continuously, and if you stop stirring for any reason, put the lids back on you storage container.
Electrolyte concentration DOES have a direct impact upon maximum obtainable efficiency. If the electrolyte concentration is run at below peak conductivity, it is just like inserting resistance in series with a cell. Current flow is limited by the increased resistance of the solution. This causes less power to flow, BUT, more of the power that does flow, is wasted as heat. Therefore, if one wishes to achieve peak efficiency, even at brute force DC, one would want to run the electrolyte concentration at peak conduction, and use another means to control current, such as a current regulator.
Note that this cannot be applied to a Smacks Booster. This design actually uses the increased resistance of more dilute electrolyte to obtain it's step-gap current differential. Since his design has these criteria, it cannot be improved in efficiency by increasing electrolyte concentration to peak conductivity.
KOH is added into distil water to bring conductivity. Without KOH / NaOH the current does not pass through the water from +Ve to -Ve. With the quantity of KOH / NaOH we
control the current draw by the booster. That means if you add more KOH then more conductivity and less resistance hence more current and more gas production for applied voltage and vice versa. Hence the concentration of KOH is directly related to the current draw / gas production.
10% KOH concentration (by weight) is so far reported and understood to be the optimum. NaOH weighs 1.829 g/cm3. If you can find out how many cm3 in a teaspoon this will be very useful. KOH it weighs 11 grams per heaping teaspoon. The following is based on an engineer’s empirical example. This was based on using a Smacks booster where it took @ 3liters of water to which 1 TEASPOONFUL of KOH was added. The amperage reading on startup was @ 20 AMPS which is too high. Recommended starting amperage draw for a cold booster is @ 16 amps per the instructions.
Adjust concentration based on amperage draw. He removed 1 liter of the electrolyte and replenished with distilled water and my starting amperage is now @ 15 amps. This is close enough as the normal loss of water due to use will gradually increase the concentration and subsequent amperage draw as it runs.
Example- To make 1 Kg of a 28% KOH solution by weight, add 280 grams of KOH to 720 cc of water. To make 1 Kg of a 20% KOH solution by weight, add 200 grams of KOH to 800 cc of water. To make 1 Kg of a 10% KOH solution by weight, add 100 grams of KOH to 900 cc of water. The total weight is always 1,000 grams containing whatever percentage of KOH that is wanted.
If using off the shelf NaOH (drain cleaner or “caustic soda” you must check that there are no other impurities in it. Warning about Drain Cleaners for use in Hydroxy Production
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Continuação : http://forum-hho.forumeiros.com/discussao-geral-assuntos-gerais-que-nao-se-enquadram-noutras-categorias-especificas-f1/elementos-quimicos-a-usar-nos-geradores-parte-2-2-t17.htm