Hydrogen seperation from water

In summary, there are different methods for separating hydrogen and oxygen from water, such as using a catalyst and semi-permeable membranes. These methods work by rejecting molecules based on size, electrical potential, or vander Waal's forces. However, some of these methods may also have drawbacks, such as recombining the gases or stability issues. One specific technology, called Pressure Swing Adsorption (PSA), utilizes a combination of these methods to separate the gases.
  • #1
jack001
38
0
hello folks,

i was wondering if any other possible process of separating hydrogen from water without or less risk, any alternative method of electrolysis.

i have googled this thing and stuck to process of introducing a catalyst 'titania(titanium oxide)' in the presence of sunlight, directly converts water into the molecules of hydrogen and oxygen.
But now what? I mean how to separate this two different gases?
i suppose semi-permeable membrane can help in separation.

guide me if i am wrong.
 
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  • #3
jedishrfu said:
wont the hydrogen float above the oxygen?

I don't think you want to be mixing hydrogen and oxygen. They tend to explode when combined. Hence the need to separate them before they get out of the water.
 
  • #4
^^ yes of course, they explode, so i need to separate them.
 
  • #5
Take a look at PSA's.
 
  • #6
so if hydrogen floats above oxygen then you could separate them by knowing where the dividing line is amd by placing valves at two distinct vertical levels to remove some gas at a time while the reaction is taking place.
 
  • #7
Gasses do not separate just because one of them is 'lighter' than the other. They will mix just like two different sized ping pong balls bouncing around in a box.
 
  • #8
Agreed, unless you cool the mix and separate via liquefaction.
 
  • #9
but won't it explode as soon as it is converted into gas?
 
  • #10
Q_Goest said:
Take a look at PSA's.

can you please elaborate this technology.
 
  • #11
The Wiki article describes PSA pretty well- it somewhat fits into the first method below for semipermeable membrane separation, but needs a driving force to release the adsorped molecules from the pores (usually atomic dimensioned channels in Xeolites).-semi-permeable membranes rely on pores that can be used to exclude by one of several mechanisms. The most obvious one is to select by size and that H2 molecules are smaller than O2 molecules, so pores on the order of a few Angstroms can reject O2- a pressure differential exists between the two sides to drive the process.

Other methods can place an electrical or Donnan potential barrier at the pore's mouth that helps reject one type of molecule over another (mostly seen in R.O. membranes where charged dissociated salts are rejected while largely neutral H2O passes through).

Some vander Waal's forces can also create a selectivity for one type of molecule over the other, and the attractive forces used to help coax the right molecule through a pore. In this sense, the metals that are known to adsorb H2 can act as an appropriate barrier for other molecules- the downside is that these metals also recombine O2 and H2 to water catalytically, so efficiency suffers.

Thus the interest in CNT and graphenes as H2 separators; O2 stability is still a problem.
 
Last edited:

1. How is hydrogen separated from water?

Hydrogen can be separated from water using a process called electrolysis. This involves passing an electric current through water, which breaks the water molecules into hydrogen and oxygen gas.

2. What is the purpose of separating hydrogen from water?

The purpose of separating hydrogen from water is to obtain a clean and renewable source of hydrogen gas, which can be used as a fuel for various applications such as powering vehicles, generating electricity, and producing industrial chemicals.

3. What are the main methods used for hydrogen separation from water?

Apart from electrolysis, other methods for separating hydrogen from water include steam reforming, which involves reacting water with a high-temperature heat source to produce hydrogen gas, and biological processes, where certain microorganisms can produce hydrogen gas through fermentation.

4. Is hydrogen separation from water an energy-intensive process?

Yes, hydrogen separation from water requires a significant amount of energy, especially when using electrolysis. However, advancements in technology are being made to make the process more efficient and cost-effective.

5. Can hydrogen separation from water be used for large-scale production?

Yes, hydrogen separation from water can be used for large-scale production. However, the process is currently more commonly used for smaller-scale applications, and further developments are needed to make it a viable source of hydrogen on a larger scale.

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