97675728 Electrolyzer (ionizer or activator) vs Hydrogen water genetators -  Hydrogen water generators from the official distributor PAINO

Electrolyzer (ionizer or activator) vs Hydrogen water genetators

  • Reading time: 15 minutes
  • Theme: about ionizers
  • Date: 2023-12-12

How Inonizers and H2 Water Generators Work

Often, electrolyzers are also called ionizers or water activators. However, it is more accurate to call them electrolyzers, as this name reflects the essence of the processes occurring in the devices. What is the difference in the operation of water ionizers and hydrogen water generators?

 Type of device  Ionizer  h2 water generator with NO SPE membrane  h2 water generator with SPE membrane   Super consetration h2 water generator with SPE membrane 
 Presence of Hydrogen  +(low)  +(low)  + (medium)  +( hidh and extra high)
 Presence of Clorine  +  +  no  no
 Does the device work with salt-free water?  NO  NO  YES  YES
 Does the pH of the liquid change during the operation of the device?  YES  YES  NO  NO

 

What is an electrolyzer (ionizer or activator)? What is activared or alcaline water?

Often, electrolyzers are also called ionizers or water activators. However, it is more accurate to call them electrolyzers, as this name reflects the essence of the processes occurring in the devices.

In electrolyzer (ionizers) , water is divided into two types - alkaline water with a pH above 8 and acidic water with a pH below 6. 

  • The principle of operation of water electrolyzers (ionizers)
    A water ionizer is a device in which 2 or more electrodes are immersed in a salt solution in water.
    If there are 2 electrodes: Anode - positively charged electrode A(+) and Cathode C(-) - negatively charged electrode , the scheme of the electrolyzer looks like this:electrolyzers sm

In essence, hydrogen water generators without a proton exchange membrane are the simplest hydrogen water ionizers with 2 electrodes

 To make the processes more intense, more expensive electrolyzers use several electrode plates. 

 What processes occur in an electrolyzer?

As the name suggests, the process that occurs in an electrolyzer is electrolysis. Electrolysis is the decomposition of a substance into its components using electric current. Current passes through chemically pure (distilled or even cleaner, deionized) water very weakly, hence the electrolysis of pure water is difficult. Try pouring distilled water into a household ionizer; it will not work.


The electrolysis of ordinary drinking water, for example, taken from a tap, is possible precisely because of the presence of various salts in the water, such as calcium, sodium, magnesium, etc. For electrolyzers to work, it's important that there are enough salts, for which the water is additionally mineralized.

Essentially, we're talking about the electrolysis of a saline water solution.

The most common salts in drinking water are bicarbonates, calcium sulfates, magnesium, sodium chloride (table salt).
When dissolved in water, salts dissociate into ions - particles with an electrical charge. Additionally, water molecules themselves also partially dissociate into H+ and OH-.
In drinking water “float”:

positively charged Ca2+, Mg2+, Na+, K+, H+
negatively charged HCO3-, SO42-, Cl-, OH-.
The list of ions is always indicated on the labels of bottled water.

Under the influence of an electric field, ions start moving towards the electrode with the opposite charge, where chemical reactions occur with them.
Let's clarify that the electrodes must be inert, meaning during electrolysis they only serve as electron transmitters. The material of such electrodes does not participate in electrode processes (this can be, for example, Pt (platinum), Ir (iridium), meaning the electrodes themselves do not participate in the reaction. Otherwise, the electrode itself will first react and be destroyed (dissolved): Me (metal) —> Me+ + e-, before other reactions begin. Understandably, electrodes made of platinum or iridium are very expensive, so they are only made with a platinum coating, and the quality of this coating is critically important.

Since all the metals whose ions are present in our drinking water - Ca, Mg, Na, K - are placed in the electrochemical series: 

LiCsRbKBaSrCaNaMgAlTiMnZnCrFeCdCoNiSnPbHSbBiCuHgAgPdPtAu

to the left of aluminum inclusive, metal is not reduced at the cathode, but hydrogen from water is reduced. This happens as follows:
At the cathode (-) 2 molecules of water combine with electrons to form hydrogen gas and OH- ions - i.e., an alkaline environment.

K(-) 2H2O + 2e‾ → H2 + 2OH-

Several reactions occur at the anode (+):

Since the anion of an oxygen-containing acid (SO42-) is present, oxidation of oxygen atoms from water to oxygen molecules occurs, and hydrogen ions H+ are also formed:
2H2O - 4e → O2 + 4H+, oxygen gas is released and an acidic environment is formed - hydrogen ions H+
In our case, there is also the anion of a non-oxygen acid (Cl-). Its oxidation to a simple substance occurs:
gaseous chlorine is formed
2Cl- - 2e → Cl2
So, at the negative electrode, hydrogen gas and an alkaline environment are produced, at the positive electrode - oxygen and chlorine gases and an acidic environment. It is important to note that chlorine is a poisonous gas.

However, it is important that the reaction products will mix and react with each other.

During this mixing, hypochlorite is formed by the reaction:
Cl2 + 2OH- → Cl- + ClO- + H2O
Then, at room temperature in an acidic solution, chlorate (a compound of chlorous acid) is formed by the reaction:
2HClO + ClO- → ClO3- + 2H+ + 2Cl-

Why is it essential for hydrogen water generators to have an SPE/PEM membrane?

Advantages of Proton Exchange SPE/PEM Membrane

Thanks to the presence of the PEM/SPE membrane, hydrogen is separated from the by-products of electrolysis - oxygen and other impurities (such as ozone and chlorine). This means the user does not need to meticulously monitor the water composition. Without a proton exchange membrane, using water with the presence of chlorine salts, the electrolysis process would be accompanied by the emission of a strong chlorine odor. The proton exchange membrane acts as a solid polymer electrolyte, where electrolysis occurs, i.e., electrolysis happens within the membrane, and water is not the electrolyte but is only saturated with hydrogen. This allows the use of distilled water or water purified by reverse osmosis (RO water). In devices without a PEM/SPE membrane, using distilled or RO water will not produce hydrogen.

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 Proton exchange membranes are made from solid polymer electrolytes (SPE). These electrolytes, comprising materials with a polymeric structure, include functional groups capable of dissociating to form cations or anions. The directed movement of these ions within the polymer structure is what gives it ionic conductivity.

In our devices, the membrane is a fluorocarbon polymer containing functional sulfonic groups capable of exchanging electrostatically bound cations (positively charged particles, like protons, the nuclei of hydrogen atoms) with the external environment. The ionic conductivity of a proton exchange membrane, a type of solid polymer electrolyte (SPE), is due to the movement of cations that are already part of its composition. During the direct electrolysis of a salt solution, the conductivity is facilitated by the ions of these salts in the water solution.

During water electrolysis in a solid polymer electrolyte (SPE), the process begins with distilled water being supplied to the anode compartment of the electrolyzer. The water permeates through the pores of the anode to the interface between the electrode and the membrane (PEM-SPE). At this interface, water undergoes electro-oxidation, releasing oxygen:
2H2O ——► O2 + 4H+ + 4e-

Oxygen is then removed from the reaction zone. The protons (H+) move through the membrane towards the cathode, where they are reduced to form gaseous hydrogen:
2H+ + 2e- —► H2

​Simply put, in a hydrogen water generator, protons are conducted from the anode (positively charged electrode) to the cathode (negatively charged electrode).

A proton that has passed through the proton exchange membrane to the cathode gains an electron from the cathode and becomes a hydrogen atom. Instantly, two hydrogen atoms bond to form a hydrogen molecule, which then dissolves in water.

The impermeability of the PEM membrane to oxygen prevents its penetration into the cathode space, thus avoiding the formation of a potentially explosive oxyhydrogen mixture.

The cathodic and anodic reactions are facilitated by introducing catalysts such as finely dispersed platinum and iridium oxide (IV) at the electrode/SPE interfaces, making the electrolysis process more efficient.

Simultaneously, the proton exchange membrane serves as an insulator for electrons and a barrier to reagents, such as oxygen, hydrogen, ozone, and chlorine.

The primary function of the proton exchange membrane in a membrane electrode assembly (MEA) is to separate reactants and transfer protons across the membrane while blocking the direct path of electrons through the membrane.

The use of PEM for electrolysis was first introduced in the 1960s by General Electric, which developed this technology to overcome the drawbacks of alkaline electrolysis technology.

The electrolysis process using a Proton Exchange Membrane (PEM) has several advantages:

High Current Density Operations: One of the most significant benefits of PEM electrolysis is its ability to operate at high current densities. This capability is due to the use of a polymer electrolyte that allows the PEM electrolyzer to work with a very thin membrane (approximately 100-200 micrometers) under high pressure. This setup results in low ohmic losses, primarily due to proton conduction through the membrane (0.1 S/cm), and leads to a high yield of hydrogen.

High Product Purity: The polymer electrolyte membrane, with its solid structure, has a low gas permeation rate. This attribute contributes to the very high purity of the produced hydrogen. The low permeability ensures minimal cross-contamination of gases, which is crucial in applications where high-purity hydrogen is required.

These features make PEM electrolysis particularly suitable for scenarios where high efficiency, high purity, and high-pressure hydrogen production are required. Additionally, the compact nature of the electrolyzer, due to the thin membrane, allows for a smaller system footprint compared to other electrolysis technologies.

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