Hydrogen

1. Basic Information

Hydrogen is the first chemical element in the periodic table with the symbol H. It has an atomic number of 1 and an atomic weight of 1.00784 g/mol. Under normal conditions, hydrogen is a colorless, odorless, and tasteless gas composed of the diatomic molecule H2.

2. Physical and Chemical Properties

Hydrogen is the most flammable material known. Slightly soluble in organic solvents compared to water. Many metals can absorb hydrogen. At normal temperatures, hydrogen is fairly unreactive unless activated by a catalyst. At high temperatures, hydrogen is highly reactive and can react with many metallic and non-metallic elements to form hydrides.

3. Presence in Water and Health Effects

Hydrogen is the main component of water (H2O). In high amounts in water, hydrogen can cause the environment to lack oxygen which can trigger symptoms of headaches, dizziness, nausea, vomiting, and even death in extreme cases. However, hydrogen itself is not considered mutagenic, embryo toxic, teratogenic, or reproductive toxic.

4. Applications and Removal Methods in Water Treatment

Hydrogen generally does not need to be removed from water. However, as a component of water, hydrogen is involved in various water treatment processes such as:

• Deionization to remove hydrogen ions (and other ions) from water
• Reverse osmosis to separate water (H2O) from impurities
• Deaeration to remove dissolved gases including H2

5. Regulations and Standards

There are no specific guidelines or standards for hydrogen levels in drinking or wastewater. However, maximum limits of Total Dissolved Gas (including H2) are often set to prevent the effects of gas saturation such as gas bubble disease on aquatic life.

6. Environmental Impacts and Sustainability Considerations

Hydrogen is not a pollutant of concern in the aquatic environment. Instead, hydrogen is expected to be a clean and sustainable energy source in the future to replace fossil fuels, if obtained from renewable sources such as water. Research continues on electrolysis, fuel cells, and other clean hydrogen technologies.

7. Future Trends and Research

In water treatment, hydrogen is studied in context:

• Hydrogen storage in metal hydrides for energy storage applications
• Microbial fuel cells to generate electricity from organic waste in water
• Separation of hydrogen from gas mixtures (biogas, syngas) using polymer membranes and other technologies, to produce pure hydrogen fuel

8. Fun Facts

One of the advanced water treatment methods is Advanced Oxidation Processes (AOPs) which can produce hydroxyl radicals (OH-), powerful oxidative species formed from hydrogen and oxygen. These radicals can degrade many complex organic pollutants in water.

That's a thorough summary of hydrogen relevant to the world of water treatment. Although rarely targeted for removal, understanding the properties and behavior of hydrogen is important for optimizing various water treatment processes and the development of future clean and sustainable water technologies.