Benzene as an ingredient in water
Benzene, also known as benzene, is a chemical substance that is only soluble in trace amounts in water - but that doesn't make it unproblematic.
What is Benzene?
Benzene is an aromatic hydrocarbon and its chemical formula is C6H6. In nature it occurs in small quantities in petroleum and coal tar , and small quantities are also produced in forest fires and volcanic eruptions.
The substance is harmful to humans and animals even in low concentrations. It is considered to be carcinogenic and when broken down in the human metabolism, substances are created that cause damage to the genetic material.
While benzene was handled quite carelessly a hundred years ago - it was used in normal households, for example as a stain remover or as a fragrance - today its use is subject to strict regulations. In Germany, no products may be placed on the market that contain more than 0.1% benzene. The only exception is the fuels for internal combustion engines: In Germany, gasoline may contain up to 1% benzene in accordance with the European standard EN 228.
Benzene is only permitted in larger quantities for research and industry under appropriate safety conditions. Numerous industrial chemicals originate from benzene; These include dyes, plastics such as nylon and styrene, pesticides and detergent substances. Benzene from these processes must not be released into the environment.
The vast majority of benzene in the environment today, an estimated 75%, comes from internal combustion engine exhaust . Small amounts are also contained in cigarette smoke (10-100 micrograms per cigarette).
How does benzene get into water?
Because of its low boiling point (80 °C), benzene from the residues of internal combustion engines mainly evaporates directly into the atmosphere . Here it is gradually broken down in a chemical reaction.
However, some of the released benzene also penetrates the soil and groundwater . Some of it is broken down there by specialized microorganisms. However, the natural processes in the atmosphere, soil and water are not sufficient to completely remove the released benzene.
Limits
Benzene in drinking water
Water is a polar solvent, which means that the individual water molecules show an asymmetrical distribution of electrical charges. But benzene is a non-polar molecule in which electrical charges are evenly distributed. This is why benzene is very poorly soluble in water: a maximum of 1.7 g of benzene can be dissolved per liter.
However, this does not mean that the benzene content in drinking water is unproblematic. Even small traces of it are harmful to humans and animals.
For the benzene content inde/glossary/drinking water" target="_self">Drinking water limit values are therefore set, which, however, differ significantly depending on the legislative organization:
- WHO Drinking Water Quality Guideline 2006:
0.01 milligrams per liter - EU Drinking Water Directive of 1998:
0.001 milligrams per liter - Drinking Water Ordinance Germany from 2001:
0.0001 milligrams per liter
The EU therefore allows a benzene concentration ten times higher than the German drinking water regulation.
How can benzene be removed from drinking water and industrial water?
Unlike desalination, neither ion exchange nor distillation systems are suitable for separating benzene. However, it can be reliably removed with activated carbon filters .
