Carbon

Carbon (C)

1. Basic Information

2. Physical and Chemical Properties

• Density: 2.26 ^g/cm3 for graphite, 3.51 ^g/cm3 for diamond

• Melting point: 3550°C for graphite

• Boiling point: 4827°C

• Water solubility: Insoluble

• Valence: Generally +4, but can also be +2 or -4 in some compounds

• Carbon can form a wide variety of organic and inorganic compounds. Its tendency to form long chains and atomic rings is the structural basis for all living things.

3. Presence in Water and Health Effects

• Carbon is found in water mainly as carbonate and bicarbonate compounds, or as dissolved organic substances (e.g. humus acids).

• Certain organic compounds containing carbon such as pesticides, solvents, and aromatic hydrocarbons can be harmful to health if ingested in large amounts.

• Carbon in its free form (e.g. activated carbon) is generally non-toxic, but long-term exposure to carbon black dust can damage the lungs and heart.

• Some simple carbon compounds such as carbon monoxide (CO) and cyanide (^CN-) are highly toxic.

4. Water Treatment Applications and Removal Methods

• Activated carbon is used extensively in water treatment to adsorb organic contaminants, odor, taste, and color.

• Carbonic and organic acids and their salts can be removed using anion exchange resins in water treatment.

• Volatile organic compounds (VOCs) such as BTEX can be removed by adsorption using specialized polymer adsorbents.

• Natural organic matter (NOM) and disinfection by-products (DBPs) can be reduced by using scavenger resins to prevent membrane fouling.

• Decolorization of sugar syrups and fruit juices is often done with activated carbon or polymer adsorbents to meet stringent color specifications.

5. Industrial Use in Water Treatment

• Activated carbon in granular or powder form is the most commonly used adsorbent in industry for water purification.

• Scavenger resins are placed before demineralization or reverse osmosis equipment to protect against fouling of organic substances.

• Polymer adsorbents offer an alternative to activated carbon for the removal of various synthetic organic materials from industrial effluents.

• Decolorization is an important step in the food and beverage industry for processing sugars, syrups, and juices.

6. Case Study or Real Application Example

• The town of Haverhill, Massachusetts uses powdered activated carbon to control seasonal tastes and odors in its drinking water supply.

• Dow Chemical's Freeport, Texas plant uses ultrafiltration and activated carbon systems to treat 5 million gallons per day of wastewater into quality process water.

• Nestle's plant in Mogi Guacu, Brazil, uses organic scavenger resins to protect ion exchange resins from humus acids when treating glucose syrup.

• Miller Brewing Company installed a carbon adsorption system for color and flavor purification of malt compounds before beer blending.

7. Regulatory Guidelines and Standards

• The US Environmental Protection Agency (EPA) sets legal limits for more than 90 contaminants, including organic compounds, in drinking water.

• In Indonesia, Permenkes No.492/2010 regulates drinking water quality requirements, including maximum allowable levels for organic substances.

• The EPA and other organizations such as WHO provide detailed guidelines on the use of activated carbon for water treatment.

8. Environmental Impact and Sustainability Considerations

• The use of carbon-based adsorbents helps remove harmful organic pollutants from wastewater before it is released into the environment.

• Regeneration and reuse of carbon adsorbents and resins can minimize waste and improve sustainability.

• Polymer adsorbents offer environmental advantages over activated carbon in terms of longer service life and easier regeneration.

9. Future Trends and Research

• Carbon-based nano adsorbents such as graphene oxide are being explored for efficient removal of emerging water pollutants.

• Surface modification and functionalization of carbon and polymer adsorbents are being studied to improve selectivity and capacity for target contaminants.

• Development of magnetic adsorbents enables easy magnetic separation after treatment.

• Combining carbon adsorption with other processes such as photocatalyst oxidation is being investigated for effective wastewater treatment.

10. Interesting Facts

• Activated carbon has been used for water purification since the ancient times of Egypt, Greece and ancient Rome.

• One pound of activated carbon has a surface area of over 100 acres, allowing for incredible absorption of pollutants.

• Activated carbon can be made from almost any carbon-containing material, including coconut shells, coal, wood, and even animal bones.

• Filtration using carbon has become such a common practice that the term "carbon filtration" is sometimes interchangeably used for "water purification".