The main difference between activated carbon and biochar is their production. Activated carbon is produced through the activation of carbonaceous materials, such as coal, wood, coconut shells, or peat, at high temperatures (typically between 600°C and 900°C) in the presence of gases like steam or carbon dioxide. On the other hand, biochar is produced by heating organic biomass materials, such as wood chips, agricultural waste, or crop residues, in a low-oxygen environment (pyrolysis) at temperatures generally below 700°C. The absence of oxygen during the process prevents the material from combusting and converts it into a stable form of carbon.
Activated carbon and biochar are both carbon-based materials derived from organic sources. But they serve vastly different purposes and find applications in diverse fields.
Key Areas Covered
1. What is Activated Carbon
– Definition, Features, Applications
2. What is Biochar
– Definition, Features, Applications
3. Similarities Between Activated Carbon and Biochar
– Outline of Common Features
4. Difference Between Activated Carbon and Biochar
– Comparison of Key Differences
Key Terms
Activated Carbon, Biochar
What is Activated Carbon
Activated carbon, often referred to simply as “activated charcoal,” is a highly porous and adsorbent material primarily derived from natural sources like coconut shells, wood, or coal. Activated carbon production is a carefully controlled process that transforms carbon-rich materials into highly porous structures with an extensive surface area. These characteristics are what give activated carbon its remarkable adsorption properties.
Moreover, the production process involves two main steps: carbonization and activation. During carbonization, the raw material is heated in a low-oxygen environment, typically in the absence of air, which prevents combustion. This process converts the carbon-rich material into char, a blackened substance with a high carbon content. After carbonization, the char undergoes the activation process, which generally occurs at temperatures between 600°C and 900°C.
Activation involves introducing oxidizing agents, such as steam or carbon dioxide, to the char. This step opens up and enlarges the pores within the material, creating a highly porous structure. The resulting activated carbon possesses a vast network of pores, including micro-, meso-, and macropores, which contribute to its remarkable adsorption capacity.
Applications of Activated Carbon
Activated carbon is widely used in water treatment processes to remove organic contaminants, chlorine, odors, and taste compounds. It plays a crucial role in ensuring the safety and quality of drinking water.
Activated carbon filters are used in air purification systems to capture volatile organic compounds (VOCs), gases, and odors. They are in household air purifiers, industrial ventilation systems, and gas masks for respiratory protection. In the food industry, activated carbon helps to decolorize and deodorize food and beverages. It is also useful in the production of sugar, alcoholic beverages, and edible oils.
In addition, activated carbon is useful in medicine as an antidote for poisoning. Its porous structure adsorbs toxins and drugs in cases of overdose or poisoning, preventing their absorption by the body.
What is Biochar
Biochar is a carbon-rich material produced through the pyrolysis of organic biomass. This production involves the heating of organic biomass in the absence of oxygen. This absence of oxygen prevents combustion and instead transforms the biomass into a stable form of carbon. Common biomass sources used for biochar production include wood chips, agricultural residues, crop residues, and waste materials like coconut shells or nut shells.
The pyrolysis process typically occurs at temperatures ranging from 300°C to 700°C. One can adjust the specific temperature and duration of pyrolysis to produce biochar with varying properties and characteristics. Slow pyrolysis, for instance, involves lower temperatures and longer residence times and can yield biochar with greater carbon stability and surface area.
Biochar primarily works as a soil amendment to improve soil quality and enhance crop productivity. In fact, it promotes healthier root development, increases water and nutrient retention, and reduces the need for synthetic fertilizers. Biochar is particularly valuable in regions with nutrient-poor soils or drought-affected regions.
Biochar can remediate contaminated soils and mine tailings by adsorbing heavy metals and organic pollutants, thereby reducing environmental risks. It is also useful in water treatment processes to remove contaminants, such as heavy metals, organic compounds, and pathogens. Its porous structure enhances filtration efficiency.
Similarities Between Activated Carbon and Biochar
- Both activated carbon and biochar are predominantly composed of carbon.
- The production processes for both activated carbon and biochar involve thermal treatments in the absence of oxygen.
- Both materials possess a porous structure.
- Moreover, both have an environmental significance.
Difference Between Activated Carbon and Biochar
Definition
Activated carbon is a highly porous and adsorbent material primarily derived from natural sources like coconut shells, wood, or coal, whereas biochar is a carbon-rich material produced through the pyrolysis of organic biomass.
Production Process
Activated carbon is produced through the activation of carbonaceous materials, such as coal, wood, coconut shells, or peat, at high temperatures (typically between 600°C and 900°C) in the presence of gases like steam or carbon dioxide. On the other hand, biochar is produced by heating organic biomass materials, such as wood chips, agricultural waste, or crop residues, in a low-oxygen environment (pyrolysis) at temperatures generally below 700°C.
Porosity
Moreover, activated carbon has a very high degree of porosity. Biochar is also porous, but its porosity is typically lower than that of activated carbon.
Applications
Activated carbon is primarily used for adsorption, where it traps and removes a wide range of impurities and contaminants from air, water, and liquids. It is useful in applications like water purification, air filtration, gas masks, and medical treatments. Meanwhile, biochar is designed for soil enhancement and carbon sequestration. Furthermore, it is incorporated into soil to improve its structure, water retention, and nutrient-holding capacity.
Conclusion
In brief, the main difference between activated carbon and biochar is their production. The production of activated carbon involves heating carbon-rich materials, such as coconut shells, wood, or coal, in the presence of an activating agent, usually steam or chemicals while the production of biochar involves pyrolysis, where organic biomass (such as wood chips, crop residues, or agricultural waste) is heated in the absence of oxygen.
Reference:
1. “Biochar – An Overview.” Science Direct.
2. “Activated carbon.” Wikipedia. Wikipedia Foundation.
Image Courtesy:
1. “Activated carbon” By Ravedave (talk) – Own work (CC BY 2.5) via Commons Wikimedia
2. “Biochar pile” By Oregon Department of Forestry –(CC BY 2.0) via Commons Wikimedia
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