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Activated Carbon Production from Coconut Husks for Supercapacitors


From UPSC perspective, the following things are important :

Prelims level: Activated Carbon, Supercapacitors

Why in the News?

Researchers at Government College for Women, Thiruvananthapuram, have developed a way to make activated carbon from coconut husks, which are a common leftover from farming in Kerala. This activated carbon is well-suited for making supercapacitors.

Back2Basics: Supercapacitors

  • Supercapacitors, also known as ultra-capacitors or electrochemical capacitors, are energy storage devices that bridge the gap between conventional capacitors and batteries.
  • They store energy through the electrostatic separation of charges rather than through chemical reactions as in batteries.
  • This allows supercapacitors to charge and discharge much faster than batteries.

Key Characteristics:

  • High Power Density: Supercapacitors can deliver and accept charge much more rapidly than batteries.
  • Long Cycle Life: They can endure millions of charge-discharge cycles without significant degradation.
  • Wide Operating Temperature Range: Supercapacitors perform well in a broad range of temperatures, making them suitable for various applications.

Structure and Components:

  • Electrodes: Made of materials like activated carbon, carbon aerogels, or graphene, which have high surface areas.
  • Electrolyte: The medium that allows ionic conductivity between the electrodes, typically a liquid or gel.
  • Separator: A porous membrane that prevents electrical contact between the electrodes but allows ionic movement.

What is Activated Carbon?

  • Activated Carbon, also known as activated charcoal, is a highly porous form of carbon.
  • It is processed to have small, low-volume pores with increased surface area available for adsorption or chemical reactions.
  • It is widely used for purification, decontamination, and as a filtration medium.
  • Key Characteristics:
    • High Surface Area: Due to its extensive network of pores, activated carbon has a very high surface area, typically ranging from 500 to 1500 m²/g.
    • Porosity: The structure includes micropores, mesopores, and macropores, allowing it to adsorb a variety of molecules.

How is it produced?

  • Activated carbon is produced from carbonaceous source materials such as coconut shells, peat, wood, coir, lignite, coal, and petroleum pitch.
  • The production involves two main steps:
  1. Carbonization: The raw material is subjected to high temperatures (600-900°C) in an inert atmosphere (usually nitrogen or argon) to remove volatile components.
  2. Activation/Oxidation: The carbonized material is treated with oxidizing agents (such as steam or carbon dioxide) at high temperatures (800-1000°C) to develop a porous structure.


  • Powdered Activated Carbon (PAC): Finely ground carbon particles primarily used in liquid phase applications.
  • Granular Activated Carbon (GAC): Larger particles used in both liquid and gas phase applications, such as water and air filtration.
  • Extruded Activated Carbon (EAC): Cylindrical pellets used mainly for gas phase applications due to their low pressure drop and high mechanical strength.
  • Impregnated Activated Carbon: Activated carbon treated with chemicals to enhance its adsorption capacity for specific contaminants.


  • Water Treatment: Removes contaminants like chlorine, odors, and organic compounds from drinking water.
  • Air Purification: Adsorbs volatile organic compounds (VOCs), odors, and airborne pollutants.
  • Medical Uses: Used in poisoning cases to absorb toxins in the gastrointestinal tract.
  • Industrial Processes: Utilized in the recovery of solvents, purification of gases, and in gold purification.
  • Food and Beverage: Helps in decolorization and purification processes in sugar, wine, and juice production.

About Coconut Husk-Derived Activated Carbon

  • Coconut husk-derived activated carbon is a sustainable and efficient green solution for high-performance supercapacitors.
  • This material is readily available, low-cost, and eco-friendly.
  • It was produced by Microwave-Assisted Method designed at the Centralised Common Instrumentation Facility (CCIF) at the college.

Importance of Supercapacitors

  • Energy Storage: Supercapacitors have significantly higher capacitance and energy storage capacity compared to conventional capacitors.
  • Search for Ideal Material: Finding the ideal supercapacitor electrode material has been a significant challenge in sustainable energy storage solutions.

Research Findings:

  • Efficiency: Prototype supercapacitors made from coconut husk-derived activated carbon are four times more efficient than existing supercapacitors.
  • Cost-Effective and Efficient: Activated carbon produced using this technology is inexpensive and exhibits exceptional supercapacitor capability.

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