I think Chemical process is more efficient and higher yield and more surface area, but activated carbon, Depending on the required properties of the final product, Different sorts of activated carbon Activated carbon can be manufactured from a wide variety of raw materials such as coal, coconut and wood. both at elevated temperatures. It tends to depend on exactly what you do, including heating rate, particle division, etc. I assume that carboxylic groups are leaving as CO2 and aldehydes leaves as CO. Both activations are performed using nitrogen flushing.
https://www.researchgate.net/post/Chemical_vs_physical_activation
Dear Ammar, Chemical activation is much efficient than thermal activation. However, there are some negatives to chemical activation. Depending upon your end application you can select activation methods. Moreover, chemical activated carbon is not suitable for drinking water purification.
Dear Ammar Hamdoon,
Chemical process is prefered over the thermal. 60% of activated carbon is processed chemically.
In chemical activation processes, the precursor is first treated with a chemical activation agent, often phosphoric acid, and then heated to a temperature of 450 – 700 °C in an activation kiln. The char is then washed with water to remove the acid from the carbon. It’s an easy going process. Granular activated carbon is made from raw organic materials (such as coconut shells or coal) that are high in carbon. The activated carbon removes certain chemicals that are dissolved in water passing through a filter containing GAC by trapping (adsorbing) the chemical in the GAC.
Thermal process is comparatively complicated. The preparation of activated carbons (ACs) generally comprises two steps, the first is the carbonization of a raw material or precursor and the second is the carbon activation. The carbonization consists of a thermal decomposition of raw materials, eliminating non-carbon species and producing a fixed carbon mass with a rudimentary pore structure (very small and closed pores are created during this step). On the other hand, the purpose of activation is to enlarge the diameters of the small pores and to create new pores and it can be carried out by chemical or physical means. In a physical or thermal activation process, the lignocellulosic precursor is carbonized under an inert atmosphere, and the resulting carbon is subjected to a partial and controlled gasification at high temperature with steam, carbon dioxide, air or a mixture of these. Steam and CO2 are the two activating gases more used in the physical activation of carbons.
Chemical activation is the most used method for the preparation of ACs (~60 %) from lignocellulosic precursors. Physical activation methods is used in 28% of the studies. However, when thermal process compared with chemical activation, this method is not corrosive and does not require a washing step.That is a advantage of thermal process activation.
Ashish
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