ACTIVATED CARBON PRODUCTION & APPLICATIONS

What is activated Carbon?

Activated carbon is a form of carbon that has been treated to make it extremely porous and thus to have a very large surface area available for adsorption and chemical reactions. It is usually derived from charcoal (also called active carbon, activated charcoal, or activated coal).¹

Importance of activated carbon:

Activated carbons are considered to be the most successful adsorbent materials due to:

• High adsorption capacity for pollutants, e.g. dyes, heavy metals, pharmaceuticals, phenols.
• They possess large surface area.
• They possess different surface functional groups, which include carboxyl, carbonyl, phenol, quinone, lactone and other groups bound to the edges of the graphite-like layers.

So that, they are considered as good adsorbents both in liquid and gas phases.²

The most widely used carbonaceous resources for the manufacturing of activated carbons are coal, wood and coconut shell. These types of origins are quite expensive and often imported, in many countries; later making it necessary, for developing countries, to find a cheap and available source for the preparation of activated carbon.³

Surface area of activated carbon:

It is treated physically or chemically to generate microfissures that hugely rise its adsorptive surface area. The great surface area (between 500 and 1500 m²/g) and electrical charge successfully adsorb a wide range of polar combinations, particularly phenols and their derivatives.⁴

Examples of Activate Carbon Applications:

• Drinking water purification
• Wastewater treatment.
• Glycerin manufacturing.
• Dye removal
• Decolorize wine.
• Odor control systems.⁵

Deodorizing carbons are valuable in removing mercaptan off-odors, but may also remove desired flavor compounds. Activated carbon may also give the treated wine an atypical odor.⁶

Additionally, activated carbon has an oxidizing assets. Although this can be valuable, trials using small wine samples are vital to avoiding undesirable, unexpected effects.⁷

Alternative sources:

To reduce the production cost of activated carbons, some green by products are lately suggested like:⁸

1. Olive-waste cakes ⁹
2. Cattle-manue compost.¹⁰
3. Bamboo materials.¹¹
4. Apple pulp.¹²
5. Potato peel. ¹³
6. Banana peel.¹⁴

Environmental pollution:

Environmental pollution can be defined as the contamination of the physical and biological components of the earth/atmosphere system to such a normal level of environmental processes are badly affected. The presence of contaminants into the environment lead to harm to humans or other living organisms.

Environmental pollution is categorized in three main groups:

• Air pollution.
• Water pollution.
• Soil pollution.⁸

lignocellulosic bio-mass

Biomass derived from plants, called lignocellulosic bio-mass, is the richest and bio-renewable bio-mass on earth. The major components of woody plants, as well as grasses and agricultural residues are:

three structural polymers:

• Lignin (10–25%),
• Hemicellulose (20–30%)
• Cellulose (40– 50%).

non-structural components such as:

• proteins,
• chlorophylls,
• ash,
• waxes,
• tannins (in the case of wood)
• and pectin (in most of fibers). ⁸

Specifically, lignocellulosic wastes are a low cost natural carbon source for the production of various materials including activated carbon.

The lignin is considered to be the main sponsor for activated carbons production, properties such as the mean pore size versus the specific porous volume are achieved by all originator’s components whatever is its weight input.

Activated Carbons Production:

The production of activated carbons from lignocellulosic materials is a two stage process:

1. Carbonization at low temperatures (700–800 K), in the absence of oxygen, to eliminate volatile materials.
2. Subsequent activation at higher temperatures (1100–1300 K) to increase the porosity and the surface area of the solid.⁸

Activation Process:

The process of activation can be carried out through different ways:

• Chemical activation using chemicals such as (KOH, H₃PO4, ZnCl₂.
• Physical / Thermal activation using CO, air or water vapor.
• Previous two methods combined.⁸

Advantage of physical activation:

• Low-cost process with a lower environmental impact.¹⁵

Advantage of chemical activation:

• Porosity improvement (adsorption capacity) of the final material.¹⁵

Diagram for activated carbon production:

 

Source: http://www.acarbons.com/activated-carbon-manufacture-steam-activation/

Source : https://pubs.rsc.org/en/content/articlehtml/2016/gc/c6gc03206k

Source: https://rbpaonline.com/activated-carbon-process-flow-chart/high-surface-area-oxygenenriched-activated-carbon-synthesized/

Pre-treatment process of biomass should follow the following criteria: ⁸

1. Low energy and resource consumption.
2. Low water and chemical consumption.
3. Low operation risk and safe to operate.
4. Cost effective
5. Eco-friendly.

Optimized manufacturing processes allow the production of materials with surface areas ranging up to 3000 m²g^-1 and pore volumes of up to 1.8 cm³g^-1, bringing about an immense diversity of applications.¹⁶

The challenge is to develop adsorbents which are not only cost effective and environmentally friendly, but also have high efficiency, selectivity and regeneration δ rate and cycles. ⁸

Factors affecting activated carbon properties:

The preparation conditions of carbonaceous materials affect the physicochemical properties of the produced material such as:

• Surface area.
• Pore size distribution.

Another critical factor is physicochemical properties of the origin itself; depending on:

• Weather conditions.
• Harvesting methods.
• The season that it is collected.
• Initial moisture and oxygen content.
• Derived components fraction of cellulose, hemicellulose and lignin.⁸

By/ Ahmed Hasham

        M.Sc. Env. Analytical Chemistry

      Ahmedhasha83@outlook.com

        ORCID: 0000-0002-0202-6664

 

^References

• Pierson, H. O. (2012).Handbook of carbon, graphite, diamonds and fullerenes: processing, properties and applications. William Andrew.
• Pan, B., Pan, B., Zhang, W., Lv, L., Zhang, Q., & Zheng, S. (2009). Development of polymeric and polymer-based hybrid adsorbents for pollutants removal from waters.Chemical Engineering Journal, 151(1-3), 19-29.
• Emrich, W. (2013).Handbook of charcoal making: The traditional and industrial methods (Vol. 7). Springer Science & Business Media.
• Kalderis, D., Bethanis, S., Paraskeva, P., & Diamadopoulos, E. (2008). Production of activated carbon from bagasse and rice husk by a single-stage chemical activation method at low retention times.Bioresource technology, 99(15), 6809-6816.
• Hiltzik, Laurence, Edward Tolles, and David Walker. “Coated activated carbon for contaminant removal from a fluid stream.” U.S. Patent Application 10/929,845, filed February 17, 2005.
• Bhatnagar, A., Hogland, W., Marques, M., & Sillanpää, M. (2013). An overview of the modification methods of activated carbon for its water treatment applications.Chemical Engineering Journal, 219, 499-511.
• Olivares-Marín, M., Del Prete, V., Garcia-Moruno, E., Fernández-González, C., Macías-García, A., & Gómez-Serrano, V. (2009). The development of an activated carbon from cherry stones and its use in the removal of ochratoxin A from red wine.Food Control, 20(3), 298-303.
• Crini, G., & Lichtfouse, E. Green Adsorbents for Pollutant Removal.
• Baccar, R., Bouzid, J., Feki, M., & Montiel, A. (2009). Preparation of activated carbon from Tunisian olive-waste cakes and its application for adsorption of heavy metal ions.Journal of Hazardous Materials,162(2-3), 1522-1529.
• Kosheleva, R., Mitropoulos, A. C., & Kyzas, G. Z. (2018). Activated Carbon from Food Waste. InGreen Adsorbents for Pollutant Removal (pp. 159-182). Springer, Cham.
• Hameed, B. H., Din, A. M., & Ahmad, A. L. (2007). Adsorption of methylene blue onto bamboo-based activated carbon: kinetics and equilibrium studies.Journal of hazardous materials, 141(3), 819-825.
• Srinivasakannan, C., & Bakar, M. Z. A. (2004). Production of activated carbon from rubber wood sawdust.Biomass and Bioenergy, 27(1), 89-96.
• Moreno-Piraján, J. C., & Giraldo, L. (2011). Activated carbon obtained by pyrolysis of potato peel for the removal of heavy metal copper (II) from aqueous solutions.Journal of Analytical and Applied Pyrolysis, 90(1), 42-47.
• Mopoung, S. (2008). Surface image of charcoal and activated charcoal from banana peel.Journal of Microscopy Society of Thailand, 22, 15-19.
• Maciá-Agulló, J. A., Moore, B. C., Cazorla-Amorós, D., & Linares-Solano, A. (2004). Activation of coal tar pitch carbon fibres: Physical activation vs. chemical activation.Carbon,42(7), 1367-1370.
• Leimkuehler, E. P. (2010).Production, characterization, and applications of activated carbon (Doctoral dissertation, University of Missouri–Columbia).