TITLE: PREPARATION AND CHARACTERIZATION OF ACTIVATED CARBON FROM LOCALLY AVAILABLE MATERIALS, VIZ. COCONUT SHELLS
Project Report on Activated Carbon – Activated carbon has been there with us for centuries. It has wide applications in various industries e.g. in the water-treatment, dye, sugar refining, among others. All the activated carbon available in Kenya is imported.
Therefore production of activated carbons locally and from locally available materials would be one of the most lucrative and environment-friendly solutions to this as it would transform negative–valued wastes to valuable materials.
Thus, the main objective of this research was to prepare activated carbons from coconut shells using a two-step method, and to establish the optimum conditions of production. Thecarbonization process was carried out at 520°C for 45 minutes, and physical activation carried out at 850oC for a range of soaking times of 30, 60 and 75 minutes.
The activated carbon was prepared under limited supply of oxygen from coconut shells as the precursor. The coconut shells are the ones from coconut trees scientifically known as cocos nucifera. This species is the most prevalent in the Kenya’s coast.
Three different pyrolysis temperatures were considered with each three different soaking times investigated. Then also three different activation temperatures were used. The effect of the different activation conditions was investigated by comparing adsorbance of Methylene blue in samples which had undergone the different conditions.
The optimum temperature for pyrolysis was obtained by optimizing carbon yield and costs, while optimum activation temperature and time were obtained by plotting graphs of temperature against Methylene blue adsorbance and soaking time versus Methylene blue adsorbance respectively. The most suitable conditions for the preparation of activated carbons were found to be pyrolysis temperature of 520°C for 45 minutes, and activation temperature of 850oC with steam gasification time 60 minutes.
The On-going Research There has been an on-going research on the Production and Characterization of Activated Carbon from locally available precursors at the University of Nairobi’s Mechanical Engineering department.
The precursors which have been previously dealt with are tires, coffee husks, coconut shells and rice husks. Though coconut shells had been previously studied and had proved to be a formidable source of carbon, there were loopholes which could be better sealed in a further research. It is against this background that this project is anchored.
The various studies had been using inert gas, argon, to lock out oxygen in the carbonation process (see later sections). Since one of the targets of the project was the informal sector popularly known as the Jua Kali industry, the use of inert gas could turn the whole project costly. The project will look for ways of circumventing this.
Again, there were gaps in the results which we would seek to fill. Some of these will be captured in the following statement of objectives. It is worth to remember that the wheel is not being reinvented. Activated Carbon has been with us for centuries and commercial ones are available, though all are imported in Kenya. However, the project seeks to use locally available precursors. Also the project wants to involve local manufacturers in the production of activated carbon to meet the fast growing local market. This is in line with Vision 2030 tenet.
Statement of Objectives
- To prepare activated carbons from coconut shells through physical activation under different operating parameters and preparation variables such as Pyrolysis time and temperature, Activation time and temperature.
- To establish the best conditions for producing activated carbons using coconut shells.
- To investigate the physical characteristics and surface chemistry of the prepared activated carbons.