A team of Indian scientists has used tea and banana waste to prepare non-toxic activated carbon, which could useful for industrial pollution control, water purification, food and beverage processing, and odour removal. The newly developed process avoids usage of toxic agent for synthesising activated carbon, thus making the product cost-effective as well as non-toxic.
The processing of tea generates a lot of waste, generally in the form of tea dust. This could be converted to useful substances. The structure of tea was favourable for conversion to high-quality activated carbon. However, conversion to activated carbon involves use of strong acid and bases, making the product toxic and hence unsuitable for most uses. So a non-toxic method of conversion was needed to overcome this challenge.
N. C. Talukdar, former director, Institute of Advanced Study in Science and Technology (IASST), Guwahati, an autonomous institute of the Department of Science & Technology, and Devasish Chowdhury, associate professor, used banana plant extract as an alternative activating agent for making activated carbon from tea waste.
Oxygenated potassium compounds contained in the banana plant extract help in activating carbon from tea waste. An Indian patent has recently been granted for this.
The banana plant extract used in the process was prepared by traditional way and is known as khar, which is an alkaline extract from the ashes of burnt dried banana peels. The most preferred banana for this is called ‘Bheem Kol’ which is an indigenous variety of banana found in Assam and parts of northeast India.
The IASST team said, “The reason for the use of tea as a precursor for the synthesis of active carbon is that in tea structure, the carbon atoms are conjugated and having polyphenols bond. This makes the quality of activated carbon better compared to other carbon precursors.”