Functionalised carbon from Musa Balbisiana stems - a byproduct of edible alkali preparation and a suitable adsorbent for fluoride and arsenic from contaminated water

Abstract

A popular traditional food additive amongst the Assamese people of North East India is Kol-Khar or banana peel alkali. The preparation of this edible alkali is carried out by aqueous extraction of ashes obtained from slow burning of hard sun dried banana stems and peels of Musa Balbisiana. The alkali is extracted from the ashes by water washing. The carbon fraction obtained in the process remains as a byproduct. This carbon due to exposure to high alkalinity during alkali extraction undergoes a base mediated surface functionalisation. From FESEM images, some holes and cave type openings are found on the surface of this carbon. From EDX spectra the chemical composition of the carbon was obtained. The number of acidic and basic sites so formed could be determined by Boehm titration. This functionalized waste bio carbon was used as an adsorbent for fluoride and arsenic from ground water. Effect of different parameters like adsorbent dose, contact time, temperature and pH of adsorbate on defluoridation capacity of the material was studied in the present work. The adsorption isotherm and adsorption kinetics were also investigated. From batch mode study 73 % removal of fluoride and 79.8 % removal of arsenic are obtained from each 5 mg/L spiked fluoride and arsenic solution. Show more