Potential application of activated carbon from maize tassel for the removal
of heavy metals in water
a b s t r a c t
Water-pollution problems worldwide have led to an acute shortage of clean and pure water for both
domestic and human consumption. Various technologies and techniques are available for water treatmentwhich includes the use of activated carbon. In this study activated carbons used for the removalof lead (II) ions from water samples were prepared from maize tassels (an agricultural waste residue)which were modified using physical and chemical activation. In the physical activation CO2 was usedas the activating agent, while in chemical activation H3PO4 with an impregnation ratio ranging from 1to 4 was employed. The maize tassel was pyrolysed at different temperatures ranging from 300 C to700 C in an inert atmosphere for a period of 60 min and activated at 700 C for 30 min. The effects of activationtemperature, impregnation ratio and duration were examined. The resultant modified tassels werecharacterised by measuring their particle-size distribution, porosities, pore volume, and pore-size distributionusing scanning electron microscopy (SEM). The activated carbon produced by chemical activationhad the highest BET surface area ranging from 623 m2 g1 to 1262 m2 g1. The surface chemistry characteristicsof the modified tassels were determined by FT–IR spectroscopy and Boehm’s titration method.The experimental data proved that properties of activated carbon depend on final temperature of the process,impregnation ratio and duration of the treatment at final temperature. The adsorption studiesshowed that chemically prepared activated carbon performed better than physically prepared activatedcarbon.