Activated Carbon from Lignocellulosic Waste Residues: Effect of Activating Agent on Porosity Characteristics and Use as Adsorbents for Organic Species O. F. Olorundare & T. A. M. Msagati & R. W. M. Krause & J. O. Okonkwo & B. B. Mamba Received: 7 September 2013 /Accepted: 15 January 2014 /Published online: 6 February 2014 # Springer International Publishing Switzerland 2014 Abstract This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the per- formance of porous activated carbon from waste resi- dues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m 2 /g) and a large pore volume (1.592 cm 3 /g) of AC produced from maize tassel (MT) using a convec- tional chemical activating agent (phosphoric acid). Im- pregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon. Keywords Activating agents . Impregnation ratio . Maize tassel . Porous activated carbon 1 Introduction Lignocellulosic wastes generated especially from agri- cultural wastes have been an issue for environmentalist and eco-friendly activists due to their disposal. Millions of tonnes of wastes generated annually, especially of biomass origin, have turned our cities to glorified dumpsites. The lignocellulosic agricultural wastes have no specific technical usage apart from the generation of fossil fuel. Maize tassel (MT), an agricultural waste, is the male flowering part of the maize plant. The tassel is the stemmy flower that sits on the apex of the maize stalk. These tassels, during pollination through cross- fertilization, are responsible for the production of kernel which in turn produces the maize cob. The whole pro- cess involved the tassel-producing pollen, which is blown off by wind in order to reach the silk ear (female flowering part of maize plant) for fertilization. MT has no production value after fertilization except for the farmer to cut them off in ensuring maximum utilization of maize grain production. The possible use of MT as a biosorbent for inorganic compounds has been extensively explored by different researchers (Zvinowanda et al. 2008a, b, c), while its application in commercial production of activated car- bon (AC) has not been fully explored. Apart from maize tassels, activated carbon has been produced from other diverse organic materials rich in carbon such as different agricultural wastes, coal, lignite, and wood (Daud and Ali 2004; Prahas et al. 2008; Olorundare et al. 2012). The possible use of agricultural residues in the produc- tion of good quality AC has been highlighted by a Water Air Soil Pollut (2014) 225:1876 DOI 10.1007/s11270-014-1876-2 O. F. Olorundare : T. A. M. Msagati (*) : B. B. Mamba (*) Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Johannesburg, South Africa e-mail: tmsagati@uj.ac.za e-mail: bmamba@uj.ac.za R. W. M. Krause Department of Chemistry, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa J. O. Okonkwo Department of Environmental, Water & Earth Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa