Journal of Colloid and Interface Science, Vol.382, 74-81, 2012
Mechanistic aspects of nitrogen-heterocyclic compound adsorption on bamboo charcoal
Adsorption of three nitrogen-heterocyclic compounds (NHCs), pyridine, indole, and quinoline, on a new porous carbonaceous adsorbent, bamboo charcoal (BC), is investigated. Different structures and surface properties of BC are created by HNO3 and NaOH treatment as well as by microwave (MW) radiation. HNO3 treatment decreases surface area, micropore volume, and surface hydrophobicity, whereas NaOH treatment increases surface area and micropore volume. MW treatment dramatically increases hydrophobicity and fraction of aromatic structure. Adsorption isotherms of NHCs are nonlinear and better fitted by Freundlich model (FM) compared with Langmuir model (LM) and Polanyi-Manes model (PMM). The maximum adsorption capacities for pyridine, indole, and quinoline reach 42.92, 93.24, and 91.74 mg g(-1), respectively, at an initial concentration of 200 mg L-1. Surface area, hydrophobicicty, and electrostatic and pi-pi electron-donor-acceptor (EDA) interactions are accountable for NHC adsorption. A model relating NHC adsorption (log K) and adsorbent-adsorbate physicochemical properties is developed to measure the relative contribution of these interactions giving the sequence of surface area > hydrophobic interaction > electrostatic interaction > pi-pi EDA interaction. (C) 2012 Elsevier Inc. All rights reserved.