Two most suggested papers for pseudo-second-order kinetic model were published in 1984 and 1995 by Blanchard et al. and Ho, respectively. Blanchard et al. noted the overall exchange reaction of NH4+ ions fixed in zeolite by divalent metallic ions in the solution using a second-order kinetic model. Ho used the pseudo-second-order kinetic model to the copper ion/peat adsorption system. The adsorption involved chemical bonding and cation exchange. In this comment citation error and quotation error were pointed. (c) 2009 Elsevier Inc. All rights reserved.