<p>The purpose of this work was to demonstrate the feasibility of kinetic interpretation of Full Factorial experimental design factor interactive effects observed during biosorption experiments. The biosorption of Pb(II) and Zn(II) ions from aqueous solution using <i>Typha capensis</i> biomass adsorbent was studied as a typical example. Four factors were studied: A (biosorbent particle size), B (pH), C (biosorbent dose) and D (initial metal ion concentration). Kinetic interpretation of the interaction effects was based on the assumption that since adsorption is reversible, and if the interacting main factors can be expressed as concentrations, then the product of the interacting factors gives the law-of-mass-action equation of the interaction. Biosorbent particle size and dose were defined in terms of number of active adsorption sites per biosorbent particle. When applied to the biosorption of Pb(II) and Zn(II) ions using <i>T.capensis</i> biosorbent, full factorial design (FFD) standardized interactive effects data obtained show that biosorption was subject to several factor interaction equilibria, 12 of which significantly affected the biosorption, and comprise 2 biosorbent particle aggregation/de-aggregation equilibria (AC, ABC), 2 surface active functional group ionization/de-ionization equilibria (AB, BC), 2 metal-ion biosorption via ion exchange equilibria (ABD, CBD), 3 metal-ion biosorption via physical adsorption (AD, CD, ACD), 2 metal ion hydration/de-hydration equilibria (D, BD), and 1 water molecule ionization/de-ionization equilibrium (B). Physical adsorption, ion exchange and biosorbent particle aggregation mediated metal biosorption were identified as the operative biosorption mechanisms. Data are presented showing that kinetic modelling of the interaction reactions identified leads to a generalized biosorption kinetic model consistent with experiment.</p>