Selective adsorption of Pb(II) from aqueous solution using porous biosilica extracted from marine diatom biomass: Properties and mechanism

Abstract

Biosilica with a surface area of 143 m(2) g(-1) derived from marine diatoms was prepared using an easy two-step method involving washing with dilute acid and baking. The extracted biosilica was used to remove divalent lead ions, i.e., Pb(II), from aqueous solution. The effects on Pb( II) adsorption of initial pH, shaking speed, and adsorbent loading were investigated. The adsorption of Pb( II) in the presence of other ions was also investigated. The biosilica showed a high adsorption capacity with high selectivity for Pb( II). The experimental maximum adsorption capacity was 108.2-120.4 mg g(-1) at an adsorbent loading of 1 g L-1. The adsorption process was best described by the Langmuir model. The adsorbent selectively adsorbed Pb( II) from binary ion systems in the presence of Cu(II), Cd(II), Ni(II), and Ag(I). The results of this study show that biosilica extracted from fresh marine diatoms is a more efficient and selective adsorbent for Pb( II) than other inorganic adsorbents. (C) 2016 Elsevier B. V. All rights reserved.