Removal of Zinc from Aqueous Solutions Using Bagasse Fly Ash − a Low Cost Adsorbent

Abstract

Bagasse fly ash, a sugar industry waste, has been converted into an inexpensive and efficient adsorbent. The product obtained has been characterized and utilized for the removal of zinc from aqueous solutions over a wide range of initial metal ion concentration (3.06 × 10-4 to 3.06 × 10-3 M), contact time (24 h), adsorbent dose (5−20 g L-1), and pH (1.0−6.0). The removal of Zn2+ is 100% at low concentrations, whereas it is 60−65% at higher concentrations at an optimum pH of 4.0, using 10 g L-1 of adsorbent in 6−8 h of equilibration time. The uptake decreases with a rise in temperature indicating the process to be exothermic in nature. Kinetic studies have been performed to understand the mechanism of adsorption. The removal takes place through film diffusion mechanism at lower concentrations (≤1.84 × 10-3 M) and by particle diffusion at higher concentrations (≥ 3.06 × 10-3 M).