Activated carbon prepared from biomass as adsorbent: elimination of Ni(II)from aqueous solution

Activated carbon (AC) prepared from waste Parthenium was used to eliminate Ni(II) from aqueous solution by adsorption. Batch mode adsorption experimen ts are carried out, by varying contact time, metal ion concentration, carbo n concentration, pH and desorption to assess kinetic and equilibrium parame ters. They allowed initial adsorption coefficient, adsorption rate constant and maximum adsorption capacities to be computed. The adsorption data were modeled by using both Langmuir and Freundlich classical adsorption isother ms. The adsorption capacity (Q(0)) calculated from the Langmuir isotherm wa s 54.35 mg Ni(II)/g of AC at initial pH of 5.0 and 20 degreesC, for the par ticle size 250-500 mum. Increase in pH from 2 to 10 increased percent remov al of metal ion. The regeneration by HCl of Ni(II)-saturated carbon by HCl, allowed suggestion of an adsorption mechanism by ion-exchange between meta l ion and H+ ions on the AC surfaces. Quantitative recovery of Ni(II) was p ossible with HCl. (C) 2001 Elsevier Science Ltd. All rights reserved.