Kinetics of heavy-metal removal and recovery in sepiolite

Abstract

Fixed beds of Mg-enriched sepiolite were percolated through Co2+, Cu2+, Zn2+, Cd2+ and Pb2+ single- and multicomponent heavy-metal solutions to study both the dynamic interactions between mineral and heavy-metal cations and the ion-sorption kinetics. The metal concentrations in the eluates were determined by atomic adsorption and/or inductively-coupled plasma and kinetics by the classical kinetic approach, using isothermal experiments at room temperature. The experimental results suggest that: (i) the amount of heavy metal sorbed by the mineral increases for smaller cations; ii) the sepiolite sorption efficiency sequence is, for single component solution, Pb2+ < Cd2+ < Co2+ < Zn2+ < Cu2+, and, for multicomponent solution, Pb2+ = Co2+ < Cd2+ < Zn2+