Removal of heavy metals from water by lignite-based sorbents

Abstract

Calcium-loaded lignite was used to remove heavy metals from wastewater by ion exchange. The following quantities were determined experimentally: calcium-loading capacity for different types of lignite, selectivity coefficients of Cu, Zn, Pb, Cd, Ni, Co and Fe(II) ions, kinetic sorption dependences and the effect of flow rate on the shape of break-through curves in column experiments. Sorption kinetics was relatively slow and consequently, the sorption dynamics was influenced by this phenomenon. A numerical code taking into account the sorption kinetics was used for modelling, which proved its applicability for scaled-up columns. The process is very efficient especially in the case of low concentrations of pollutants in water, where common methods are either economically unfavourable or technically complicated. This is very often the case of various metals in the environment, and thus the method could be convenient for their removal.