Possibilities of using biosorbents and synthetic sorbents in monitoring heavy metal pollution of surface waters

This article presents the findings of fundamental research designed to assess the viability of utilising a range of sorbents to determine whether preset concentration thresholds for specific heavy metals – namely nickel, zinc, cadmium, and lead – have been exceeded in prepared aqueous solutions. The biosorbents employed in the study were mosses, lichens and algae, modified zeolites, and synthetic cationites. It was demonstrated that a state of heterophasic ion exchange equilibrium was attained following an exposure period of approximately two hours. Of the heavy metal sorbents tested, synthetic cationites were found to exhibit the most favourable sorption properties. Furthermore, the sorption processes of heavy metal cations by synthetic cationites were found to be influenced by the pH and salinity of the solution. No significant changes were observed in the pH range of 4.0 to 8.0. A reduction in heavy metal sorption of up to 25% was observed in solutions with conductivity ranging from 300 to 1500 μS cm−1, and up to 15% in solutions with conductivity between 300 and 800 μS cm−1. The results presented here indicate that, with relatively stable water salinity levels, it is possible to detect exceedances of permissible heavy metal concentrations in surface waters on the basis of an analysis of metal concentrations in synthetic cationites exposed in water.