DANIELA SIMINA STEFAN, MIHAI BELCU, MIRCEA STEFAN, IOANA ANDREEA MARINESCU SORPTION OF HG2+ AND PB2+ IONS FROM AQUEOUS SOLUTIONS ON CORN COBS BIOMATERIALS I. STUDY OF SORPTION EQUILIBRIUM OF HG2+ AND PB2+ CATIONS ON CORN COBS
The sorption capacities of grinded corn cobs for Hg2+ and Pb2+ cations from wastewaters were established for various particle dimensions and pH values. The (local) structure of Hg2+ and Pb2+ sorbed on corn cobs biomass has been investigated by secondary electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The sorption isotherms indicate a slightly greater affinity for the Pb2+ cations, compared to the Hg2+ ones. The Langmuir model equation satisfactorily characterizes the experimental results. The values of calculated free energy changes correspond to physical actions, IR spectres and the structural modifications evidenced by electronic microscopy (SEM) analysis on biomass samples after Hg2+ or Pb2+ ions retention indicate that the heavy –metals binding mechanism is mainly a physical interaction and ion exchange process.