Adsorption of Cr(VI) by the hygrophyte with chromium hyper-accumulative plant Leersia Hexandra Swart was studied, with the effect of physico-chemical parameters pH and contact time focused. The test results of sorption kinetics conformed to the pseudo-second order kinetics equation. Meanwhile, the correlation coefficient values indicated that the data of sorption thermodynamic fit better the Langmuir model. The adsorption process was found to be first controlled by the electrostatic interaction due to the formation of H＋/H3O＋ barrier, and then the function groups could coordinate the Cr(VI). The morphology and elemental distribution in the leaf cell biomass were evaluated by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). IR analysis of Leersia Hexandra Swart biomass revealed the presence of carboxyl, amide, hydroxyl and carbonyl groups, which are responsible for biosorption of the metal ion. The functional atoms bind Cr(VI) with different interaction on the surface of cell wall, which indicates the selectivity of adsorption.

Key words: Leersia hexandra Swartz, chromium(VI), adsorption, speciation