RESUMO
Nanoparticles of manganese-dioxide synthesized by mechano-chemical reaction were used for As[III] and As[V] sorption from water environment. The influence of a milling time of manganese-dioxide on sorption was examined with batch procedure. Sorption as a function of contact time was investigated. Kinetic of sorption, for both As[III] and As[V], was fast. The equilibrium condition for milled sorbents was achieved after one hour of mixing. Experimental data were fitted to Freundlich and Langmuir adsorption models. Both models represent experimental data well with slightly better regression coefficient for Freundlich isotherm model. With the increase of the milling time manganese-dioxide adsorption capacity for As[III] and As[V] increased. The decrease of average particle size with milling could be responsible for increase of sorption capacity. The influence of pH on sorption was also investigated. The sorption of both, As[III] and As[V], in investigated pH range [6.0-9.0] was not significantly disturbed and showed similar behaviour, what could indirectly imply oxidation of As[III] to As[V] before sorption