INFLUENCING FACTORS OF Cr( Ⅲ) OXIDATION BY ALKALINE BIRNESSITE

Alkaline birnessite had been synthesized by an oxidation-reduction method，and its crystal structure，specific surface area and surface chemical property were characterized． The influencing factors of Cr ( Ⅲ) oxidation by alkaline birnessite was also studied． The results indicated with decrease of Mn7 + /Mn2 + in synthetic method，the AOS and specific surface area of synthetic birnessite decreased，but the PZC of synthetic birnessite increased． The effect of reaction conditions ( pH，concentration of Cr( Ⅲ) ，birnessite loadings and AOS) was studied． The oxidation rate of Cr( Ⅲ) increased with the increase of pH in the low pH range，but it decreased with the increase of pH in high pH range． In addition，the oxidation rate of Cr( Ⅲ) decreased with the increase of concentration of Cr( Ⅲ) ，but it increased with the increase of birnessite loadings and AOS respectively．