水钠锰矿对Cr(III)离子的吸附解吸及氧化行为

Cr(Ⅲ) adsorption, desorption and oxidation by birnessite was studied in this paper. Results show that amount of total Cr(Ⅲ) increased with the amount of Cr(Ⅲ) added, and the adsorption process could be well described with the Langmuir equation. The concentration of Cr(Ⅲ) resulting from oxidation of Cr(Ⅲ) showed an extremely significant positive linear relationship with the initial concentration of Cr(Ⅲ) added, while the oxidation rate did a reverse one. Moreover, effects of pH, temperature on the adsorption and oxidation processes were also examined. TI adsorption at 308.2 K was remarkably lower than at 298.2 K, while the oxidation and oxidation rate at 308.2 K were obviously higher than at 298.2 K, which suggest that high temperature favored oxidation, hut disfavored adsorption. This finding could also be proved by thermodynamic parameters (△G° and △H°) of the adsorptive process. Adsorption decreased with increasing pH of the adsorption solution, while the oxidation and oxidation rate increased. The results indicated that high pH favored oxidation, but disfavored adsorption.