Adsorption and Desorption of Cr(Ⅲ) and (Ⅵ) by Substrate Sludge of Ming Tombs Reservoir

The authors collected samples of the substrate sludge from different places of Ming Tombs Reservoir (in the suburb of Beijing),and tested their adsorption and desorption to Cr(Ⅲ)(Cr³⁺) and Cr(Ⅵ)(Cr₂O₇^2-) separately by means of colorimetric analysis.The results show that the substrate sludge has nearly no adsorbing ability to Cr₂O₇^2-,the adsorption rate is only 1~3%;On the contrary,the adsorbing ability to Cr³⁺ is exceedingly strong,the adsorption rate is 35~66%,and the desorption rate is only 1~6%.This reveals that the adsorbed Cr³⁺ could hardly be desorbed.