Adsorption of Pb~(2+) and Cd~(2+) on Sediment in Hengyang Section of Xiang River

To provide a basis for prevention and control of heavy metal pollution in Xiang River Basin,the influencing factors and thermodynamic law of the adsorption of Pb2 +and Cd2 +on sediment in Hengyang section of Xiang River were studied. Results showed that adsorption effect of Pb2+was better than that of Cd2+. When pH value ranged from 2 to 6,the adsorption quantity increased with the increase of pH value,and it decreased sharply when pH value was less than 4. Increasing mud to water ratio would lead to decreasing of both adsorption quantity and heavy metal remaining concentration in water. Adsorption quantity also increased as concentration of Pb2 +and Cd2 +increased. The amount of sediment on the adsorption of Pb2+and Cd2+increased slightly with the increases of temperature. The adsorption isotherms of Pb2+followed the Langmuir equation better,while Cd2 + fitted the Freundlich equation better. The adsorption process was spontaneous and endothermic.