Study On The Removal Of Cd(Ⅱ) And Phenol On Sediments From Xiangjiang River Under The Condition Of Combined Pollution

Sediments were taken from the Xiangjiang riverbed( depth 1.5m-2m) as the research object, and the typical pollutants cadmium and phenol in Xiangjiang River, were prepared as the reference elements. Study had been carried out for removing cadmium and phenol from the combined pollution samples. In addition, the influence and mechanism of cadmium and phenol on the adsorption of each other on sediments had also been studied.First of all, the physical and chemical properties and morphology features of sediments were ditermined and analyzed. Secondly, the adsorption characteristics of cadmium on Xiangjiang sediments when phenol existed were investigated. The adsorption dynamics and thermodynamics, and the effect of p H of synthetic water samples, the difference of sediments and the concentration of phenol on the adsorption of cadmium were also studied. The results showed that, whether phenol existed or not, the rapid adsorption played the main role in the adsorption of cadmium on Xiang Jiang sediments. The pseudo-second-order model described the adsorption kinetics well and the adsorbing thermodynamics fitted better with Langmuir isotherm model, which indicated that the existing of phenol had small influence on the law of the adsorption dynamics and thermodynamics of cadmium on sediments. The adsorption capacity increased when phenol exist. The main reason is that the O-H bond on phenol and cadmium has a complex function which increases the adsorption capacity of cadmium on sediments. The influence of phenol on the adsorption of cadmium on sediments reduced with the p H increased, and the removal rate of cadmium in both synthetic water samples increased with the increase of sediments concentration. The enhancement effect reached the maximum of cadmium on the sediments when the concentration of phenol was 30mg/L.Finally, the adsorption characteristics of phenol on Xiangjiang sediments when cadmium existed were investigated. Further study had also been carried out on the adsorption dynamics and thermodynamics, and the influence of p H of synthetic water samples, the difference of sediments and the concentration of cadmium on the adsorption of phenol when cadmium existed. The results showed that, whether cadmium existed or not, The pseudo-second-order model and the intramolecular diffusion model described the adsorption kinetics well when cadmium existed and not, respectively, which indicated that the existing of cadmium had great influence on the law of the adsorption dynamics of phenol on sediments. The adsorption capacity decreased when cadmium exist. The main reason may be that, a large amount of cadmium was adsorbed on the surface of the sediments duing to the effection of O-H bond of the sediments when there was a high concentration of cadmium. And the adsorbed cadmium exists in the form of hydrated ion and the radius of cadmium hydrated ion is longer than others(4.26?), thus hindering the adsorption of phenol on the surface sediments, resulting in the phenol adsorption capacity on sediments decreased; The adsorbing thermodynamics fitted better with Langmuir isotherm model and Freundlich isotherm model whether cadmium existed or not. The adsorption of phenol on Xiangjiang sediments was strongest when p H at 3 and 4 when cadmium existed and not, respectively. The removal rate of phenol in both synthetic water samples increased with the increase of sediments concentration. And cadmium had more obvious inhibition on the adsorption of phenol on sedments when the concentration of cadmium was 10mg/L.Above all, phenol contamination to some extent enhanced the adsorption of cadmium on the sediments while cadmium contamination to some extent weakened the adsorption of phenol on the sediments. The result obtained from this study provided an important reference value for the further research about variation and removal patterns of pollutants in the phenol and heavy metals complex polluted water.