菲对湘江沉积物吸附镉的影响

制备了镉单独污染和镉-菲复合污染的模拟水样，研究了菲对湘江沉积物吸附模拟水样中镉的动力学和热力学特征的影响，并进一步研究了在不同水样pH和ρ(沉积物)下，菲存在与否及ρ(菲)对沉积物吸附镉的影响.结果表明，无论菲存在与否，湘江沉积物吸附镉的热力学数据均能够用Langmuir方程拟合，相关系数达到0.99以上，属单分子层吸附；动力学数据均可用拉格朗日二级动力学方程拟合，相关系数接近1；以化学吸附过程为主，且在湘江沉积物上的吸附均以快速吸附为主；但是菲的存在削弱了沉积物对镉的吸附能力，提高了镉的解吸率.在试验范围内随着水样pH逐渐增大，菲对沉积物吸附镉的影响越小；ρ(菲)越大，沉积物对镉的吸附量越小；菲对沉积物吸附镉的影响主要是由于菲与镉竞争沉积物颗粒矿物之间的孔隙以及甲醇化的菲分子与颗粒的结合掩蔽了颗粒物表面的部分极性基团两方面原因造成的. 

Effect of Phenanthrene on Adsorption of Cd on Xiangjiang River Sediments

Two synthetic water samples, one contaminated by cadmium (Cd) and phenanthrene (phe), and the other contaminated by Cd, were prepared. The effects of phe on the dynamics and thermodynamics of adsorption of Cd on Xiangjiang River sediments in both water samples were investigated. The influences of pH, mass concentration of sediment and mass concentration of phe on the adsorption of Cd were also studied. The results showed that the Langmuir equation described the adsorption isotherms well, with a correlation coefficient up to more than 0.99, whether phe existed or not. The Lagrangian second-order dynamic equation described the adsorption dynamics well, with a correlation coefficient of about 1. This indicated that the adsorption of Cd on Xiangjiang River sediments was monolayer adsorption, and that the dominant mechanism was chemical adsorption in both water samples. Rapid adsorption played the main role in the adsorption of Cd on Xiangjiang River sediments. The adsorption capacity reduced and the desorption ratio increased when phe existed. The degree of the effect of phe on the adsorption of Cd on Xiangjiang River sediments decreased when pH increased. The adsorbance of Cd reduced with the increase of phe concentration. The effect of phe on the adsorption of Cd on Xiangjiang River sediments is due to two reasons: one is competition on the particulates surface between phe and Cd; the other is the particulates polar groups being reduced as a result of the combination of methanolized phe and sediment particulates.