湘江底泥对氨氮的解吸动力学研究

Study on Ammonia Nitrogen Desorption from Sediment of Xiangjiang River and Kinetics of Desorption

以湘江底泥为研究对象,探讨了湘江底泥解吸氨氮的影响因素和动力学规律。实验结果表明,当水溶液pH处于中性时氨氮的解析量最小,酸性或者碱性条件都能够使氨氮解析量增加;温度越高,氨氮的解吸量越大且解吸初期的速度越快,能够更快的达到解吸平衡状态;泥水比的增大虽会使上覆水的氨氮浓度升高,但单位底泥的氨氮的解析量会减小;粒径对解吸的影响是2个方面共同作用的结果。湘江底泥解吸氨氮的动力学实验结果表明,一级动力学模型和扩散方程不能很好的描述底泥对氨氮的解吸过程,Elovich方程能够较好的描述解吸过程。

The factors influencing ammonia nitrogen release and the desorption kinetics were studied on a laboratory scale with sediment sample taken from Xiangjiang River. The study found that desorption amount of ammonia nitrogen was the lowest when pH of the aqueous solution was neutral, while the desorption amount increased under acidic or alkaline condition; as the temperature rose, the amount of ammonia nitrogen increased too and desorption rate at the initial stage became higher, so that desorption attained to the equilibrium state faster. In addition, as the sediment-water ratio increased, so did the concentration of ammonia nitrogen in overlying water, however the amount of ammonia nitrogen released by unit sediment decreased; the effect of sediment grain size on desorption was also investigated. The relevant study of desorpfion kinetics showed that either the first-order kinetic model or the diffusion equation could hardly describe desorption process of ammonia nitrogen from sediment adequately. Rather, the Elovich equation was able to achieve higher degree of fitting.