Study on the Thermodynamics and Kinetics of Ammonia Nitrogen Adsorption by the Sediments of Plain River Network under Moving Water Conditions

Under the oscillation of a constant-temperature oscillator in the water area,experiments were carried out on the thermodynamics of nitrogen adsorption by sediments of the Taihu River network at 113 rpm,119 rpm,128 rpm,and 139 rpm and the kinetics of nitrogen adsorption. The results showed that the maximum adsorption capacity of NH₄⁺-N at S1 sampling point was 15. 136 mg/kg,29. 132 mg/kg,30. 896 mg/kg,88. 83 mg/kg. The maximum adsorption capacity of NH₄⁺-N at S2 sampling point was 17. 474 mg/kg,32. 396 mg/kg,32. 908 mg/kg,55. 364 mg/kg,which fits Langmuir model. At the same time,under the disturbance of different rotation speeds,the adsorption kinetics of NH₄⁺-N in the sediments of the Taihu river network has a similar trend that the adsorption rate was the fastest in the first 5 minutes of the adsorption reaction,and the adsorption was slow and gradually became saturated from the 5 th minute to the 120 th minute. After 120 minutes,the adsorption reaction basically reached saturation,which conformed to the parabolic diffusion model. Moreover,the sediments in Nanxi had stronger NH₄⁺-N adsorption capacity than the sediments in Caoqiao River.