不同温度条件下氨氮在砂土中的吸附实验研究

温度的变化能够改变水体的环境,引起周围环境中的离子吸附解吸作用的变化。不同于其他土壤,砂土的保水保肥能力更差,砂土地区一旦发生氨氮(NH₄⁺-N)污染,情况会更加严重和突出。为防治砂土地区N H₄⁺-N污染提供理论依据与技术支持,通过N H₄⁺-N的静态吸附试验,研究不同温度条件下N H₄⁺N在粗砂、中砂、细砂中的吸附转化特征,得到如下结论: 在试验设置的温度区间内,总的趋势是温度越低,砂土对N H₄⁺-N的吸附量越高,表明温度升高对N H₄⁺-N的吸附有抑制作用,这主要是因为吸附过程中会产生弱放热效应,进而降低渗滤介质对N H₄⁺N的平衡吸附量; 在25~30 ℃区间内存在硝化与反硝化作用的临界温度,当温度低于临界温度时,N H₄⁺-N吸附量的减少主要是由于发生了硝化反应,当温度高于临界温度时,N H₄⁺-N的吸附量减少主要是由于发生了反硝化反应。

Experimental study on the adsorption of ammonia nitrogen in sand under different temperature conditions

Temperature variation can change water environment, which causes the variation of adsorption and desorption of the ions in surroundings. The capability of preserve moisture and fertility in sand is worse than that in the other soil. Once the pollution of ammonium nitrogen (N H₄⁺-N) happens in sand, the problems will be more serious. To provide theory and technology for preventing the pollution of ammonium nitrogen (N H₄⁺-N) in sand, the authors studied the adsorption and transformation characteristics of ammonium nitrogen (N H₄⁺-N) in coarse sand, medium sand and fine sand under different temperature conditions, based on the static adsorption experiment. The results show that in the setup temperature range, the lower the temperature is, the higher the adsorption capacity of ammonium nitrogen (N H₄⁺-N) is, which indicates that the adsorption of ammonium nitrogen (N H₄⁺-N) is inhibited by high temperature. And it is the cause that low exotherm of adsorption process can reduce the capability of equilibrium adsorption for ammonium nitrogen (N H₄⁺-N). The transform temperature of nitrification and denitrification is between 25℃ and 30℃. When the temperature is lower than the transform temperature, the reduction of adsorption capability for ammonium nitrogen (N H₄⁺-N) is due to nitrification. And when the temperature is higher than the transform temperature, the reduction of adsorption capability for ammonium nitrogen (N H₄⁺-N) is due to denitrification.