不同生物炭对氮的吸附性能

为探究不同类型生物炭对氮的吸附性能,寻求最佳的氮素吸附材料,本文选择稻壳炭、山核桃壳炭和竹炭作为吸附剂,开展不同pH环境、反应时间、初始浓度及生物炭添加量条件下的吸附实验,研究生物炭对硝酸铵溶液中氮的最佳吸附条件,并对结果进行等温吸附拟合与吸附动力学研究。结果表明:3种生物炭对硝酸铵溶液中的氮均有一定的吸附效果,且pH环境、反应时间、初始浓度及生物炭添加量均影响生物炭对氮的吸附量。生物炭添加量为0.05 g时,在pH环境为9、吸附时间为3 h、初始浓度为100 mg·L-1的条件下,平衡吸附量达到最大,稻壳炭、山核桃壳炭和竹炭在此条件下的最大吸附量分别为23.79、13.00 mg·g~(-1)和17.60 mg·g~(-1),表明稻壳炭对氮的吸附效果最佳;Langmuir方程能更好地拟合3种生物炭对氮的等温吸附过程,表明生物炭对氮的吸附主要是单分子层吸附;准二级动力学模型能更好地描述3种生物炭吸附氮的动力学过程,表明生物炭对氮的吸附为化学吸附。综上说明,稻壳炭在最佳吸附条件下可吸附较多氮素,有望作为一种良好的吸附剂应用于土壤和水体氮素污染治理。

Study on the adsorption properties of nitrogen by different biochars

This paper explored the adsorption properties of nitrogen by different biochars and identified a suitable material to prevent nitrogen pollution. The project selected three kinds of nitrogen adsorbents:rice husk biochar, pecan shell biochar and bamboo biochar. Adsorption experiments, coupled with isothermal adsorption models and kinetic models, were applied to assess the optimum adsorption conditions of the selected biochar on nitrogen in ammonium nitrate solution. The results demonstrated that all three kinds of biochar had certain adsorption effects on nitrogen in ammonium nitrate solution, and that the adsorption capacity of biochar on nitrogen was affected by the pH of the environment, reaction time, initial concentration and biochar addition. For instance, while the amount of biochar was 0.05 g under experimental conditions of pH 9, adsorption time 3 h and initial concentration 100 mg·L^-1, the optimum nitrogen adsorption quantities of the three biochars were 23.79, 13.00 mg·g^-1, and 17.60 mg·g^-1, respectively. Moreover, the Langmuir equation best fit the process of isothermal adsorption of nitrogen by the three kinds of biochar, indicating that the adsorption of nitrogen by biochar was due mainly to monomolecular adsorption. Again, the pseudo-second-order kinetics model could better define the kinetics of the three kinds of biochar adsorption nitrogen, was suggesting that the biochar adsorption of nitrogen was chemical in nature. The results showed, that rice husk biochar had a good nitrogen adsorption performance and could be used as a quality adsorbent to control nitrogen pollution in soil and water.