生物炭对稀土尾水中NH_(4)^(+)-N和NO_(3)^(-)-N的吸附特性

Adsorption Characteristics of Biochar for NH_(4)^(+)-N/NO_(3)^(-)-N in Rare Earth Tailwater

“双级渗滤耦合生物系统”是目前处理离子型稀土矿山尾水应用广泛、效果稳定、成本可控的处理工艺,滤料的筛选是工艺升级优化的重点。本研究以木屑、花生壳、稻壳生物炭作为吸附型滤料,研究生物炭对NH_(4)^(+)-N和NO_(3)^(-)-N的吸附特性及影响因素。实验结果表明,生物炭在500℃的热解温度下的吸附性能超过300℃,其中,500℃的稻壳生物炭(RBC500)对NH_(4)^(+)-N的吸附效果最佳,其平衡吸附量达到25.06 mg/g。同样,500℃的花生壳生物炭(PBC500)在NO_(3)^(-)-N的吸附上表现最优,其平衡吸附量为0.82 mg/g。动力学拟合表明RBC500对NH_(4)^(+)-N的吸附符合准二级动力学模型,对NO_(3)^(-)-N的吸附更符合准一级动力学模型,吸附等温线拟合表明RBC500对NH_(4)^(+)-N、NO_(3)^(-)-N的吸附更符合Langmuir模型,主要为单分子化学吸附。本研究使用的生物炭对NH_(4)^(+)-N和NO_(3)^(-)-N的吸附效果均优于常用滤料陶粒和沸石,可以作为渗滤耦合生物处理工艺吸附型滤料。

The“Two-stage Infiltration Coupled Biological System”is widely used tailwater treatment process to treat the tailwater of ion type rare earth mines,with stable treatment effect and controllable cost.The selection of filter materials is the focus of process upgrading and optimization.In this study,sawdust,peanut shell and rice husk biochar were used as adsorption filter materials to study the adsorption characteristics of biochar on NH_(4)^(+)-N and NO_(3)^(-)-N and the influencing factors.The experiment shows that the adsorption effect of biochar prepared at 500℃is better than that at 300℃.Among the raw materials,rice husk biochar(RBC500)has the best adsorption effect on NH_(4)^(+)-N,and the equilibrium adsorption amount is 25.06 mg/g.Peanut husk biochar(PBC500)has the best adsorption capacity for NO_(3)^(-)-N,with an equilibrium adsorption capacity of 0.82 mg/g.The adsorption of NH_(4)^(+)-N by RBC500 is in accordance with the quasi-second-order kinetic model,and the adsorption of NO_(3)^(-)-N is more in accordance with the quasi-first-order kinetic model.The adsorption of NH_(4)^(+)-N and NO_(3)^(-)-N by RBC500 is more in accordance with the Langmuir model,which is mainly single molecule chemical adsorption.The adsorption effect of the biochar used in this study on NH_(4)^(+)-N and NO_(3)^(-)-N is better than that of commonly used filter materials such as ceramsite and zeolite,and can be used as an adsorption type filter material for the coupled biological treatment process of infiltration.