选择新型强碱性阴离子交换树脂Amberlite IRA 402和Amberlite IRA 900,与201×7(717)树脂对比,进行吸附去除水中硝氮的实验研究。通过拟合3种树脂的控速步骤和动力学模型,研究吸附过程的动力学行为,并考虑了不同初始浓度的硝酸盐溶液、温度、溶解性有机质(DOM)、pH和转速等的影响。结果表明,IRA 402树脂对硝氮的吸附效果最好(吸附率99.3%),717次之(吸附率98.2%),IRA900稍弱(吸附率93%),但相差不大,且IRA402比较适合去除高浓度DOM废水的硝氮,没食子酸对硝氮去除的影响高于单宁酸。3种树脂吸附硝氮的过程主要受化学反应控制,并符合准二级动力学方程。温度的变化对3种树脂吸附硝氮的行为影响不是很大,可以选择在室温下(25℃)进行。在pH 7.0时,3种树脂吸附硝氮的效果最好,树脂吸附硝氮的转速可设置为200 r/min。
Ion exchange adsorption is the most effective and promising means of removing nitrate from water at low cost and high practicability. Anion exchange resins,in particular,are characterized by high chemical stability and near 100% removal efficiency. In this study,nitrate nitrogen adsorption experiments were carried out using three strong base anion-exchange resins( two new American products,Amberlite IRA 402 and Amberlite IRA 900,and a Chinese product,201 × 7( 717)) to investigate adsorption kinetics. The rate-determining step was identified and data was fitted to kinetic models. The effects of initial nitrate concentration,temperature,dissolved organic matter( DOM),p H and rotational speed on adsorption were studied to find the most effective resin and the optimal conditions for removing nitrate nitrogen from water. Adsorption kinetic experiments on the three resins were carried out at room temperature( 298K) and an initial KNO3 concentration of 10 mg / L. Solutions were sampled at selected times to monitor nitrate concentration during the adsorption experiments. The nitrate adsorption rate of each resin( IRA402,IRA 900 and 717) was initially high and then declined until equilibrium was established. IRA 402 resin reached equilibrium after 1 hour,with an adsorption efficiency of 99. 3% and an equilibrium absorption capacity for nitrate of 0. 2484 mg / g; 717 resin reached equilibrium after 1. 5 h,with an adsorption efficiency of 98. 2% and an equilibrium absorption capacity of 0. 2456 mg / g; IRA 900 reached equilibrium after 2 h with an adsorption efficiency of 93% and equilibrium absorption capacity of 0. 2326 mg / g. The adsorption kinetics of the three resins was well described by a pseudo-second-order model. The equilibrium absorption capacities of all three resins increased significantly with KNO3 concentration,up to 30 mg / L. The maximum saturation adsorption capacity of nitrate for IRA402,717 and IRA 900 were,respectively,0. 4934 mg / g,0. 4898 mg / g and 0. 4621 mg / g. Furthermore,I