造粒的氮掺杂碳纳米管基吸附剂对卤水中硼的吸附行为与机理

Adsorption Behavior and Mechanism of Nitrogen-doped Carbon Nanotube-based Adsorbents for Boron in Brine

盐湖卤水中硼资源丰富,存在形式复杂多样,分离和回收硼的意义重大。基于N掺杂强静电与多羟基协同作用能够有效提高硼阴离子的分离机制,设计以水合肼为N源,多羟基的一维纳米材料碳纳米管(CNTs)为多羟基络合基,采用简单的一锅水热法合成了N掺杂的碳纳米管硼吸附材料(N-CNTs)。此外,以改性的聚丙烯腈为造粒剂,经造粒后,最大硼吸附容量为20.45 mg/g,特别在低浓度硼的分离中表现出优异的性能,这使N-CNTs成为硼的高效吸附材料。吸附机理为一维碳纳米管和改性聚丙烯腈的高比表面积上多羟基与N掺杂位置发生强静电协同增强络合吸附。硼吸附过程符合朗格缪尔吸附等温模型和准二阶动力学模型,在高浓盐多离子溶液中表现出优异的选择性硼吸附性能。该吸附剂在东台吉乃尔盐湖卤水中硼的吸附容量达18.92±1 mg/g,该技术在盐湖卤水及水处理行业具有较高的应用潜力。

Boron of salt lake brine is rich in resources and exists with complex and diverse forms,so it is of great significance to separate and recover boron.N doping can effectively improve the separation mechanism of boron anions by the synergistic effect of strong electrostatic and polyhydroxy groups on the surface of the material.N-doped carbon nanotube boron adsorption materials(N-CNTs)were synthesized by a simple one-pot hydrothermal method using hydrazine hydrate as N source and one-dimensional carbon nanotubes(CNTs)as polyhydroxyl groups.In addition,using modified polyacrylonitrile as granulator.The maximum boron adsorption capacity is 20.45 mg/g,especially in the separation of low concentration boron,which makes N-CNTs the best adsorption material for boron.The adsorption mechanism is that polyhydroxyl groups and N-doped sites on the high specific surface area of one-dimensional carbon nanotubes and modified polyacrylonitrile are enhanced by strong electrostatic coordination adsorption.The process of boron adsorption accords with Langmuir adsorption isothermal model and Second-order kinetic model,which shows excellent selective boron adsorption performance in high concentration salt multi-ion solution.The adsorption capacity of boron in East Taigener salt lake brine is 18.92±1 mg/g.The simple technology has high application potential in salt lake brine and water treatment industry.