Fe3O4@Zr-MOF的制备及其去除废水中氨氮的性能和机理分析

Preparation of Fe3O4@Zr-MOF and its performance and mechanism analysis of removing ammonia nitrogen from wastewater

为高效去除废水中的氨氮,采用水热法合成了四氧化三铁@锆基金属有机框架(Fe_(3)O_(4)@Zr-MOF)材料,采用SEM、XRD、BET等技术对其进行了表征,通过静态吸附试验探究了吸附材料投加量、氨氮初始浓度、pH值、反应时间对模拟废水中氨氮吸附效果的影响,并进行了吸附等温线及吸附动力学拟合,最后采用FTIR、XPS法对其吸附机理进行了分析。结果表明:在中性条件下Fe_(3)O_(4)@Zr-MOF投加量为1 g/L时,其对模拟废水中的氨氮具有较好的吸附效果,吸附过程在6 h基本达到平衡;当氨氮初始浓度为50 mg/L时,Fe_(3)O_(4)@Zr-MOF对氨氮的平衡吸附量为47.18 mg/g,去除率为94.41%;吸附等温线拟合结果表明Fe_(3)O_(4)@Zr-MOF吸附水体中氨氮符合Langmuir吸附模型(R^(2)=0.981),该吸附行为是发生在吸附剂表面的单分子层吸附;吸附动力学拟合结果表明伪二阶动力学曲线(R^(2)=0.993)对试验数据有更优的拟合效果,该吸附为典型的化学吸附;使用0.5 mol/L的HCl作为解吸剂进行解吸再生试验,5次循环后吸附量及解吸率分别仅下降了6.63%和4.85%,表明该复合材料有良好的重复使用性能;Fe_(3)O_(4)@Zr-MOF吸附氨氮的吸附机理为Fe—O—Fe、Zr—O—Zr通过配体交换作用形成了Fe—O—N、Zr—O—N,从而能够高效吸附水体中的氨氮。该研究可为吸附材料的开发与应用提供参考。

To efficiently remove ammonia nitrogen from wastewater,a hydrothermal method was used to synthesize ferroferric oxide@zirconium based metal organic framework(Fe_(3)O_(4)@Zr-MOF)material.The synthesized material was characterized using techniques such as SEM,XRD,BET,et al.The effects of adsorption material dosage,initial concentration of ammonia nitrogen,pH value and reaction time on the adsorption effect of ammonia nitrogen in simulated wastewater were investigated by the static adsorption test,and adsorption isotherms and adsorption kinetics was fitted.Finally,the adsorption mechanism was analyzed by FTIR and XPS.The results show that Fe_(3)O_(4)@Zr-MOF has a good adsorption effect on ammonia nitrogen in simulated wastewater when the dosage is 1 g/L under neutral conditions,and the adsorption process basically reaches equilibrium in 6 h.With initial concentration of ammonia nitrogen at 50 mg/L,the equilibrium adsorption capacity of Fe_(3)O_(4)@Zr-MOF for ammonia nitrogen is 47.18 mg/g,and the removal rate is 94.41%.The adsorption isotherm fitting results show that the adsorption of ammonia nitrogen in water by Fe_(3)O_(4)@Zr-MOF fits Langmuir adsorption model(R^(2)=0.981),and the adsorption behavior is a monolayer adsorption on the adsorbent surface.The adsorption kinetic fitting results show that the pseudo-second-order kinetic curve(R^(2)=0.993)has a better fitting effect on the test data,and this adsorption is a typical chemisorption.After using 0.5 mol/L HCl as a desorbent for regeneration experiment,the adsorption capacity and desorption rate only decreased by 6.63%and 4.85%after 5 cycles,indicating that the composite material has good reusability.The adsorption mechanism of Fe_(3)O_(4)@Zr-MOF for ammonia nitrogen is Fe—O—Fe,Zr—O—Zr through ligand exchange to form Fe—O—N,Zr—O—N,thus adsorbing ammonia nitrogen in water efficiently.The paper can provide a reference for the advancement and utilization of adsorbent materials.