氨基修饰磁性蒙脱土对水中As(Ⅴ)的吸附特性研究

Adsorption characteristics of amino modified magnetic montmorillonite for As(Ⅴ)in water

为解决粉末蒙脱土使用后难以泥水分离以及材料吸附能力较差等问题,通过共沉淀法制备Fe_(3)O_(4)@蒙脱土复合材料,并通过氨基修饰磁性蒙脱土(N-Fe_(3)O_(4)@MT),研究了初始pH、投加量、共存离子、吸附时间和温度等因素对N-Fe_(3)O_(4)@MT去除As(Ⅴ)的影响,探讨吸附动力学和吸附等温线特征。通过元素分析、扫描电镜(SEM)、傅里叶红外光谱(FTIR)、X射线衍射(XRD)和X射线光电子能谱(XPS)分析As(Ⅴ)吸附去除的机理。结果表明,N-Fe_(3)O_(4)@MT在pH=3.0、固液比为0.6 g/L和吸附时间240 min的适宜条件下,在温度30℃时对As(Ⅴ)的最大吸附量为59.93 mg/g。拟二级动力学模型和Langmuir吸附等温模型能更好地描述N-Fe_(3)O_(4)@MT对As(Ⅴ)的吸附行为。As(Ⅴ)吸附去除机理主要包括静电作用和络合作用。通过5次吸附-解吸试验后,N-Fe_(3)O_(4)@MT对As(Ⅴ)去除率均在85%以上,表明N-Fe_(3)O_(4)@MT能实现较好的固液分离,且具备高效的重复利用率,这为修复酸性含As(Ⅴ)废水污染提供了一种高效、环保和经济的吸附材料。

It is difficult to separate mud and water after use of powdered montmorillonite and poor adsorption capacity.In order to solve these problems,this paper prepared Fe_(3)O_(4)@montmorillonite composite material by co-precipitation method,and modified magnetic montmorillonite(N-Fe_(3)O_(4)@MT)by amino group.The effects of initial pH,dosage,coexisting ions,adsorption time and temperature on the removal of As(Ⅴ)by N-Fe_(3)O_(4)@MT were studied,and the adsorption kinetics and adsorption isotherm characteristics were discussed.Elemental analysis,Scanning Electron Microscopy(SEM),Fourier Infrared Spectroscopy(FTIR),X-ray Diffraction(XRD)and X-ray Photoelectron Spectroscopy(XPS)were used to analyze the mechanism of As(Ⅴ)adsorption and removal.The result shows that N-Fe_(3)O_(4)@MT can adsorb 59.93 mg/g of As(Ⅴ)at a temperature of 30℃under suitable conditions of pH=3.0,solid-liquid ratio of 0.6 g/L and adsorption time of 240 min.The pseudo-second-order kinetic model and Langmuir adsorption isotherm model can better describe the adsorption behavior of N-Fe_(3)O_(4)@MT to As(Ⅴ).As(Ⅴ)adsorption mechanism mainly includes electrostatic interaction and complexation.After 5 times of adsorption-desorption tests,the removal rate of As(Ⅴ)by N-Fe_(3)O_(4)@MT is above 85%,which shows that N-Fe_(3)O_(4)@MT can achieve better solid-liquid separation and has an efficient recycling rate.The result can provide an efficient,environmentally friendly and economical adsorption material for repairing the pollution of acidic As(Ⅴ)-containing wastewater.