海泡石负载型纳米零价铁对水中Cu(II)、Zn(II)的去除研究

The removal of Cu(II) and Zn(II) from water using sepiolite-supported nanoscale zero-valent iron

针对日益突出的水体重金属污染问题,采用液相还原法制备海泡石负载纳米零价铁(S-nZVI),并研究其对Cu(II)、Zn(II)的去除效果.同时,利用比表面积与孔径分析(BET)、透射电子显微镜(TEM)、X射线衍射(XRD)对制备出的材料进行表征,研究pH、S-nZVI投加量、重金属离子溶液初始浓度对去除率的影响,拟合S-nZVI材料去除Cu(II)、Zn(II)的动力学模型和吸附等温模型,并对反应后的S-nZVI进行回收及再生.结果表明,液相还原法可以成功制备出S-nZVI,且颗粒分布均匀.在60 min左右,S-nZVI对Cu(II)、Zn(II)的去除达到平衡.Cu(II)、Zn(II)的去除率随着pH值的升高而升高.当Cu(II)、Zn(II)溶液初始浓度为20 mg·L^(-1)时,最佳S-nZVI投加量分别为0.030、0.050 g,此时去除率分别为98.98%、98.97%.当Cu(II)浓度为90 mg·L^(-1)时,S-nZVI材料对Cu(II)的去除量最大,为127.57 mg·g^(-1);对Zn(II)来说,当浓度为110 mg·L^(-1)时去除量最大,为109.13 mg·g^(-1).去除过程符合准二级动力学模型和Langmuir吸附等温模型.S-nZVI可通过外加磁场进行回收,5次再生处理后其对Cu(II)、Zn(II)的去除率仍维持在96.84%、80.25%.实验结果显示,S-nZVI在废水除Cu(II)、Zn(II)领域具有很好的应用前景.

With the increasingly severe problem of heavy metal contamination in water body, this paper studies the effect of removing Cu(II) and Zn(II) by applying sepiolite-supported nanoscale zero-valent iron(S-nZVI) that was prepared by liquid phase reduction method. The prepared materials were characterized by specific surface area and pore size analysis(BET), transmission electron microscopy(TEM) and X-ray diffraction(XRD). The impacting factors including pH values, S-nZVI dosage and initial concentration of heavy metal ion solution were studied. The kinetic model and adsorption isotherm model of S-nZVI for removing Cu(II) and Zn(II) were fitted, and the reacted S-nZVI was recovered and regenerated. The results showed that the liquid phase reduction method can successfully prepare S-nZVI with uniform particle distribution. The removal of Cu(II) and Zn(II) by S-nZVI reached to a balance at about 60 min.The removal rates of Cu(II) and Zn(II) increased with pH values. When the initial concentration of Cu(II) and Zn(II) solution was 20 mg·L-1, the optimal S-nZVI materials dosage were 0.030 g and 0.050 g, respectively, and the removal rates were 98.98% and 98.97%, respectively. When Cu(II) concentration was 90 mg·L-1, the removal capacity of Cu(II) by S-nZVI material was the highest, which was 127.57 mg·g-1. For Zn(II), when its concentration was 110 mg·L-1, the maximum removal capacity was 109.13 mg·g-1. The removal process conformed to the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. After the reaction was removed, S-nZVI can be recovered by applied magnetic field. The removal rate of Cu(II) and Zn(II) after 5 times of regeneration treatment maintained at 96.84% and 80.25%, respectively. The results show that S-nZVI has a good prospect to application in the removal of Cu(II) and Zn(II) for wastewater treatment.