壳聚糖-纳米零价铁球去除水中二价镉的研究

Removing Cd(Ⅱ)from water by nanoscale zero-valent iron entrapped in chitosan beads

为了更好地利用纳米零价铁修复水体镉污染,以壳聚糖为载体,制备出壳聚糖-纳米零价铁球用以去除水中的镉(Cd(Ⅱ)).利用扫描电子显微镜和透射电子显微镜对壳聚糖-纳米零价铁球进行表征分析,通过对比与Cd(Ⅱ)溶液反应前后的样品的X线光电子能谱探讨壳聚糖-纳米零价铁球对Cd(Ⅱ)的去除机理,并进行批实验研究环境因素对去除效果的影响.研究结果表明:制备出的壳聚糖-纳米零价铁球为规则均一的黑色球体,粒径约为3.1 mm;所有壳聚糖-纳米零价铁球均具有多孔结构,平均孔径约为40.6μm,且纳米零价铁均匀分布在球内;壳聚糖-纳米零价铁球对Cd(Ⅱ)的去除机理包括物理吸附过程和化学还原过程,且化学还原过程起主要作用;批实验结果显示壳聚糖-纳米零价铁球对Cd(Ⅱ)的去除率随pH值、反应温度和纳米零价铁投加量的增加而增大,随Cd(Ⅱ)初始质量浓度的升高而减小.

Abstract： To better repair cadmium pollution in water using nanoscale zero-valent iron, the chitosan nanoscale zero-valent iron （CS-NZVI） beads were prepared on ehitosan to remove Cd（ Ⅱ） in the water. CS-NZVI beads is analyzed by scanning electron microscope （SEM） and transmission scanning electron microscope （TEM）, the removal mechanism of CS-NZVI beads to Cd（ Ⅱ） is discussed by comparing the X-ray photoelectron spectroscopy of the samples before and after reacting with CS-NZVI beads, and the influence of environmental factors to the effects of Cd（Ⅱ） removal rate is researched by batch experiments. The research results show as follows： CS-NZVI beads are black sphere and their sizes are uniform with a mean diameter of 3.1 ram; all CS-NZVI beads have porous structure and the pore sizes are heterogeneous with the average of 40.6 μm, the nanoscale zero-valent iron evenly distributed in the CS-NZVI beads; the Cd（ Ⅱ ） removal mechanism in- clude absorption and reductive process, in which reduction plays a main role; the removal rate of Cd（ Ⅱ） is increased with increasing pH value, reaction temperature and NZVI dosage but decreased with the increasing initial mass concentration of Cd（ Ⅱ）.