膨胀石墨负载纳米铁的制备及其对水中Cr(Ⅵ)及染料的去除

Synthesis of nanoscale iron supported on expanded graphite for removal of chromium(Ⅵ)and dyes from water

为有效去除印花废水中的染料和花筒剥铬时形成的Cr(Ⅵ),合成了纳米零价铁(GS-NZVI)和膨胀石墨负载纳米零价铁(GS-EG-NZVI)2种新型吸附剂。借助场发射扫描电子显微镜、能谱仪、X射线衍射仪等对二者进行表征。探讨了GS-EG-NZVI对水中的Cr(Ⅵ)和染料去除效果以及动力学和稳定性。结果表明:纳米级零价铁成功负载到膨胀石墨(EG)表面,且分散性较好;对于含有50 mg/L汽巴克隆藏青染料和20 mg/L Cr(Ⅵ)的溶液,加入2.5 g/L GS-EG-NZVI,在温度为50℃,pH值为2,超声波辅助的条件下反应35 min,染液脱色率为90.6%,Cr(Ⅵ)去除率为53.6%;GS-EG-NZVI对二者的去除符合伪二级动力学方程;将吸附剂置于空气中不同时间,GS-EG-NZVI对Cr(Ⅵ)的去除活性明显高于GS-NZVI,GS-EG-NZVI较GS-NZVI有更高的稳定性。

For dyes and Cr(VI)stripped from metallic roller in the printing process,two new adsorbents,nanoscale zero-valent iron(GS-NZVI)and nanoscalezero-valent iron supported on expanded graphite(GS-EG-NZVI)were green-synthesized.The two adsorbents were characterized by field emission electron microscopy,energy dispersive spectrometer,X-ray diffraction,etc.GS-EG-NZVI was investigated on the removal of Cr(VI)and dyes of aqueous solution,and on the corresponding dynamics and stability.Results indicated that nanoscalezero-valent iron was successfully loaded on the surface of EG with good dispersion.For the aqueous solution including 50 mg/L Cibacron Dark Blue and 20 mg/L Cr(Ⅵ),addition of 2.5 g/L GS-EG-NZVI led to the achievements of the removal rates of 90.6%of dyes and 53.6%of Cr(VI)respectively under the conditions of at 50℃,pH=2,35 min reaction time with ultrasound assistance.The two removal processes fitted well with the pseudo second-order dynamic model.GS-EG-NZVI showed higher potential for removing Cr(Ⅵ)in aqueous solution than GS-NZVI due to its high stability after being placed in the air for different time.