蒙脱石/氧化石墨烯对Cr(Ⅵ)的吸附

Adsorption of Cr(Ⅵ)on Montmorillonite/Graphene Oxide

为开发水中重金属去除的新型吸附剂,以蒙脱石(Mt)、氧化石墨烯(GO)和苄基二甲基十八烷基氯化铵水合物(BCH)为原料,通过溶胶-凝胶法和真空过滤法制备蒙脱石/氧化石墨烯复合材料(MGB),并将其用于水中Cr(Ⅵ)的去除。采用分批实验探究了MGB投加量、溶液初始pH、吸附时间和重金属初始浓度等因素对吸附性能的影响,并用扫描电镜(SEM)、零电荷点(pH_(pzc))、能量色散光谱(EDS)、X射线衍射(XRD)和傅里叶红外光谱(FTIR)对MGB进行表征。结果表明:MGB具有较好的疏水性和较大的层间距;pH对吸附效果有很大的影响,pH=2.0时,MGB对Cr(Ⅵ)的去除效果最好;吸附动力学和等温吸附表明,MGB吸附Cr(Ⅵ)属于多分子层吸附,以离子交换、螯合作用以及氧化还原等化学吸附为主;MGB对Cr(Ⅵ)的理论最大吸附量可达107.56 mg/g,循环利用5次后,依旧有很好的吸附效果。

In order to develop new adsorbent for heavy metal removal from water,montmorillonite/graphene oxide composites(MGB)were prepared by sol-gel method and vacuum filtration method using montmorillonite(Mt),graphene oxide(GO)and benzyl two methyl eighteen alkyl ammonium chloride hydrate(BCH)as raw materials and used for the removal of Cr(Ⅵ)in water.The MGB was characterized by scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR).The results showed that MGB has better hydrophobicity and larger interlayer spacing;pH has a great influence on the adsorption behavior of Cr(Ⅵ)on MGB,and the removal efficiency of Cr(Ⅵ)is best at pH=2.0.The results of kinetics and isothermal adsorption indicated that Cr(Ⅵ)was adsorbed on MGB by multi molecular layer,dominated by chemical adsorption such as ion exchange,chelation and oxidation-reduction;the theoretical maximum adsorption capacity of Cr(Ⅵ)on MGB reached 107.56 mg/g.Even after recycling 5 times,MGB still showed good adsorption capacity.