菠萝皮生物炭负载纳米零价铁去除水中的铬

Removal of Cr( Ⅵ) from Aqueous Solution Using Nanoscale Zerovalent Iron Supported on Biochar Made by Pineapple Peel

以菠萝皮制成的生物炭为载体负载纳米零价铁(n ZVI)合成功能性生物炭(n ZVI/BC),采用X射线衍射(XRD)、扫描电镜(SEM)和X射线光电子能谱(XPS)等方法对材料进行表征,考察了p H和初始Cr(Ⅵ)浓度对Cr(Ⅵ)的去除率的影响,并对其机理进行研究。结果表明:n ZVI/BC对Cr(Ⅵ)的去除效率在p H=3时达到峰值90. 3%,而在p H=9时去除效率最低。吸附动力学实验数据符合准二级动力学(PSO)模型;当Cr(Ⅵ)的初始浓度由10 mg/L增加到30 mg/L时,速率常数由0. 466 0 min-1减小到0. 237 1 min-1,说明反应速率随着溶液Cr(Ⅵ)初始浓度的增大而减小。SEM图像显示n ZVI与生物炭的表面结合良好。反应前后的XRD和XPS分析表明,在反应过程中,n ZVI和Cr(Ⅵ)发生吸附,还原和共沉淀。因此,菠萝皮生物炭负载n ZVI可作为水中Cr(Ⅵ)去除的有效复合材料。

Nanoscale zerovalent iron supported on biochar made by pineapple peel (nZVI/BC) was synthesized and its Cr (Ⅵ) removal capability was evaluated and compared with pure nZVI and raw biochar.The effects of pH and initial Cr (Ⅵ) concentration on the removal of Cr (Ⅵ) were investigated.The removal mechanism was studied.The Cr (Ⅵ) removal efficiency by nZVI/BC achieved 90.3% at pH=3 and the minimum removal efficiency was observed at pH=9.The adsorption kinetics data agreed well with the pseudo-second-order (PSO) model.When the initial concentration of Cr (Ⅵ) increased from 10 mg/L to 30 mg/L,the rate constant decreased from 0.466 0 to 0.237 1,indicating that the reaction rate decreased with the initial concentration of Cr (Ⅵ) increasing.SEM images revealed that nanoscale was well attached to the surface of the biochar.XRD and XPS analysis of before and after reaction proved that nZVI and Cr (Ⅵ) underwent adsorption,reduction and coprecipitation during the reaction.Therefore,Nanoscale zerovalent iron supported on biochar made by pineapple peel can be used as an effective composite material for Cr (Ⅵ) removal in water.