针铁矿改性生物炭的制备及对Cr(Ⅵ)的吸附性能研究

PREPARATION OF GOETHITE-MODIFIED BIOCHAR AND ITS ADSORPTION CAPACITY ON Cr(Ⅵ)

在不同热解温度及原料配比条件下,采用水解共沉淀方法制备针铁矿改性生物炭材料(GMB),借助SEM-EDS、XRD、FTIR、XPS进行表征,并进行Cr(Ⅵ)吸附实验,探究吸附性能和机理。结果表明:1)经改性后生物炭表面生成了羟基氧化铁(FeOOH),吸附能力有大幅提升;2)热解温度为600℃,生物炭与Fe(NO_(3))_(3)·9H_(2)O的质量比为1∶12时制备的GMB600-12表现出最佳吸附性能,最大吸附容量为20.67 mg/g;3)准二级动力学揭示Cr(Ⅵ)的吸附以化学吸附为主,Langmuir和Freundlich模型都能很好地描述GMB对Cr(Ⅵ)的吸附特征;4)XPS的结果进一步表明GMB去除水溶液中Cr(Ⅵ)是氧化还原和表面吸附协同作用的结果。

Goethite-modified biochar(GMB) was prepared by hydrolytic co-precipitation under different pyrolysis temperatures and raw material ratios,characterized by SEM-EDS,XRD,FTIR and XPS.Adsorption experiments of Cr(Ⅵ) for exploring the adsorption performance and mechanism were carried out.The results showed that:1) modification with goethite formed iron hydroxyl oxide(FeOOH) on the surface of biochar and greatly improved its adsorption capacity;2) the best adsorption capacity of 20.67 mg/g was performed by modified biochar GMB600-12 with pyrolysis temperature at 600 ℃ and mass ratio of biochar and Fe(NO_(3))_(3)·9 H_(2)O at 1∶12;3) the adsorption of Cr(Ⅵ) was mainly chemisorption as revealed by quasi-second-order kinetics,and both Langmuir model and Freundlich model could well describe the adsorption characteristics of Cr(Ⅵ) by GMB;4) the removal of Cr(Ⅵ) from aqueous solution by GMB is a synergistic effect of redox and surface adsorption.