磁性生物质炭对水体中芘的去除效果研究

以柳树枝为原料,于600℃制备原始生物质炭LZ,再通过化学沉淀法制备两种磁性强度不同的生物质炭LZ1.5和LZ2.5。利用静态氮吸附(BET-N2)、傅里叶红外光谱(FTIR)、扫描电镜(SEM)、X射线衍射(XRD)等分析手段对生物质炭的表面结构和化学组成等理化性质进行表征,并研究生物质炭对水体中芘的吸附行为。结果表明:原始生物质炭在24 h吸附即达到表观吸附平衡,磁性生物质炭在72 h吸附达到表观吸附平衡;LZ1.5的吸附效果最佳,其最大吸附容量Qm=2 758.6μg·g-1,其次是LZ2.5和LZ,Qm分别为833.3、322.6μg·g-1;LZ1.5投加量在375 mg·L~(-1)时,芘的去除率达到90%以上。三种生物质炭的吸附行为均符合Freundlich模型和Langmuir模型。磁性生物质炭对芘吸附较多的原因一方面在于其保留了原有的芳香性官能团,另一方面是Fe3O4的存在造成了磁性炭表面微孔化以及表面羟基化。

The removal effect of magnetic biochar on pyrene in aqueous phase

Biochar has been proved effectively in removing pollutants form aqueous phase. However,powdered biochar,was difficult to be separated from the aqueous solution. Introducing magnetic medium to biochar is an efficient method to separate sorbent effectively from aqueous phase by magnetic separating technique. In the present study,magnetic biochars(LZ1.5 and LZ2.5)were prepared by chemical co-precipitation of iron oxide on willow wood biochar(LZ)which was produced at 600 ℃. The surface structure,element composition and functional group of biochars were analyzed by the analysis methods of BET-N2 specific surface,fourier transform infrared spectroscopy (FTIR),scanning electron microscopy(SEM)and powder X-ray diffraction(XRD). The adsorption behavior of pyrene on biochars was stud-ied to verify the removal effect of magnetic biochar on organic pollutants in aqueous phase. Adsorption equilibrium of pyrene on pristine biochar(LZ)and magnetic biochars were obtained at 24 h and 72 h,respectively. Both the Langmuir and Freundlich equations fit the isothermal data well(P<0.05). LZ1.5 showed the best adsorption capacity,with the maximum adsorption capacity of 2 758.62μg·g-1,followed by LZ2.5(833.3μg·g-1)and LZ(322.6μg·g-1). 90%of pyrene was removed when LZ1.5 was added at the dose of 375 mg·L-1. The re-sults suggested that the magnetic biochar was a promising sorbent for removing organic pollutants from wastewater. The enhanced adsorption of pyrene was partly due to the original aromatic functional groups. Additionally,the increased micropore structure and the hydroxylation of the magnetic biochar surface by introducing Fe3O4 were also contributed to the adsorption.