炭化核桃壳对废水中Cr(Ⅵ)的吸附

Absorption of Cr(Ⅵ)from wastewater on carbonized walnut shell

制备了炭化核桃壳,采用SEM,EDX,FTIR等方法对炭化核桃壳进行了表征,研究了炭化核桃壳对废水中Cr(Ⅵ)的吸附效果。表征结果显示,炭化后的核桃壳为片状结构,且形成了大量的微孔,微孔数量的增加使得核桃壳的比表面积明显增大。实验结果表明,炭化核桃壳吸附处理含Cr(Ⅵ)废水的最佳工艺条件为:初始废水pH 2.0、炭化核桃壳加入量16 g/L、吸附温度25℃、转速150 r/min、吸附时间180 min,在此最佳工艺条件下吸附处理Cr(Ⅵ)质量浓度为20 mg/L废水,Cr(Ⅵ)去除率高达98.7%,最大吸附量为8.731 mg/g。Langmuir吸附等温模型可更好地描述炭化核桃壳对Cr(Ⅵ)的吸附过程,吸附属于单分子层吸附。拟二级动力学方程能更好地描述炭化核桃壳对Cr(Ⅵ)的吸附行为,此吸附过程以化学吸附为主控步骤。

The carbonized walnut shells was prepared and characterized by SEM, EDX and FTIR methods. The effect of carbonized walnut shells on adsorption of Cr （Ⅵ） from wastewater was studied. The characterization results show that the carbonized walnut shell has a flake structure with a large number of micro pores, which increase the specific surface area of carbonized walnut shell significantly. The experimental results show that the optimum process conditions for treatment of Cr （Ⅵ） -containing wastewater on carbonized walnut shells are as follows： initial wastewater pH 2.0, carbonized walnut shells dosage 16 g/L, adsorption temperature 25 ℃, rotating speed 150 r/min and adsorption time 180 min. When the wastewater with 20 mg/L of Cr （Ⅵ）mass concentration is treated under these conditions, the Cr （Ⅵ）removal rate is up to 98.7%, and the maximum adsorption capacity is 8.731 mg/g. The adsorption process can be well described by the Langmuir model, which indicates that the adsorption is monolayer adsorption. Moreover, the adsorption behaVior of carbonized walnut shell to Cr （Ⅵ） fits the pseudo-second-order kinetic equation well, which shows that chemical adsorption is the control step.