化学改性强化活性炭纤维吸附重金属离子

Enhancement of heavy metals adsorption on activated carbon fibers by chemically modification

为提高活性炭纤维(ACF)对水中重金属离子的吸附性能,采用两种不同改性方法对ACF进行改性处理,比较其对水中Pb(II)、Cu(II)和Co(II)的竞争吸附效能,并对改性前后ACF表面的物理化学特征变化进行分析.结果表明:改性ACF均具有较大的比表面积和孔容积;HNO3及Fe改性后ACF结晶程度较未改性ACF有所降低,且Fe改性ACF具有明显的Fe衍射峰.ACF对重金属离子吸附速率较快,60 min吸附基本达到平衡,HNO3及Fe改性ACF的吸附平衡时间有所增加.初始p H变化直接影响ACF对Pb(II)、Cu(II)和Co(II)的去除效果.3种ACF对重金属离子的亲和力顺序均为Pb(II)>Cu(II)>Co(II),随着平衡质量浓度的增加,其对Pb(II)和Cu(II)的吸附量增大,而对Co(II)的吸附量呈先增加再下降趋势.Langmuir和Freundlich模型均能较好地描述竞争吸附中Pb(II)和Cu(II)离子的吸附过程,但不能有效模拟Co(II)离子的吸附过程.

To enhance the adsorption capacity of activated carbon fibers （ ACF） towards heavy metals, the surface modification of ACF was conducted and the physical and chemical characteristics were analyzed. Additionally, the competitive adsorption of Pb（ Ⅱ） , Cu（ Ⅱ） and Co（ Ⅱ） from liquid solution on the modified ACF were evaluated. It was found that both the modified and unmodified ACF had large specific surface areas and pore volumes. Compared with the unmodified ACF, the crystallinity of Fe and HNO3 modified ACF showed a trend of decrease, and the Fe modified ACF appeared on obvious Fe characteristic diffraction peak. The rate of heavy metal ions adsorption onto ACF were so fast that the adsorption equilibrium achieved at about 60 minutes, and the adsorption equilibrium time increased after the Fe and HNO3 modification. The removal of Pb （ Ⅱ）, Cu （ Ⅱ） and Co （ Ⅱ） were influenced significantly by the initial pH. The adsorption affinity to the three heavy metals was in the order of Pb〉Cu〉Co for all types of ACF. With the increase of initial concentration, the adsorption amount of Pb （ Ⅱ ） and Cu （ Ⅱ ） increased, while the adsorption amount of Co （ Ⅱ ） increased firstly and then decreased. The Langmuir and Freundlich models could well describe the competitive adsorption process of Pb （ Ⅱ ） and Cu （ Ⅱ ） , but not effectively simulate the adsorption process of Co （ Ⅱ） .