基于有效去除铅(Ⅱ)的中孔炭乙二胺改性与影响因素分析

Ethylenediamine modification on mesoporous carbons and its influencing factors for removal of lead(Ⅱ)

通过硝酸氧化和乙二胺聚合成功在蔗渣基生物质中孔炭孔道内修饰多胺基团,以铅(Ⅱ)为探针,通过L9(34)正交实验探讨了硝酸浓度、氧化时间、乙二胺用量和反应时间等对多胺生物质炭吸附性能的影响,获得适宜的改性条件是硝酸浓度17.5%、氧化时间5 h、乙二胺用量125 m L、乙二胺改性时间48 h,根据正交实验数据分析了不同胺化条件下生物质炭对铅(Ⅱ)的吸附特性与机制。结果表明,乙二胺改性条件对生物质炭对铅(Ⅱ)吸附性能影响显著,不同条件下制备的胺化改性生物质炭铅(Ⅱ)吸附量相差35%;硝酸浓度对多胺生物质炭铅(Ⅱ)吸附性能的影响最大,高于乙二胺用量与改性时间,说明调节生物质炭孔道内羧酸基含量是调控胺化改性介孔炭的铅吸附性能的关键因素。胺化改性后生物质炭对铅(Ⅱ)的吸附行为更加符合Langmuir模型,表明改性后多胺生物质炭表面能量分布更加均衡,对铅(Ⅱ)的吸附更趋向于单分子层的均质吸附。

Polyamine groups were modified on the biomass-based carbon channels＇ surfaces by nitric acid oxidation followed by reaction with ethylenediamine,polyamine-modified biomass-based carbon composites with high efficiency for aqueous Pb（ Ⅱ） removal were prepared. A L9（34）（four three-level factors） orthogonal design table was established to discuss the experimental program and process conditions of mesoporous polyamine-modified carbon. The appropriate modified conditions were as follows： nitrate concentration of 17. 5%,oxidation time of 5 hours,ethylenediamine dosage at 175 m L and activation time of 48 hours. According to the results of orthogonal design,the influence of nitric acid concentration,oxidation time,ethylenediamine dosage and reaction time on the Pb（ Ⅱ） adsorption capacity of the polyamine-modified carbon was analyzed. The results showed that there are 35% differences in adsorption capacity of these polyamine-modified carbons. Compared with ethylenediamine dosage and reaction time,nitric acid concentration is the most important factor in preparation of ethylenediaminemodified mesoporous carbon for Pb（ Ⅱ） adsorption. This demonstrated that the adsorption properties of lead on ethylenediamine-modified mesoporous carbons could be more effectively regulated by adjusting the concentration of nitric acid. Lead（ Ⅱ） adsorption on ethylenediamine-modified carbon was well fitted by the Langmuir model,which suggested that the surface energy of the polyamine-modified carbon is more uniform. Lead（ Ⅱ） adsorption on ethylenediamine-modified carbon is more likely to homogeneous sub-layer adsorption.