新型胺化介孔炭的制备及其对Pb(II)的吸附

采用微波辅助磷酸活化制备了高中孔率蔗渣基介孔炭,并通过硝酸氧化和乙二胺聚合在其孔道内修饰了含氮多胺基团,探索了溶液浓度、温度、吸附剂剂量等对改性介孔炭的Pb(II)吸附性能、行为和热力学特性的影响.结果表明,蔗渣基介孔炭较宽的孔道结构可通过乙二胺缩水聚合反应在其表面接枝酰胺、仲胺等含氮基团;胺化改性增强化了介孔炭对水溶液中Pb(II)的固定作用,改性后介孔炭对Pb(II)的吸附量高达180mg/g,是改性前介孔炭的1.5倍;改性介孔炭对Pb(II)的去除率显著增加,对溶液浓度<60mg/L的Pb(II)去除率接近100%.等温吸附与热力学数据表明,胺化改性介孔炭对Pb(II)的吸附位能量存在差异化,吸附是自发的吸热反应过程,温度对铅(II)离子吸附有促进作用,化学作用在吸附过程中发挥了重要作用.

Preparation of amine-modified mesoporous activated carbon and its adsorption of lead (II) from aqueous solution

Biomass-based mesoporous carbons were prepared from bagasse by microwave assisted H3PO4 activation. Polyamine groups were modified on the prepared carbon channels’ surfaces by nitric acid oxidation followed by reaction with ethylenediamine. The influence of initial concentration, temperature, carbon dose on the adsorption capacity, characteristic and thermodynamics of Pb (II) on the modified mesoporous carbon was investigated. The results showed that nitrogen-containing groups such as amido and imido group were successfully grafted on the surface of mesoporous carbon. The introduction of nitrogen-containing polyamine groups greatly enhanced the separation of Pb (II) from aqueous solution. The Langmuir Pb (II) adsorption capacity on the polyamine-modified carbon reached nearly 180mg/g, which was 1.5times of that on the untreated mesoporous carbon. The removal rate of Pb (II) from aqueous solution was significantly improved on the polyamine-modified carbon. Almost 100% of Pb (II) was adsorbed on the modified carbon with Pb (II) initial concentration less than 60mg/L. The adsorption amount of Pb (II) was increased with increasing temperature. The adsorption behavior and thermodynamic data suggested that the polyamine-modified material had a heterogeneous surface energy distribution, the adsorption was a spontaneous endothermic process, and chemical reaction could be involved and play an important role.