双孔介孔碳的合成及其对亚甲基蓝的吸附

Synthesis of mesoporous carbon with dual-pore structure and their adsorption of methylene blue

以三嵌段共聚物F108为模板剂,苯酚/甲醛为碳源,在中性条件下制备了平均孔径为3.14 nm,最可几孔径分布为3 nm和8 nm,BET比表面积为1541 m2·g-1,孔容为1.01 cm3·g-1的双孔分布介孔碳.通过静态实验法测定了介孔碳对亚甲基蓝的吸附特性,分析了初始浓度、溶液p H、温度对吸附量的影响,并从热力学及动力学角度探讨了介孔碳对亚甲基蓝的吸附机理.结果表明,溶液初始浓度、溶液p H以及温度对吸附量有较大的影响,介孔碳对亚甲基蓝的吸附随着初始浓度、p H、温度的上升而增大,吸附为吸热反应,提高温度有利于吸附的进行.实验制备的介孔碳对亚甲基蓝的最大吸附量为421 mg·g-1,相比于普通活性炭,双孔分布介孔碳对亚甲基蓝显示了更优的吸附性能.亚甲基蓝在介孔碳上的吸附行为符合Langmuir吸附等温线和Elovich动力学模型.计算得到的吸附吉布斯自由能(ΔG0)<0,吸附标准焓变(ΔH0)>70 k J·mol-1,说明亚甲基蓝在介孔碳上的吸附是自发进行的单分子层吸热反应,且化学反应在吸附过程中发挥了重要作用.

Mesoporous carbon of diplopore distribution with the mean pore size of 3.14 nm, the most probable pore size distribution of 3 nm and 8 nm, BET surface area of 1541 m2·g^-1 , pore volume of 1.01 cm3·g^-1 was synthesized under neutral conditions by use of triblock copolymers F108 as template agent and phenol / formaldehyde as carbon source. The adsorption characteristic of methylene blue on the mesoporous carbon was investigated by conducting a series of batch adsorption experiments. The influence of solution pH, initial concentration and temperature was examined. The adsorption mechanism was investigated from kinetics and thermodynamic point of view. The results showed that the adsorption depended on the initial concentration, pH value and temperature. The adsorption amount increased with the increase of initial concentration, pH value, and temperature. The adsorption was an endothermic reaction, and high temperature was conducive to the adsorption. The maximum adsorption capacity of methylene blue on the mesoporous carbon was 421 mg·g^-1 . Compared to ordinary carbon, mesoporous carbon of diplopore distribution showed better adsorption performance for methylene blue. The adsorption behavior of methylene blue on mesoporous carbon conformed to the Langmuir isotherm and Elovich dynamics model. The Gibbs free energy of adsorption （ΔG0 ）〈0, adsorption standard enthalpy （ΔH0 ）〉70 kJ·mol^-1 , indicated that the adsorption was spontaneous endothermic reaction of single molecule layer, and the chemical reaction played an important role in the adsorption process.