表面活性剂改性活性炭对阳离子染料的吸附

以阴离子表面活性剂十二烷基硫酸钠(SDS)为改性剂对粉末活性炭(AC)改性,研究了SDS在活性炭表面的吸附稳定性,用比表面积测定仪、Zeta电位测定仪对改性前后活性炭进行表征,并将其用于吸附模拟废水中的阳离子染料。结果表明,改性剂SDS浓度等于临界胶束浓度时,改性后活性炭(SDS-AC)对SDS吸附稳定,SDS在纯水和染料溶液中的解吸率分别为19.4%和1.6%。pH对活性炭吸附阳离子橙染料影响较小,SDS-AC和AC对染料的吸附平衡时间分别为4 h和12 h,SDS-AC和AC对阳离子橙染料的吸附动力学模型符合拟二级反应模型,吸附等温线更符合Langmuir吸附等温方程,SDS-AC对阳离子橙染料的最大吸附量较AC提高47.8%,SDS-AC对阳离子橙染料的吸附机制为物理吸附和化学吸附共同作用下的单分子层吸附,其中化学吸附是主要控速步骤。

Adsorption of cationic dye by surfactant-modified activated carbon

Powdered activated carbon (AC) was modified by an anionic surfactant, sodium dodecyl sulfate (SDS), which was evaluated for its stability of adsorption on the surface of AC. Characterizations of AC before and after the modification were made using specific surface area and zeta potential analyzers. The SDS modified AC (SDS-AC) was applied in the adsorption of cationic dye in the synthetic wastewater. The results showed that the SDS adsorption on the AC was stable when the SDS concentration equaled to critical micelle concentration (CMC). Desorption of SDS from the modified AC in the pure water and dye solution were 19.4% and 1.6%, respectively. The pH of solution had a minor effect on the dye adsorption, which reached equilibrium within 4 h and 12 h for the SDS-AC and AC, respectively. The adsorption kinetics of SDS-AC and AC followed pseudo-second-order kinetic model. The adsorption isotherms may be described by Langmuir equation. Compared to the AC, the maximum adsorption capacity of cationic orange dye on the SDS-AC increased 47.8%. The mechanism of cationic dye adsorption on the SDS-AC was monomolecular layer adsorption, jointly acted by physical and chemical adsorptions, in which the chemical adsorption was the major rate limiting step.