改性花生壳吸附亚甲基蓝动力学与机理研究

Adsorption Kinetics and Mechanism of Modified Peanut Hull for Removal of Methylene Blue

吸附法是去除水中有机污染物的一种重要方式。以农业废弃物花生壳为原料,通过稀酸改性制备对亚甲基蓝吸附性能良好的生物质基吸附材料。FT-IR分析表明改性花生壳表面含有羟基、羧基等有利于吸附的官能团,SEM和孔结构分析结果显示稀硫酸改性花生壳表面形成大量孔结构。亚甲基蓝浓度为100 mg/L时,改性花生壳的去除效率为91.5%。亚甲基蓝吸附过程符合准二级动力学,热力学数据符合Langmuir和Redlich-Peterson模型,表明改性花生壳对亚甲基蓝是化学吸附为主的单分子层吸附过程,氢键、范德华力和电子作用是吸附的主要机理。Langmuir拟合可知稀硫酸改性花生壳对亚甲基蓝的最大吸附量为174.9 mg/g。这种价廉、高效的生物质基吸附材料为低成本、环境友好地利用废弃生物质资源提供了理论依据。

Adsorption is an important pathway for removal of organic pollutant from water.The present study aimed at the removal of methylene blue(MB)using peanut hull modified by sulphuric acid treatment.FT-IR showed that there are plenty of hydroxyl and carboxyl groups,as well as other functional groups,conducive to adsorption.Scanning electron microscope(SEM)results showed that a rough surface with pore structure was presented on the modified peanut hull surface,which was confirmed by specific surface area analysis.The removal efficiency was 91.5%under the MB initial concentration of 100 mg/L.For H_(2)SO_(4) modified sorbents tested,pseudo-second-order model was more suitable for fitting adsorption,and MB adsorption followed both Langmuir and Redlich-Peterson model.The MB removal was a monolayer adsorption process dominated by chemisorption,which was also a spontaneous and endothermic process.Adsorption mechanisms involve hydrogen bonds,electrostatic,and Van der Waals force.The maximum absorption capacity is 174.9 mg/g by Langmuir model.The results suggest that the modified agricultural waste is an environmentally friendly and low-cost bio-sorbent for effective removal of MB from aqueous solutions.