烟末生物质对Pb(Ⅱ)的吸附性能研究

Adsorption Performance of Pb(Ⅱ) by Tobacco Scrap Biomass

为促进烟草废弃物——烟末的资源化,将其制备成吸附剂材料,用于吸附废水中的Pb(Ⅱ)。研究了pH值、烟末投加量、Pb(Ⅱ)初始浓度、反应时间、反应温度对吸附的影响。结果表明:p H值在很大程度上影响烟末去除Pb(Ⅱ)的效果,pH=6时去除效果最佳;随着烟末投加量的增加,其对Pb(Ⅱ)的吸附量逐渐减少;Pb(Ⅱ)初始浓度增大,其去除率降低;去除率与温度成正比关系;在100 min左右吸附达到平衡。通过等温吸附模型和动力学方程对数据的拟合,吸附过程符合Langmuir等温吸附模型(R2≈0.997)和准二级动力学模型(R2≈0.999),说明吸附反应为单分子层化学吸附,并且在Langmuir等温吸附模型下计算出的饱和吸附量为11.27 mg/g。扫描电镜(SEM)及能谱分析(EDS)显示烟末表面有利于Pb(Ⅱ)的附着,同时烟末表面的离子与Pb(Ⅱ)发生离子交换反应。红外光谱(FTIR)证明起主要吸附作用的基团为羟基、羧基等活性基团,这些基团与Pb(Ⅱ)发生配位反应。

In order to promote the recycling of tobacco waste-tobacco,it was prepared as an adsorbent material to adsorb Pb( Ⅱ) in solution.The effects of p H value,amount of tobacco dust addition,initial concentration of Pb( Ⅱ),reaction time and reaction temperature on adsorption were studied. Results showed that the effect of removing Pb( Ⅱ) from tobacco scrap was greatly affected by p H value,and the removing result was the best when p H value was 6. The adsorption capacity decreased gradually with the increase of dosage. The removal rate decreased with the increase of initial Pb( Ⅱ) concentration. The removal rate was proportional to temperature. The adsorption reached equilibrium at about 100 min. According to the data fitting of isothermal adsorption model and kinetic equation,the adsorption process conformed to Langmuir isothermal adsorption model( R2≈0.997) and quasi-second-order kinetic model( R2≈0.999),indicating that the adsorption reaction was single-molecular layer chemical adsorption,and the saturated adsorption capacity calculated by Langmuir isothermal adsorption model was 11. 27 mg/g. Scanning electron microscope( SEM) and energy spectrum analysis( EDS) showed that the tobacco scrap end surface was beneficial to the adhesion of Pb( Ⅱ),which could improve the adsorption performance,and the ions on the smoke end surface would have ion exchange reaction with Pb( Ⅱ). Infrared spectroscopy( FTIR) proved that hydroxyl,carboxyl and other active groups coordinated with Pb( Ⅱ).