柚子皮生物活性炭的改性及对异戊二烯的吸附性能研究

Modification of Activated Carbon from Pomelo Peel and Its Adsorption Properties of Isoprene

柚子Citrus maxima在我国广受欢迎,柚子皮所具有的海绵状多孔结构,使其具有很强的吸附作用。本文拟采用柚子皮制备生物活性炭-VOCs固气型复合体,并进行苯系污染物降解性能研究。对柚子皮进行炭化后,经过碱溶液活化,分别以NaNO_(2)、KMnO_(4)、(NH_(4))_(2)S_(2)O_(8)氧化改性处理得到改性柚皮活性炭。选用不同氧化改性柚皮活性炭吸附回收VOCs中的异戊二烯以促进苯系污染物降解。实验得出,NaNO_(2)、KMnO_(4)、(NH_(4))_(2)S_(2)O_(8)改性的柚皮活性炭对异戊二烯的吸收过程均遵循准二级动力学,说明反应速率与反应物浓度的二次方成正比;吸附热力学实验发现其显著符合Langmuir模型,与Freundlich拟合较差,1/n不具备参考价值。符合Langmuir说明其吸附为单分子层吸附,且吸附位点能量均统一。其中(NH_(4))_(2)S_(2)O_(8)改性的柚皮生物活性炭对异戊二烯的吸附量在25℃时为3.93mg∙g^(-1),吸附性能最好。

Pomelo(Citrus maxima)peel was used to prepare activated carbon.Modified activated carbon was resulted by alkaline solution and by treat-ments with NaNO_(2),KMnO_(4) and (NH_(4))_(2)S_(2)O_(8).Experiment was carried out on different modified pomelo peel biochar to adsorb and recover isoprene from VOCs for the degradation of benzene pollutants.The results showed that the absorption process of isoprene by NaNO_(2),KMnO_(4) and (NH_(4))_(2)S_(2)O_(8) modified pomelo peel biochar followed a pseudo-second-order kinetics,indicating that the reaction rate was proportional to the square of reactant con-centration.Thermodynamic experiments revealed significant conformity to the Langmuir model,while poor fitting with the Freundlich model,suggest-ing negligible reference value of 1/n parameter.The result indicated monolayer adsorption and uniform adsorption site energies.Among them,(NH_(4))_(2)S_(2)O_(8)modified pomelo peel biochar had the highest adsorption capacity for isoprene at 25℃,with a value of 3.93 mg/g.