石墨烯和超高交联树脂对苯和对二甲苯的动态吸附特性

Dynamic adsorption characteristics of benzene and p-xylene on graphene oxide and hypercross linked polymeric adsorbent

芳香烃对人类和环境健康有害,为高效吸附、回收芳香烃气体,选择氧化石墨烯(GO)为吸附剂,并与超高交联树脂(HPA)比较,研究苯和对二甲苯的动态吸附性能。结果表明:在2种吸附剂上,苯和对二甲苯的穿透时间都会随温度升高而降低,而吸附速率常数会随温度升高而增大;在相同条件下,苯和对二甲苯在GO的穿透吸附时间受温度的影响较小,但在HPA和GO 2种吸附剂上的吸附速率相近。当VOCs质量浓度相同时(15 mg/L),苯的动态吸附速率比对二甲苯高。值得注意的是,由于π-π作用力的存在,苯在GO上的单比表面积穿透吸附量比HPA高,而对二甲苯在HPA和GO上的单比表面积穿透吸附量相近。石墨烯是治理回收VOCs非常有潜力的吸附剂,尤其是小分子VOCs。

Aromatic hydrocarbons are harmful to humans and the environment.Dynamic adsorption is important for evaluating the performance of adsorbents when separating gas mixture and recovering VOCs.The adsorbent is a core role during the adsorption process.To adsorb and recover aromatic hydrocarbon gases efficiently,graphene oxide(GO)was selected as adsorbents in the present study,compared with hypercoss linked polymeric adsorbent(HPA).Being representative aromatics,benzene and p-xylene were chosen as adsorbates.Dynamic adsorption of benzene and p-xylene were conducted at an isothermal condition(308 K,318 K,and 328 K),and the breakthrough curves were obtained.The influence of column adsorption temperature,VOCs concentration,VOCs properties and adsorbent properties on dynamic adsorption performance were investigated.Firstly,the results show that the breakthrough time of benzene and p-xylene on the two adsorbents decreases with increasing temperature,but the dynamic adsorption rate constant increases with increasing temperature.And the increase of VOCs concentration can shorten the breakthrough time and increase the dynamic adsorption rate.Secondly,under the same condition,the dynamic adsorption rate constant of VOCs on HPA and GO are similar.But by comparing benzene and p-xylene,when the VOCs concentration id the same,the adsorption rate of benzene is higher than that of p-xylene,which may come from the plane structure of benzene and its smaller molecule.Thirdly,it is worthy to note that for benzene,the breakthrough adsorption capacity on GO is higher than that on HPA,while the breakthrough adsorption capacity of p-xylene shows a contrary phenomenon.Furthermore,due to the high thermal conductivity of GO,benzene is less affected by temperature during the adsorption process on GO,compared with HPA.While for p-xylene,which is a larger molecule,the thermal conductivity of GO is weakened during its adsorption.The negative influence by temperature is close to that of hypercross linked polymeric adsorbents.In conclusion,GO,with higher thermal conductivity,is a promising alternative adsorbent for VOCs removal,especially for small molecules.