不同含水量活性炭的丙酮动态吸附性能研究

为深入研究活性炭的含水量对其吸附丙酮/空气混合气(VLA)中丙酮气体的影响,通过制备不同含水量的活性炭,分析含水量对活性炭丙酮吸附性能的影响。结果显示,丙酮在活性炭上的吸附穿透时间和吸附饱和时间随其含水量的增加而缩短,床层利用率下降。通过Thomas模型拟合结果发现,水分低于20%时,吸附曲线与模型吻合程度较高,平衡吸附量(q0-T)随着活性炭含水量的增加而下降; 丙酮吸附速率则随着含水量的增加先增加后下降,当含水量达到20%后,活性炭的丙酮吸附速率达到最大值0.698 L/(min？mmol),表明活性炭含有一定水量有助于提升其丙酮回收效率。通过分析活性炭含水量和孔容的关系,发现丙酮主要以简单的形式吸附,即与单分子层吸附机理类似。当湿炭含水量较高时,丙酮除了单分子层吸附,还伴有溶解于水中的现象。
Acetone is used extensively as a solvent in the industrial production process. In order to prevent environmental pollution and reduce the cost, the volatile acetone usually is adsorbed and recovered by porous adsorbents such as activated carbon. It is essential to steam-treat the used activated carbon before the next round of adsorption. After the acetone adsorption bed was desorbed by steam, the bed of activated carbon would contain a certain amount of water. It is generally accepted that the competitive adsorption of water and acetone on activated carbon would lead to a decrease in adsorption capability of acetone. The present study mainly analyzed the influence of the water content on the acetone adsorption of activated carbon through preparing the activated carbon with different water contents. The results showed that breakthrough time and saturation time of activated carbon decreased with the increase of water content, and the utilization ratio of the adsorption bed also decreased. According to the fitting results, the adsorption curve coincided with the Thomas model well when the water content was lower than 20%. Meanwhile, the equilibrium adsorption amount(q0-T)decreased with the increase of the water content of the activated carbon. In contrast, the adsorption rate of acetone firstly increased and then decreased with the increase of water content. The adsorption rate reached the maximum of 0.698 L/(min？mmol)while the water content was 20% in the activated carbon. Thus, a certain amount of water in the activated carbon could contribute to enhancing the recovery efficiency of acetone. Through in-depth analysis on the relationship between the water content and pore volume of activated carbon, it was found that the adsorption was simple in form and compatible physically with the mechanism of monolayer adsorption. When the water content of activated carbon was higher, acetone not only was adsorbed in the monolayer form, but also accompanied by the phenomenon of dissolving in water