吸附-热再生法回收废水中醋酸的研究

Recovery of Acetic Acid from Wastewater by Adsorption and Heating Regeneration

针对浓度为3%的醋酸废水,选用YK-15椰壳炭为吸附剂,采用吸附和分步热再生法从废水中分离醋酸,达到了废水处理和醋酸回收的双重目的。系统地考察了动态吸附和分步热再生的工艺条件,结果表明,在温度为30℃,废水流速为7.3×10-5m·s-1的适宜条件下,YK-15椰壳炭对醋酸的动态吸附容量为161.0mg·g-1,穿透点处废水的处理能力为4.7g(废水)·g-1(活性炭)。对吸附剂进行分步热再生的适宜条件是,第一步控制温度为110～130℃,脱除吸附柱内35%～40%的残余水,以浓缩醋酸。第二步继续升温至320℃,脱附并回收醋酸,醋酸的脱附率可达96%以上,收率为87%,回收醋酸的浓度为30%左右。吸附–脱附的循环实验表明,活性炭的吸附和脱附性能稳定,数据重现性好。

The YK-15 cocoanut based active carbon was selected to be used as adsorbent for recovery of acetic acid from wastewater by adsorption and stepwise heating regeneration, through which, the two goals of wastewater treatment and acetic acid recovery were reached at once. The suitable conditions of the dynamic adsorption and heating regeneration for the recovery of acetic acid from wastewater by YK-15 active carbon were studied. It was found that for the wastewater with acetic acid of 3%（Wt）, the suitable adsorption temperature is 30℃and the wastewater flow rate is 7.3× 10^-5 m·s^-1, using them, the dynamic adsorption capacity of acetic acid is 161.0 mg·g^-1 YK-15 active carbon, and the treating capacity for wastewater at breakthrough point is about 4.7 g·g^-1 YK-15 active carbon. The feasible procedures for stepwise heating regeneration were found as follows. Firstly, the temperature was controlled at 110-130℃ to remove 35%-40% residual water in adsorbent bed and concentrate the adsorbed acetic acid at the same time. Then the temperature was elevated to 320℃ to desorb and recover acetic acid. The desorption ratio of acetic acid is above 96%, the yield of acetic acid is almost 87% and the concentration of recovered acetic acid is about 30%. Experiments of repeatedly reusing the used and regenerated adsorbent YK-15 to remove acetic acid from wastewater were conducted, and the results show that the capabilities of adsorption and desorption of YK-15 active carbon are stable.