Alternative technology for the recovery of butyl acetate with low concentration: high capacity adsorbent and high efficiency adsorption

Industrial pharmaceutical wastewater usually contains butyl acetate (BA) with a concentration of 1 wt%–7 wt%, and the traditional method for BA recovery is distillation with high energy consumption. Adsorption method is developed to recover BA with low concentration for the high efficiency and low energy consumption. Medium polar polyacrylate resins with macroporous structure of 233.1 nm and average particle size of about 526.5 μm are successfully synthesized by suspension polymerization and used for the BA adsorption and desorption. The maximum adsorption capacity reaches 171.1 mg g⁻¹ with relative standard deviation (RSD) value of 0.2%, which is more than twice the results in the literature. The BA desorption rate is 97.0% at 100 °C with RSD value of 0.4%, and the resins are beneficial to the reuse in the adsorption-desorption cycle. The adsorption thermodynamics and kinetics are investigated, and the BA adsorption is a spontaneous and endothermic process with the increase of disorder degree. This process is mainly contributed by physical absorption and agree well with Freundlich model and pseudo-first-order adsorption kinetic model. The adsorption method avoids boiling a large amount of wastewater and hopefully provides a novel alternative technology for the BA recovery.