Recovery of Butyl Acetate in Wastewater of Penicillin Plant by Solvent Sublation I. Experimental Study

Abstract

Recovery of butyl acetate (BA) in the wastewater from solvent extraction of penicillin by solvent sublation into n‐nonane is studied. Emulsification at water‐solvent interface in the sublation was discussed, and nonpolar n‐nonane was representatively used as the immiscible organic solvent to minimize the emulsification. Effects of operation variables, such as gas flow rate, Q a , and initial solvent volume, v oi , were explored. Gas flow rate, Q a , was an important operation parameter and initial volume of solvent, v oi , had a little effect on the sublation efficiency, E ss , which could be more than 65% under optimal operation conditions with semibatch sublation after about 180 min operation. Experimental results also showed the axial concentration of BA along the column height first increased and then decreased from bottom to top because of the mutual effect of diverse mass transports. With initial concentration of BA in the wastewater of about 1%, the volume of solvent, v o , could be increased by more than 30% at the end of the sublation. Qualified butyl acetate could be obtained through distillation and n‐nonane obtained could be recycled in the solvent sublation. Air stripping was not so effective as sublation in the recovery of BA. The sublation was carried out in a sieve plate column. Experimental results showed the sieve plate could increase the axial Peclet number of water in sublation column, or minimize the back mixing of the aqueous phase in the sublation. This work was supported by a grant from North China Pharmaceutical Corporation Limited. We would like to thank the National Natural Science Foundation of China for financial support (No. 20406021, No. 20221603, and No. 20236050). We would also like to thank Prof. Mooson Kawuk and Prof. Chia‐yung Chen for their revision of language.