Abstract:

In this work，the combination of salt desorption，gas absorption and salt-added distillation was used to conduct experimental research of concentrating dilute hydrochloric acid. The influence of salt concentration，absorbent flow rate，still capacity on the process was investigated. For the lab experiment，the desorption still was connected directly with the absorption tower，and hydrochloric acid（20%） was used as both desorption solution and absorbent. It was shown that when 0.3 g/mL MgCl₂ was added in the desorption solution，hydrochloric acid enriched gas from the solution could be absorbed by the absorbent，whose concentration then increased to 32.80%. After that，salt-added distillation was carried out to deal with the residue hydrochloric acid（6.5%）in the desorption still. Hydrochloric acid（20%），which was recycled in the experiment as both desorption solution and absorbent，could be wihdrawn from the top of the distillation tower. The method mentioned in this work is suitable for small scale batch operation of concentrating dilute hydrochloric acid.