Hydrogen chloride gas may be introduced, or a water absorbent and a desiccant may be added.

Heating is not desirable!

You can refer to the master's thesis,

Hydrochloric acid is a common pickling agent and raw material in chemical and pharmaceutical fields, and a large amount of low-concentration waste hydrochloric acid will be discharged during these production processes. Because hydrochloric acid and water form the substance with the highest boiling point, its boiling point component is 20.2 wt% of hydrogen chloride, and its boiling point is 108.6℃. Ordinary distillation methods cannot concentrate dilute hydrochloric acid to obtain high concentration hydrochloric acid higher than boiling components. In this paper, a combined method of salt desorption-gas absorption-salt rectification is proposed and experimentally studied to concentrate dilute hydrochloric acid to obtain concentrated hydrochloric acid with a concentration of more than 30wt% and discharged water with extremely low hydrogen chloride content. In this paper, the experimental study on concentration of dilute hydrochloric acid by salting-out-gas absorption method was carried out at first. In this method, the diluted hydrochloric acid to be concentrated is divided into two parts, one part is desorbed by adding salt in the tower kettle, so that the desorbed hydrogen chloride gas rises along the tower body; The other part flows downward in the packing layer of the tower as an absorbent to absorb the hydrogen chloride gas rising along the tower body, thus concentrating the dilute hydrochloric acid (absorbent) into concentrated hydrochloric acid. In this experiment, the effects of salt concentration, liquid-gas ratio, bottom feed rate and bottom temperature on the process were studied respectively. The experimental results show that the higher the concentration of magnesium chloride at the bottom of the tower, the greater the desorption degree of hydrochloric acid at the bottom of the tower and the higher the concentration of hydrochloric acid in the absorption solution. After adding magnesium chloride, the distillation experiment with salt was carried out with the residual liquid of hydrochloric acid desorption in the tower bottom as raw material. The effects of different salt concentrations and reflux ratio on the concentration of hydrochloric acid at the top and bottom of the tower were observed experimentally. The experimental results show that the higher the salt concentration at the bottom of the tower, the higher the average concentration of hydrochloric acid products extracted from the top of the tower and the higher the output of 20% (mass fraction) hydrochloric acid.