Process and apparatus for producing an aqueous solution containing chlorine dioxide

A process for producing an aqueous solution containing chlorine dioxide from gaseous chlorine dioxide and from an aqueous phase,

• comprising the following steps:
• (a) production of a first aqueous solution comprising dissolved chlorine dioxide and further dissolved constituents,
• (b) transfer of dissolved chlorine dioxide from the first aqueous solution produced into a first gas stream comprising a carrier gas, resulting in a second gas stream which comprises carrier gas and is enriched in gaseous chlorine dioxide,
• (c) transfer of gaseous chlorine dioxide from the second gas stream into an aqueous phase, with chlorine dioxide being dissolved in the aqueous phase to form the aqueous solution containing chlorine dioxide and a third gas stream which is depleted in chlorine dioxide being formed,
• (d) production of further amounts of the first gas stream
• from the third gas stream
• or
• from a chlorine dioxide-containing fraction of the third gas stream and further added gaseous compounds
• and repetition or continuation of the above process steps (b) and (c) so that further amounts of chlorine dioxide are dissolved in the aqueous phase,
• where
• the production of a first aqueous solution comprising dissolved chlorine dioxide and further dissolved constituents in step (a) is carried out by a process selected from the group consisting of:
• acid-chlorite process,
• hydrochloric acid-chlorite process,
• acid-hypochlorite-chlorite process,
• peroxodisulfate-chlorite process,
• peroxodisulfate-peroxomonosulfate-chlorite process,
• chloride electrolysis process,
• chlorite electrolysis process
• wherein the process is carried out in a closed apparatus so that no gaseous chlorine dioxide escapes from the apparatus
• and where
• the first aqueous solution in step (b) has a temperature T1 and the aqueous phase in step (c) has a temperature T2, where T2 is less than T1.