Novolak recovery from waste water contg. phenol - by reacting with formaldehyde in hot turbulent zone under high pressure

Recovery of novolak (I) from water contg. phenol and HCHO in 1:0.2-0.9, pref. 1:0.6 molar ratio, with pH =5, pref. 0.9-1.2, involves pumping it continuously into the turbulent zone through a tubular reactor or cascade of vessels, whilst heating under high pressure, and then cooling. This is carried out so that the mixt. is kept in the hot turbulent zone under pressure for another 1-20 min. after reaching the reaction temp. of 130-200, pref. 190 degrees C before cooling and releasing the pressure in a separator, where (I) is sepd. from the supernatant aq. phase. The water initially contains 5-60, pref, 20-40 wt.% phenol. E.g. a 97.0 wt.% resin yield was obtd. from an aq. 10 wt.% phenol soln. using a phenol/HCHO ratio of 1:0.7 ay 16-17 at. g. and max. 155 degrees C in a tubular reactor. The process operates continuously and gives waste liquor with a phenol content of 0.5 to under 5 wt.% from waste liquor with a phenol content of >5 wt.%. The (I) obtd. can be processed and used in the normal way.