METHOD FOR PURIFYING WASTEWATERS FROM THE WORKUP OF CRUDE AROMATIC NITRO COMPOUNDS

摘要

The invention relates to a method for purifying crude aromatic nitro compounds that originate from the nitration of aromatic compounds, comprising the following washing steps (a1) and (a2), wherein each of the steps (a1) and (a2) can be carried out once or several times successively: (a1) contacting the crude aromatic nitro compound (N1-in) with a first aqueous phase (W1-in) comprising at least one base (B), and subsequently separating the phases, obtaining an organic phase (N1-res) and an aqueous phase (W1-res); and then (a2) contacting the organic phase (N1-res) obtained in step (a1) with a second aqueous phase (W2-in) and subsequent phase separation, obtaining a purified organic phase (N2-res) and at least one aqueous phase (W2-res), wherein the aqueous phase (W2-in) used has a pH of 6 to 9.