METHOD OF REMOVING HEAVY METAL IONS FROM SEWAGE Russian patent published in 1999 - IPC

FIELD: purification of industrial sewage by flotation, more particularly removed of ions of toxic metals such as chromium, copper, iron, nickel, and zinc from water. SUBSTANCE: method comprises one-stage flotation purification at pH of 7.5-8.0, and flotation agent is mixture of higher carboxylic acid hydrazides of general formula C_nH_2n+1CONHNH₂, wherein n is 6-8. Said mixture which is 0.5% aqueous emulsion prepared with addition of hydrochloric acid in equimolar ratio is added to sewage. EFFECT: simplified process flowsheet, higher process rate and shorter (up to 5 min) flotation time. 3 ex, 2 tbl