New Membranes for Reverse Osmosis Treatment of Metal Finishing Effluents.

摘要

An important new membrane has been developed for the reverse osmosis treatment of both highly alkaline and acidic (non-oxidizing) metal finishing rinse waters. This membrane designated NS-1,and originally developed for seawater desalination,consists of the following: a microporous support film (polysulfone) coated with polyethylenimine which is cross-linked with tolylene 2,4-diisocyanate. Simulated alkaline copper and zinc cyanide plating rinses at pH's of 11.8and 12.9were treated by NS-1membranes during 500-and 340-hour tests without deterioration of reverse osmosis properties. Water fluxes above 10gallons per square foot (of membrane) per day (gfd) were observed with cyanide rejections between 95and 99percent. The NS-1membrane also treated simulated copper sulfate rinse waters effectively at pH 0.5during 550-hour tests without deterioration of reverse osmosis properties (fluxes above 10 gfd with 99.8percent rejection of copper). Preliminary engineering considerations indicated the feasibility of applying the NS-1membrane to reverse osmosis treatment and recycle of nickel and zinc cyanide electroplating rinse waters.