Reverse Osmosis Separation of Some Heavy Metallic Salts in Aqueous Solution

Abstract

In order to study the applicability of reverse osmosis technique to the removal of harmfull metalions from the waste water of mines, factories ane others, a funamental experiment was carried out on the membrane separation of properties of some chloride and sulfate salts contained in aqueous dilute soiutions. For this experiment was used a bached type reverse osmosis test apparatus combined with ‘loose’ Loeb type cellullose acetate semipermeable membranes which were cured at 75°C and 80°C. In case the membrane cured at 75°C and having the salt rejection of 75 percent for aqueous sodium chloride solution was tested by the applied pressure of 4o atm with 0.01mol/l feed solutions, the salt rejections of zinc, manganese, cadmium, cupper and nickel sulfates were more than 98.7 percent, and the fluxes were about 1.05m³/m²/day. Under the same conditions, the membrane rejected about 93 percent of chlorldes of these heavy metals with the fluxes of about 0.9m³/m²/day.The membrane cured at 80°C resulted the salt rejections of more than 99.7 percent ane the fluxes of less than 0.8m³/m²/day for these heavy metal sulfates. It was observed that the membrane permeation of these sulfate salts was due to purely diffusive transport, and a volumetric flow combined with diffusion also contributed to the permeation of chloride salts.