Rejection of anionic dyes and salt using polypropylene microfilters

Previous work showed that inorganic membranes such as stainless steel and c eramic microfilters were capable of rejecting anionic dyes and sodium nitra te from water solutions. The interest arose to learn if this rejection was possible with organic membranes such as propylene microfilters. Experimenta l data is presented showing that a polypropylene microfilter will reject bo th salt and acid or direct dyes from aqueous solutions when the conductivit y of the solution is below 500 mu Siemens. The effect of pH and salt concen tration on the filtration rate and color rejection is also presented.