The rejection of anionic dyes and salt from water solutions using a polypropylene microfilter

Previous work reported by this laboratory showed that inorganic membranes s uch as stainless steel and ceramic microfilters were capable of rejecting a nionic dyes and sodium nitrate from water solutions, It was of interest to see if this were possible with organic membranes such as propylene microfil ters, Experimental data are presented showing that a polypropylene microfil ter will reject both salt and Direct Red 2 from aqueous solutions when the conductivity of the solution is below 500 mu Siemens. The use of microfiltr ation to remove color is an important phenomenon considering that microfilt ration comprises the largest fraction of the total membrane production in t he world and is now used commercially for tertiary biological wastewater tr eatment. The effect of pH and salt concentration on the filtration rate and color rejection is also presented.