Removal of Acid Red and sodium chloride mixtures from aqueous solutions using nanofiltration

A spiral wound nanofiltration membrane was used to remove mixtures of sodium chloride and Acid Red 114 (AR) from aqueous solutions. Three Acid Red concentrations (0, 10, 100 and 200 ppm) and three NaCl concentrations (0, 1000, 10000 and 50000 ppm) were used. For each experiment measurements were taken at four pressures from 4 to 12 bar. The measurements included conductivity, permeate flow rate and dye absorbance using a UV-visible spectrophotometer. The effects of varying each of the dye and salt concentrations on the permeate flux and dye removal were evaluated. In the absence of NaCl, a color removal of 97.2% was achieved and this number was elevated to 98.2% at a dye concentration of 200 ppm when 1000 ppm NaCl was added to the colored water.