Removal of crystal violet by advanced oxidation and microfiltration

Advanced oxidation process (AOP) followed by microfiltration (MF) was proposed for the removal of crystal violet from aqueous solutions to save energy, time and cost. Fenton's reagent was used to degrade the dye. The optimal composition of Fenton's reagent for an initial dye concentration of 100 mg L− 1 was 1000 mg L− 1 H2O2 and 100 mg L− 1 FeSO4 7H2O. A microfiltration membrane (average pore size of 0.31 μm) was used to remove the oxidation product at transmembrane pressures of 138, 207 and 276 kPa. Small changes in pH (6.4 to 6.2), total dissolved solid (360 mg L− 1 to 350 mg L− 1) and density (999.7 kg m−3 to 997.1 kg m−3) were observed during microfiltration. No dye and dispersed particles were found in the permeate. Thus, 100% dye removal was achieved by the hybrid process.

Research Highlights
► Advanced oxidation followed by microfiltration was proposed for dye removal.
► Low-cost microfiltration membrane was prepared from kaolin and natural clay.
► Optimum composition of Fenton’s reagent was determined.
► Microfiltration successfully removed the post-oxidation products.
► 100% dye removal was achieved by this hybrid process.