HPLC detection of synthetic dyes in residual waters from wastewater treatment using adsorption on magnetic materials

Surface water contamination by synthetic dyes generates human and wildlife adverse health effects and causes photosynthesis decrease due to intense sun-light absorption of these pollutants. 50% of total discharged industrial effluents contain azo dyes. Congo Red is a benzidine based anionic azo dye that is usually employed in rubber, paper, and plastic industries. Congo Red can cause eye and skin irritation and is potentially carcinogenic in nature. This study explores the development of a new HPLC method to detect synthetic dyes in residual waters coming from wastewater treatment technologies based on magnetic material adsorption. Cobalt ferrite (CoFe2O4) and chitosan coated cobalt ferrite (CoFe2O4-Chit) prepared by a simple co-precipitation method were tested as adsorbents for Congo Red (CR). Effect of contact time, solution pH, and initial dye concentration were studied with respect to Congo Red adsorption efficiency. The adsorption experiments were performed at pH = 4.5 and 10.8. Highest value for the removal efficiency using magnetic material of cobalt ferrite coated with chitosan (CoFe2O4-Chit) was obtained at pH 10.8