Investigation the Ability of Magnetic Nanoparticles Coated with Humic Acid to Remove Color from Aqueous Media

In this research, a method for treating colored wastewater is proposed by magnetic nanoabsorbents coated with humic acid. The surface of the mentioned nanoabsorbent was modified with humic acid as a combination that includes hydroxyl, carboxyl and amine groups. Iron(III) oxide/humic acid nanoparticles were prepared by co-precipitation method and analyzed using dynamic light scattering techniques, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and vibrating sample magnetometer. The average diameter of nanoparticles was measured around 15 nm. The effect of adsorbent dose, contact time and initial concentration was also investigated. The best results are obtained by using 15 mg/ml of nanoparticles in 45 min for methylene blue dye, 20 mg/ml of nanoparticles in 30 min for indigo-carmine dye and 5 mg/ml of nanoparticles in 20 min for 4-(2-pyridylazo)resorcinol dye was obtained. In these conditions, 95.96, 99.34 and 99.11% of methylene blue, indigo carmine and 4-(2-pyridyl azo) resorcinol can be removed from the solutions made in the laboratory ,respectively. The maximum absorption capacity for methylene blue, indigo carmine, and 4-(2-pyridyl azo)resorcinol was 0.0085, 0.0439, and 0.0307 mmol/g respectively, which was based on the Freundlich isotherm model for methylene blue and for indigo carmine and 4-( 2- Pyridyl azo) resorcinol was fitted to the Langmuir isotherm model. In the reuse of nanoabsorbents, an average of 12.94% of each color was removed from the aqueous medium. The results indicate the efficiency of the nanoabsorbent for the removal of colored wastewater.