Removal of cationic dye methylene blue (Mb) from aqueous solution by coffee and peanut husk modified with magnetite iron oxide nanoparticles

Abstract

This study was focused on the adsorption of methylene blue (MB) as a cationic dye on magnetite nanoparticles loaded with coffee (MNLC) and magnetite nanoparticles loaded with peanut husk (MNLPH) as naturally cheap sources of adsorbent. Coffee and Peanut husk were magnetically modified by contact with water-based magnetic fluid. These new type of magnetically natural materials can be easily separated by means of magnetic separators. They were characterized with Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) instruments. Different parameters affecting MB removal efficiency such as contact time, pH of solution and amount of adsorbents were studied and optimized. Dye adsorption process was studied from both kinetic and equilibrium point. The studies of MB sorption kinetic showed rapid dynamic sorption with second-order kinetic model, suggesting chemisorption mechanism with R 2 = 0.9988, q eq= 10.28 mg g -1 and R 2 =0.9967, q eq= 128.20 mg g -1 , respectively. Equilibrium data were fitted well to the Langmuir isotherm more than Freundlich and Temkin isotherm. The modified adsorbents showed MB removal with 88.49 and 74.62 mg g -1 sorption capacity for MNLC and MNLPH, respectively. This study showed a simple, efficient and reliable method for removal of MB from aqueous solutions with MNLC and MNLPH as efficient adsorbents.