Adsorption of Crystal Violet and Methylene Blue on Azolla and Fig Leaves Modified with Magnetite Iron Oxide Nanoparticles

Abstract

This study was focused on the adsorption of Crystal violet and Methylene blue as cationic dyes on the surface of magnetite nanoparticles loaded Fig leaves (MNLFL) and magnetite nanoparticles loaded Azolla (MNLA) as natural cheap sources of adsorbents. MNLFL and MNLA were prepared with chemical precipitation method and they were characterized with Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Different parameters affecting the dyes removal efficiency such as contact time, pH of solution, and amount of adsorbents were optimized. Dyes adsorption process was studied from both kinetic and equilibrium point. The kinetic of adsorption was tested for pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models. At optimum conditions, the sorption of the Crystal violet and Methylene blue on the surface of MNLFL and MNLA adsorbents was best described by a pseudo-second-order kinetic model. Equilibrium data were fitted better to the Langmuir isotherm more than Freundlich and Temkin isotherm. The synthesized sorbent showed complete Crystal violet removal with sorption capacity equal to 53.47 mg g−1 for MNLFL and 30.21 mg g−1 for MNLA and complete Methylene blue removal with sorption capacity equal to 61.72 mg g−1 for MNLFL and 25 mg g−1 for MNLA, respectively. The results showed that MNLFL and MNLA can be used as efficient adsorbents for removal of Crystal violet and Methylene blue from aqueous solutions.