Using zeolite and Fe3O4@zeolite composites in removal of Reactive Red 120 from wastewater: Isotherm, kinetic, thermodynamic and adsorption behaviors

Abstract

It is a well-known fact that the release and dispersion of complex organic dyestuffs into the environment adversely affect human health and other living organisms. Due to industrial activities, pollution of water resources, which are vital for living organisms, is one of the most critical environmental problems nowadays. It is essential to remove the pollutants before they are discharged into the environment to eliminate environmental damage. In this study for the removal of Reactive Red 120 (RR120) dyestuff from an aqueous solution, we employed natural zeolite and iron oxide-zeolite (Fe3O4@Z) as adsorbents. The adsorbents were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, X-ray fluorescence spectrometry, Scanning electron microscopy energy dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analysis. The effects of parameters such as pH, contact time, and temperature on RR120 adsorption were also investigated. In addition, the adsorption equilibrium was analyzed with kinetic, isotherm, and thermodynamic parameters. It was found that the adsorption of RR120 on natural zeolite and Fe3O4@Z followed the Langmuir and Freundlich isotherm, respectively, and the adsorption process for both adsorbents proceeded spontaneously (ΔG∘ <0) and exothermic (ΔH∘ <0) with a pseudo-second-order kinetic model. Zeolite and Fe3O4@Z adsorption capacities for RR120 were 145.9 and 154.3 mg/g at 20 °C, respectively. It was determined that no significant matrix effect occurs in adsorption with synthetic wastewater prepared to evaluate the potential performance of adsorbents. According to the results obtained, Fe3O4@Z composite was found more effective adsorbent than natural zeolite for RR120 removal.