Preparation of granular red mud supported zero-valent iron for Crystal Violet removal from aqueous solution

Abstract

In this study, the granular red mud supported zero-valent iron (GRM@ZVI) was successfully synthesized with bentonite as binder and maize straw as pore former. zero-valent iron (ZVI) was synthesized by direct reduction of iron oxide in red mud with maize straw as reductant at 900°C. The synthesized material was characterized with different methods such as scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Brunauer, Emmett and Teller. Various parameters affecting CV removal are as initial dye concentration (100–1,000 mg/L), initial pH (3.0–11.0), dosage (2–1.4 g/L) and temperature (303–323 K) have been investigated in present study. In addition, the three-adsorption kinetics has been employed to study the removal process of CV. The adsorption process was well fitted with the pseudo-second- order kinetic model which indicated that the chemisorption was the rate controlling step and internal particle diffusion controlled in some degrees. The Langmuir model good described the adsorption isotherms indicated the adsorption of CV occurring on a homogeneous surface. According to adsorption kinetics and isotherms, the maximum adsorption capacity of GRM@ZVI for CV was 305.84 mg/g. Summarily, the GRM@ZVI can be prepared as a low cost and effective adsorbent for the removal of dyes from aqueous solutions.