Synthesis of Fly Ash and Bentonite-Supported Zero-Valent Iron and Its Application for Removal of Toxic Cationic Dyes from Aqueous Solutions

摘要

A new adsorbing material for crystal violet (CV) and methylene blue (MB) dye removal, fly ash and bentonitesupported microscale zero-valent iron (FB-mZVI), was synthesized by using iron-ore tailings (IOT) as the iron source. Palm kernel shells (PKSs) were used to reduce the iron oxide of the IOT to Fe o. A statistical orthogonal method was used to evaluate the factors determining the adsorbent synthesis. It was found that the important factors were the mass ratio of the fly ash, bentonite, IOT, and PKSs as well as the synthesis time, temperature, and heating rate. Optimum mass ratio of the fly ash, bentonite, PKSs, and IOT was found to be 2: 2: 1: 1, and optimum synthesis temperature, time, and heating rate were found to be 800 degrees C, 10 min, and 10 degrees C/min, respectively. An FB-mZVI adsorbent was used to remove the CV andMBfrom aqueous solutions. Removal efficiency for CV wasmuch higher than that for MB. UV, XRD, and FTIR analyses revealed that the adsorption mechanisms for removal of CV were different from those for MB. Adsorption process was well described by the pseudo-second-order kinetic model, and Langmuir isotherm model better represented the adsorption isotherm data.