Controlled synthesis of silkworm cocoon-like α-Fe2O3 and its adsorptive properties for organic dyes and Cr(VI)

Industrial wastewater containing both organic and inorganic pollutants is being generated all the time. Efficient materials are highly needed to purify the polluted water. Thus, a hierarchical structured alpha-Fe2O3 with excellent adsorptive property has been synthesized by using a facile hydrothermal method. It can be prepared in macroscopic quantity. The as-synthesized alpha-Fe2O3 with silkworm cocoon-like morphology shows high efficiency in adsorbing Congo red (CR), Methyl orange (MO) and Cr(VI). The removal efficiency of CR, MO and Cr(VI) can reach 99.2%, 83.9% and 100% under appropriate conditions. Besides, this alpha-Fe2O3 shows high adsorptive ability for mixed CR and Cr(VI) in aqueous solution and the final removal rates can reach 94.7% and 97.9%, respectively. The adsorption kinetics fits well with the pseudo-second-order kinetic model. The results indicate that the product may find potential application in purification of wastewater containing both organic and inorganic pollutants.