Herein,
we have described a simple and viable approach to use the
waste byproduct of steel industries: red iron oxide dust (IOD) for
synthesizing its reduced version as reduced-IOD (r-IOD). The r-IOD
possess active multiphases of iron oxides (Fe@Fe3O4@Fe2O3) and is used for the adsorption
of three organic dyes. The surface area of magnetically active r-IOD
is found to be ∼4.5 times than that of IOD and shows better
mesoporosity. Due to having a larger surface area, r-IOD is used for
the efficient adsorption of three organic dyes that include two anionic
azo dyes, namely, RG 19 (Reactive Green 19), RO 16 (Reactive Orange
16) and one cationic MG (Malachite Green) dye, with maximum adsorption
capacities of ∼2162.9, ∼2273.1, and ∼1400.2 mg
g–1, respectively. Various batch experiments related
to kinetics, isotherms, and adsorption thermodynamics are studied
to understand the rate, order, type, and feasibility of adsorption.
The effects of temperature, pH, loading, and concentration, on the
adsorption process are also investigated. Moreover, the adsorption
capacity of r-IOD is satisfactorily tested via an external spiking
method toward the dye removal from industrial wastewater and laboratory
wastewater.