Comparative adsorption of Eriochrome black T onto recyclable steel dust wastes: Isotherm, kinetics and thermodynamic studies

In this study, low-cost steel dust wastes from two different steel-manufacturing plants were investigated for the decontamination of water containing an anionic dye, Eriochrome black T (EBT). The characterization results indicated that the steel dust particles are mesoporous material with heterogenous structure and exhibit different surface functionalities that, mainly, included metal oxides and C-O groups. The steel dust particles showed high affinity towards EBT dye (100% removal) at pH 2, and dye concentration 20 mg/L. The kinetic data was better described by pseudo-second order model indicating chemisorption interactions. The isotherm results showed good fitting to the Langmuir isotherm model implying monolayer EBT adsorption onto steel dust particles. The maximum adsorption capacity of Q-Steel and L-Steel was 100.20 mg/g and 94.18 mg/g, respectively. The thermodynamic study demonstrated endothermic nature of EBT adsorption process. The steel dust particles showed excellent removal performance of EBT dye (i.e., less than 10% reduction) after five regeneration cycles. This demonstrated that steel dust particles can be directly, used as potential low cost and recyclable adsorbent material for treating dye contaminated water streams.