New insights into the activity of green supported nanoscale zero-valent iron composites for enhanced acid blue-25 dye synergistic decolorization from aqueous medium

This work investigates how organic and inorganic support for innovatively modified nanoscale zero-valent iron (Fe-0) as an integrated green technology to play a constructive role in the remediation of Acid Blue-25 (AB-25) dye in an aqueous solution. Silica gel and starch are used as a support material to solve the problem of aggregation and de-stabilization of Fe(0 )which has limited the application in an industrial scale. The modified Fe(0 )is successfully fabricated via a facile, one-step and environmentally-friendly approach. The systematic characterization, including SEM, TEM, STEM-XEDS and XRD for modified Fe-0 compared with unmodified bare Fe degrees is applied to study the morphological and structural properties. This study is also demonstrated that Fe-0 and modified dosage, initial pH value, and reaction temperature and time have played an important role in the reduction of AB-25. Batch experiments showed that the removal efficiency of AB-25 has reached 100% at 6 min. under the optimum condition. Studies on the kinetics and isotherms of AB-25 reduction are well fitted using pseudo-first-order kinetics and Langmuir model, respectively. Thermodynamic studies indicated that these processes are endothermic, spontaneous and naturally favorable. Starch and silica do not only work as a carrier for Fe-0 nanoparticles, but also contributes to the decolorization through an "adsorption-enhanced reduction, oxidative degradation, corrosion, and precipitation" mechanisms. The unmodified and modified Fe-0 also exhibited easily regeneration and recycling at least for ten adsorption-desorption recycles. This study offers new insights into the promising green technology as a good performance for potential long term applications and magnetic separation for efficiently applied to dyecontaminated water. (C) 2019 Elsevier B.V. All rights reserved.