Decoloration of acid violet red B by bentonite-supported nanoscale zero-valent iron: Reactivity, characterization, kinetics and reaction pathway

• Bentonite-supported nanoscale zero-valent iron (Fe0Bent)
• Acid violet red B (95.6%) was removed using Fe0Bent.
• Fe0Bent has the potential to be used for in situ remediation.

In this study, bentonite (Bent)-supported nanoscale zero-valent iron (Fe0) (Fe0Bent) was prepared to remove acid violet red B from an aqueous solution. Scanning electron microscopy (SEM) images of Fe0Bent and batch experiments indicated that the presence of bentonite decreased aggregation of iron nanoparticles and increased their reactivity. After reacting for 9 min, Fe0Bent removed 95.6% of acid violet red B with a concentration of 800 mg/l compared to Fe0, which removed 75.1%. Iron oxide and hydroxide were the reaction products of the reaction of Fe0Bent with acid violet red B. UV–vis spectra showed that the absorption peak of acid violet red B was degraded due to the break of azo linkages. Kinetic studies showed that the degradation rate suited the pseudo-first-order model well. The apparent activation energy was 40.86 kJ/mol, which is typical of a chemically controlled reaction on the smectite surface. The Fe0Bent used to remove acid violet red B has the potential to be used for in situ remediation.