Rapid reductive degradation of azo and anthraquinone dyes by nanoscale zero-valent iron

• Reactive azo dye Remazol Brilliant Orange 3RID (RBO3RID) was removed using nanoscale zero-valent iron (NZVI) particles. Dye concentrations varies from 100 to 500 mg/L. NZVI could remove up to 2757 mg of RBO3RID dye. More than 80% dye removal was achieved within the first 15 minutes of reaction.
• Anthraquinone dye Reactive Blue MR (RBMR) was removed using NZVI particles. Dye concentrations varies from 100 to 500 mg/L. NZVI could remove up to 2207 mg of RBMR dye. More than 80% dye removal was achieved within the first 15 minutes of reaction.
• Dyes degraded up to 97% (NZVI dosages varied from 0.15 to 0.3 g/L).
• pH range used in the study was 2–12 and NZVI worked the best at pH=8–12 which is the typical range of pH in textile wastewater.

The presence of residual dyes in textile effluent is not desired as they are very toxic to the ecosystem components and carcinogenic in nature. The removal of reactive azo dye Remazol Brilliant Orange 3RID (RBO3RID) and anthraquinone dye Reactive Blue MR (RBMR) by nanoscale zero-valent iron (NZVI) particles was investigated in this study. The dyes were degraded up to 97% by NZVI particles under different experimental conditions like NZVI dosages (0.15–0.3 g/L), initial dye concentrations (100–500 mg/L), and pH values (2–12). NZVI was found to work the best in the pH range of 8–12 which is the typical range of pH in textile wastewater. One gram of NZVI could remove up to 2757 mg of RBO3RID dye and 2207 mg of RBMR dye, and more than 80% dye removal was achieved within the first 15 minutes of reaction. FT-IR analyses showed the end products after the degradation are amines.

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