Application of Micron-Sized Zero-Valent Iron (ZVI) for Decomposition of Industrial Amaranth Dyes.

Dyes are highly toxic and persistent in the environment. Their presence in water causes environmental and social problems. Dyes must be effectively removed from the water. A UV/ZVI/HO process was applied to decompose two organic dyes, AM E123 and AM ACID. A commercial ZVI product, Ferox Flow, was used, and its properties were determined using SEM and XRF. The zeta potential, surface area, and optical properties of ZVI were also determined. The efficiency of dye removal in optimal conditions was 85.5% and 80.85% for AM E123 and AM ACID, respectively. Complete decolorization was observed in all samples. The decomposition of both dyes occurred according to a modified pseudo-second-order reaction and there was a statistically significant correlation between the TOC decrease, pH, and process time. The catalyst was observed to have high stability, and this was not affected by the performance of the treatment process even after the third cycle, as confirmed by the results of the catalyst surface analysis and iron diffusion test. Slight differences in process efficiency were observed after each cycle. The need for only a small amount of catalyst to decompose AM E123 and AM ACID, coupled with the ability to reuse the catalyst without the need for prior preparation, may reduce catalyst purchase costs.