Textile wastewater decolorization by zero valent iron activated peroxymonosulfate: Compared with zero valent copper

• PMS–ZVI system can effectively decolorize real textile wastewater.
• Zero valent iron in comparison with zero valent copper had a better performance.
• Simultaneous application of PMS and H2O2 increased decolorization significantly.
• Average oxidation state was considerably increased after PMS-based processes.

Textile wastewater must be decolorized before discharging into the environment. In this study, peroxymonosulfate (PMS) was activated by zero valent iron (ZVI) to produce sulfate radical for degradation of organic compounds. The optimum condition for activation of PMS was provided in pH of 4 and 3000 mg/L ZVI. ZVI compared to zero valent copper (ZVC) was more effective in terms of COD and color removals. PMS and H2O2 performances were compared and the results showed that PMS had more efficiency in similar conditions. Simultaneous use of PMS and H2O2 synergically increased decolorization rate. The TOC and COD removal efficiencies of various processes were in the following order: ZVI–PMS–H2O2 ≥ ZVI–PMS > ZVI–H2O2 > ZVC–PMS > ZVC–H2O2. The average oxidation state (AOS) was considerably increased after oxidation processes using PMS and H2O2. This result indirectly proves biodegradability improvement of real textile wastewater. Finally, the oxidative processes were economically compared based on cost of chemicals.