Application of UV/chlorine processes for the DR83:1 degradation from wastewater: Effect of coexisting anions

In the present work, effect of coexisting anions on the degradation performance of UV/chlorine (UV/Cl) processes as an advanced oxidation treatment for the dye containing wastewater was investigated. The results showed that by increasing pH of the solution from 3 to 11, degradation efficiency of UV/Cl process was reduced from 96.2 +/- 1.4% to 62.9 +/- 3.1%. In the case of 100 mg/L of DR83:1, the removal efficiency was improved from 30.2 +/- 1.5% to 93.3 +/- 4.7% when the chlorine dose was increased from 100 to 1000 mu M. The HCO3 and Br ions were the main inhibitor and promotor anions responsible for the degradation of DR83:1. The relative contribution of Cl-center dot was higher than that for HO center dot. and UV, which was about three-times higher than that for HO center dot. The lowest and highest amounts of trihalomethanes were generated at acidic and alkaline conditions as well as low disinfection by products at low pH due to the generation of more HO center dot radicals at acidic pH in comparison to higher pH such that less intermediates were remained to react with chlorine.

Automated summary

The study found that the coexisting anions had an impact on the degradation performance of UV/chlorine processes for dye-containing wastewater. Increasing pH reduced the efficiency, while increasing chlorine dose improved removal efficiency. HCO3 and Br ions were found to be the main inhibitors and promoters, respectively.