Title : Photodegradation of total cyanide with the synergistic approach of H2O2 and NaOCl
Abstract:
The coke plant wastewater contains hazardous pollutants such as cyanide, phenol and ammoniacal nitrogen. The cyanide being the most toxic in nature and even a small dose of cyanide can be fatal. Due to toxicity of cyanide and to abide by environmental norms /Cyanide in the wastewater of steel industry arises during the quenching of coke-oven gas. Due to toxicity of cyanide and environmental norms, there is a need to degrade the cyanide before discharging the treated wastewater. Advanced oxidation methods using strong oxidants like H2O2, O3, and NaOCl have been recently adopted, with the prime motive of attaining cyanide levels below 0.2 ppm. Photodecyanation of coke plant wastewater using H2O2 has been studied in the past research work. Oxidation method using NaOCl (without UV exposure) on cyanide and color removal is also studied and found to be effective for free cyanide only. Due to explosive nature and costly treatment of H2O2, an alternate route is explored in the current study. The synergistic action of H2O2 and NaOCl under Ultraviolet (UV) light for total cyanide remains undiscovered. Individually, NaOCl/UV/air was observed to be less effective for total cyanide degradation and was ineffective in color removal. However, the synergistic action of H2O2 and NaOCl was found to be effective in total cyanide mitigation. The H2O2/NaOCl exhibited total cyanide degradation upto 0.15ppm while individual effect of H2O2 degrade cyanide only till 0.36ppm.
Audience Takeaway Notes:
- The process aims in zero liquid discharge.
- The audience will be able to learn about advanced oxidation technique to remove impurities from wastewater effluents.
- The method can be extended to all the effluents containing phenol, and ammoniacal nitrogen.
- The technique can be easily scaled up. The method doesn’t need any additional process unit to filter out the residue.
