Extremely efficient mineralizing CN- into N2 via a newly developed system of generating sufficient ClO○/Cl2○- and self-decreasing pH

IIn the presence of the difficulties pertinent to the selective oxidation of cyanide and the high-efficient hydrolysis of cyanate, the mineralization of cyanide into nitrogen could not be realized during the traditional processes. Herein, a novel system of electrocatalysis coupled with ultraviolet-based advanced oxidation processes (UV/EC/ PS, PS: persulfate) is developed, exhibiting astonishingly high activity and selectivity for cyanide mineralization. The achieved results reveal that adequate active-chlorine species (ClO circle/Cl-2(circle-)) are generated due to the synergistic effects of electrocatalysis and advanced oxidation processes and these are high-selective for cyanide mineralization. Concurrently, induced by the interconversion between active species, the pH value in the UV/EC/PS system vigorously lessens from 11.5 to 3.3 at a rate of 1.1 x 10(-2) min(-1), hugely speeding up the hydrolysis of cyanate intermediates. The results display that PS plays a pivotal role in the formation of ClO circle/Cl-2(circle-) and the selfreduction of pH value in the UV/EC/PS system. Under the action of ClO circle/Cl-2(circle-) and self-decreased pH value, 0.25 mM of ferricyanide is thoroughly mineralized into nitrogen within 80 min and no HCN evolves. Additionally, the UV/EC/PS system exhibits exceptional feasibility for the practical purifications of cyanide-containing wastewater (CCWW). This study aims to give new insights into developing technologies associated with the mineralization treatment of CCWW.

Automated summary

In this study, a novel UV/EC/PS system is developed, which utilizes the synergistic effects of electrocatalysis and ultraviolet-based advanced oxidation processes to achieve highly efficient mineralization of cyanide into nitrogen. The system shows exceptional selectivity and feasibility for the treatment of cyanide-containing wastewater.