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Cyanide is a typical toxic reducing agent prevailing in wastewater with a well-defined chemical mechanism, whereas its exploitation as an electron donor by microorganisms is currently understudied. Given that conventional denitrification requires additional electron donors, the cyanide and nitrogen can be eliminated simultaneously if the reducing HCN/CN - and its complexes are used as inorganic electron donors. Hence, this paper proposes anaerobic cyanides oxidation for nitrite reduction, whereby the biological toxicity and activity of cyanides are modulated by bimetallics. Performance tests illustrated that low toxicity equivalents of iron-copper composite cyanides provided higher denitrification loads with the release of cyanide ions and electrons from the complex structure by the bimetal. Both isotopic labeling and Density Functional Theory (DFT) demonstrated that CN - -N supplied electrons for nitrite reduction. The superposition of chemical processes reduces the biotoxicity and enhances the biological activity of cyanides in the CN - /Fe 3+ /Cu 2+ /NO 2 - coexistence system, including complex detoxification of CN - by Fe 3+ , CN - release by Cu 2+ from [Fe(CN) 6 ] 3- , and NO release by nitrite substitution of -CN groups. Cyanide is the smallest structural unit of C/N-containing compounds and serves as a probe to extend the electron-donating principle of anaerobic cyanides oxidation to more electron-donor microbial utilization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, iodide ion (I−) was introduced as an electron shuttle to significantly accelerate the elimination of sulfamethazine (SMT) with hydrogen peroxide (H 2 O 2) activated by amorphous zero-valent iron microsphere (A-mZVI) under neutral condition. Compared with the A-mZVI/H 2 O 2 system, the removal efficiency of SMT was improved by 80.8% after supplying with trace amounts of I−. It was that 1O 2 was the primary reactive species responsible for SMT degradation, although •OH, O 2 •−, FeIVO2+, and hypoiodous acid (HOI) also existed in the A-mZVI/H 2 O 2 /I− system. Furthermore, the possible degradation pathways of SMT were recommended, and the toxicity assessment of the degradation intermediates were also conducted. In addition, the influences of some key factors, the application in different water matrix, the degradation performance of some diverse pollutants, and the reusability of A-mZVI were also explored. This study proposed a promising process for improving the Fenton-like reaction under neutral condition by using I−. [Display omitted] • SMT removal was markedly enhanced in A-mZVI/I−/H 2 O 2 system under neutral condition. • Iodide ion played a role of electron shuttle in the A-mZVI/I−/H 2 O 2 reaction system. • 1O 2 was the primary reactive species responsible for SMT degradation. • Degradation pathway of SMT was inferred via DFT calculation and intermediate products. • The A-mZVI/I−/H 2 O 2 system exhibited a selectivity towards different micropollutants. [ABSTRACT FROM AUTHOR]

Herein, zero-valent iron-copper bimetallic nanoparticles were firstly applied to efficiently activate peracetic acid (PAA) for the removal of sulfamethazine (SMT) under neutral condition. Compared with the system of nano zero-valent iron (nZVI)-activated PAA, nZVIC/PAA system could significantly increase the removal efficiency of SMT by 70.8% at pH 7.0. It was demonstrated that the doped Cu could greatly accelerated Fe2+/Fe3+ cycle on the surface of the nZVIC and triggered the interaction between iron and copper. CH 3 C(O)OO• and 1O 2 acted a dominant role on SMT removal in the nZVIC/PAA system. The transformation pathways of SMT were inferred based on DFT theory calculations and determined intermediates, and the luminescent bacteria test and toxicity prediction of degradation intermediates showed that the biotoxicity of SMT was reduced during degradation. Finally, based on the results of the practicability evaluation, the proposed nZVIC/PAA process is a promising approach for the rapid decontamination of antibiotic-polluted water. [Display omitted] • nZVIC could effectively activate PAA to degrade SMT under neutral conditions. • CH 3 C(O)OO• and 1O 2 played a dominant role in the removal of SMT. • Degradation pathways of SMT were proposed based on DFT calculation and LC-MS analysis. • The nZVIC/PAA system was effective in different real water samples. • nZVIC had an excellent reusability in the nZVIC/PAA system for the removal of SMT. [ABSTRACT FROM AUTHOR]