Cobalt/nitrogen co-carved carbon nanorod for efficient Fenton-like reaction:Degradation efficacy,reaction mechanism and singlet oxygen generation

The Fenton-like process shows promising potential to generate reactive oxygen species for the reme-diation of increasingly environmental pollutants.However,the slow development of high-activity cata-lysts with strong stability and low leaching of metal ions has greatly inhibited scale-up application of this technology.Here,cobalt(Co)/nitrogen(N)atom co-curved carbon nanorod(CoNC)containing highly uniform CoN_(x)active sites is developed as a Fenton-like catalyst for the effective catalytic oxidation of various organics via peroxymonosulfate(PMS)activation with high stability.As confirmed by the exper-imental results,singlet oxygen(^(1)O_(2))is the dominant active species for the degradation of the organ-ics,with a proportion of 100%.Furthermore,density functional theory calculations indicate that CoN_(2)C_(2)is the most effective ligand structure with more negative adsorption energy for PMS and the shortest length Co-O bond,while the most reasonable generation pathway for^(1)O_(2)was CoN_(2)C_(2)-PMS→CoN_(2)C_(2)-OH∗→2O∗→^(1)O_(2).Further studies demonstrate that the electron can be transferred from the highest occupied molecular orbitals of the organics to the lowest unoccupied molecular orbitals of the PMS via CoN_(2)C_(2)action.In addition,the CoNC presents strong resistance to inorganic ions and natural organic matter in the Fenton-like catalysis process.The presence of CoN_(2)C_(2)active centre can significantly shorten the migration distance of the^(1)O_(2)generated from PMS activation,which further enhances the Fenton-like catalytic activity in terms of mineralising various organic contaminants with high efficiency over a wide pH range.

Insights into the enzymatic degradation of DNA expedited by typical perfluoroalkyl acids

Perfluoroalkyl acids(PFAAs)are considered forever chemicals,gaining increasing attention for their hazardous impacts.However,the ecological effects of PFAAs remain unclear.Environmental DNA(eDNA),as the environmental gene pool,is often collected for evaluating the ecotoxicological effects of pollutants.In this study,we found that all PFAAs investigated,including perfluorohexanoic acid,perfluorooctanoic acid,perfluorononanoic acid,and perfluorooctane sulfonate,even at low concentrations(0.02 and 0.05 mg/L),expedited the enzymatic degradation of DNA in a nonlinear dose–effect relationship,with DNA degradation fragment sizes being lower than 1,000 bp and 200 bp after 15 and 30 min of degradation,respectively.This phenomenon was attributed to the binding interaction between PFAAs and AT bases in DNA via groove binding.van der Waals force(especially dispersion force)and hydrogen bonding are the main binding forces.DNA binding with PFAAs led to decreased base stacking and right-handed helicity,resulting in loose DNA structure exposing more digestion sites for degrading enzymes,and accelerating the enzymatic degradation of DNA.The global ecological risk evaluation results indicated that PFAA contamination could cause medium and high molecular ecological risk in 497 samples from 11 contamination-hot countries(such as the USA,Canada,and China).The findings of this study show new insights into the influence of PFAAs on the environmental fates of biomacromolecules and reveal the hidden molecular ecological effects of PFAAs in the environment.