Efficient and harmless removal of insecticide diazinon via the stepwise combination of biodegradation and photodegradation.

Diazinon, an organophosphorus insecticide, is predominantly removed through photodegradation and biodegradation in the environment. However, photodegradation can generate diazoxon, a highly toxic oxidation byproduct, while biodegradation is hard to complete mineralize diazinon, showing limitations in both methods. In this study, we provided an efficient strategy for the complete and harmless removal of diazinon by synergistically employing biodegradation and photodegradation. The diazinon-degrading strain X1 was capable of completely degrading 200 µM of diazinon into 2-isopropyl-6-methyl-4-pyrimidinol (IMP) within 6 h without producing the highly toxic diazoxon. IMP was the only intermediate metabolite in biodegradation process, which cannot be further degraded by strain X1. Through RT-qPCR and prokaryotic expression analyses, the hydrolase OpdB was pinpointed as the key enzyme for diazinon degradation in strain X1. Photodegradation was further used to degrade IMP and a pyridazine ring-opening product of IMP was identified via high resolution mass spectrometry. The acute toxicity of this product to aquatic organisms were 123 times and 6630 times lower than that of diazinon and IMP, respectively. The stepwise application of biodegradation and photodegradation was proved to be a successful approach for the remediation of diazinon and its metabolite IMP. This integrated method ensures the harmless and complete elimination of diazinon and IMP within only 6 h. The research provides a theoretical basis for the efficient and harmless remediation of organophosphorus insecticide residuals in the environment.

Polyaniline-Coated Porous Vanadium Nitride Microrods for Enhanced Performance of a Lithium-Sulfur Battery.

To solve the slow kinetics of polysulfide conversion reaction in Li-S battery, many transition metal nitrides were developed for sulfur hosts. Herein, novel polyaniline-coated porous vanadium nitride (VN) microrods were synthesized via a calcination, washing and polyaniline-coating process, which served as sulfur host for Li-S battery exhibited high electrochemical performance. The porous VN microrods with high specific surface area provided enough interspace to overcome the volume change of the cathode. The outer layer of polyaniline as a conductive shell enhanced the cathode conductivity, effectively blocked the shuttle effect of polysulfides, thus improving the cycling capacity of Li-S battery. The cathode exhibited an initial capacity of 1007 mAh g-1 at 0.5 A g-1, and the reversible capacity remained at 735 mAh g-1 over 150 cycles.