Investigation of in vivo toxicity of hydroxylamine sulfate and the efficiency of intoxication treatment by α-tocopherol acetate and methylene blue

Comparative studies of organic contaminant removal in different calcium sulfite-enhanced oxidant/Fe(II) systems: Kinetics, mechanisms, and differentiated degradation pathways

The application of S(IV) for the regeneration of Fe(II) has been widely investigated. As the common S(IV) sources, sodium sulfite (Na2SO3) and sodium bisulfite (NaHSO3) are soluble in the solution, resulting in excessive SO32- concentration and redundant radical scavenging problems. In this research, calcium sulfite (CaSO3) was applied as the substitution for the enhancement of different oxidant/Fe(II) systems. The advantages of CaSO3 could be summarized as follows: (1) it could sustainedly supplement SO32- for Fe(II) regeneration, preventing radical scavenging and unnecessary reagent waste; (2) the cost and toxicity of CaSO3 were extremely lower than that of other S(IV) sources; (3) the concentration of reactive species increased in the presence of CaSO3; and (4) after the reaction, SO42- would form CaSO4 precipitate, which would not increase the burden of SO42- in the solution. In the participation of CaSO3, the removal of trichloroethylene (TCE) and other organic contaminants were significantly promoted and different enhanced systems had high tolerance on complex solution conditions. The major reactive species in different systems were determined through qualitative and quantitative analyses. Eventually, the dechlorination and mineralization of TCE were measured and the differentiated degradation pathways in different CaSO3-enhanced oxidants/Fe(II) systems were elucidated.

Insights into enhanced removal of 1,2-dichloroethane by amorphous boron-enhanced Fenton system: Performances and mechanisms

In this study, amorphous boron was employed as a reductant in traditional Fenton system for the first time to accelerate the regeneration of Fe(II). The degradation of 1,2-dichloroethane (DCA) was only 40.0% in Fenton system, while in the presence of amorphous boron, it could reach to 93.0% in 60 min. HO• was demonstrated to be the major reactive oxygen species (ROSs) and responsible for DCA degradation. Further, the mechanism of amorphous boron-enhanced Fenton system was described as follows. With the addition of amorphous boron, the reduction process occurred on its surface and Fe(III) was regenerated to Fe(II) to further utilize H₂O₂ and produce more HO• for DCA removal. Meanwhile, amorphous boron was oxidized to B₂O₃ and a portion of H₃BO₃ leaching into the solution occurred. Both B₂O₃ and H₃BO₃ had no reactivity for Fe(III) reduction. Moreover, DCA could be entirely dechlorinated and mineralized to CO₂, Cl^- and H₂O. Vinyl chloride (VC) and dichloromethane (DCM) were the mainly intermediates in DCA degradation and two possible pathways were inferred. Eventually, the performance of DCA degradation in complex solution matrixes and for other contaminants removal were tested, demonstrating the broad-spectrum reactivity and superiority of amorphous boron-enhanced Fenton system in the remediation of contaminated groundwater.