Journal of hazardous materials最新文献

It has been reported that tripolyphosphate (TPP) can effectively enhance the activation of O₂ by Fe(II) to remove organic pollutants in the environment. However, the influence of solution pH on the generation and conversion of reactive oxygen species (ROS) and their degradation of pollutants in the Fe(II)/O₂/TPP system needs further investigation. In this study, we demonstrated that O₂^•- and •OH were the main ROS responsible for degradation in the system at different pH conditions, and their formation rates were calculated using a steady-state model. Experiments combined with density functional theory (DFT) calculations showed that the p-nitrophenol (PNP) degradation pathway in the Fe(II)/O₂/TPP system is regulated by solution pH. Specifically, at pH = 3, the existence of Fe(II) in the solution is dominated by [Fe(II)(HTPP)₂]^2-, which leads to a rapid conversion from O₂ and HO₂• to generate •OH, and PNP is primarily oxidatively degraded. However, at pH = 5/7, [Fe(II)(TPP)₂]^4- is taking the lead with which O₂^•- is accumulated in the solution due to the slow conversion to •OH in this condition, and the PNP is mainly reductively degraded. This study proposes a new strategy to achieve the targeted oxidative/reductive removal of different types of pollutants by simply varying the solution pH in the Fe(II)/O₂/TPP system.

This study systematically explored the role of Mn(II) in the removal of 4-chlorophenol (4-CP) by electro-oxidation (EO) employing anodes with low oxygen evolution potential (OEP), i.e., Ti/RuO₂-IrO₂, Ti/Pt, and Ti/Ti₄O₇, as well as anodes with high OEP, namely, Ti/PbO₂, Ti/SnO₂, and boron-doped diamond (Si/BDD). Mn(II) significantly promoted 4-CP removal on the anodes with low OEP at fairly low current density (0.04 to 1 mA/cm²), but had minimal to negative impact on those with high OEP. Cyclic voltammetry and X-ray photoelectron spectra revealed that Mn(II) was oxidized to Mn(III), then to Mn(IV) on the anodes with low OEP, whereas its was oxidized directly to Mn(IV) on those with high OEP. Deposition of manganese oxide on the anodes with low OEP suppressed oxygen evolution reaction (OER) in EO process, but enhanced OER on those with high OEP. Quenching and spectral results consistently indicated that Mn(III) and Mn(IV) were the primary species responsible for enhancing 4-CP removal on the anodes with low OEP. These findings provide mechanistic insights into the redox transformation of Mn(II) in EO and the theoretical basis for a novel strategy to boost pollutant degradation in EO systems using low OEP anodes through coupling with the redox chemistry of manganese.

The composition of dissolved black carbon (DBC) could be influenced by adsorption on minerals, subsequently affecting DBC's photoactivity and the photoconversion of contaminants. This study investigated the changes in photoactivity of DBC after absorption on ferrihydrite at Fe/C ratios of 0, 1.75, 7.50, and 11.25, compared the influences of DBC₀ and DBC_7.50 on the photodegradation of four typical antibiotics (AB) including sulfadiazine, tetracycline, ofloxacin, and chloramphenicol. The selective adsorption led to the compounds with high aromaticity, high oxidation states, and more oxygen-containing functional groups being more favorably adsorbed on ferrihydrite, further causing the steady-state concentrations of ³DBC*, ¹O₂, and •OH respectively to drop from 1.83 × 10^-13 M, 7.45 × 10^-13 M, and 3.32 × 10^-16 M in DBC₀ to 1.22 × 10^-13 M, 0.93 × 10^-13 M and 2.30 × 10^-16 M in DBC_11.25, while the light screening effect factor increased from 0.740-0.921 in DBC₀ with above four antibiotics to 0.775-0.970 for that of DBC_11.25. Unexpectedly, DBC after adsorption played a dual role in the photodegradation of various antibiotics. This difference might be caused by antibiotics' chemical composition, functional groups interacting with reactive intermediates, and the overlap in UV-vis spectra between antibiotics and DBC. Our data are valuable for understanding the dynamic roles of DBC in the photodegradation of antibiotics.

Antibiotic resistance is currently an unfolding global crisis threatening human health worldwide. While antibiotic resistance genes (ARGs) are known to be pervasive in environmental media, the occurrence of antibiotic resistance at interfaces between two or more adjacent media is largely unknown. Here, we designed a microcosm study to simulate plastic pollution in paddy soil and used a novel method, stimulated Raman scattering coupled with deuterium oxide (D₂O) labelling, to compare the antibiotic resistance in a single medium with that at the interface of multiple environmental media (plastic, soil, water). Results revealed that the involvement of more types of environmental media at interfaces led to a higher proportion of active resistant bacteria. Genotypic analysis showed that ARGs (especially high-risk ARGs) and mobile genetic elements (MGEs) were all highly enriched at the interfaces. This enrichment was further enhanced by the co-stress of heavy metal (arsenic) and antibiotic (ciprofloxacin). Our study is the first to apply stimulated Raman scattering to elucidate antibiotic resistance at environmental interfaces and reveals novel pathway of antibiotic resistance dissemination in the environment and overlooked risks to human health.

This work proposes a novel plasma-assisted 2D/2D g-C₃N₄/Ti₃C₂ system for treatment of organics-heavy metals composite wastewater. Unlike traditional materials in plasma system, 2D/2D g-C₃N₄/Ti₃C₂ not only improved the mass transfer efficiency of plasma by gathering both reactive species and pollutants onto the surface, but also induced photocatalytic reactions. Besides, the higher specific surface area and faster carrier separation rate can enhance the oxidation and reduction activity, and then promoted organic matter degradation and heavy metal reduction. Remarkably, the removal efficiency of sulfamethoxazole (SMX) and Cr(VI) increased by 16.5 % and 73.1 % respectively when introducing 2D/2D g-C₃N₄/Ti₃C₂. Roles of·OH,·H,·O₂^-, ¹O₂, e^-, and h⁺ in SMX oxidation and Cr(VI) reduction are clarified. The primary aggregated·OH and ¹O₂ dominate the degradation of SMX. The influencing factors, synergistic mechanism between plasma and catalyst, and redox mechanism were clarified. This work provides a breakthrough idea for treatment of organics-heavy metals composite wastewater.

Plastic products offer remarkable convenience for modern life. However, growing concerns are emerging regarding the potential health hazards posed by nanoplastics, which formed as plastics break down. Currently, the biological effects and mechanisms induced by nanoplastics are largely underexplored. In this study, we report that polystyrene nanoplastics can enter the bloodstream and enhance thrombus formation. Our findings show that polystyrene nanoplastics adsorb plasma proteins, particularly coagulation factor XII and plasminogen activator inhibitor-1, play a key role in this process, as demonstrated by proteomics, bioinformatic analyses, and molecular dynamics simulations. The adsorption of these proteins by nanoplastics is an essential factor in thrombosis enhancement. This newly uncovered pathway of protein adsorption leading to enhanced thrombosis provides new insights into the biological effects of nanoplastics, which may inform future safety and environmental risk assessment of plastics.

The catalytic membrane-based oxidation-filtration process integrates physical separation and chemical oxidation, offering a highly efficient water purification strategy. However, the oxidation-filtration process is limited in practical applications due to the short residence time of milliseconds within the catalytic layer and the interference of coexisting organic pollutants in real water. Herein, a dual-layer membrane containing a top selective layer and a bottom catalytic layer was fabricated using an in situ co-casting method with a double-blade knife. Experimental results demonstrated that the selective layer rejected macromolecular organic pollutants, thereby alleviating their interference with bisphenol A (BPA) degradation. Concurrently, the catalytic layer activated peracetic acid oxidant and achieved a high BPA degradation exceeding 90 % in milliseconds with reactive oxygen species (especially •OH). The finite-element analysis confirmed a high-concentration reaction field occupying the pore cavity of the catalytic layer, enhancing collision probability between reactive oxygen species and BPA, i.e., the nano-confinement effect. Additionally, the dual-layer membrane achieved a long-term stable performance for emerging contaminant degradation in surface water treatment. This work underscores a novel catalytic membrane structure design for high-performance oxidation-filtration processes and elucidates its mechanisms underlying ultrafast degradation.

Melamine (MA) enhanced Cu-Fenton process was developed for the degradation of anthracyclines. Taking daunorubicin (DNR) degradation as an example, we found that the initial first-order apparent constant of Cu²⁺/MA/H₂O₂ system with a molar ratio of 1:8 for Cu²⁺:MA was 5.2 times higher than that of conventional Cu²⁺/H₂O₂ system. The in-situ reductive coordination between Cu²⁺ and MA facilitated the generation and stabilization of Cu⁺ species, thereby accelerating the rate-limiting step of Cu²⁺/Cu⁺ conversion and maintaining high levels of Cu⁺ during the degradation process. Moreover, pre-synthesized Cu⁺-MA complexes (e.g., CM-250) further enhanced the efficiency of the Cu-Fenton reaction by increasing both the Cu⁺ proportion and MA chelation. The apparent activation energy for DNR degradation in CM-250 mediated Fenton reaction (15.9 kJ mol^-1) was lower than that in systems involving Cu²⁺/MA (41.2 kJ mol^-1) and Cu²⁺ (65.6 kJ mol^-1). Enhanced generation of various reactive oxygen species (·OH,·O₂^-, and ¹O₂) was confirmed, with ¹O₂ playing a dominant role, significantly improving both degradation rate and mineralization degree for DNR. MA-enhanced Cu-Fenton process also offers a convenient alternative to effectively remove other anthracyclines and organic micropollutants, holding great promise for advancing advanced oxidation processes as well as practical large-scale degradation applications targeting multiple pollutants.

Reducing nitrate (NO₃^-) in an aqueous solution to ammonia under ambient conditions can provide a green and sustainable NH₃-synthesis technology and mitigate global energy and pollution issues. In this work, a CuNi_0.75-1,3,5-benzenetricarboxylic acid/nickel foam (CuNi_0.75-MOF/NF) catalyst grown in situ was prepared via a one-pot method as an efficient cathode material for electrocatalytic nitrate reduction reaction (NO₃RR). The CuNi_0.75-MOF/NF catalyst exhibited excellent electrocatalytic NO₃RR performance at -1.0 V versus a reversible hydrogen electrode, achieving an outstanding faradaic efficiency of 95.88 % and an NH₃ yield of 51.78 mg h^-1 cm^-2. The ¹⁵N isotope labeling experiments confirmed that the sole source of N in the electrocatalytic NO₃RR was the NO₃^- in the electrolyte. The reaction pathway for the electrocatalytic NO₃RR was derived by in situ Fourier transform infrared spectroscopy and in situ differential electrochemical mass spectrometry. Density functional theory calculations revealed that the Ni element in the CuNi_0.75-MOF/NF catalyst had excellent O-H activation ability and strong *H adsorption capacity. These *H species were transferred from the Ni sites to the *NO adsorption intermediates located on the Cu sites, providing a continuous supply of *H to Cu, thereby promoting the formation of *NOH intermediates and enhancing the hydrogenation process of the electrocatalytic NO₃RR.

Calcium peroxide nanoparticles (nCP) as a versatile and safe solid H₂O₂ source, have attracted significant research interst for their application potential in groundwater remediation. Compared to the traditional Fenton system, the nCP-based Fenton-like system has a wider pH-working window for contaminants degradation. This results from the dominant radical transformation under different pH. Unlike the traditional Fenton system which is only effective in acid conditions with hydroxyl radical (•OH) as the main active species, the release of H₂O₂ and O₂ from nCP provides multiple contaminants degradation pathways. In acidic environments, •OH and Fe(IV) predominate as the active species, facilitated by substantial H₂O₂ production which activates the Fenton reaction. In neutral or alkaline conditions, the production of H₂O₂ was dramatically decreased. While the O₂ released from nCP can be catalyzed by Fe(II) to form superoxide radical (•O₂^-), which subsequently generate singlet oxygen (¹O₂). The formation pathway of •O₂^- was tracked by O¹⁸ isotope labeling experiment. The impact of the water matrix on radical generation in the Fe(II)/nCP Fenton-like system was also studied. This research deepens the understanding of the radical formation mechanisms in nCP-based Fenton-like system, offering insights to support their application in remediating contaminated groundwater.