Nitrate Yield Research Articles

Integrating Ozone Pollutant Elimination in N2 Electrolysis to Produce Nitrate with Reduced Reaction Steps.

The synthesis of nitrate by the electrochemical N2 oxidation reaction (NOR) is currently one of the most promising routes. However, the traditional generation of nitrate depends on the oxidation reaction between N2 and H2O (or ·OH), which involves complex reaction steps and intermediates, showing strong competition from oxygen evolution reaction (OER). Here, an effective NOR method is proposed to directly oxidize N2 by using O3 as a reactive oxygen source to reduce the reaction step. Electrochemical tests demonstrate that the nitrate yield of Pd-Mn3O4/CNT electrocatalyst reaches the milligram level, which is the highest yield reported so far for electrocatalytic NOR. Quantitative characterization is employed to establish a comprehensive set of benchmarks to confirm the intrinsic nature of nitrogen activation and test the O3-mediated reaction mechanism. Density functional theory (DFT) calculations show that the heterostructure Pd-Mn3O4 leads to a strong adsorption preference for N2 and O3, which greatly reduces the activation energy barrier for N2. This accelerates the synthesis of nitrate based on the direct formation mechanism, which reduces energy barriers and the reaction steps, thus increasing the performance of electrocatalytic nitrate production. The techno-economic analysis underscores the promising feasibility and sustainable economic value of the presented method.

Climate and landform interact to control the source and transport of nitrate in Pacific Northwest rivers

The hydrological effects of climate change are documented in many regions; however, climate-driven impacts to the source and transport of river nutrients remain poorly understood. Understanding the factors controlling nutrient dynamics across river systems is critical to preserve ecosystem function yet challenging given the complexity of landscape and climate interactions. Here, we harness a large regional dataset of nitrate (NO3–) yield, concentration, and isotopic composition (δ15N and δ18O) to evaluate the strength of hydroclimate and landscape variables in controlling the seasonal source and transport of NO3–. We show that hydroclimate strongly influenced the seasonality of river NO3–, producing distinct, source-dependent NO3– regimes across rivers from two mountain ranges. Riverine responses to hydroclimate were also constrained by watershed-scale topographic features, demonstrating that while regional climate strongly influences the timing of river NO3– transport, watershed topography plays a distinct role in mediating the sensitivity of river NO3– dynamics to future change.

Synergistic mechanisms between chlorine-mediated electrochemical advanced oxidation and ultraviolet light for ammonia removal

The combination of chlorine-mediated electrochemical advanced oxidation (Cl-EAO) and ultraviolet (UV) radiation (UV-E/Cl) can efficiently remove ammonia from wastewater. However, the synergistic mechanisms between Cl-EAO and UV need to be explored in more detail. Thus, in this study, the ammonia oxidation performance of Cl-EAO and UV-E/Cl systems were compared, while the synergistic mechanisms were identified by the performance of UV/chlorine oxidation (UV–ClO) system and the results of electron paramagnetic resonance (EPR) analysis, free radical inhibition assays, and determination of steady-state concentration of free radicals. It was found that, compared with the Cl-EAO system, UV increased the ammonia removal rate by 42.85% and reduced the active chlorine concentration (56.64%) and nitrate yield (53.61%). In the Cl-EAO, and UV-E/Cl systems, Cl• were detected, and the free radical inhibition assays and determination of steady-state concentration of free radicals suggested that UV increased the concentration of Cl• by 51.47%, resulting in Cl• becoming the major contributor to ammonia oxidation in the UV-E/Cl system. Besides, UV also increase the concentrations of HO• and Cl2•-, which further promoted the organic matter removal in the real domestic wastewater. This study also discussed the ammonia oxidation performance of the UV-E/Cl system in real domestic wastewater, even with the presence of significant levels of organic and inorganic anions in the wastewater, UV increased the ammonia oxidation by 21.95%. The results of this study thus clarify the mechanisms and potential applications of UV-E/Cl technology.

Insights into the Peroxide-Bicyclic Intermediate Pathway of Aromatic Photooxidation: Experimental Yields and NOx-Dependency of Ring-Opening and Ring-Retaining Products.

Aromatic hydrocarbons are important contributors to the formation of ozone and secondary organic aerosols in urban environments. The different parallel pathways in aromatic oxidation, however, remain inadequately understood. Here, we investigated the production yields and chemical distributions of gas-phase tracer products during the photooxidation of alkylbenzenes at atmospheric OH levels with NOx present using high-resolution mass spectrometers. The peroxide-bicyclic intermediate pathway emerged as the major pathway in aromatic oxidation, accounting for 52.1 ± 12.6%, 66.1 ± 16.6%, and 81.4 ± 24.3% of the total OH oxidation of toluene, m-xylene, and 1,3,5-trimethylbenzene, respectively. Notably, the yields of bicyclic nitrates produced from the reactions of bicyclic peroxy radicals (BPRs) with NO were considerably lower (3-5 times) than what the current mechanism predicted. Alongside traditional ring-opening products formed through the bicyclic pathway (dicarbonyls and furanones), we identified a significant proportion of carbonyl olefinic acids generated via the 1,5-aldehydic H-shift occurring in subsequent reactions of BPRs + NO, contributing 4-7% of the carbon flow in aromatic oxidation. Moreover, the observed NOx-dependencies of ring-opening and ring-retaining product yields provide insights into the competitive nature of reactions involving BPRs with NO, HO2, and RO2, which determine the refined product distributions and offer an explanation for the discrepancies between the experimental and model-based results.

Physiological adaptation and population dynamics of a nitrifying sludge exposed to ampicillin.

Antibiotics in wastewater treatment plants can alter the physiological activity and the structure of microbial communities through toxic and inhibitory effects. Physiological adaptation, kinetic, and population dynamics behavior of a nitrifying sludge was evaluated in a sequential batch reactor (SBR) fed with 14.4mg/L of ampicillin (AMP). The addition of AMP did not affect ammonium consumption (100mg NH4+-N/L) but provoked nitrite accumulation (0.90mg NO2--N formed/mg NH4+-N consumed) and an inhibition of up to 67% on the nitrite oxidizing process. After 30 cycles under AMP feeding, the sludge recovered its nitrite oxidizing activity with a high nitrate yield (YNO3-) of 0.87 ± 0.10mg NO3--N formed/mg NH4+-N consumed, carrying out again a stable and complete nitrifying process. Increases in specific rate of nitrate production (qNO3-) showed the physiological adaptation of the nitrite oxidizing bacteria to AMP inhibition. Ampicillin was totally removed since the first cycle of addition. Exposure to AMP had effects on the abundance of bacterial populations, promoting adaptation of the nitrifying sludge to the presence of the antibiotic and its consumption. Nitrosomonas and Nitrosospira always remained within the dominant genera, keeping the ammonium oxidizing process stable while an increase in Nitrospira abundance was observed, recovering the stability of the nitrite oxidizing process. Burkholderia, Pseudomonas, and Thauera might be some of the heterotrophic bacteria involved in AMP consumption.

Photochemically-induced protein tyrosine nitration in vitro and in cellula by 5-methyl-1,4-dinitro-1H-imidazole (DNI): synthesis and biochemical characterization

The photochemical nitrating agent 5-methyl-1,4-dinitro-1H-imidazole (DNI) has been recently described as an effective tool for nitrating tyrosine residues in proteins under 390 nm irradiation (Long T. et al., 2021). Herein, we describe the one-step synthesis of DNI from the precursor 4-methyl-5-nitro-1H-imidazole with good yield (66%) and high purity (>99%). Spectral analysis of DNI reveals two maximum peaks (228 and 290 nm) with maximum nitration yields and kinetics occurring at 290 nm. Electron paramagnetic resonance (EPR)- and mass spectrometry (MS)- spin trapping analysis evidenced the formation of nitrogen dioxide (•NO2) upon irradiation of DNI, implying the homolysis of the N–N bond in the DNI molecule. Irradiation of DNI at 290, 390 nm, or UVA light (315–400 nm), produced tyrosine nitration, with yields approaching ca. 30% with respect to DNI at 290 nm exposure. Indeed, using alpha-synuclein as a model protein, the main protein post-translational modification triggered by DNI was the generation of 3-nitrotyrosine as shown by MS analysis. Additionally, the formation of di-tyrosine was also observed. Finally, intracellular •NO2 production upon DNI photolysis in bovine aortic endothelial cells was evidenced by the nitration of the tyrosine analog probe p-hydroxyphenylacetic acid (PHPA) and cellular protein tyrosine nitration.

Effects of different rates of nitrogen fertilizer on apple yield, fruit quality, and dynamics of soil moisture and nitrate in soil of rainfed apple orchards on the Loess Plateau, China

Nitrogen (N) and water deficiency jointly limit apple production in semiarid apple-producing regions worldwide. A 4-year field experiment (2017–2020) was conducted on China’s Loess Plateau to systematically identify the responses of apple yields, fruit quality, and the dynamics of soil water and NO3−-N in 6-m soil profiles to different N (i.e., urea) application rates of 0, 300, 450, 600, 750, and 900 kg N ha−1. The results showed that apple yield averaged 30.02 t ha−1, with remarkable interannual fluctuations, although its differences between N rates were not statistically significant during 2017–2020. Similar responses were recorded for fruit quality indices, except that N-fertilization significantly increased total soluble solids compared with the non-N treatment. Interestingly, soil moisture differed considerably between N rates within the 100–300 cm depth, showing increasing soil moisture with increasing N rates, while an opposite trend was observed at 500–600 cm. The calculated minimum N rates achieving the balanced and maximum soil water storage within the 6-m profile (SWS6 m) were 244 and 323 kg ha1, respectively. Distinctive responses of NO3−-N to N rates were observed at 100–300 cm depth, whereas equivalent NO3−-N concentrations between N rates were recorded across the 520–600 cm depth. The minimum N rates achieving the balanced and maximum residual soil NO3−-N within the 6-m profile (RSN6m) were 412 and 509 kg N ha1, respectively. Notably, SWS significantly linearly increased as a function of RSN across the 6-m soil profile, implying the capacity of N fertilizer to facilitate soil moisture. Collectively, N fertilization slightly affected apple yield and fruit quality but significantly altered soil moisture and NO3−-N within the 6-m soil profile. An N application rate of 412 kg ha1 was recommended to support apple production and maintain balanced SWS6 m and RSN6 m for rainfed apple orchards on China's Loess Plateau.

Oxygen-deficient WO3-x spheres for electrochemical N2 oxidation to nitrate

Nitrate synthesis via the electrochemical nitrogen oxidation reaction (e-NOR) is widely recognized as a potential alternative to the energy-intensive Ostwald process. However, electrocatalysts with strong N2 adsorption and activation abilities remain largely undeveloped due to kinetic hindrances caused by the high bond energy of NN. Here we designed a hollow WO3 sphere with an optimal concentration of oxygen vacancies and studied its e-NOR performance. The optimally synthesized oxygen-deficient WO3 (WO3-x) achieved a high nitrate yield of 311.15 µmol h−1gcat.-1 and a Faraday efficiency of 2.00 %, which is probably due to the presence of a moderate amount of oxygen vacancies on the WO3-x surface and the hollow spherical structure, which further improves the accessibility of the inner active surface. Our work could potentially stimulate research into transition metal oxide-based materials for e-NOR applications.

Replacing Mineral Fertilizer with Nitrified Human Urine in Hydroponic Lettuce (Lactuca sativa L.) Production

Source-separated, nitrified, and decontaminated human urine constitutes a promising plant fertilizer that contains a large share of the nitrogen and phosphorus in household wastewater, and other plant nutrients. However, human urine contains high levels of sodium and chloride that can affect salt-sensitive greenhouse crops. Replacing mineral fertilizer with nitrified urine fertilizer could reduce the environmental impact of lettuce production in hydroponic systems, if marketable yield, appearance, and produce quality are not affected. In the present study, a treatment combination of a nitrified urine fertilizer and mineral fertilizers was used to grow lettuce through the nutrient film technique. This was compared to a conventionally fertilized control treatment. No significant differences were observed regarding yield, phenotype, and contents of nitrate, heavy metals, phenolic acids, and chlorophyll in leaf tissue. Calcium content was significantly reduced and sodium was elevated in nitrified urine treatment. For the elements nitrogen, phosphorous, and potassium, a saving of 48%, 13%, and 15% was calculated, respectively. The calculated carbon footprint from the total fertilizer production was reduced by 34.25%, caused by the nitrified urine treatment. Based on these results, a nutrient solution composed of nitrified urine fertilizer combined with mineral fertilizer may be a promising alternative for growers to produce lettuce with a reduced environmental impact without loss of plant quantity and quality.

Nitration of Phenol with Water Activated by Pulsed Hot Plasma Radiation

The nitration of phenol with plasma-activated water (PAW) generated by pulsed radiation of an electric spark discharge has been studied. Long-lived nitrogen-containing active species that accumulate in water during treatment are nitrous acid and the …ONOOH/ONOO− complex, which decomposes into peroxynitrite and peroxynitrous acid. Their concentration in PAW after 10 min of treatment was ~10−3 mol/L. When PAW is mixed with phenol in a 1 : 1 ratio, the identified reaction product is 4-nitrophenol. The yieldof nitration through PAW is equal to the nitration yield by the direct action of hot plasma radiation on a phenol solution.

Partial nitritation-anammox for treatment of saline wastewater: Hydrazine-assisted salinity adaptation and nitrate control

In biological wastewater treatment, salinity can significantly restrict bacterial activity, and a long adaptation period to the saline condition is needed. This study investigated the feasibility of using partial nitritation-anammox (PNA) in an integrated fixed-film activated sludge (IFAS) reactor for enhanced biological nitrogen removal from saline municipal wastewater. The experimental results show that the salinity increase in the influent seriously affected the activity of anammox bacteria and disrupted the PNA process for autotrophic nitrogen removal when seawater was added to a 20% proportion with a resultant salinity of around 6.5‰. However, the addition of N2H4 (dosage: 5 mg/L for 3 weeks), an exogenous enhancer of both ammonia-oxidizing bacteria and anammox bacteria, effectively facilitated the rapid recovery and adaptation of PNA to salinity stress with a negligible additional cost for long-term operation. The PNA-IFAS reactor achieved a nitrogen removal capacity of 83.4 ± 5.9 mg N/(L‧d) in treating the saline municipal wastewater containing 40% seawater and an ammonia-N concentration of around 60 mg N/L. Salinity in the influent advantageously suppressed the activity and growth of the co-existing nitrite-oxidizing bacteria (NOB). The relative abundances of NOB in the suspended sludge (0.15%) and biofilms (0.33%) were kept at low levels, maintaining a low nitrate yield of 6.6 ± 1.5% in the bioreactor. The result suggests that salinity in the influent may offer potential benefits for reducing the risk of nitrate build-up and increasing the robustness of the PNA process for sustainable wastewater treatment.

River Basin Simulations Reveal Wide-Ranging Wetland-Mediated Nitrate Reductions.

River basin-scale wetland restoration and creation is a primary management option for mitigating nitrogen-based water quality challenges. However, the magnitude of nitrogen reduction that will result from adding wetlands across large river basins is uncertain, partly because the areal extent, location, and physical and functional characteristics of the wetlands are unknown. We simulated over 3600 wetland restoration scenarios across the ∼450,000 km2 Upper Mississippi River Basin (UMRB) depicting varied assumptions for wetland areal extent, physical and functional characteristics, and placement strategy. These simulations indicated that restoring wetlands will reduce local nitrate yields and nitrate loads at the UMRB outlet. However, the projected magnitude of nitrate reduction varied widely across disparate scenario assumptions─e.g., restoring 4500 km2 of wetlands (i.e., 1% of UMRB area) decreased mean annual nitrate loads at the UMRB outlet between 3 and 42%. Higher magnitude nitrate reductions correlated with best-case assumptions, particularly for characteristics controlling nitrate loading rates to the wetlands. These results show that simplified claims about basin-scale wetland-mediated water quality improvements discount the breadth of possible wetland impacts across disparate wetland physical and functional conditions and highlight a need for greater clarity regarding the likelihood of these conditions at river basin scales.

Biocatalytic Nitration of Phenols in Microemulsions at Elevated Temperatures Using Enzymes Stabilized on Magnetic Beads

AbstractEnzymes as catalysts in organic syntheses can provide high regio‐ and stereo‐selectivity, which is often not possible with chemical catalysts. Biocatalysis with iron heme enzymes has proven efficient when the enzyme is sequestered in thin films. An added feature is improved stability. For example, peroxidases chemically crosslinked in poly‐lysine in films on silica nanoparticles were stable for 9 hrs or more at 90 °C, and were used for biocatalysis up to 90 °C. We show here for a series of para‐substituted phenols, single nitro‐phenol products can be selectively synthesized using biocatalytic magnetic beads coated with horseradish peroxidase (HRP) crosslinked in polylysine films. Nitrophenols moieties are important as synthetic intermediates and in drugs. For a series of para‐substituted phenols, biocatalytic nitration gave average turnover numbers 1.8‐fold larger at 75 °C than at 25 °C. For phenols giving <50 % conversion after 1 hr at 25 °C, twice the nitration yield was achieved in 1 hr at 75 °C. Results indicate that this approach should be valuable as a general tool for biocatalytic chemical synthesis.

Coupling geochemical and microbial molecular techniques to reveal catchment-scale nitrate yield and fluvial export dynamics

The disturbance of reactive nitrogen (N) on ecosystems and biogeochemical cycles is now one of the most severe environmental problems worldwide. Nitrate (NO3−) is usually a dominant reactive N species in river ecosystems. Excessive NO3− concentrations in rivers have led to eutrophication and consequent ecological and environmental damages. Quantifying catchment-scale NO3− yield and export dynamics is crucial for effective remediation of river NO3− pollution. Frequently, natural abundance isotopes of NO3− in a river (δ15N/δ18O-NO3−) are applied to identify sources and potential transformations of NO3− at a catchment scale, while microbial molecular techniques and 15N pairing experiments are employed to reveal the NO3− production and removal processes and their underlying mechanisms in microenvironments (e.g., sediments and soils). In this study, we developed a novel protocol that couples these complementary geochemical and molecular techniques to quantify catchment-scale NO3− yield and fluvial export dynamics. The protocol links microscopic processes with catchment-scale geochemical characteristics to explicitly describe the NO3− cycling processes and their underlying abiotic and biotic mechanisms within a catchment. We applied the protocol to the Dadu and Jiazela catchments on the Qinghai-Tibet Plateau, and demonstrated the effectiveness of the protocol in determining NO3− yield and export dynamics in the catchments.

Enhanced photocatalytic urea oxidation under neutral medium by reduced graphene oxide coated TiO2 nanoparticles

Nowadays, fertilizers are used to boost crop production. Nitrogenous fertilizers are assimilated as nitrate. Unfortunately, 60–70% of nitrogen is lost due to different leaching processes. Photocatalytic urea oxidation is now emerging as a new methodology. Nitrate conversion is favorable under alkaline pH. However, it can subsequently cause deprotonation of ammonium ions to result ammonia leaching. In this report, efficiencies of bare and RGO loaded TiO2 were examined. In the presence of NaF, the nanocomposite possesses a 9.8(1)% nitrate yield, significantly greater than the other analogous reactions. Such observation will be helpful in developing new methodologies to afford sustainable agriculture.

Long-term post-storage reactivation of a nitrifying sludge in a sequential batch reactor: physiological and kinetic evaluation.

Production, preservation and recovery of sludge with stabilized nitrifying activity over long time can be difficult. Information on the ability of nitrifying sludge to regain its nitrifying activity after long-term storage is still scarce. In this work, the physiological and kinetic changes during the reactivation and stabilization of a nitrifying sludge previously exposed to ampicillin (AMP) were evaluated in a sequential batch reactor (SBR) after its long-term storage (1year) at 4°C. After storage, both ammonium and nitrite oxidizing processes were slow, being nitrite oxidation the most affected step. During the reactivation stage (cycles 1-6), physiological and kinetic activity of the nitrifying sludge improved through the operating cycles, in both its ammonium oxidizing and nitrite oxidizing processes. At the end of the reactivation stage, complete nitrifying activity was achieved in 10h, reaching ammonium consumption efficiencies (ENH4 +) close to 100% and nitrate yields (YNO3 -) of 0.98mg NO3 --N/mg NH4 +-N consumed without nitrite accumulation. During the stabilization stage (cycles 7-17), results indicated that the sludge could maintain a steady-state respiratory process with restoration percentages of 100% for nitrifying specific rates (qNH4 + and qNO3 -) with respect to their values obtained before storage. Furthermore, during the addition of 15mg AMP/L (cycles 18-21), the sludge preserved its metabolic capacity to biodegrade 90% of AMP in 2h. Therefore, long-term storage of nitrifying sludge could be used to preserve nitrifying inocula as bioseeds for bioremediation and bioaugmentation strategies.

“Hole” traps promoting direct nitrate synthesis within flux controlled N2-rich circumstance

Electrooxidation of nitrogen to nitrate is a promising alternative to the energy-intensive process for industrially manufacturing nitrate product. However, nitrogen oxidation reaction (NOR) is still severely restricted by the adsorption and activation of nitrogen. Herein, a catalyst of Fe-doped CeO2 nanorods with “hole” traps promoting activity is designed and made full use of by constructing a flux controlled N2-rich circumstance. Density functional theory (DFT) calculations indicate that due to the narrower band gap and lower Bader charge induced by Fe-doping, the Fe-CeO2 possesses unique enhanced Ce active sites as “hole” traps to capture “hole” (lose electron) for effectively adsorbing N2 and destabilizing NN bond. Subsequently, the active sites trap external “holes” and transfer to the vulnerable activated intermediates under electrooxidation, accompanied by the transfer of electrons from intermediates through active sites, then to external circuit. This gives rise to the lower energy barriers of nitrogen oxidation for the Fe-CeO2. The electrochemical performance of Fe-CeO2 catalyst is experimentally confirmed and is further boosted by constructing a flux controlled N2-rich circumstance. As expected, a considerable nitrate Faradaic efficiency of 43.9 % and a superior nitrate yield rate of 17.41 µg h−1 mg−1 are achieved in this proof-of-concept system.

Understanding Aerobic Nitrogen Photooxidation on Titania through In Situ Time‐Resolved Spectroscopy

AbstractNitrate is an important raw material for chemical fertilizers, but it is industrially manufactured in multiple steps at high temperature and pressure, urgently motivating the design of a green and sustainable strategy for nitrate production. We report the photosynthesis of nitrate from N2and O2on commercial TiO2in a flow reactor under ambient conditions. The TiO2photocatalyst offered a high nitrate yield of 1.85 μmol h−1as well as a solar‐to‐nitrate energy conversion efficiency up to 0.13 %. We combined reactivity and in situ Fourier transform infrared spectroscopy to elucidate the mechanism of nitrate formation and unveil the special role of O2in N≡N bond dissociation. The mechanistic insight into charge‐involved N2oxidation was further demonstrated by in situ transient absorption spectroscopy and electron paramagnetic resonance. This work exhibits the mechanistic origin of N2photooxidation and initiates a potential method for triggering inert catalytic reactions.

Self-supported Mo-doped TiO2 electrode for ambient electrocatalytic nitrogen oxidation

Electrocatalytic nitrogen oxidation reaction (NOR) provides an eco-friendly pathway for ambient N2 fixation and nitrate/nitric acid synthesis but is plagued by sluggish kinetics due to the weak adsorption of N2 molecules and cleavage of NN triple bonds. Herein, a self-supported Mo-doped TiO2 electrode prepared by one-step hydrothermal method is reported for efficient nitrogen oxidation. Electrochemical measurements and spectroscopy investigations reveal that the inert TiO2 is effectively triggered by Mo substitution in terms of enhanced N2 adsorption and activation. As further confirmed by density function theory calculations, the incorporation of Mo reduces the barrier of the rate-determining step and provides an energetically favorable NOR pathway compared to pristine rutile TiO2. Electrochemical results show that Mo-doped TiO2 electrode achieves a nitrate yield of 5.44 μg h−1 mgcat−1 (or 8.77 ± 0.39 nmol h−1 cm−2) with a Faradaic efficiency of 2.88%. The formation of nitrate from N2 under positive bias is further demonstrated by in situ ultraviolet-visible spectrophotometry. This work provides experimental and theoretical evidences that Mo doping can stimulate the stable yet electrocatalytically inert Ti-based oxide toward NOR via promoting active sites formation and lowering activation energy barriers.

Detecting trace dissolved organic nitrogen (DON) in freshwater by converting DON rapidly into nitrate with VUV/H2O2 pretreatment

Dissolved organic nitrogen (DON) plays a key role in many biogeochemistry and engineering processes such as forming nitrogenous disinfection byproducts. However, detecting aqueous DON at trace levels is challenging currently because conventional DON conversion methods have very high method detection limits (MDL). In addition, DON is measured indirectly by subtracting dissolved inorganic nitrogen (DIN) from total dissolved nitrogen (TDN), which can propagate analytical errors of each analyte. In order to solve these issues, we isolated DON from DIN with electrodialysis before and herein tested vacuum ultraviolet (VUV) in tandem with several oxidants to convert DON completely into nitrate for subsequent N analysis. Results showed that H2O2 was more suitable than chlorine and persulfate because VUV/chlorine or VUV/persulfate is either inefficient to convert DON or subjected to nonnegligible N loss. To verify the efficiency, we evaluated the effects of typical water and operating variables on the conversions of four model DON compounds and their yields of nitrate. Under optimal conditions (pH 10.3 and 500 mg/L H2O2), the process converted DON completely into nitrate within just 60 min. Compared to conventional TDN analytical methods, the VUV/H2O2 method features not only better analytical precision but also lower MDL because the formed nitrate can be analyzed at very low MDL by ion chromatography (IC). So, this approach moves one step further to achieve a conceptually new DON analytical method by coupling electrodialysis, VUV/H2O2, and IC.