scholarly journals Investigations on Ozone-Based and UV/US-Assisted Synergistic Digestion Methods for the Determination of Total Dissolved Nitrogen in Waters

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 490 ◽  
Author(s):  
Xiaofang Sun ◽  
Huixuan Chen ◽  
Zhengyu Liu ◽  
Mengfei Zhou ◽  
Yijun Cai ◽  
...  
Keyword(s):  
Water Sample ◽  
Reaction Temperature ◽  
Conversion Rate ◽  
Digestion Method ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
On Line ◽  
Digestion Efficiency ◽  
Uv Lamp ◽  
N Compounds

Over the past two decades, the alkaline persulfate oxidation (PO) with thermal and/or ultraviolet (UV) assisted digestion method has been widely used for digestion of nitrogen containing compounds (N-compounds) in water quality routine analysis in laboratory or on-line analysis, due to its simple principle, high conversion rate, high percent recovery, low-cost. However, this digestion method still has some inevitable problems such as complex operations, high contamination potential, batch N blanks, higher reaction temperature (120–124 °C) and time-consuming (30–60 min). In this study, ozone (O3) was selected as the oxidant for digestion of N-compounds through analysis and comparison firstly. Secondly, we proposed and compared the UV and/or ultrasound (US) combined with ozone (UV/O3, US/O3 and UV/US/O3) synergistic digestion methods based on O3 with sole O3 oxidation method on digestion efficiency (digestion time and conversion rate) of standard N-compounds. Simultaneously, the influence of reaction temperature, pH of water sample, concentration of O3 and mass flow rate, UV intensity, US frequency and power on digestion efficiency were investigated, and then the optimum parameters for digestion system were obtained. Experimental results indicated that UV radiation can effectively induce and promote the decomposition and photolysis of O3 in water to generate hydroxyl radicals (•OH), while US can promote the diffusion and dissolution of O3 in water and intensify the gas-liquid mass transfer process for the reaction system. Meanwhile, results showed that the UV/US/O3 synergistic digestion method had the best digestion efficiency under the optimum conditions: water sample volume, 10 mL; pH of water sample, 11; O3 mass flow rate, 3200 mg/h; reaction temperature, 30 °C; digestion time, 25 min; UV lamp power, 18 W; distance between UV lamp and reactor, 2 cm; US frequency, 20 kHz; US power, 75 W. The conversion rate (CR) of synthetic wastewater samples varied from 99.6% to 101.4% for total dissolved nitrogen (TDN) in the range of 1.0~4.0 mg/L. The UV/US/O3 synergistic digestion method would be an effective and potential alternative for digestion of N-compounds in water quality routine analysis in laboratory or on-line analysis.

scholarly journals Novel AOPs-Based Dual-Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Water

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2751
Author(s):  
Rongyao Cai ◽  
Weiqiang Shou ◽  
Xiaochun Hu ◽  
Luyue Xia ◽  
Mengfei Zhou ◽  
...  
Keyword(s):  
Online Monitoring ◽  
Digestion Time ◽  
Digestion Method ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Digestion Efficiency ◽  
N Compounds

Based on a synergistic digestion method of ultraviolet combined with ozone (UV/O3), this article investigates the reaction characteristics of nitrogen-containing compounds (N-compounds) in water and the influence of ions on digestion efficiency. In this respect, a novel and efficient AOPs-based dual-environmental digestion method for the determination of total dissolved nitrogen (TDN) in waters with complex components is proposed, in the hopes of improving the detection efficiency and accuracy of total nitrogen via online monitoring. The results show that inorganic and organic N-compounds have higher conversion rates in alkaline and acidic conditions, respectively. Meanwhile, the experimental results on the influence of Cl−, CO32−, and HCO3− on the digestion process indicate that Cl− can convert to radical reactive halogen species (RHS) in order to promote digestion efficiency, but CO32− and HCO3− cause a cyclic reaction consuming numerous •OH, weakening the digestion efficiency. Ultimately, to verify the effectiveness of this novel digestion method, total dissolved nitrogen samples containing ammonium chloride, urea, and glycine in different proportions were digested under the optimal conditions: flow rate, 0.6 L/min; reaction temperature, 40 °C; pH in acidic conditions, 2; digestion time in acidic condition, 10 min; pH in alkaline conditions, 11; digestion time in alkaline conditions, 10 min. The conversion rate (CR) of samples varied from 93.23% to 98.64%; the mean CR was greater than 95.30%. This novel and efficient digestion method represents a potential alternative for the digestion of N-compounds in the routine analysis or online monitoring of water quality.

Analysis of total dissolved nitrogen in natural waters by on-line photooxidation and flow injection

1994 ◽  
Vol 293 (1-2) ◽  
pp. 155-162 ◽  
Author(s):  
I.D. McKelvie ◽  
M. Mitri ◽  
B.T. Hart ◽  
I.C. Hamilton ◽  
A.D. Stuart
Keyword(s):  
Flow Injection ◽  
Natural Waters ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
On Line

UVC-Thermal Coupled Digestion without Oxidant for the Detection of Total Phosphorus

2015 ◽  
Vol 645-646 ◽  
pp. 847-852
Author(s):  
Long Li ◽  
Chao Bian ◽  
Jian Hua Tong ◽  
Heng Li ◽  
Shan Hong Xia
Keyword(s):  
Water Sample ◽  
Hydroxyl Radicals ◽  
Total Phosphorus ◽  
Uv Light ◽  
Quartz Tube ◽  
Digestion Method ◽  
Heating Unit ◽  
Digestion Rate ◽  
Type Device ◽  
Digestion Efficiency

In this paper, a catalyst-free and non-oxidant digestion method based on UVC and thermal coupled mechanism was developed for the digestion of total phosphorus (TP). Two kinds of digestion devices, “hamburg-type” and “screw-type”, were designed and compared to get higher digestion efficiency. Both of the two devices contain a quartz tube, UV light tubes, a flexible heating unit, UV light reflecting layer, and a temperature meter, etc. UVC light with the wavelength of 254nm is used to produce hydroxyl radicals to degrade TP into phosphate in water. Compared with the “hamburg-type” digestion device, the “screw-type” device exhibited a higher digestion rate. At the condition of 1 hour and 80°C, the digestion rate of 1mg/L (by weight of P) water sample can come to 96% by using the “screw-type” device.

On-Line Technique To Determine the Isotopic Composition of Total Dissolved Nitrogen

2007 ◽  
Vol 79 (22) ◽  
pp. 8644-8649 ◽  
Author(s):  
Dries Huygens ◽  
Pascal Boeckx ◽  
Jan Vermeulen ◽  
Xavier De Paepe ◽  
Andrew Park ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
On Line

The Effect of Technological Parameter on the Co-liquefaction of Coal with Lignin

2012 ◽  
Vol 577 ◽  
pp. 167-170
Author(s):  
Qing Jie Tang ◽  
Zhi Hong Wang
Keyword(s):  
High Pressure ◽  
Production Rate ◽  
Reaction Temperature ◽  
Conversion Rate ◽  
Technological Parameter ◽  
Initial Pressure ◽  
Oil Production ◽  
Important Influence ◽  
Mixture Ratio

The co-liquefaction of coal with lignin was studied by minisize high pressure reactor, tetralin and Fe2O3 were used as solvent and catalyst, and the study was focused on the reaction temperature, initial pressure of hydrogen and mixture ratio of lignin with coal. The results showed that the reaction temperature, the initial pressure and mixture ratio has the important influence on the conversion rate of coal, the oil production rate in the process of co-liquefaction with coal and the lignin. Effect of co-liquefaction is best in reaction temperature 440°C, initial pressure 9Mpa, mixture ratio of lignin and coal for 2∶8, the conversion rate of coal and the oil production rate respectively achieves 87.66% and 50.39%.

scholarly journals Quantification of multiple simultaneously occurring nitrogen flows in the euphotic ocean

2016 ◽  
Author(s):  
Min Nina Xu ◽  
Yanhua Wu ◽  
Li Wei Zheng ◽  
Zhenzhen Zheng ◽  
Huade Zhao ◽  
...  
Keyword(s):  
Matrix Equation ◽  
Ammonia Oxidation ◽  
Mass Conservation ◽  
Quantitative Information ◽  
Nitrite Oxidation ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Transformation Rates ◽  
The Matrix ◽  
Multiple Transformation

Abstract. The general features of the N cycle in the sunlit ocean are known, but quantitative information about multiple transformation rates among nitrogen pools, i.e., ammonium (NH4+), nitrite (NO2−), nitrate (NO3−) and particulate/dissolved organic nitrogen (PN/DON), are limited due to methodological difficulties. By adding a single 15N-labelled NH4+ tracer into incubators, we monitor ed the changes in concentration and isotopic composition of the total dissolved nitrogen (TDN), PN, NH4+, NO2−, and NO3− pools to trace the 15N and 14N flows. Based on mass conservation and isotope mass balance, we formulate d a matrix equation that allow edus to simultaneously derive the rates of multiple transformation processes in the nitrogen reaction web . We abandoned inhibitors and minimized the alteration of the system by adding a limited amount of tracer. In one single incubation, solution of the matrix equation provided the rates of NH4+, NO2−, and NO3− uptake; ammonia oxidation; nitrite oxidation; nitrite excretion; DON release; and potentially, the remineralization rate. To our knowledge, this is the first and most convenient method designed to quantitatively and simultaneously resolve complicated nitrogen transformation rates, albeit with some uncertainties. Field examples are given, and c omparisons with conventional labeling methods are discussed.

scholarly journals Active layer slope disturbances affect seasonality and composition of dissolved nitrogen export from High Arctic headwater catchments

2017 ◽  
Vol 3 (2) ◽  
pp. 429-450 ◽  
Author(s):  
Melissa J. Lafrenière ◽  
Nicole L. Louiseize ◽  
Scott F. Lamoureux
Keyword(s):  
Active Layer ◽  
High Arctic ◽  
Rainfall Runoff ◽  
Headwater Catchments ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Nitrate Export ◽  
Limiting Nutrient ◽  
Seasonal Discharge ◽  
The Impact

This study investigates the impacts of active layer detachments (ALDs) on nitrogen in seasonal runoff from High Arctic hillslope catchments. We examined dissolved nitrogen in runoff from an undisturbed catchment (Goose (GS)) and one that was disturbed (Ptarmigan (PT)) by ALDs, prior to disturbance (2007) and 5 years after disturbance (2012). The seasonal dynamics of nitrogen species concentrations and fluxes were similar in both catchments in 2007, but the mean seasonal nitrate concentration and mass flux from the disturbed catchment were on the order of 30 times higher relative to the undisturbed catchment in 2012. Stormflow yielded 45% and 60% of the 2012 total dissolved nitrogen flux in GS and PT, respectively, although rainfall runoff provided less than 25% of seasonal discharge. Results support that through the combined effects of increased disturbance and rainfall, climate change stands to significantly enhance the export of nitrate from High Arctic watersheds. This study highlights that the increase in the delivery of nitrate from disturbance is especially pronounced late in the season when downstream productivity and the biological demand for this often limiting nutrient are high. Our results also demonstrate that the impact of ALDs on nitrate export can persist more than 5 years following disturbance.

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