Nitrite In Wastewater Research Articles

Kinetics of Nitrite Adsorption onto a Styrene Divinylbenzene Macroporous Strong Base Polymer

A suitable adsorbent for the treatment of nitrite in wastewater was investigated using a macroporous styrene divinylbenzene strong base polymer for 10−3 M to 6 x 10−3M NaNO2 at room temperature using a batch protocol. The supernatant concentrations were determined rapidly and inexpensively by an electrochemical method. To investigate the sorption mechanism and the rate-determining step, four kinetic models were investigated. The pseudo-second order kinetic model best fit the nitrite adsorption onto the polymer. The highest correlation coefficient (0.9999) and chi square (7.59 x 10−4) values were obtained for 0.046 to 0.276 g L−1 NO2 - which is characteristic of chemosorption. The results demonstrate that the investigated polymer is suitable at room temperature for removing nitrites for water to the legally allowed values for 10−3 M to 1.5 x 10−3 M NaNO2 but dilution is required for higher concentrations.

Nitrite anodic oxidation at Ni(II)/Ni(III)-decorated mesoporous SnO2 and its analytical applications.

Hydrothermally formed mesoporous SnO2 was used as a support for nickel chemical deposition and, after subsequent thermal treatment, a high specific surface area (36 m2 g-1) Ni/SnO2 material was obtained. XPS analysis has shown that in the Sn 3d region the spectrum is similar to that of pristine SnO2, whereas Ni species are present on the surface as NiO, Ni2O3 and Ni(OH)2. Mixing Ni/SnO2 with a small amount of Black Pearls (BP) leads to a significant enhancement of the resulting Ni/SnO2-BP composite activity for nitrite anodic oxidation, presumably due to the higher surface area (115 m2 g-1), to better electrical conductivity and to a certain contribution of the BP to an increase in surface density of the active sites. Ni/SnO2-BP also outperforms pristine BP (in terms of Tafel slopes and electron-transfer rates), most likely due to the fact that the Ni(II)/Ni(III) couple can act as an electrocatalyst for nitrite oxidation. A voltammetric method is proposed for the determination of nitrite, over a concentration range of three orders of magnitude (0.05 to 20 mM), with good reproducibility, high stability and excellent sensitivity. The high upper limit of the dynamic range of the analytically useful response might provide a basis for the reliable quantification of nitrite in wastewater.

High-Efficiency Ammonia Electrosynthesis on Anatase TiO2-x Nanobelt Arrays with Oxygen Vacancies by Selective Reduction of Nitrite.

Electrocatalytic reduction of nitrite to NH3 provides a new route for the treatment of nitrite in wastewater, as well as an attractive alternative to NH3 synthesis. Here, we report that an oxygen vacancy-rich TiO2-x nanoarray with different crystal structures self-supported on the Ti plate can be prepared by hydrothermal synthesis and by subsequently annealing it in an Ar/H2 atmosphere. Anatase TiO2-x (A-TiO2-x) can be a superb catalyst for the efficient conversion of NO2- to NH3; a high NH3 yield of 12,230.1 ± 406.9 μg h-1 cm-2 along with a Faradaic efficiency of 91.1 ± 5.5% can be achieved in a 0.1 M NaOH solution containing 0.1 M NaNO2 at -0.8 V, which also exhibits preferable durability with almost no decay of catalytic performances after cycling tests and long-term electrolysis. Furthermore, a Zn-NO2- battery with such A-TiO2-x as a cathode delivers a power density of 2.38 mW cm-2 as well as a NH3 yield of 885 μg h-1 cm-2.

The eco enzyme application to reduce nitrite in wastewater as the sustainability alternative solution in garbage and wastewater problems

The increasing population growth has an impact on increasing problems in wastewater quality and garbage volume. It is a need to develop a sustainability solution for both problems. In this research, the papaya fruit and spinach vegetable garbage were used as raw organic materials and fermented for six months. This study objective was to determine whether eco enzymes can be used to reduce nitrite concentration in wastewater. The research method was conducted on a laboratory scale with the artificial samples in a batch system. The result showed that eco enzyme made from a mixture of papaya and spinach can reduce the nitrite concentration in the water sample. The t-test showed that the effect of eco enzyme application in reducing nitrite in water samples was significant. The application of eco enzyme 0%, 2%, 4%, and 6% respectively during 10 hours exposure showed the nitrite removal were 0.3 %, 20%, 29%, and 35 %. It can be seen that the reduction of nitrite concentration in samples added by eco enzyme was caused by eco enzyme activity. The application at a higher concentration of 10%, 15%, and 20% showed that nitrite removal efficiencies were 35.7%, 36.7%, 46.7%, 49.4% respectively during 7 hours exposure. It can be concluded that a longer time exposure, and also the more eco enzyme concentration, showed the more result in the effect of nitrite reduction concentration in water. 4. By this study it is proven that application of eco enzyme made from organic garbage can be an alternative solution for garbage and wastewater quality problem.

Fast and simultaneous detection of dissolved BOD and nitrite in wastewater by using bioelectrode with bidirectional extracellular electron transport

Timely and simultaneously detecting BOD and nitrite concentrations is of great significance for curbing of water pollution and adjusting wastewater treatment strategies. However, existing BOD and nitrite biosensors cannot perform synchronous detection due to their single electroactivity and differences in detection time. This study reported a novel dual-function electrochemical biosensor (DFEB) that could perform fast, simultaneous detection of nitrite and dissolved BOD. DFEB conducted a potential-step chronoamperometry on the mixed-bacteria bioelectrode with bidirectional electron transfer ability to obtain response signals. DFEB accurately measured dissolved BOD in the range of 5 ∼ 100 mg BOD L−1 and nitrite in the range of 0.05 ∼ 16 mg NO2−-N L−1 within 20 min and maintain stable performance over 200 tests. DFEB performed well in artificial wastewater, aquatic wastewater, anaerobic tank effluent and anammox effluent, with relative errors < 15.7% and 16.8% in detecting nitrite and dissolved BOD, respectively. Our study provided a feasible way to develop multifunctional biosensors for detecting pollutants with different redox properties in wastewater.

Analytical Chemistry Optical Chemosensor for Spectrophotometric Determination of Nitrite in Wastewater

AbstractAn easy, sensitive, and rapid spectrophotometric method has been documented for determining nitrite (NO2−) in water and wastewater. To detect and adsorb harmful nitrite ions from wastewater efficiently; a stable optical nanosensor was manufactured by immobilization of 1‐Naphthylamine (1‐NA) over mesoporous silica nanospheres (MSNs). The determination of nitrite was based on the reaction of nitrite with the optical sensor (1‐NA chemosensor) and forming diazonium salt which was subsequently coupled with N‐(1‐Naphthyl) ethylenediamine dihydrochloride (NED) to form a stable brownish azo dye. The dye shows an absorption maximum at 457 nm. The optimal conditions for the reaction and the analytical parameters were evaluated. The method has been designed by controlling the acidity, the quantity of reagents required and the amount of tolerance of certain ions. The range of linearity was found to be 0.108‐10.8 μM of nitrite. The nitrite identification detection limit and quantitation limit are 0.106 μM and 0.353 μM, respectively. The performance of the chemosensor in extracting the NO2− ions was tested. According to the Langmuir isotherms, the adsorption pattern was highly competent, where the removal capacity for NO2− ion was 156.0 mg/g by the chemosensor. Some cations and anions have been identified as the competing ions; these ions were not affected on the NO2− ion in both detection and adsorption processes.

Effect of external hydrazine addition on anammox reactor start-up time

Hydrazine is an intermediate product of the anaerobic ammonium oxidation (Anammox) process where both ammonium and nitrite in wastewater are converted to nitrogen gas by bacteria. In this study the effect of external hydrazine addition (5, 10, 15, and 20 mg/L) on the start-up period of the Anammox process was studied using sequencing batch reactors (SBRs). The SBR with an addition of 10 mg/L hydrazine took only 7 weeks to stabilize and achieve the maximum removal of ammonium and nitrite, whereas the SBR without the addition of hydrazine took 12 weeks. The amount of Heme C extracted from the biomass indicated that externally added hydrazine accelerated the growth of Anammox bacteria and reduced the release of nitrous oxide gas from the reactors.

Construction of iron porphyrin/titanoniobate nanosheet sensors for the sensitive detection of nitrite

The single-layered well-dispersed HTi2NbO7 nanosheets (NSs) with the thickness of ~ 1.08 nm were obtained by a simple exfoliation method. The electrochemical sensors based on HTi2NbO7 NSs and 5,10,15,20-tetrakis (N-methylpyridinium-4-yl) porphyrinato iron(III) (FeTMPyP) for sensitive detection of nitrite were then fabricated through the self-assembly technique, which was certified by Zeta potential analysis. The prepared samples were fully characterized by X-ray diffraction, X-ray energy dispersive spectrometer, scanning electron microscope, atomic force microscope, high-resolution transmission electron microscope, Fourier transform infrared and ultraviolet–visible spectrum. Electrochemical measurements demonstrated that FeTMPyP/HTi2NbO7 NSs nanocomposites exhibited enhanced electrocatalytic activities toward the oxidation of nitrite due to increased electron-transport properties. The oxidation peak current of nitrite was linearly associated with its concentration in the range from 0.0999 to 3.15 mmol L−1, with the detection limit of 3.15 × 10−5 mol L−1 (S/N = 3). The possible mechanism for nitrite oxidation on the surface of modified electrode was proposed. This study indicated that this biosensor has satisfactory stability, and detects nitrite in wastewater with strong anti-interference performance and good recovery.

Aerobic granular sludge for simultaneous accumulation of mineral phosphorus and removal of nitrogen via nitrite in wastewater

Lab-scale experiments were conducted to investigate the aerobic granular sludge process for simultaneous phosphorus (P) accumulation by chemical precipitation and biological nitrogen removal via nitrite. The P-rich granules were successfully incubated in a sequencing batch reactor, in which simultaneous nitrification-denitrification occurred via nitrite. The average diameter of the P-rich granules was 2.47 mm and the P content in granules was much higher than that in other granular systems with enhanced biological phosphorus removal process. Filamentous bacteria (genus Thiothrix) in the granules and the long sludge retention time (30 d) of the granular system played a crucial role in accumulation of precipitated phosphate. X-ray diffraction analysis, scanning electron microscopy coupled with energy dispersive X-ray and the experimental design using response surface methodology confirmed that the main mineral patterns in P-rich granules were Ca-Mg phosphate and whitlockite.

UV-Spectral Probe for Measuring Chemical Oxygen Demand, Nitrate and Nitrite in Wastewater

UV-Spectral Probe for Measuring Chemical Oxygen Demand, Nitrate and Nitrite in Wastewater

Microwave enhanced chemical reduction process for nitrite-containing wastewater treatment using sulfaminic acid

High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced chemical reduction process (MECRP) using sulfaminic acid (SA) was proposed as a new manner to treat such type of wastewater. Based on lab-scale experiments, it was shown that 75%–80% nitrite (NO 2 −) could be removed within time as short as 4 min under 50 W microwave irradiation in pH range 5–10 when molar ratio of SA to nitrite (SA/NO 2 −) was 0.8. Pilot-scale investigations demonstrated that MECRP was able to achieve nitrite and chemical oxygen demand (COD) removal with efficiency up to 80% and 20%, respectively under operating conditions of SA concentration 80 kg/m 3, SA/NO 2 − ratio 0.8, microwave power 3.4 kW, and stirring time 3 min. Five-day biological oxygen demand (BOD 5)/COD value of treated effluent after MECRP was increased from 0.05 to 0.36 (by 620%), which clearly suggested a considerable improvement of biodegradability for subsequent biological treatment. This study provided a demonstration of using microwave irradiation to enhance reaction between SA and nitrite in a short time, in which nitrite in wastewater was completely converted into nitrogen gas without leaving any sludge and secondary pollutants.

Characterisation of a gas-diffusion membrane-based optical flow-through sensor exemplified by the determination of nitrite

A membrane-based optical flow-through sensor is described which can be alternatively used for absorbance and reflectance detection within the receiver channel of a sandwich-type gas-diffusion separation cell. Using the common spectrophotometric detection scheme for nitrite based on azo-dye formation, the principle features of the flow-through sensor are investigated and the performance is characterised particularly with regard to selectivity and sensitivity aspects. The determination of nitrite in waste waters and meat extracts was used to demonstrate the applicability to real sample analysis. The main advantage of the proposed flow-through sensor is the absence of interferences due to sample colour and turbidity enabling direct sample admission of complex samples without tedious sample pretreatment.

Stability of Nitrite in Wastewater and Its Determination by Ion Chromatography

Stability of Nitrite in Wastewater and Its Determination by Ion Chromatography

Determination of Nitrite by a Modified Electrode of Poly(1-Naphthylamine) Film Doped with Dawson-Type Heteropolyanions

The voltammetric behavior of the electrode modified with poly(1-naphthylamine) film doped with α-P2W18 heteropolyanions was investigated. The concentration of the modifier, the acidity of the medium and the scan range of potential had obvious effects on the electrochemical characteristics of the electrode. The electrocatalytical characteristics of the film electrode were studied by cyclic voltammetry and other methods. It is suggested that the electrocatalytic reaction of nitrite is controlled by its diffusion. The applicability of the electrode was assessed by the determination of nitrite in waste-water. Determination limit for nitrite was 5 × 10−7 mol.L−1.

Simultaneous determination of no3 – and no2 – in fisheries wastewaters high in chloride concentration by capillary ion electrophoresis with direct uv detection

The simultaneous determination by capillary ion electrophoresis of nitrate and nitrite in wastewaters with chloride concentrations of 15 to 23g/l is described. Chloride concentrations over 200mg/l hampered the determination; thus, lead, mercuric and silver acetate were used to precipitate chloride. Silver acetate added in 1.5 times the stoichiometric amount for AgCl formation gave the best results in terms of nitrate and nitrite peak resolution.

Determination of Nitrite by Reverse Flow Injection Analysis

Abstract A simple method for the determination of nitrite using reverse flow injection analysis is proposed. Safranine-T is quickly diazotised by nitrite and coupled with an excess of this dye. The reverse FIA mode with a single-channel gives maximum sensitivity. The influence of reaction variables and rFIA manifold, the precision and accuracy of the method and the effects of foreign ions are studied. The procedure is applied to the determination of nitrite in waste waters and cured meats.

Kinetic determination of trace amounts of nitrite based on its inhibitory effect on the photochemical reaction between iodine and ethylenediaminetetraacetic acid

A kinetic method for the determination of trace amounts of nitrite based on its inhibitory effect on the photochemical reaction between l2 and EDTA (6 × 10–5M l2, 2 × 10–4M EDTA, pH 5, 40 °C and 2000 lux) is reported. The reaction is monitored amperometrically (Pt-SCE, 100 mV) by measuring the time required for the current due to iodine to decrease to zero. Nitrite can be determined at concentrations between 3 and 100 ng ml–1. The proposed method has been applied to the determination of nitrite in waste waters and alkaline nitrates.

Spectrophotometric Determination of Nitrite in Wastewater with 4,5-Dihydroxycoumarin

Abstract A rapid and simple spectrophotometric method was developed for the determination of nitrite in wastewater. The procedure was based on the extraction of nitrite with ethyl acetate solution of 4,5-dihydroxycoumarin. Beer's law obeyed up to 0.75 ppm of nitrite-nitrogen. Results obtained by using the proposed method on waste-water samples agreed well with those obtained by the diazotising-coupling method.