Nitrate Anions Research Articles

Proton nuclear magnetic resonance (1H NMR) of flammable organic chemicals in radioactive high-level supernatant waste at the Savannah River Site (SRS).

The Savannah River Site stores approximately 36 million gallons of radioactive and hazardous waste that contains approximately 245 million curies. The waste is sent through various chemical processes to reduce its volume and to separate various components. The facility plans to replace formic acid (a chemical used to reduce soluble mercury) with glycolic acid. Recycle solution with glycolate may flow back to the tank farm, where the glycolate can generate hydrogen gas by thermal and radiolytic mechanisms. The current analytical method for detecting glycolate (ion chromatography) in supernatant requires a large dilution to reduce interference from the nitrate anions. Hydrogen nuclear magnetic resonance is an analytical method that requires less sample dilution. It takes advantage of the CH2 group in glycolate. Liquid samples were spiked with four different levels of glycolate to build a calibration line, as it is recommended in the standard addition method. The detection and quantitation limits determined were 1 and 5ppm, respectively, for 32 scans, which is well below the process limit of 10ppm. In one test, 800 scans of a supernatant spiked with 1ppm glycolate resulted in a -CH2 peak with a signal-to-noise ratio of 36.

ВИКОРИСТАННЯ БІОЧАРУ І МІСКАНТУСУ ГІГАНТСЬКОГО (MISCANTHUS GIGANTEUS) ДЛЯ РЕМЕДІАЦІЇ ҐРУНТУ, ЗАБРУДНЕНОГО НАФТОПРОДУКТАМИ

The dynamics of changes in the chemical composition of soils contaminated with oil products during the vegetation of Miscanthus giganteus, as well as under the conditions of adding biochar (biochar) were studied. The possibility of using the culture of Miscanthus giant and biochar for soil remediation under conditions of oil pollution was analyzed. It was shown that the introduction of biochar into the soil enriched it with nitrate nitrogen, which was actively assimilated by giant miscanthus plants during the growing season. The absorption of nitrate anions by plants was especially active in the second series of the experiment, when the soil + biochar was contaminated with diesel fuel. It was established that the content of NH4+ ions in both series of the experiment increased until the end of the growing season. Obviously, ammonium nitrogen is absorbed to a lesser extent by M. giganteus plants, compared to nitrate. The increase in ammonium content can be additionally caused by the activity of soil microbes in the rhizosphere of plants, which contributes to the accumulation of ammonium nitrogen in the soil. It has been shown that miscanthus plants actively absorbed water-soluble forms of phosphorus, especially in the period from June to September. The application of biochar was a significant source of phosphorus, although its release into the soil is a rather slow process. It was determined that additional amounts of potassium were added to the soil with biochar, which was actively used by the M. giganteus culture. The minimum amounts of potassium in both series of studies were absorbed by plants of E groups, where the content of diesel fuel in the soil was the highest. The introduction of petroleum products had a minor effect on the value of exchangeable acidity. The addition of biochar contributed to the shift of the acid-base balance in the direction of alkalinity, but after the end of the miscanthus vegetation (September), a decrease in the pH of the saline extract of the soil was noted. It is shown that the most noticeable decrease in the concentration of diesel fuel in the soil was noted under the conditions of adding biochar and after growing miscanthus, which can be effectively used for the remediation of lands contaminated by oil products.

Molecular modeling and simulation of aqueous solutions of alkali nitrates.

A set of molecular models for the alkali nitrates (LiNO3, NaNO3, KNO3, RbNO3, and CsNO3) in aqueous solutions is presented and used for predicting the thermophysical properties of these solutions with molecular dynamics simulations. The set of models is obtained from a combination of a model for the nitrate anion from the literature with a set of models for the alkali cations developed in previous works of our group. The water model is SPC/E and the Lorentz-Berthelot combining rules are used for describing the unlike interactions. This combination is shown to yield fair predictions of thermophysical and structural properties of the studied aqueous solutions, namely the density, the water activity and the mean ionic activity coefficient, the self-diffusion coefficients of the ions, and radial distribution functions, which were studied at 298K and 1bar; except for the density of the solutions of all five nitrates and the activity properties of solutions of NaNO3, which were also studied at 333K. For calculating the water the activity and the mean ionic activity coefficient, the OPAS (osmotic pressure for the activity of selvents) method was applied. The new models extend an ion model family for the alkali halides developed in previous works of our group in a consistent way.

Supramolecular Behaviour of N,N′‐Bridged Guanidinium Nitrates in the Crystalline State: Identification of Privileged Hydrogen Bond Networks

AbstractUsing the marine natural product ptilocaulin as a starting point, the supramolecular behavior of N,N′‐bridged guanidinium nitrates in the crystalline state was investigated. For this purpose, various N,N′‐bridged guanidines were synthesized (typically by condensation of a 1,2‐ or 1,3‐diamine with cyanogen bromide) and subsequently converted into their nitrate salts with nitric acid. The crystal structures of 28 samples were determined by single crystal X‐ray crystallography and revealed the existence of a few privileged, recurring supramolecular motifs (hydrogen bond networks) formed by charge‐assisted self‐assembly. A topological analysis of possible pseudo‐2D‐patterns derived from the 1 : 1 ion pairs (generated by salt bridge formation between a N,N′‐bridged guanidinium cation and a nitrate anion) through additional H‐bonding uncovered only five conceivable regular structural motifs: (1) a linear chain, (2) an alternating (zig‐zag) chain, (3) a double chain, (4) a tape/ribbon‐type structure, and (5) a cyclotrimer. Experimentally, only the first four of these motives were observed while the cyclotrimer, as a non‐infinite and therefore particular super‐structure, did not occur. Other H‐bonding patterns were found (in three cases) when water was incorporated in the crystals. In two cases, polymorphism was observed. The identified supramolecular preferences prove the value of N,N′‐bridged guanidines as useful and easily tunable building blocks for supramolecular chemistry and crystal engineering.

Solution Structures of Europium Terpyridyl Complexes with Nitrate and Triflate Counterions in Acetonitrile.

Lanthanide-ligand complexes are key components of technological applications, and their properties depend on their structures in the solution phase, which are challenging to resolve experimentally or computationally. The coordination structure of the Eu3+ ion in different coordination environments in acetonitrile is examined using ab initio molecular dynamics (AIMD) simulations and extended X-ray absorption fine structure (EXAFS) spectroscopy. AIMD simulations are conducted for the solvated Eu3+ ion in acetonitrile, both with or without a terpyridyl ligand, and in the presence of either triflate or nitrate counterions. EXAFS spectra are calculated directly from AIMD simulations and then compared to experimentally measured EXAFS spectra. In acetonitrile solution, both nitrate and triflate anions are shown to coordinate directly to the Eu3+ ion forming either ten- or eight-coordinate solvent complexes where the counterions are binding as bidentate or monodentate structures, respectively. Coordination of a terpyridyl ligand to the Eu3+ ion limits the available binding sites for the solvent and anions. In certain cases, the terpyridyl ligand excludes any solvent binding and limits the number of coordinated anions. The solution structure of the Eu-terpyridyl complex with nitrate counterions is shown to have a similar arrangement of Eu3+ coordinating molecules as the crystal structure. This study illustrates how a combination of AIMD and EXAFS can be used to determine how ligands, solvent, and counterions coordinate with the lanthanide ions in solution.

Comparison of ion selectivities of nitrite channel NirC and water channel aquaporin.

nirC gene coding for the nitrite channel of E. coli K12 was cloned into the pET28a vector and expressed in E. coli BL21 cells. 28.5kDa NirC monomer was purified from membrane components of E. coli. Selectivity of NirC for different ions including nitrite, nitrate, sulfate, formate, and acetate anions, and a divalent cation, magnesium, was compared with that of bacterial aquaporin from Halomonas elongata. Water and ion permeability values were determined by measuring the light scattering rates of proteoliposomes containing NirC and aquaporins during their water loss and gain. NirC shows a selective permeability to nitrite and is more resistant to the entry of other anions as compared to aquaporin. The single channel permeability of NirC for nitrite is about 10-fold that of a single aquaporin channel. Both aquaporin and NirC channel proteins were impermeable to MgCl2 and (NH4)2SO4 and their permeability to other tested ions was remarkably lower as compared to nitrite ions. The study also presents the 3D model and channel characteristics of NirC. The translocation channel of E. coli NirC is determined to be larger, and its length is shorter than aquaporin channels. Although the NirC channel throat is more hydrophobic than aquaporin, its water permeability is almost equal to that of aquaporin. The hydrophobic nature of the NirC channel might play an important role in the selective permeability of the channel for nitrite ions.

Adsorption of nitrate and nitrite anion by modified maize stalks from aqueous solutions.

The newly developed aminated maize stalk (AMS) was prepared by a chemical process using charred maize stalk (CMS). The AMS was used for the removal of nitrate and nitrite ions from aqueous media. The effects of initial anion concentration, contact time, and pH were studied by the batch method. The prepared adsorbent was characterized by FT-IR, XRD, FE-SEM , and elemental analysis. The concentration of the nitrate and nitrite solution before and after was determined with the help of a UV-Vis spectrophotometer. The maximum adsorption capacities were found to be 294.11 mg/g for nitrate and 232.55 mg/g for nitrite, respectively, at pH 5 for both ions attaining equilibrium within 60 min. The BET surface area of AMS was found to be 25.3 m2/g with a pore volume of 0.02cc/g. The pseudo-second-order kinetics model fit well, and the adsorption data supported the Langmuir isotherm. The findings revealed that AMS has a high capability for removing nitrate (NO3-) and nitrite (NO2-) ions from their aqueous solutions.

Part I: Predicting performance of Purolite A532E resins for remediation of comingled contaminants in groundwater

Ion exchange (IX) resins are used in pump-and-treat (P&T) facilities to remove soluble groundwater contaminants. However, natural anions present at concentrations orders of magnitude higher than contaminants can compete for IX sites and impact resin lifecycles. Here, the Hanford Site’s 200 West Area P&T facility (Washington State, USA) was selected as a case study because it currently uses two IX resins: Purolite® A532E (A532E) to remove pertechnetate (TcO4-) and DOWEX 21K (DOWEX) to remove uranium from groundwater. Nitrate (NO3-), sulfate (SO42-), chloride (Cl-), and carbonate (CO32-) anions have been identified to potentially compete for A532E and DOWEX IX sites. Hanford-relevant anion groundwater concentrations were used to design a series of laboratory-scale batch experiments to evaluate the impact of competing anions on resin performance and potential kinetic effects. These data are then modeled to obtain Cl--normalized equilibrium exchange coefficients (K) needed to predict IX resin performance. The work is presented in two parts, with IX performance evaluated for A532E in Part I and DOWEX in Part II. Part I results demonstrate that TcO4- uptake is not impacted by NO3-, SO42-, Cl-, CO32- (as HCO3-) and U(VI) carbonate anions, with KTcO4-/Cl- > 4,000, likely due to the high selectivity of A532E trihexylammonium sites for the large, weakly hydrated TcO4- anion. Other anion K values were KNO3-/Cl- = 20, KSO4--/Cl- = 0.2, KHCO3-/Cl- = 0.09, KU/Cl- = 370–1000. These K values provide conservative parameters for predicting A532E performance, and demonstrate that, under these test conditions, A532E will remove TcO4- from current and future influent streams to meet groundwater treatment objectives.

Part II: Predicting performance of DOWEX 21K resin for remediation of comingled contaminants in groundwater

The selectivity of ion exchange (IX) resins for aqueous contaminant removal can be impacted by changing concentrations of competing natural groundwater ions. In a two-part investigation, the Hanford Site 200 West Area pump-and-treat (P&T) facility in Washington State, USA is used as a case study to evaluate the performance of two IX resins for groundwater treatment: Purolite® A532E for pertechnetate (TcO4-) removal, explored in Part I, and DOWEX 21K (DOWEX) for uranium (U) removal. In Part II, DOWEX selectivity for U, as uranyl carbonate species, and uptake kinetics is quantified in a series of laboratory-scale aqueous batch experiments containing Hanford-relevant concentrations of competing anions nitrate (NO3-), sulfate (SO42-), chloride (Cl-), and carbonate (CO32-), as well as co-mingled contaminant TcO4-. The results demonstrate that DOWEX trimethylammonium functional groups are highly selective for U carbonate species (85–100 % uptake) under all conditions investigated. Only NO3- concentrations of 100 mM were shown to decrease U removal, with the extent (85–99 %) depending on competing anion concentrations present in solution. However, at the highest NO3- concentrations reported for groundwaters treated at the P&T facility (25 mM), the effect on U uptake is minimal. The batch sorption results are modeled to obtain chloride normalized equilibrium exchange coefficients (K) for predicting DOWEX performance: KSO4--/Cl- = 2.0, KNO3-/Cl- = 5.0, KHCO3-/Cl- = 1.5, KTcO4-/Cl- = 2,000, and KU/Cl- = 50,000. These K values predict little effect of current and future influent chemistries on U removal by DOWEX, where both uranyl carbonate species and TcO4- are removed such that effluent concentrations meet groundwater treatment requirements.

Unveiling Structural Diversity of Uranyl Compounds of Aprotic 4,4'-Bipyridine N,N'-Dioxide Bearing O-Donors.

As an aprotic O-donor ligand, 4,4'-bipyridine N,N'-dioxide (DPO) shows good potential for the preparation of uranyl coordination compounds. In this work, by regulating reactant compositions and synthesis conditions, diverse coordination assembly between uranyl and DPO under different reaction conditions was achieved in the presence of other coexisting O-donors. A total of ten uranyl-DPO compounds, U-DPO-1 to U-DPO-10, have been synthesized by evaporation or hydro/solvothermal treatment, and the possible competition and cooperation of DPO with other O-donors for the formation of these uranyl-DPO compounds are discussed. Starting with an aqueous solution of uranyl nitrate, it is found that an anionic nitrate or hydroxyl group is involved in the coordination sphere of uranyl in U-DPO-1 ((UO2)(NO3)2(H2O)2·(DPO)), U-DPO-2 ((UO2)(NO3)2(DPO)), and U-DPO-3 ((UO2)(DPO)(μ2-OH)2), where DPO takes three different kinds of coordination modes, i.e. uncoordinated, monodentate, and biconnected. The utilization of UO2(CF3SO3)2 in acetonitrile, instead of an aqueous solution of uranyl nitrate, precludes the participation of nitrate and hydroxyl, and ensures the engagement of DPO ligands (4-5 DPO ligands for each uranyl) in a uranyl coordination sphere of U-DPO-4 ([(UO2)(CF3SO3)(DPO)2](CF3SO3)), U-DPO-5 ([UO2(H2O)(DPO)2](CF3SO3)2) and U-DPO-6 ([(UO2)(DPO)2.5](CF3SO3)2). Moreover, when combined with anionic carboxylate ligands, terephthalic acid (H2TPA), isophthalic acid (H2IPA), and succinic acid (H2SA), DPO works well with them to produce four mixed-ligand uranyl compounds with similar structures of two-dimensional (2D) networks or three-dimensional (3D) frameworks, U-DPO-7 ((UO2)(TPA)(DPO)), U-DPO-8 ((UO2)2(DPO)(IPA)2·0.5H2O), U-DPO-9 ((UO2)(SA)(DPO)·H2O), and U-DPO-10 ((UO2)2(μ2-OH)(SA)1.5(DPO)). Density functional theory (DFT) calculations conducted to probe the bonding features between uranyl ions and different O-donor ligands show that the bonding ability of DPO is better than that of anionic CF3SO3 -, nitrate, and a neutral H2O molecule and comparable to that of an anionic carboxylate group. Characterization of physicochemical properties of U-DPO-7 and U-DPO-10 with high phase purity including infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and luminescence properties is also provided.

Synthesis, Empirical and Theoretical Investigations on New Histaminium Bis(Trioxonitrate) Compound

In this paper, a novel hybrid material, entitled histaminium bis(trioxonitrate), with the general chemical formula (C5H11N3)(NO3)2, denoted by HTN was presented. Single-crystal X-ray diffraction was used to determine the structural characteristics of this compound after it was made using a slow evaporation method at room temperature. This compound was elaborated and crystallized to the monoclinic system with space group P21/c, and the lattice parameters obtained were: a = 10.4807 (16)Å, b = 11.8747 (15)Å, c = 16.194 (2)Å, β = 95.095 (6)°, V = 2007.4 (5)Å3 and Z = 8. The title compound's atomic structure couldbe modeled as a three-dimensional network. Organic cations and nitrate anions were connected via N-H...O and C-H...O hydrogen bonds in the HTN structure. The intermolecular interactions responsible for the formation of crystal packing were evaluated using Hirshfeld surfaces and two-dimensional fingerprint plots. The compound's infrared spectrum, which ranged from 4000 to 400 cm-1, confirmed the presence of the principal bands attributed to the internal modes of the organic cation and nitrate anions. Additionally, spectrofluorimetry and the ultraviolet-visible spectrum was used to investigate this compound. DFT calculations were used to evaluate the composition and properties of HTN. The energy gap, chemical reactivity and crystal stability of HTN were quantified by performing HOMO-LUMO frontier orbitals analysis. Topological analysis (AIM), Reduced Density Gradient (RDG), molecular electrostatic potential surface (MEPS) and Mulliken population were processed to determine the types of non-covalent interactions, atomic charges and molecular polarity in detail.

A Promising 1,3,5-Triazine-Based Anion Exchanger for Perrhenate Binding: Crystal Structures of Its Chloride, Nitrate and Perrhenate Salts.

The reaction of pyridine with cyanuric chloride was studied under microwave activation as well as in the presence of silver nitrate. The product of hydrolysis containing two pyridinium rings and chloride anion was isolated. The structures of these anion exchanger salts with chloride, nitrate and perrhenate anions are discussed.

Heuristic-Based Alkaline Hydrolysis Mechanism of Nitrate Ester (Nitrocellulose Monomer) and Nitroamine (Hexogen) Compounds: Electrostatic Attraction Effect of the Nitro Group

The alkaline hydrolysis reaction of energetic materials is important and complex. With improved performance, AMK_Mountain was used to systematically study the alkaline hydrolysis of the nitrocellulose monomer and hexogen. The reaction pathways showed that the nitrocellulose monomer produces the nitrate anion and nitrite anion differently, while hexogen only produces the nitrite anion. Electronic structure results at the M06-2X/6-311G(d,p)/PCM(Pauling) level showed that the nitrocellulose monomer and hexogen have a similar pathway in their main energy-releasing process (nitrite anion production): with electrostatic attraction effects after proton transfer, the nitrite anion dissociates from the original structure with a low barrier. Moreover, during the alkaline hydrolysis of the nitrocellulose monomer, the metastable intermediates after proton transfer may be directly generated following transition states that, structurally, tend to produce nitrite anions "proximal" to the proton transfer site and produce nitrate anions "distal" to the proton transfer site. Electronic structure analysis showed that representative metastable intermediates revealed that the charge transfer caused by electrostatic attraction may be the direct cause of these reactions.

Preparation of novel acyl pyrazoles and triazoles by means of oxidative functionalization reactions

Abstract Novel acyl pyrazoles and acyl triazoles have been prepared by means of the oxidative amidation of aldehydes in the presence of the requisite azole. Yields range from modest to good in both cases, and some limitations of the substrate scope have been discovered. Acyl pyrazoles were prepared by treatment of a mixture of aldehyde and pyrazole with an oxoammonium salt bearing the nitrate anion. In the case of acyl triazoles, the oxidative functionalization was performed using sodium persulfate as a terminal oxidant in the presence of a catalytic quantity of a nitroxide.

Redox-transitions in NO/NH3 adlayers on a Pt(111) electrode in an acidic solution

The process of electroreduction of nitrate anions is of considerable interest for researchers both as a fundamental (investigation of a multistage reaction, properties of intermediate products) and practical (water treatment) problem. A key intermediate product of nitrate anion electroreduction is nitric oxide NO that occupies two different types of sites on the Pt(111) surface: atop and 3-fold hollow. This paper studies redox transitions of N-containing species in the adsorption layer on Pt(111) in a wide range of potentials in a nitrate solution and in a preadsorbed saturated NO layer after its partial reduction in a negatively going potential sweep. Such partial reduction results in the appearance of a stable reversible pair of peaks in voltammograms at 0.6 V RHE. Analysis of charge densities of partial NO reduction and of this redox process shows that this pair of peaks corresponds to a one–electron redox transition between NH3(ads) and NH2(ads). We suggest a scheme based on the obtained results and literature data that explains the voltammetric signals observed in a wide range of potentials on an adsorption layer on Pt(111) formed by partial reduction of full NO adlayer. In this scheme, NH3(ads) molecules are formed in reduction of atop-bound NO and do not desorb from the surface owing to formation of coadsorption complexes with unreduced hollow-bound NO molecules. Such complexes are quite stable up to the potentials of hollow-bound NO reduction. In the potential range around 0.6 V, NH3(ads) molecules in such complexes are reversibly oxidized to NH2(ads) species that do not desorb either and remain within the coadsorption lattice. Moreover, the obtained NO/NH2(ads) is so stable that it suppresses oxidation of unreduced hollow-bound NO molecules in this complex to nitrite species.

Experimental and computational anion binding studies of meso-substituted one-walled phthalimide-based Calix[4]pyrrole

Anion binding studies of meso‑substituted one-walled phthalimide-based calix[4]pyrrole (m-PC4P, 6) were investigated through UV–vis spectroscopy in acetonitrile and corroborated by time-dependent density functional theory (TD-DFT) calculations using 6–311G(d) basis set. Notably, to our expectation, the m-PC4P (6) displayed higher anion binding affinities in comparison to the parent C4P system, probably due to the additional weak CH-anion interactions besides four NH-hydrogen bonds of the C4P framework (supported by 1H NMR evidence). Herein, we have observed the usual trend with halide anions (used as their tetrabutylammonium salts), i.e. with increase in size of the halides from fluoride to iodide, the anion binding affinity decreases. Moreover, with the nitrate anion, appreciable better binding was observed in the case of m-PC4P (6) as compared to the simple C4P (1).

Synthetic Receptors with Micromolar Affinity for Chloride in Water.

A water-soluble coordination cage was obtained by reaction of Pd(NO3 )2 with a 1,3-di(pyridin-3-yl)benzene ligand featuring a short PEG chain. The cavity of the metal-organic cage contains one nitrate anion, which is readily replaced by chloride. The apparent association constant for chloride binding in buffered aqueous solution is Ka =1.8(±0.1)×105 M-1 . This value is significantly higher than what has been reported for other macrocyclic chloride receptors. The heavier halides Br- and I- compete with binding or self-assembly, but the receptor displays very good selectivity over common anions such as phosphate, acetate, carbonate, and sulfate. A further increase of the chloride binding affinity by a factor of 3 was achieved using a fluorinated dipyridyl ligand.

Synthetic Receptors with Micromolar Affinity for Chloride in Water

AbstractA water‐soluble coordination cage was obtained by reaction of Pd(NO3)2with a 1,3‐di(pyridin‐3‐yl)benzene ligand featuring a short PEG chain. The cavity of the metal‐organic cage contains one nitrate anion, which is readily replaced by chloride. The apparent association constant for chloride binding in buffered aqueous solution isKa=1.8(±0.1)×105 M−1. This value is significantly higher than what has been reported for other macrocyclic chloride receptors. The heavier halides Br−and I−compete with binding or self‐assembly, but the receptor displays very good selectivity over common anions such as phosphate, acetate, carbonate, and sulfate. A further increase of the chloride binding affinity by a factor of 3 was achieved using a fluorinated dipyridyl ligand.

Ionic liquid route for the corrosion inhibition of Al alloys: the effect of butylammonium nitrate on the corrosion of AA2024-T6

In this work, the effect of an ammonium nitrate ionic liquid on the corrosion susceptibility of an Al-Cu-Mg alloy was investigated. The effect of the nitrate anion and the ammonium cation on the anodic and cathodic kinetics were studied separately using potentiodynamic polarisation testing, electrochemical impedance spectroscopy and scanning electron microscopy. The results revealed a significant anodic inhibition, associated with a cation/anion synergy. The cathodic kinetics however increase with the presence of nitrates, associated with nitrate reduction reaction. Conversely, longer alkyl chain seemed to reduce the effect of nitrates. Such findings are promising in the context of developing ecofriendly chromate alternatives.

KNO3⋅3H2SeO3 and NaHSeO3⋅3H2SeO3: Two non-centrosymmetric co-crystals

A new compound KNO3⋅3H2SeO3 was synthesized via reaction of KNO3 and H2SeO3 in an acidic aqueous solution. Its crystal structure (P21, a = 10.2709 (8) Å, b = 6.2840 (3) Å, c = 10.3886 (8) Å, β = 118.83 (1)°, R1 = 0.036) can be described as a monoclinically distorted hydrogen-bonded hexagonal net of KO9 tricapped trigonal prisms linked by H2SeO3 molecules. The nitrate anions behave as hydrogen bond acceptors filling the channels in the [K(H2SeO3)3]+ net. The structure is totally different from that of the chemically related NaHSeO3⋅3H2SeO3 compound, for which a new structural solution was obtained (Pc, a = 5.7803 (3) Å, b = 4.9390 (2) Å, c = 21.283 (1) Å, β = 111.836 (6)°, R1 = 0.028). Yet, there are some common features in the mode of KO9 and NaO6 polyhedra linkage by the HSeO3− and H2SeO3 species in two studied compounds. The SHG signal from KNO3⋅3H2SeO3 was registered using the Kurtz – Perry technique. A moderate SHG signal of 5–6 SiO2 units was observed. Relationships to other salt-selenious acid molecular co-crystals and hydrogen selenites are discussed.