Ultraviolet Spectroscopic Detection of Nitrate and Nitrite in Seawater Simultaneously Based on Partial Least Squares

A direct, reagent-free, ultraviolet spectroscopic method for the simultaneous determination of nitrate (NO₃⁻), nitrite (NO₂⁻), and salinity in seawater is presented. The method is based on measuring the absorption spectra of the raw seawater range of 200–300 nm, combined with partial least squares (PLS) regression for resolving the spectral overlapping of NO₃⁻, NO₂⁻, and sea salt (or salinity). The interference from chromophoric dissolved organic matter (CDOM) UV absorbance was reduced according to its exponential relationship between 275 and 295 nm. The results of the cross-validation of calibration and the prediction sets were used to select the number of factors (4 for NO₃⁻, NO₂⁻, and salinity) and to optimize the wavelength range (215–240 nm) with a 1 nm wavelength interval. The linear relationship between the predicted and the actual values of NO₃⁻, NO₂⁻, salinity, and the recovery of spiked water samples suggest that the proposed PLS model can be a valuable alternative method to the wet chemical methods. Due to its simplicity and fast response, the proposed PLS model can be used as an algorithm for building nitrate and nitrite sensors. The comparison study of PLS and a classic least squares (CLS) model shows both PLS and CLS can give satisfactory results for predicting NO₃⁻ and salinity. However, for NO₂⁻ in some samples, PLS is superior to CLS, which may be due to the interference from unknown substances not included in the CLS algorithm. The proposed method was applied to the analysis of NO₃⁻, NO₂⁻, and salinity in the Changjiang (Yangtze River) estuary water samples and the results are comparable with that determined by the colorimetric Griess assay.     

碳酸酯类电解液中Mg(NO3)2添加剂抑制锂枝晶生长的研究

在锂-硫化聚丙烯腈电池体系中,负极锂枝晶的形成和生长严重恶化了电池充放电性能,并给电池带来了安全隐患。而在更有利于稳定正极硫化聚丙烯腈材料的碳酸酯类电解液中,锂枝晶生长尤为严重。本文通过将硝酸镁添加到碳酸酯类电解液中,研究硝酸根和镁离子对锂金属表面改性的共同作用。实验数据发现,在硝酸根和镁离子共同作用下,锂枝晶生长被有效抑制。当硝酸镁浓度为100 mmol·L^-1时,锂铜半电池的库仑效率明显提高,并显著改善了锂-硫化聚丙烯腈电池的循环性能。300次循环后容量保持率为71%,远高于硝酸锂的61%和无添加剂的50%。     

New green process to increase the solubility of soil fertilizer based on Potassium Nitrate (KNO3)

Fertilization is the set of operations that consists of fertilizing the soil so that the plant finds all these mineral nutrition needs, among these nutrients is found potassium nitrate (KNO₃), as an important source of two elements which are nitrogen (N) and potassium (K). The need for potassium nitrate for plants will increase dramatically as its demand for nutrition growing up. However, the application of this potassium in fertilization is limited by a physicochemical parameter which is solubility. The availability of potassium and nitrogen in ionic form, which can be assimilated by the plant, is closely related to its solubility in irrigation water. Herein, we have chosen three experimental parameters such as the KNO₃ content, the magnetization time, and the type of water, to optimize the factors which have the maximum effect on KNO₃ solubility.We adopted a model from nine experiments performed with Minitab software, which informed us that the solubility of KNO₃ in irrigation water is strongly influenced by water type, magnetization time and KNO₃ content. The best conditions which allow the best solubility of potassium nitrate are 24% KNO₃, 30 ​min of water magnetization, and salt water (SW).     

嫁接Al改性MCM-41介孔分子筛催化合成双酚F

以十六烷基三甲基溴化铵和正硅酸乙酯为原料,合成纯硅MCM-41介孔分子筛。 再利用九水硝酸铝为改性剂来嫁接改性纯硅MCM-41介孔分子筛,NH3-TPD结果表明,嫁接后的AlMCM-41产生了中强酸。 用改性后不同n(Si)/n(Al)的AlMCM-41催化合成双酚F,在n（苯酚）/n（甲醛）=30、反应时间5 h、反应温度90 ℃、m（甲醛）/m（AlMCM-41）=7的反应条件下,在一定范围内,双酚F的产率随Al含量增加而增加,但在n（Si）/n（Al）＜50时,双酚F的产率反而下降,当n（Si）/n（Al）=50时,双酚F的产率最高,为42.28%。     

A facile synthesis of a novel energetic surfactant 1-amino-3-dodecyl-1, 2, 3-triazolium nitrate

1-Amino-3-dodecyl-1,2,3-triazolium nitrate, as a novel energetic surfactant, has been synthesized in four steps, namely addition-elimination, cyclization, alkylation and metathesis. Its structure was confirmed by 1H NMR, IR, and MS. The effects of various reaction parameters, including stoichiometry, reaction temperature and time, were investigated in details. In addition, the physical and chemical properties of this energetic surfactant were measured.     

Ceric ammonium nitrate supported HY-zeolite：An efficient catalyst for the synthesis of 1, 8-dioxo-octahydroxanthenes

Ceric ammonium nitrate （CAN） supported HY-zeolite has been used as an efficient catalyst for the one- pot synthesis of 1,8-dioxo-octahydroxanthenes from the readily available 1,3-diketone and aromatic aldehydes under solvent-free conditions. The present methodology is cost-effective in addition to other advantages like high yields of products in shorter reaction time and simple workup procedure without the use of any injurious solvents.     

Assessment of Thermal Stability and Detonation Performance of 4-Amino-1,2,4-triazolium Nitrate as compared to 2,4,6-Trinitrotoluene for Melt-cast Explosives

4-Amino-1,2,4-triazolium nitrate (4-ATN) is an energetic and non-sensitive ionic liquid, which was introduced as a good candidate in previous works for the replacement of 2,4,6-trinitrotoluene (TNT) in melt-cast explosives. Since previous studies used pure nitric acid for nitration of 4-ATN, the effect of the use of low price industrial nitric acids (50 %, 70 % and 98 %) is investigated on the percent yields of 4-ATN. The thermogravimetric and differential scanning calorimetry (TGA/DSC) are done on the synthesized 4-ATN with impure nitric acid at a heating rate of 10 K · min^–1 by the vacuum system. The obtained TGA/DSC curves confirm decomposition of 4-ATN involving melting and dissociation. Derivative thermogravimetric (DTG) curves of 4-ATN at various heating rates are applied to obtain activation energy of thermolysis by several model-free techniques. The calculated activation energies are in the range 78.7–87.7 kJ · mol^–1, which are about 10 kJ · mol^–1 more than the reported activation energy of industrial TNT (purity 98.2 %), i.e. 66–70 kJ · mol^–1. Assessments of detonation performance of 4-ATN are also compared with TNT, which show higher detonation performance of 4-ATN. Thus, 4-ATN can be used with nitramine compounds as melt-cast explosives with higher thermal stability and detonation performance than corresponding nitramine compound/TNT explosives.     

硝酰氯的大气化学

硝酰氯(nitryl chloride,ClNO₂)是大气中一种重要的气态污染物,对大气氧化性、一次污染物的降解和二次污染物的生成具有重要影响,并在全球氮循环和氯循环中扮演着不可忽视的角色。本文归纳了ClNO₂的基本物理化学性质及其在大气中的生成和去除机制,并介绍了实验室研究和外场观测中ClNO₂的主要测量方法。在此基础上,本文总结了过去十几年报道的ClNO₂在实际大气中的时空分布特征,通过分析实验室模拟和外场观测的研究结果系统讨论了ClNO₂非均相生成的机制、产率及其影响因素,探讨了ClNO₂对氯自由基、大气氧化性以及臭氧和硝酸盐形成的影响。我们指出,ClNO₂既耦合了气相化学和非均相化学,又耦合了夜间大气化学和日间光化学,在我国大气复合污染中可能起着非常重要的作用。最后,本文提出了ClNO₂大气化学研究中尚待解决的关键科学问题,并简要讨论了该领域的未来发展方向。     

Electrochemical Oxidation of Nitrogen towards Direct Nitrate Production on Spinel Oxides

Nitrates are widely used as fertilizer and oxidizing agents. Commercial nitrate production from nitrogen involves high‐temperature‐high‐pressure multi‐step processes. Therefore, an alternative nitrate production method under ambient environment is of importance. Herein, an electrochemical nitrogen oxidation reaction (NOR) approach is developed to produce nitrate catalyzed by ZnFe_xCo_2?xO₄ spinel oxides. Theoretical and experimental results show Fe aids the formation of the first N?O bond on the *N site, while high oxidation state Co assists in stabilizing the absorbed OH^? for the generation of the second and third N?O bonds. Owing to the concerted catalysis, the ZnFe_0.4Co_1.6O₄ oxide demonstrates the highest nitrate production rate of 130±12 μmol h^?1 g_MO^?1 at an applied potential of 1.6 V versus the reversible hydrogen electrode (RHE).     

A Computational Study of CIONO2H+: Structure and Vibrations

Two protonated forms of chlorine nitrate, HClONO⁺ ₂ and ClONO₂H⁺, are treated ab initio by the Hartree-Fock and the second order Møller-Plesset perturbation approach with the standard 6–31G* basis set. Both minimum energy structures are planar (C ₃ symmetry) and their structural, energy, and vibrational parameters are reported. The computations conclude that the proton attacks the chlorine nitrate at its central, not end, oxygen atom. The protonation causes a considerable elongation of the central ON bond which becomes most probable place of cleavage. The dissociation should yield the neutral HOCl and NO⁺ ₂. These quantum-chemical findings well agree with the previous experimental indications.