Introduction Of Nitrogen Functional Groups Research Articles

Enhanced removal of lead ions from wastewaters by electrochemical adsorption using nitrogen-doped Ti3C2Tx MXene

As a two-dimensional material containing transition metal carbides and nitrides, MXene is often used in capacitive deionization for its excellent hydrophilic and pseudocapacitive properties. Nitrogen doping is widely used to improve the adsorption properties of certain materials. However, the effect of nitrogen doping on the electrochemical adsorption properties of MXene remains unclear. In this work, nitrogen-doped Ti3C2Tx MXene was synthesized using a simple hydrothermal method to achieve highly selective and efficient removal of Pb(II) at a constant cell voltage. The concentration of Pb(II) decreased from 4.95 to 0.02 mg L−1 in a 100 mg L−1 NaCl supporting electrolyte after electrosorption. The removal efficiency of Pb(II) reached 99.5%, whereas it was only 15.2% for Na+. The introduction of nitrogen functional groups increased the electrical conductivity and layer spacing of MXene, thereby improving the pseudocapacitive adsorption performance in the presence of Pb(II). The complexation function of the Ti-OH group on nitrogen-doped Ti3C2Tx surface increased and contributed to the selective adsorption of Pb(II). The removal efficiency of Pb(II) increased with increasing solution pH and cell voltage, reaching the maximum value at pH 5.0 and 1.5 V, respectively. The effect of supporting electrolyte type on the removal of Pb(II) was negligible. In addition, the removal efficiency for mixed heavy metal ion solutions, including Cu(II), Ni(II), and Pb(II), exceeded 79.0%. It exhibited the highest removal efficiency for Pb(II) at 97.9%. After five cycles of electrochemical adsorption–desorption, the nitrogen-doped Ti3C2Tx maintained a stable Pb(II) removal efficiency of 97.0%. This work provides a promising material for the electrochemical removal of low-concentration heavy metal ions from wastewaters.

Construction of the Akuammiline Alkaloid Core Structure via Stereoselective E-Ring Formation.

Construction of the core structure of akuammiline alkaloids with three-dimensional cage-like structures for their diversity-oriented synthesis was investigated. Extensive exploration centered around the introduction of nitrogen functional groups and construction of the E-ring in an intramolecular or intermolecular manner revealed that a Claisen rearrangement approach involving intramolecular amination provided a common precursor, potentially facilitating divergent access to various types of akuammiline alkaloids.

Nitrogen-doped magnetic porous carbon nanospheres derived from dual templates-induced mesoporous polydopamine coated Fe3O4 for efficient extraction and sensitive determination of volatile nitrosamines by gas chromatography-mass spectroscopy

N-nitrosamines (NAs) are highly carcinogenic compounds commonly found in food, beverages, and consumer products. Due to their wide polarity range, it is challenging to find a suitable carbon adsorbent that can simultaneously adsorb and enrich both polar and nonpolar NAs with good recovery. In this study, nitrogen-doped magnetic mesoporous carbon nanospheres (M-MCN) were prepared and employed as an adsorbent for magnetic solid-phase extraction (MSPE) to extract and concentrate four NAs. The introduction of nitrogen functional groups enhanced the hydrophilicity of the carbon material, allowing M-MCN to achieve a balance between hydrophilicity and hydrophobicity, resulting in good recovery for both polar and nonpolar NAs. A method combining MSPE with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of NAs in processed meat and alcoholic beverages. The method exhibited a good linear range (1–100 ng g−1, r2 > 0.9967) and trace-level detection (0.53–6.6 ng g−1). The recovery rates for the four NAs ranged between 85.7 and 110.7 %, with intra-day precision expressed as relative standard deviation (RSD) between 4.1 and 10.7 %, and inter-day precision between 4.8 and 12.9 %. The results demonstrated not only good accuracy and precision but also provided a new adsorbent for the enrichment of trace-level NAs in processed meat and alcoholic beverage samples.

Removal of Heavy Metal Ions from One- and Two-Component Solutions via Adsorption on N-Doped Activated Carbon.

This paper deals with the adsorption of heavy metal ions (Cu2+ and Zn2+) on the carbonaceous materials obtained by chemical activation and ammoxidation of Polish brown coal. The effects of phase contact time, initial metal ion concentration, solution pH, and temperature, as well as the presence of competitive ions in solution, on the adsorption capacity of activated carbons were examined. It has been shown that the sample modified by introduction of nitrogen functional groups into carbon structure exhibits a greater ability to uptake heavy metals than unmodified activated carbon. It has also been found that the adsorption capacity increases with the increasing initial concentration of the solution and the phase contact time. The maximum adsorption was found at pH = 8.0 for Cu(II) and pH = 6.0 for Zn(II). For all samples, better fit to the experimental data was obtained with a Langmuir isotherm than a Freundlich one. A better fit of the kinetic data was achieved using the pseudo-second order model.

Nitrogen‐rich melamine cyanurate derived hollow porous carbon microspheres prepared through CuCl2 activation for VOCs adsorption

AbstractNitrogen‐enriched porous carbon material with large specific surface area is of great demand in various applications. Herein, CuCl2 is adapted as a mild activator to transform the mixture of soybean meal and melamine cyanurate into a novel type of nitrogen‐enriched hollow porous carbon microspheres with well‐defined hierarchically structure. Excitingly, this mild activation agent not only helps generating porous structure, but also helps increasing the nitrogen content (mainly pyrrolic‐N) of products. The product NPC‐800‐4 exhibits the highest specific surface area (1672.45 m2 g−1) while a pretty high nitrogen content (13.09 at%). The NPC‐800‐4 sample performs the largest toluene and acetone adsorption capacity (818.46 mg g−1 and 758.87 mg g−1 respectively). Furthermore, Grand canonical Monte Carlo (GCMC) and density functional theory (DFT) calculations prove that the introduction of nitrogen functional groups can heighten the polarity of carbon framework and the electrostatic interaction, thus enhance the acetone adsorption capacity.

Carbon nanotubes-supported Pt catalysts for decalin dehydrogenation to release hydrogen: A comparison between nitrogen- and oxygen-surface modification

The effect of carbon nanotubes (CNT) surface chemistry on supported Pt catalytic performance in decalin dehydrogenation to release hydrogen was investigated through modifying CNT surface with nitrogen and oxygen functional groups. The results indicate that the mechanism of improving Pt dispersion is different for nitrogen and oxygen groups. Although oxygen groups can improve Pt dispersion, their electron donating feature inhibits the electron transfer from Pt to carbon support. DFT calculations have clarified the negative effect of oxygen group on decalin dehydrogenation in aspect of adsorption energy. Moreover, the abundant oxygen species on catalyst surface lead to a bad wettability of catalyst in non-polar reaction liquid, which significantly weaken the approaching of reactant onto catalyst. Therefore, the introduction of oxygen groups is unfavorable to the catalyst activity. In contrast, the highly dispersed Pt nanoparticles anchored by nitrogen groups may be one reason for the high activity of Pt supported on CNT modified with nitrogen groups. Furthermore, nitrogen groups promote the electron transfer from Pt to CNT, leading to lower Pt d-band and weaker naphthalene adsorption. Meanwhile little change happened on the non-polar characteristics of CNT during nitrogen doping treatment. Therefore, the introduction of nitrogen functional groups is conducive to the catalytic dehydrogenation.

N-doped catalytic graphitized hard carbon for high-performance lithium/sodium-ion batteries

Hard carbon attracts wide attentions as the anode for high-energy rechargeable batteries due to its low cost and high theoretical capacities. However, the intrinsically disordered microstructure gives it poor electrical conductivity and unsatisfactory rate performance. Here we report a facile synthesis of N-doped graphitized hard carbon via a simple carbonization and activation of a urea-soaked self-crosslinked Co-alginate for the high-performance anode of lithium/sodium-ion batteries. Owing to the catalytic graphitization of Co and the introduction of nitrogen-functional groups, the hard carbon shows structural merits of ordered expanded graphitic layers, hierarchical porous channels, and large surface area. Applying in the anode of lithium/sodium-ion batteries, the large surface area and the existence of nitrogen functional groups can improve the specific capacity by surface adsorption and faradic reaction, while the hierarchical porous channels and expanded graphitic layers can provide facilitate pathways for electrolyte and improve the rate performance. In this way, our hard carbon provides its feasibility to serve as an advanced anode material for high-energy rechargeable lithium/sodium-ion batteries.

Effect of pre-oxidation for introduction of nitrogen containing functional groups into the structure of activated carbons and its influence on Cu (II) adsorption

Modification of surface structure of adsorbents in order to enhance their adsorption capacity toward special adsorbates has gained great interest in the recent years. Introduction of nitrogen functional groups such as amine, pyridinic, and pyrrolic onto the surface of adsorbents and replacing them with oxygen groups has been known as one of the modification methods for producing strong adsorbents toward heavy metals like Cu (II) ion. In the present work, a new procedure for nitrogenation of commercial activated carbon was proposed: heat treatment of adsorbent under the atmosphere of NH3 after pre-oxidation with HNO3; and the influence of this treatment on the characteristics and adsorption properties of activated carbon toward Cu (II) were investigated. Characterization of produced samples was performed by several analyses, including N2 adsorption/desorption, pH of zero point charge, elemental analysis and FTIR spectroscopy. Comparison of the foresaid sample with another one modified by NH3 without pre-treatment, showed that the pre-oxidation of adsorbent has a good influence on increasing of the amount of nitrogen functional groups introduced onto structure of adsorbent. Besides it was found that the introduction of nitrogen functional groups has negligible effect on the porous properties of activated carbon. The higher adsorption rate and capacity toward Cu (II) was obtained in the case of nitrogenated carbons.

Surface Modifications of Polyester Films by Ammonia Plasma

Effects of treatment using ammonia plasma on poly(lactic acid) (PLA), poly(ethylene terephthalate) (PET), and liquid-crystal polymer (LCP) were investigated to elucidate differences related to polymer structures and the mode of introduction of nitrogen functional groups onto the polyester surfaces. Nitrogen functional groups were introduced into PET and LCP, but were not introduced into PLA. Those results indicate reductions in the contact angle for PET and LCP. No decrease in the contact angle was observed for PLA. Reasons for differences in attachment of nitrogen functional groups by ammonia plasma processing on polyester surfaces were discussed. The respective actions of active species were investigated for radicals, electrons, and ions in plasma.

ChemInform Abstract: Highly Stereoselective Introduction of Nitrogen Functional Groups into Carbon Frameworks

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

高立体選択的な窒素官能基の導入法の開発

アミノ酸, アルカロイド等を例に挙げるまでもなく, 医薬品を含めた生理活性物質の多くはその分子内に窒素原子を有し, その大多数は光学活性体である。したがって, 含窒素骨格の立体選択的構築法の開発と, その生理活性物質合成への応用は有機合成化学に大きなインパクトを与えるばかりでなく医薬品の工業化にもっながる有機合成化学上重要な分野である。さて, 有用な物質の含窒素骨格を効率よく合成するためには新しい反応や合成手法の開発が重要であろう。さらに, 新しい反応を開発するためには原子や反応活性種の特性を生かすことが必要となる。本稿では, 酸素とケイ素の親和性を活かした付加反応, エステル交換を用いるニトロンの分子内環化付加反応, エノラートとクロロニトロソ化合物とのアルドール型反応を用いるN-ヒドロキシアミノ化反応, N-ビニルカルバマートとモノフルオロカルベノイドとのフルオロシクロプロパン化反応を紹介する。また, Pummerer反応を用いるカルバペネム合成の初期段階にも携わってきたが, その後の発展を含めた研究成果が北, 柴田により総説としてまとめられているので参照されたい。