Mechanochemical Synthesis of Nitrogen-containing Derivatives of Flax Boon

The influence exerted by the conditions of the mechanochemical synthesis [time (100–100 min), air pressure (1–9 atm), temperature (30–90°C), amount of ammonia (0.5–3.0 g g^?1 raw material)] on the content of nitrogen and functional groups in the products of oxidative ammonolysis of flax boon was studied. The resulting products were tested as nitrogen-containing ion exchangers in sorption of heavy metals.     

Facile Mechanochemical Synthesis of Nano SnO2/Graphene Composite from Coarse Metallic Sn and Graphite Oxide: An Outstanding Anode Material for Lithium‐Ion Batteries

A facile method for the large‐scale synthesis of SnO₂ nanocrystal/graphene composites by using coarse metallic Sn particles and cheap graphite oxide (GO) as raw materials is demonstrated. This method uses simple ball milling to realize a mechanochemical reaction between Sn particles and GO. After the reaction, the initial coarse Sn particles with sizes of 3–30 μm are converted to SnO₂ nanocrystals (approximately 4 nm) while GO is reduced to graphene. Composite with different grinding times (1 h 20 min, 2 h 20 min or 8 h 20 min, abbreviated to 1, 2 or 8 h below) and raw material ratios (Sn:GO, 1:2, 1:1, 2:1, w/w) are investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, field‐emission scanning electron microscopy and transmission electron microscopy. The as‐prepared SnO₂/graphene composite with a grinding time of 8 h and raw material ratio of 1:1 forms micrometer‐sized architected chips composed of composite sheets, and demonstrates a high tap density of 1.53 g cm^?3. By using such composites as anode material for LIBs, a high specific capacity of 891 mA h g^?1 is achieved even after 50 cycles at 100 mA g^?1.     

Porous Nitrogen‐Doped Carbon Nanotubes Derived from Tubular Polypyrrole for Energy‐Storage Applications

Porous nitrogen‐doped carbon nanotubes (PNCNTs) with a high specific surface area (1765 m² g^?1) and a large pore volume (1.28 cm³ g^?1) have been synthesized from a tubular polypyrrole (T‐PPY). The inner diameter and wall thickness of the PNCNTs are about 55 nm and 22 nm, respectively. This material shows extremely promising properties for both supercapacitors and for encapsulating sulfur as a superior cathode material for high‐performance lithium–sulfur (Li‐S) batteries. At a current density of 0.5 A g^?1, PNCNT presents a high specific capacitance of 210 F g^?1, as well as excellent cycling stability at a current density of 2 A g^?1. When the S/PNCNT composite was tested as the cathode material for Li‐S batteries, the initial discharge capacity was 1341 mAh g^?1 at a current rate of 1 C and, even after 50 cycles at the same rate, the high reversible capacity was retained at 933 mAh g^?1. The promising electrochemical energy‐storage performance of the PNCNTs can be attributed to their excellent conductivity, large surface area, nitrogen doping, and unique pore‐size distribution.     

Facile Synthesis of Nitrogen‐Containing Mesoporous Carbon for High‐Performance Energy Storage Applications

Porous carbon with high specific surface area (SSA), a reasonable pore size distribution, and modified surface chemistry is highly desirable for application in energy storage devices. Herein, we report the synthesis of nitrogen‐containing mesoporous carbon with high SSA (1390 m² g^?1), a suitable pore size distribution (1.5–8.1 nm), and a nitrogen content of 4.7 wt % through a facile one‐step self‐assembly process. Owing to its unique physical characteristics and nitrogen doping, this material demonstrates great promise for application in both supercapacitors and encapsulating sulfur as a superior cathode material for lithium–sulfur batteries. When deployed as a supercapacitor electrode, it exhibited a high specific capacitance of 238.4 F g^?1 at 1 A g^?1 and an excellent rate capability (180 F g^?1, 10 A g^?1). Furthermore, when an NMC/S electrode was evaluated as the cathode material for lithium–sulfur batteries, it showed a high initial discharge capacity of 1143.6 mA h g^?1 at 837.5 mA g^?1 and an extraordinary cycling stability with 70.3 % capacity retention after 100 cycles.     

Entwicklung einer flieβinjectionsmethode zur bestimmung von chlorid im spurenbereich durch leitfähighkeitsdiffernzenA flow-injection method for the determination of trace amounts of chloride

The indirect determination of chloride in water is based on measurement of the difference in conductivity after the sample has passed through ion-exchange columns in the hydrogen form and silver form. The linear response range is about 0.5–10 μg g^?1 chloride (with 3 μg g^?1 nitrate and 5 μg g^?1 sulfate); the detection limit is about 50 ng g^?1 chloride but depends strongly on the concentrations of other anions.     

Preparation of activated carbon from cotton stalk and its application in supercapacitor

High specific capacitance and low cost are the critical requirements for a practical supercapacitor. In this paper, a new activated carbon with high specific capacitance and low cost was prepared, employing cotton stalk as the raw material, by using the phosphoric acid (H₃PO₄) chemical activation method. The optimized conditions were as follows: the cotton stalk and activating agent with a mass ratio of 1:4 at an activation temperature of 800 °C for 2 h. The samples were characterized by nitrogen adsorption isotherms at 77 K. The specific surface area and pore volume of activated carbon were calculated by Brunauer–Emmett–Teller (BET) and t-plot methods. With these experimental conditions, an activated carbon with a BET surface area of 1,481 cm²?g^?1 and micropore volume of 0.0377 cm³?g^?1 was obtained. The capacitance of the prepared activated carbon was as high as 114 F?g^?1.The results indicate that cotton stalk can produce activated carbon electrode materials with low cost and high performance for electric double-layer capacitor.     

Nitrogen‐Doped Porous Graphitic Carbon as an Excellent Electrode Material for Advanced Supercapacitors

An advanced supercapacitor material based on nitrogen‐doped porous graphitic carbon (NPGC) with high a surface area was synthesized by means of a simple coordination–pyrolysis combination process, in which tetraethyl orthosilicate (TEOS), nickel nitrate, and glucose were adopted as porogent, graphitic catalyst precursor, and carbon source, respectively. In addition, melamine was selected as a nitrogen source owing to its nitrogen‐enriched structure and the strong interaction between the amine groups and the glucose unit. A low‐temperature treatment resulted in the formation of a NPGC precursor by combination of the catalytic precursor, hydrolyzed TEOS, and the melamine–glucose unit. Following pyrolysis and removal of the catalyst and porogent, the NPGC material showed excellent electrical conductivity owing to its high crystallinity, a large Brunauer–Emmett–Teller surface area (S_BET=1027 m² g^?1), and a high nitrogen level (7.72 wt %). The unusual microstructure of NPGC materials could provide electrochemical energy storage. The NPGC material, without the need for any conductive additives, showed excellent capacitive behavior (293 F g^?1 at 1 A g^?1), long‐term cycling stability, and high coulombic efficiency (>99.9 % over 5000 cycles) in KOH when used as an electrode. Notably, in a two‐electrode symmetric supercapacitor, NPGC energy densities as high as 8.1 and 47.5 Wh kg^?1, at a high power density (10.5 kW kg^?1), were achieved in 6 M KOH and 1 M Et₄NBF₄‐PC electrolytes, respectively. Thus, the synthesized NPGC material could be a highly promising electrode material for advanced supercapacitors and other conversion devices.     

Effect of six triorganotin(IV) compounds on nitrification and ammonification in soil

The effects of six triorganotin(IV) compounds and of Thiram on nitrification and ammonification in soil were investigated. Low concentrations of up to 50 μg g^?1 of the triorganotin(IV) compounds enhanced nitrate-nitrogen (NO₃^?-N) production in soil. Except for diphenylbutyltin bromide, which inhibited nitrification at 250 μg g^?1, the other triorganotin(IV) compounds were inhibitory at concentrations of 100 μg g^?1 to less than 250 μg g^?1. At 10 μg g^?1, only triphenyltin acetate was less inhibitory towards nitrification compared with Thiram. At 250 μg g^?1, Thiram exerted a strongly persistent inhibitory effect towards nitrification. The NO₃^?-N level recorded 28 days after application was only 0.10 μg g^?1 soil. With the triorganotin compounds NO₃^?-N levels of 7.05–12.06 μg g^?1 soil were recorded 28 days following their application. The deleterious effects of the triorganotin(IV) compounds were less persistent and recovery of nitrification was evident seven days after application. Low concentrations of Thiram and triorganotin(IV) compounds inhibited ammonification, whereas higher concentrations enhanced ammonification. Complete inhibition of ammonification was attained 21–28 days after application of Thiram at 50 μg g^?1. On the other hand, with the triorganotin(IV) compounds, except for diphenylbutyltin bromide at 10–50 μg g^?1, ammonification persisted at all concentrations 28 days after application.     

Atomic absorption spectrometric determination of copper in calcium carbonate scale and carbonate rocks by direct atomization of solid samples

Powdered samples (1 mg) are mixed with 1 mg of powdered graphite and copper is determined by atomic absorption spectrometry in a miniature graphite cup placed in a graphite crucible. Optimum conditions were drying at 200 °C (30 s), ashing at 900 °C (30 s), atomizing at 2700 °C (15 s) and cleaning at 2800 °C (10 s). Samples were powdered to 1–10 μm particle size. Magnesium, manganese and iron did not interfere. The effect of calcium carbonate was eliminated by the graphite addition. Results for copper (0.5–5 μg g^?1) in the scale and rocks agreed well with values obtained for dissolved samples. Relative standard deviations (n=10) were 4.9% for 1.2 μg g^?1 copper and 14.8% for 0.577 μg g^?1.     

Determination of hydrogen in stainless steels by spark-source mass spectrometry

A spark-source mass spectrometric (SSMS) method capable of determining traces of hydrogen in micro-volumes of metals was developed by using a pointed metal probe technique. The hydrogen background was decreased to μg g^?1 levels by the combination of a method in which the sample in the ion source is baked under vacuum at 323–343 K for more than 25 ks and a liquid nitrogen or liquid helium cryogenic pump method. This method was applied to the analysis of austenitic stainless steels at μg g^?1 hydrogen levels, and the relative standard deviation was within 20% for samples with hydrogen concentrations ranging from 2 to 4 μg g^?1. The relative sensitivity coefficent was 2.3 (Fe=1).     

Preparation of activated carbon from organic fraction of municipal solid wastes by ZnCl2 activation method and use it for elimination of chromium(VI) from aqueous solutions

In this study, the use of the organic fraction of municipal solid waste as an abundant and low-cost raw material for producing activated carbon was investigated. For this purpose, ZnCl₂ was used as a chemical activation agent and the carbonization process took place at 800 °C in N₂ atmosphere. Seven sorbents were prepared by chemical activation (pyrolysis under N₂ atmosphere at temperature of 800 °C after impregnation with ZnCl₂) with different ratios of ZnCl₂. The optimum ratio of organic fraction of municipal solid waste to ZnCl₂ was inspected via methylene blue number and iodine number (ASTM Designation: D4607–94). The results showed that the adsorbent with 60 % ZnCl₂/raw material was the most appropriate one with a satisfactory adsorption capacity, 112.4 mg g^?1 for methylene blue and 134.0 mg g^?1 for iodine. In addition, the structural analysis of this sorbent was performed using FT-IR, BET surface area, SEM–EDX and thermal analysis. Application of this sorbent to remove Cr(VI) from wastewater was studied to find an adsorption capacity of 66.7 mg g^?1. The experimental adsorption equilibrium data were fitted to Langmuir adsorption model with an acceptable adsorption capacity of 66.7 mg g^?1.     

Water‐Stable Zirconium‐Based Metal–Organic Framework Material with High‐Surface Area and Gas‐Storage Capacities

We designed, synthesized, and characterized a new Zr‐based metal–organic framework material, NU‐1100 , with a pore volume of 1.53 ccg^?1 and Brunauer–Emmett–Teller (BET) surface area of 4020 m²g^?1; to our knowledge, currently the highest published for Zr‐based MOFs. CH₄/CO₂/H₂ adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g^?1, which corresponds to 43 g L^?1. The volumetric and gravimetric methane‐storage capacities at 65 bar and 298 K are approximately 180 v_STP/v and 0.27 g g^?1, respectively.     

Substoichiometric isotope-dilution analysis for strontium by liquid-liquid extraction with a macrocyclic crown ether or cryptand

Strontium(II) is substoichiometrically extracted into 1,2-dichloroethane with 1.0 × 10^?4 M cryptand-2.2.2 or 18-crown-6 in the presence of 1.0 ×10.2 M picrate at pH 8–10 or 7–9, respectively. A constant substoichiometric amount of strontium(II) is extracted (relative standard deviation, 0.5%). The method combined with isotope dilution is applied to determine strontium(II) in a seaweed sample (Laminaria religiosa Miyabe); the values obtained were 546 ± 9 μg g^?1 with cryptand-2.2.2 and 546 ± 7 μg g^?1 with 18-crown-6.     

MnO2 Nanosheets Grown on Nitrogen‐Doped Hollow Carbon Shells as a High‐Performance Electrode for Asymmetric Supercapacitors

A hierarchical hollow hybrid composite, namely, MnO₂ nanosheets grown on nitrogen‐doped hollow carbon shells (NHCSs@MnO₂), was synthesized by a facile in situ growth process followed by calcination. The composite has a high surface area (251 m²g^?1) and mesopores (4.5 nm in diameter), which can efficiently facilitate transport during electrochemical cycling. Owing to the synergistic effect of NHCSs and MnO₂, the composite shows a high specific capacitance of 306 F g^?1, good rate capability, and an excellent cycling stability of 95.2 % after 5000 cycles at a high current density of 8 A g^?1. More importantly, an asymmetric supercapacitor (ASC) assembled by using NHCSs@MnO₂ and activated carbon as the positive and negative electrodes exhibits high specific capacitance (105.5 F g^?1 at 0.5 A g^?1 and 78.5 F g^?1 at 10 A g^?1) with excellent rate capability, achieves a maximum energy density of 43.9 Wh kg^?1 at a power density of 408 W kg^?1, and has high stability, whereby the ASC retains 81.4 % of its initial capacitance at a current density of 5 A g^?1 after 4000 cycles. Therefore, the NHCSs@MnO₂ electrode material is a promising candidate for future energy‐storage systems.     

Development of Immunoaffinity Sample-Purification for GC–MS Analysis of Ractopamine in Swine Tissue

A method combining immunoaffinity chromatography with gas chromatography–mass spectrometry (GC–MS) has been established for determination of ractopamine residues in swine liver and urine. After clean-up on an immunoaffinity chromatography column, GC–MS analysis revealed recovery from blank swine liver and urine fortified at 2.5–20 ng g^?1 (ng mL^?1 for urine), respectively, was 68.2–78.6 and 76.2–83.1%. The limits of detection and quantification were 0.5 ng g^?1 (or ng mL^?1) and 2.0 ng g^?1 (or ng mL^?1), respectively. The procedure was used for analysis of ractopamine residues in samples of swine liver and urine in which the levels were unknown. The amounts detected were 9–216 ng g^?1 (ng mL^?1).     

Biomass Inspired Nitrogen Doped Porous Carbon Anode with High Performance for Lithium Ion Batteries

Ginkgo leave, a naturally abundant resource, has been successfully employed as the raw material to prepare nitrogen doped porous carbon (NDPC) materials. The preparation of the porous carbon does not involve assistance of any activation or template technique. The as‐obtained NDPC shows favorable features for electrochemical energy storage, which can not only provide multiple sites for the storage and insertion of Li ions, but also facilitate rapid mass transport of electrons and Li ions. As a result, the NDPC when evaluated as an anode material for lithium ion batteries delivers high reversible capacity (505 mAh·g^?1 at 0.1 C), excellent rate capability (190 mAh·g^?1 at 10 C). These favorable properties suggest that the NDPC can be a promising anode material for lithium ion batteries (LIBs).     

Elemental Analysis of Phytotherapeutic Products by Inductively Coupled Plasma–Tandem Mass Spectrometry

A procedure for the determination of As, Cd, Cr, Ni, Pb, and V in phytotherapy medicines by inductively coupled plasma–tandem mass spectrometry is reported. The use of tandem mass spectrometry with oxygen into an octopole reaction system at various gas flow rates and the combination of on-mass and mass-shift modes was evaluated. Cadmium, Cr, Ni, and Pb were determined as free atomic ions while As and V were determined as the oxides AsO⁺ and VO⁺ in the same run. Samples were prepared by microwave-assisted digestion with dilute nitric acid and hydrogen peroxide. Two plant-certified reference materials (apple leaves and tomato leaves) were used to check the accuracy. For tandem mass spectrometry with 0.5?mL min^?1 O₂, recoveries in the 85–113% were typically obtained and no statistical differences were observed at the 95% confidence level (t-test) in comparison with the certified values. Using these conditions, the limits of detection for the method were 0.01, 0.0002, 0.008, 0.008, 0.003, and 0.002?µg g^?1 for As, Cd, Cr, Ni, Pb, and V, respectively. The procedure was used for the analysis of four phytotherapic drugs and the determined concentrations were up to 0.168?µg g^?1 As, 0.03?µg g^?1 Cd, 0.82?µg g^?1 Cr, 1.18?µg g^?1 Ni, 0.52?µg g^?1 Pb, and 2.4?µg g^?1 V with average precision values of 8% as the relative standard deviation. The found concentrations were compared with limits proposed in official guidelines and, in most cases, the values were below the maximum limits allowed.     

Synthesis of micro- and mesoporous carbon spheres for supercapacitor electrode

Micro- and mesoporous carbon spheres (MMCSs) are synthesized by the polymerization of colloidal silica-entrapped resorcinol/formaldehyde in the presence of ammonia as catalyst, followed by carbonization, sodium hydroxide (NaOH) etching to remove silica template, and potassium hydroxide (KOH) activation. The morphology and microstructure are characterized by scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption. The results show that a typical sample (denoted as MMCS-3) unites the characteristics of regular spherical shape (uniform diameters of 500 nm), high specific surface area (1,620 m² g^?1), large pore volume (1.037 cm³ g^?1), and combined micropores and mesopores (11.0 nm), which endows MMCS-3 good electrochemical performance. MMCS-3 as supercapacitor electrode shows a specific capacitance of 314 F g^?1 under a current density of 0.5 A g^?1 and low internal resistance of 0.2 Ω in 6 M KOH aqueous solution. The electrochemical capacitance still retains 198 F g^?1 at a high current density of 10 A g^?1. After 500 cycle numbers of galvanostatic charge/discharge at 0.5 A g^?1, MMCS-3 electrode still remains the specific capacitance of 301 F g^?1 with the retention of 96 %. This study highlights the potential of well-designed MMCSs as electrodes for widespread supercapacitor applications.     

Non-destructive proton activation analysis for nitrogen in refractory metals

The non-destructive determination of nitrogen in some refractory metals was studied by activation analysis with the ¹⁴N(p, n)¹⁴O reaction. The samples were irradiated with 12-MeV protons from a cyclotron. The proton beam intensity was normalized by means of a copper flux monitor. After chemical etching, the ¹⁴O activity (E_γ = 2313 keV, T_{$\text{1}\text{2}$} = 70.5 s) of the sample was measured by means of a Ge(Li) or NaI(Tl) detector. Standardization was carried out by the “average cross-section” method with nylon 6 as a nitrogen standard. The method gives a sensitivity of 0.4–30 μg g^?1 for analysis of Ta, W, Nb, and Ti, and 2000–4000 μg g^?1 for Zr, Ni and Mo.     

Preparation and Characterization of Mesoporous Ce0.5Zr0.5O2 Mixed Oxide

Mesoporous （MSU） Ce0.5Zr0.5O2 mixed oxide with a high specific surface area has been synthesized under weak acidic condition in the presence of an anionic surfactant, sodium dodecylbenzenesulfonate. The effect of the pH value on the formation of mesostructure and the thermal stability of the material has been evaluated. The products were characterized by transmission electron microscopy, powder X-ray diffraction and nitrogen adsorption-desorption measurements. The results showed that the as-prepared Ce0.5Zr0.5O2 mixed oxide possessed a specific surface area of 163.3 m^2·g^-1, which had a cubic fluorite-type structure and possessed specific surface areas of 148.4 and 62.4 m^2·g^-1 after calcination at 500 and 800 ℃ for 2 h, respectively. The material showed excellent thermal stability.