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991.
Abstract A procedure for the preconcentration of Cu(II) and Ni(II) is proposed using a minicolumn filled with silica gel modified by triethylenetetramine. The retained analytes on the modified silica gel were eluted with hydrochloric acid solution. The metal ions in the eluate were determined by flame atomic absorption spectrometry. The effect of various factors, such as pH of the sample solution, sample volume, flow rate of the sample solution, type of eluent, and matrix content of the sample solution, on preconcentration were examined to obtain optimum conditions. The recoveries for Cu(II) and Ni(II) ions under optimum preconcentration conditions were 98.3±1.3 and 99.2±1.4% at 95% confidence level, respectively. The analytical detection limits of Ni and Cu were found to be 0.22 and 0.36 µg L?1, respectively. The proposed method was applied to the determination copper and nickel in river and synthetic sea water. 相似文献
992.
《Advanced Powder Technology》2021,32(8):2770-2780
To reveal the suppression characteristics of methane/coal dust deflagration flame propagation by the flue gas loading in local zones. The suppression experiments of flue gas layer (CO2 and fly ash) with different thicknesses and fly ash concentrations were conducted in semi-open vertical combustion pipe. The flue gas layer was produced by self-designed flue gas layer generator. Flame propagation characteristics which including the flame image, velocity, the ion current and temperature were recorded by the high-speed photography, the ion current probe and the thermocouple. The residues after coal dust deflagration were characterized by FTIR (Fourier transform infrared spectroscopy). The results show that the flue gas layer has a significant suppression on deflagration flame propagation. With the increasing of flue gas layer thickness and fly ash concentration, the flame velocity, height, temperature and the ion current gradually decreases, and the suppression effect was enhanced. The asphyxiation of CO2, heat absorption and insulation of fly ash were mainly methods for the suppression of coal dust deflagration flame. 相似文献
993.
《Advanced Powder Technology》2021,32(11):4210-4221
In engineering application area, it has always been a challenge to simultaneously improve flame-retardant performance and crystallization rate of polylactic acid (PLA) biomaterials, thus restricting their extensive application. In this work, a multifunctional additive (4,4′-(phenylphosphoryl)bis(piperazine-4,1-diyl))bis(diphenylphosphine oxide) (PDPO) was successfully synthesized and used to fabricate flame retardant PLA biocomposites. The crystallization behavior, fire safety, mechanical properties and flame retardant mechanisms of PLA biocomposites were studied in detail. The results indicated that PDPO notably improved the crystallization rate and crystallinity of PLA biocomposites. When 4 wt% PDPO was incorporated, PLA/PDPO biocomposites successfully passed UL-94V-0 grade and their LOI values were improved from 19.0% of pure PLA to 29.4%. The introduction of PDPO promoted the premature degradation and carbonization of PLA substrate, and inhibited the transesterification of the PLA during thermal pyrolysis process. Besides, PDPO decomposed and produced the Ph and PO, which efficiently exerted the free radical trapping effect in vapor phase. Therefore, the spread of fire for PLA/PDPO was declined and even self-extinguished. Meanwhile, the low addition of PDPO presented little effect on the mechanical properties of PLA composites. This flame retardant PLA biocomposites showed broad application prospects in emerging fields such as electronic devices, automobiles, and 3D printing materials. 相似文献
994.
Suman Pokhrel Jakob Stahl Lizhuo Wang Rui Tang Haoyue Sun Malte Schalk Marco Schowalter Andreas Rosenauer Jun Huang Johannes Kiefer Johannes Birkenstock Lutz Mädler 《Advanced functional materials》2024,34(49):2411521
The innovative development of reactive-spray systems for gas-phase production of metal sulfides are potential materials for next-generation technologies. These flame-synthesized sulfides (doped, functionalized, and heterogeneously mixed derivatives) hold significant potential as photocatalysts for water splitting. The knowledge acquired from nonaqueous precursor-solvent and high-temperature aerosol chemistries, optimal process parameters are established to generate In2-(4/3)xSnxS3, solid-solutions. The thermally driven reducing gas-phase reactions are controlled through fuel/oxygen ratio. Particles characterizations (X-ray diffraction, transmission electron microscopy (TEM) and imaging) revealed structural stability and crystallinity. The In2-(4/3)xSnxS3, at higher Sn doping had enhanced photoexcitation. Donor-acceptor levels within the material facilitated electron-hole pair trapping, crucial for redox reactions. With suitable band gap energies for water oxidation (1.9-1.1 eV) closely matched flat band potentials (4.38-4.67 eV) for redox reactions. The powder characterization showed 8% In2O3 in InSn0.75S3 after photocatalysis due to S-degradation in the initial light “on/off cycles”. The pioneering process of employing oxygen-deficient reducing flame enabled a series of photo-catalytically active metal sulfide nanoparticles with work function energies in the range of 5.19-5.37 eV. This synthesis strategy holds the potential for impactful advancements in both industry and R&D, addressing the urgent need for new materials capable of inducing water oxidation under visible light. 相似文献
995.
Novel non-toxic halogen-free flame retardants are replacing traditional flame retardants in polymer and polymer matrix composite structures. In this study, graphene nanosheet (GNS) is investigated in combination with traditional layered double hydroxide (LDH), layered rare-earth hydroxide (LRH), and phosphorus-based flame retardant (DOPO) to enhance the flame retardancy of epoxy resin. A synergistic flame retardancy effect is achieved in GNS/LDH and GNS/DOPO systems where combined GNS and LDH increased the viscosity of the epoxy melt, and limited the flame propagation through inhibition of dripping. The limiting oxygen index of epoxy increased from 15.9 to 23.6 with addition of 0.5 wt.% each of GNS and LDH. With the addition of 2.5 wt.% of both GNS and LDH, the total heat release of epoxy resin also reduced from 33.4 MJ/m2 to 24.6 MJ/m2. The synergistic effect of GNS and DOPO adopted a different mechanism. The addition of 2.5 wt.% of GNS and DOPO reduced the peak heat release rate from 1194 kW/m2 to 396 kW/m2, and the total heat release rate from 72.5 MJ/m2 to 48.1 MJ/m2. The synergistic mechanisms of the flame retardants were closely analyzed and correlated with the flame retardant properties. 相似文献
996.
To improve the large release of smoke and heat for brominated flame retardants (BFRs) in fire hazard, fullerene (C60) had been introduced in high density polyethylene (HDPE)/bromine flame retardant (Deca/Sb2O3, BFR in short) system in this study. The effects of C60 on the thermal properties, flame retardant properties, rheological behaviors, and smoke release behaviors in HDPE/BFR blends were researched. During polymer thermal degradation, C60 and BFR exhibited the trapping radical ability in condensed phase and gaseous phase, respectively. The intergrated effects of C60 and BFR on the thermal stability and flammability of HDPE were studied by thermo‐gravimetry and cone calorimeter. It was indicated that the introduction of C60 improved the thermal and thermo‐oxidative stability of HDPE/BFR blends. A remarkable advantage of adding C60 was to reduce the peak heat release rate and the average specific extinction area, especially at higher concentration of C60. The analysis of rheological behaviors and pyrolysis products revealed that C60 can capture alkyl radicals, chain radicals, and bromine radicals in the condensed phase, which was in favor of terminating the thermo‐oxidative decomposition and inhibiting the heat and smoke release of HDPE/BFR blends during combustion. 相似文献
997.
Poly(diphenolic acid‐phenyl phosphate) [poly(DPA‐PDCP)], obtained from diphenolic acid (a well‐known biomass chemical), was used together with polyethylenimine (PEI) to construct a flame retardant surface coating for ramie fabric using layer‐by‐layer self‐assembly. Attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) and scanning electron microscope (SEM) equipped with an energy dispersive X‐ray spectrometer (EDX) were used to confirm the successful formation of layer by layer assembly. Assessment of the thermal and flammability properties for poly(DPA‐PDCP)/PEI‐coated ramie fabrics showed that the thermal stability, flame retardancy, and residual char were enhanced as the concentration of poly(DPA‐PDCP) and the BL number in the LbL process increased as well as the treatment of KH550 was applied. SEM and EDX analysis of the char residue confirmed further the intumescent flame retardant mechanism. This work demonstrated the great potentials of poly(DPA‐PDCP)/PEI flame retardant nanocoating constructed by LbL assembly method in the application of ramie fabric. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44795. 相似文献
998.
A systematic study was conducted to elucidate the effects of acoustic perturbations on laminar diffusion line-flames burning in air, and to determine the conditions required to cause acoustically-driven extinction. Line-flames were produced from the fuels n-pentane, n-hexane, n-heptane, and n-octane using fuel-laden wicks. The wicks were housed inside a burner whose geometry produced line-flames that approximated a two-dimensional flame sheet. The acoustics utilized ranged in frequency from 30 to 50 Hz, and acoustic pressures from 5 to 50 Pa. Prior to acoustic testing, the unperturbed mass loss rates and flame heights were measured. These quantities were found to scale linearly, which is consistent with the Burke-Schumann theory. The mass loss rates associated with hexane-fueled flames experiencing acoustic perturbations were then studied. It was found that the strongest influence on the mass loss rate was the speed of oscillatory air movement experienced by the flame. It was also found that the average mass loss rate increased linearly with the increasing air movement speed. Finally, acoustic perturbations were imposed on the flames from all fuels to determine acoustic extinction criterion. To ascertain if the observed phenomenon was unique to the alkanes tested, flames fueled by JP-8 (a kerosene-based fuel) were also examined. Using the data collected, a model was developed which characterized the acoustic conditions required to cause flame extinction. The model was based on the ratio of a modified Nusselt number to the Spalding B number of the fuel. It was found that at the minimum speaker power required to cause extinction, this ratio was a constant (independent of the chemical nature of the fuel). 相似文献
999.
王世泰 《山东轻工业学院学报》1990,(2)
本文叙述了聚合度在4～10之间的聚磷酸铵阻燃剂的合成方法,用它作为添加型阻燃剂的阻燃原理及其添加在涂料、纤维、纸张等中的应用。 相似文献
1000.
防火封堵系统是建筑防火安全设计的一个重要内容,而防火阻燃密封胶的应用,则是整个防火封堵系统的关键技术之一。相较于传统的防火封堵材料,通过合理的配方设计,硅酮类密封胶在阻燃性、粘结性、位移能力、水密性、使用寿命等方面都具有突出的优势。本文以成都硅宝119硅酮防火密封胶为例,介绍了硅酮防火密封胶配方设计中阻燃剂的选择以及按照新国标进行的防火封堵性能检测方法。 相似文献