Determination of Natural Rubber Content in Taraxacum Kok-Saghyz by Pyrolysis Gas Chromatography-Mass Spectrometry

Nowadays,natural rubber(NR)is an indispensable material for industrial production and peoples’daily utilization.The root of Taraxacum kok-saghyz(TKS)contains a large amount of NR,which is potentially to be an alternative rubber source of conventional Hevea brasiliensis(HB).In order to find a convenient,fast and green method for qualitative and quantitative analysis of NR in TKS,a pyrolysis gas chromatography-mass spectrometric(Py-GCMS)method was developed accordingly.The results indicated that the main products of TKS rubber after pyrolysis were isoprene and limonene,respectively,and the limit of detection(LOD)of TKS rubber was 2.603 mg/g.The ratios of NR mass fractions in TKSs by Py-GC-MS ranged from 1.20%±0.20%to 8.61%±0.28%.The developed method has been used for determination of actual TKS samples and can be further applied to the field test for rapid breeding and large-scale cultivation of TKS thereof.

CO_(2) capture by double metal modified CaO-based sorbents from pyrolysis gases

High-temperature pyrolysis technology can effectively solve the problem of municipal solid waste pollution.However,the pyrolysis gas contains a large amount of CO_(2),which would adversely affect the subsequent utilization.To address this problem,a novel method of co-precipitation modification with Ca,Mg and Zr metals was proposed to improve the CO_(2)capture performance.X-ray diffraction(XRD)patterns and energy dispersive X-ray spectroscopy analysis showed that the two inert supports MgO and CaZrO_(3)were uniformly distributed in the modified calcium-based sorbents.In addition,the XRD results indicated that CaZrO_(3)was produced by the reaction of ZrO_(2)and CaO at high temperatures.The effects of doping ratios,adsorption temperature,calcination temperature,CO_(2)concentration and calcination atmosphere on the adsorption capacity and cycle stability of the modified calcium-based sorbent were studied.The modified calcium-based sorbent achieved the best CO_(2)capture performance when the doping ratio was 10:1:1 with carbonation at 700℃ under 20%CO_(2)/80%N_(2)atmosphere and calcination at 900℃ under100%N_(2)atmosphere.After ten cycles,the average carbonation conversion rate of Ca-10 sorbent was 72%.Finally,the modified calcium-based sorbents successfully reduced the CO_(2)concentration of the pyrolysis gas from 37%to 5%.

Insight into the selective separation of CO_(2)from biomass pyrolysis gas over metal-incorporated nitrogen-doped carbon materials:a first-principles study

The composition of biomass pyrolysis gas is complex,and the selective separation of its components is crucial for its further utilization.Metal-incorporated nitrogen-doped materials exhibit enormous potential,whereas the relevant adsorption mechanism is still unclear.Herein,16 metal-incorporated nitrogen-doped carbon materials were designed based on the density functional theory calculation,and the adsorption mechanism of pyrolysis gas components H2,CO,CO_(2),CH_(4),and C2H6 was explored.The results indicate that metal-incorporated nitrogen-doped carbon materials generally have better adsorption effects on CO and CO_(2)than on H_(2),CH_(4),and C_(2)H_(6).Transition metal Mo-and alkaline earth metal Mg-and Ca-incorporated nitrogen-doped carbon materials show the potential to separate CO and CO_(2).The mixed adsorption results of CO_(2)and CO further indicate that when the CO_(2)ratio is significantly higher than that of CO,the saturated adsorption of CO_(2)will precede that of CO.Overall,the three metal-incorporated nitrogen-doped carbon materials can selectively separate CO_(2),and the alkaline earth metal Mg-incorporated nitrogen-doped carbon material has the best performance.This study provides theoretical guidance for the design of carbon capture materials and lays the foundation for the efficient utilization of biomass pyrolysis gas.

热裂解气相色谱-质谱研究阻燃纤维的结构及烟雾毒性

随着高分子材料的不断开发,涌现出一大批用于阻燃和热辐射防护的耐高温纤维,如Basofil、Kermel、Visil、Nomex、P84、PBI和PBO等纤维,除了在衣着领域的应用外,在消防服、工业用阻燃防护服以及汽车等的内装饰物和家用防火材料等方面,具有更优异的防护功能和穿着舒适性.……

Fast Determination of the Rubber Content in Taraxacum kok-saghyz Fresh Biomass Using Portable Near-Infrared Spectroscopy and Pyrolysis-Gas Chromatography

Taraxacum kok-saghyz(TKS)is a plant native to the Tianshan valley on the border between China and Kazakhstan.TKS rubber is a good substitute for natural rubber.TKS's breeding work necessitates the need to screen high-yielding varieties,hence rapid determination of rubber content is essential for the screening.Conventional analytical methods cannot meet actual needs in terms of real-time testing and economic cost.Near-infrared spectroscopy analysis technology,which has developed rapidly in the field of industrial process analysis in recent years,is a green detection technology with obvious merits of fast measurement speed,low cost and no sample loss.This research aims to develop a portable non-destructive near-infrared spectroscopic detection scheme to evaluate the content of natural rubber in TKS fresh roots.Pyrolysis gas chromatography(Py-GC)was chosen as the reference method for the development of NIR prediction model.208 TKS fresh root samples were collected from the Inner Mongolia Autonomous Region of China.Near-infrared spectra were acquired for all samples.Randomly,two-thirds of them were selected as the calibration set,the remaining one-third as the validation set,and the partial least squares method was successfully established a good NIR prediction model for rubber content at 1080-1800 nm with a ratio of performance to deviation(RPD)of 5.54 and coefficient of determination(R^(2))of 0.95.This study showed that portable near-infrared spectroscopy could be used with ease for large-scale screening of TKS plants in farmland,and could greatly facilitate TKS germplasm preservation,high-yield cultivation,environment-friendly,high-efficiency and low-cost rubber extraction,and comprehensive advancement of the natural rubber industry thereof.

Modeling of the process-induced stress, damage, microstructure, and deformation evolution during the pyrolysis process manufacturing CMCs

An insightful understanding of the formation mechanism of process-inherent defects anddeformation is increasingly important for the property evaluation and structural design of ceramicmatrix composites (CMCs). For this purpose, a coupled thermal–diffusive–mechanical modelingapproach was proposed by considering three important phenomena that occur during the pyrolysisprocess for manufacturing CMCs: variations of the physical and mechanical properties of theconstituents, generation and diffusive of pyrolysis gas, and multiple thermal deformations. Thesynergistic effects of these three phenomena on the stress, damage development, microstructuralmorphology, and process deformation of SiC matrix composites were investigated using finiteelement simulations. This new approach was validated by comparing the simulation and experimentalresults. Significant volume shrinkage of the matrix during the polymer-to-ceramic transformationresulted in large tensile stresses and subsequent highly fragmented microstructure in CMCs. Thepyrolysis-gas-induced expansion on the matrix under a damage state may yield a positive processdeformation of CMCs at the macroscale, overcoming the effects of the volume shrinkage of the bulkmatrix at the microscale. The modeling approach is expected to guide high-quality manufacturing ofCMCs and comprehensive studies of structure–processing–property relationships.

Gas template-assisted spray pyrolysis： A facile strategy to produce porous hollow Co3O4 with tunable porosity for high-performance lithium-ion battery anode materials

Porous hollow Co3O4 microspheres have been synthesized from a mixed cobalt nitrate and urea solution through spray pyrolysis followed by calcination at 600 ℃ in air. This porous hollow Co3O4 is assembled by nanoparticles and exhibits variable porosity depending on the amount of gas in the system. In pyrolysis process, urea continuously decomposes into gaseous components, which act as a template to control the porous structure. The amount of gas escaping from precursor droplets can directly influence the porosity of the microspheres and the size of the nanoparticles controlled by the ratio of urea to cobalt nitrate. Electrochemical measurements show that the performance of the porous hollow Co3O4 microspheres is related to the porosity and size of the nanopartides. The sample with optimal porosity delivers a high first charge capacity of 1,417.9 mAh·g^-1 at 0.2C （1C = 890 mA·g^-1）, and superior charge cycle performance of 1,012.7 mAh.g-1 after 100 cycles. In addition, the optimized material displays satisfactory rate performance of 1,012.4 mAh.g-1 at 1C after 50 cycles and 881.3 mAh·g^-1 at 2C after 300 cycles. Superior charge/discharge capacity, excellent rate performance and high yield achieved in this study is promising for the development of high-performance Co3O4 anode materials for lithium-ion batteries.

Characterization and Three-dimensional Structural Modeling of Humic Acid via Molecular Mechanics and Molecular Dynamic Simulation

The humic acid（HA） sample obtained from the alluvial soil was characterized by elemental composition, pyrolysis gas chromatography-mass spectrometry（Py-GC-MS） and solid-state 13C nuclear magnetic resonance （13C NMR） spectroscopy. There is high fat content and a few nitrogen-containing functional groups in HA. Py-GC-MS demonstrates the characterization and structural identification of HA. One long list of identified pyrolysis products was proposed for the construction of conceptual model of HA. Solid-state 13C NMR data indicate there are higher values of alkyl-C, O-alkyl-C and aryl-C in HA. The elemental composition, structural carbon distribution and L3C NMR spectroscopy of simulated HA are consistent with those of experimental HA. HyperChem was used to simulate the three-dimensional molecular structure of the monomer, which was optimized by the molecular mechanics of the optimized potential for liquid simulations（OPLS） force field and molecular dynamics simulation to get the stable and balanced conformation. The deprotonation process study depicts that the degree of ionization of HA gets deeper, while the electronegativity of HA and the energy of van der Waals（vdW） increase. Moreover, the 3D structure of humic acid with -4 charges is the most stable. The deprotonation process is an endothermic process.