Migration analysis,antioxidant, and mechanical characterization of polypropylene-based active food packaging films loaded with BHA,BHT, and TBHQ

Polypropylene (PP) based active composite films were prepared by adding butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylated hydroquinone (TBHQ) antioxidants using the extrusion molding process. All concentrations of BHT, 2% to 3% BHA, and 3% TBHQ significantly increased the tensile strength (TS) of the composite films compared with control films. Increasing antioxidant concentration decreased TS values for BHT films, whereas an opposite trend was observed for BHA and TBHQ films. BHA at < 2%, BHT at > 2%, and TBHQ at all added concentrations significantly reduced elongation at break (E_b) of the composite films compared to control films. Water vapor permeability (WVP) of 1% BHT film was not significantly different from control. However, other antioxidants especially at increased concentrations significantly increased WVP values. TBHQ films with 300% to 662% increase had the highest WVP and BHT films with 5% to 81% increase had the lowest WVP among composite films. All three antioxidants had a negative effect on the transparency of the films; however the effect of BHA at higher concentrations was greater. The antioxidants did not change the color attributes of the films. Films containing all antioxidants showed 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, which increased with increase in their concentration, especially for those containing 3 wt.% BHT and TBHQ. Overall, incorporating BHA and BHT into a PP matrix improved mechanical, barrier, antioxidant properties, and film appearance and consequently were proposed for the development of antioxidant active PP films. TBHQ film is not recommended for food packaging because of its weak mechanical properties (lower E_b and TS values, higher WVP, and greater migration).     

油砂沥青质对油砂沥青中甲苯残留的影响

利用热重质谱联用仪（TG-MS）分析了三种油砂沥青（印尼油砂沥青、伊朗油砂沥青、加拿大油砂沥青）中的甲苯残留以及油砂沥青质含量对油砂沥青中甲苯残留的影响，并在此基础上，进一步研究了油砂沥青质中的甲苯残留。结果发现，不同油砂沥青中甲苯残留量存在一定差异，其中印尼油砂沥青中的甲苯残留量最多。进一步对沥青质质量分数分别为10%、19%、30%的油砂沥青样品进行热重质谱实验，发现随着油砂沥青中沥青质含量的增加，甲苯的残留量会成倍增加。以加拿大油砂沥青质为例，研究了油砂沥青质对溶剂残留的影响，发现油砂沥青质具有对甲苯分子的夹带能力，导致甲苯分子在超过自身沸点40℃以上才能从沥青质中分离出来。油砂沥青中其他组分的存在也会加剧沥青质对甲苯的夹带作用。此外，研究还发现，在350~650℃时，油砂沥青质可以热解产生甲苯，而且油砂沥青中的沥青质含量越高，热解生成的甲苯越多。     

Mesoporous SmMnO3/CuMnOx catalyst for photothermal synergistic degradation of gaseous toluene

Mesoporous SmMnO₃/CuMnO_x catalyst was prepared by a two-step method using flaky CuMnO_x with high specific surface and excellent catalytic ability as the carrier, which was further applied to photothermal synergistic degradation of gaseous toluene. Quantitative analysis of O₂-TPD and H₂-TPR showed that SmMnO₃/CuMnO_x exhibited abundant of the surface oxygen species and oxygen vacancies content, which enabled it to convert free oxygen to lattice oxygen more quickly during the reaction, and thus improving the reaction process. I-t and photoluminescence experiments demonstrated the improvement of photogenerated electron and hole separation ability of SmMnO₃/CuMnO_x catalyst. UV–Vis analysis manifested the full spectral range of absorption. XPS analysis verified the unequal positions of valence band of the two materials, which can facilitate the separation of photogenerated electrons from holes and improve the ability of better electron transfer. SmMnO₃/CuMnO_x catalyst has higher adsorbed oxygen content and light absorption capacity, which is beneficial to the catalytic oxidation. In situ DRIFTs proved that the oxidation reaction on the catalyst followed the Mars-van Krevelen redox cycle. The VOCs test found that SmMnO₃/CuMnOx composite catalyst is with lower onset reaction temperature (T₉₀ = 190 °C, T₉₀, corresponding to 90% conversion) and good mineralization (100% at 275 °C).     

Hydrogen carriers: Production,transmission, decomposition,and storage

Recognizing the potential role of liquid hydrogen carriers in overcoming the inherent limitations in transporting and storing gaseous and liquid hydrogen, a complete production and use scenario is postulated and analyzed for perspective one-way and two-way carriers. The carriers, methanol, ammonia and toluene/MCH (methylcyclohexane), are produced at commercially viable scales in a central location, transmitted by rail or pipelines for 2000 miles, and decomposed near city gates to generate fuel-cell quality hydrogen for distribution to refueling stations. In terms of the levelized cost of H₂ distributed to the stations, methanol is less expensive to produce ($1.22/kg-H₂) than MCH ($1.35/kg-H₂) or ammonia ($2.20/kg-H₂). Levelized train transmission cost is smaller for methanol ($0.63/kg-H₂) than ammonia ($1.29/kg-H₂) or toluene/MCH system ($2.07/kg-H₂). Levelized decomposition cost is smaller for ammonia ($0.30–1.06/kg-H₂) than MCH ($0.54–1.22/kg-H₂) or methanol ($0.43–1.12/kg-H₂). Over the complete range of demand investigated, 10–350 tpd-H₂, the levelized cost of H₂ distributed to stations is aligned as methanol « ammonia ~ MCH. With pipelines at much larger scale, 6000 tpd-H₂, the levelized cost decreases by ~1 $/kg-H₂ for ammonia and MCH and much less for methanol. Methanol is a particularly attractive low-risk carrier in the transition phase with lower than 50-tpd H₂ demand.     

Gliding arc plasma reforming of toluene for on-board hydrogen production

Hydrogen is considered as a clean and promising fuel, and hydrogen production on-board has attracted widespread research attention. In this work, a gliding arc discharge (GAD) plasma reactor was utilized to reform toluene at room temperature and atmosphere pressure. The performance of hydrogen production through oxidative reforming with toluene as raw material under different input power, oxygen to carbon molecular ratio (O/C), residence time and argon addition was investigated. The optimal yields of H₂ and CO (48.6% and 44.3%) were obtained under the condition of the input power of 32 W, the O/C of 0.68, the residence time of 18.4 s and 10 vol% Ar addition. By analyses of spectrum lines and GC-MS, the plasma reforming mechanism of toluene was proposed. It is believed that N₂(B³Πg) and Ar* could increase the formation of reactive oxygen species (O⁺, O (¹D), O and so on), and N₂(B³Πg) could impact directly the reforming of toluene.     

氨对二次有机气溶胶光学特性的影响

开展一系列甲苯/NO_x光氧化烟雾箱模拟实验,研究大气环境中氨对二次有机气溶胶（SOA）光学特性的影响. 采用特氟龙膜作为烟雾箱的反应腔材料,实验过程中同时检测颗粒的粒径分布、光学参数和质谱信息. 讨论不同氨体积分数对甲苯光氧化生成SOA的消光截面、复折射率及粒径等参数的变化特征. 研究发现,上述实验中SOA的消光作用均以散射为主;随着粒径的增大,消光截面呈指数增大,复折射率则先增大后减小. 与低湿无氨环境相比,增湿或加氨均导致SOA中元素O和C物质的量之比增大、复折射率增大;高湿加氨条件下,SOA的粒径明显减小、颗粒数密度急剧增大、SOA中元素O和C的物质的量之比、元素N和C的物质的量之比均增大.     

等离子体-催化剂体系下甲苯加氢反应

探索了等离子体介质阻挡放电甲苯加氢工艺的行为。反应产物的气相色谱分析结果表明甲基环己烷为主产物。单因素实验法考察不同因素对甲苯加氢反应行为的影响,初步推测等离子体环境下甲苯加氢反应包含三种机理:加成反应、取代反应、C-C键断裂反应。研究发现,通过增大放电功率和催化剂(Ni/SiO2)协同作用,可使甲基环己烷转化率趋于最佳值。在反应条件为:"一段式"催化剂装填方式,0.30 g催化剂固载于0.1 g玻璃纤维上,催化剂活性金属组分含量17%(wt);放电电压8.4 k V;电极直径50 mm;气体配比(VH2/VC7H8)31;停留时间21 s,其甲苯转化率可达78.4%,甲基环己烷选择性72.2%。     

基于镍铟水滑石的含异质结材料在甲苯检测中的应用

构建异质结构是提高气体传感器性能的有效方法之一。本工作通过在空气中高温煅烧不同Ni/In摩尔比的镍铟水滑石(NiIn-LDHs)合成了一系列含NiO-In2O3异质结的材料,通过氢气退火处理后,应用于甲苯气体检测。结果表明,当Ni/In为3.0,退火温度为500℃时,所得材料对0.005‰甲苯具有最高响应。此外,该材料还表现出针对其他干扰气体(如氨气、丙酮、高湿度水汽、三乙胺和二氧化硫)的高选择性和12天的连续测试的高稳定性。通过XPS、UPS等一系列表征证实,退火后形成的材料Ni/NiO-In2O3中存在肖特基能垒以及较多的氧空位,与P-N结的协同效应共同导致了其具有最佳气敏性能。     

A strategy to reduce the impact of tar on a Ni‐YSZ anode of solid oxide fuel cells

High‐temperature raw coke oven gas (COG) is a promising fuel for use in solid oxide fuel cells (SOFCs) because it is rich in both hydrogen (55%‐60%) and methane (23%‐27%). However, the tar present in COG limits its ability to directly generate power using state‐of‐art SOFCs because the presence of tar limits the cell's performance and stability. In this work, a strategy is presented in the attempt to reduce the influence of tar on SOFCs by applying a La_0.7Sr_0.3MnO₃ catalyst as a protective layer for the cell. The results showed that 44‐g Nm^?3 toluene had a profoundly negative effect on the performance of a conventional cell, which showed severely reduced performance after only 1.4 hours of exposure to toluene‐contaminated hydrogen. In contrast, the catalyst‐modified cell showed good stability for at least 110 hours under the same conditions. This work provides a promising route to directly utilize raw COG as an SOFC fuel that is also suitable for biosyngas.     

Adsorption of toluene from aqueous solutions using clay-based nanostructures

In this study, porous clay heterostructures (PCH) are synthesized through gallery template approach and characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Nitrogen adsorption–desorption techniques. Batch adsorption studies are conducted to investigate the effect of parameters such as adsorbent dosage, pH, concentration, and contact time on adsorption of toluene by PCH in aqueous solutions. Equilibrium data were fitted to the Langmuir and Freundlich models. Based on the results, by increasing the PCH dosage from 0.5 g/L to 4 g/L, toluene removal is enhanced from 34% to 88.1%.