二氧化锰/石墨烯臭氧催化氧化甲苯反应性能

采用一步水热合成法,在180℃,12 h条件下制备了30%二氧化锰/石墨烯(MnO2/G)复合材料。实验结果表明:MnO2均匀且较为牢固地锚定于石墨烯表面,同时MnO2的沉积阻止了多层石墨烯的复合,从而使得复合物具有较大的比表面积。相同条件下,MnO2/石墨烯相较于单纯MnO2或石墨烯具有很好的臭氧催化氧化甲苯性能,这可以归结于MnO2和石墨烯间的协同催化作用。     

Dietary and host-related factors influencing carotenoid bioaccessibility from spinach (Spinacia oleracea)

Several dietary and host related factors potentially influencing carotenoid (beta-carotene, lutein and zeaxanthin) bioaccessibility from spinach, including different concentrations of sodium, calcium and magnesium, were systematically investigated by means of an in vitro digestion model. Bioaccessibility was highest when milk (4% fat) and lowest when skimmed milk or more complex food matrices such as sausage were added to the meal. Micellarisation significantly depended on the presence and concentration of bile salts and pancreatin (p < 0.001, Bonferroni) but was unaffected by pepsin. Micellarisation significantly decreased to 61.4 ± 3.0% of control (p < 0.001, Dunnett’s) at high cholesterol (114 mg/test meal) but not at similar stigmasterol concentrations. Calcium and magnesium ?13.8 mM individually inhibited micelle formation ( >40% on average), presumably due to the generation of insoluble soaps with fatty acids and bile salts. Increased sodium concentrations (280 and 460 mM) altered carotenoid micellarisation patterns, favoring beta-carotene isomers (p < 0.001, Bonferroni) but decreasing lutein and zeaxanthin (p < 0.001 and p < 0.05, respectively, Bonferroni). This study suggests that minerals may impact carotenoid bioavailability.     

Phenyl modification of Mn‐containing mesoporous silica and catalytic oxidation of toluene

BACKGROUND: Catalytic oxidation of toluene with dioxygen is a fundamental industrial technology because the oxidized products are important intermediates for many fine chemicals. In this study, phenyl modification was utilized to alter catalyst surface characteristics in order to enhance activity. RESULTS: Phenyl groups were successfully immobilized on the surface of Mn‐containing hexagonal mesoporous silica (HMS) through a one‐step synthesis route, as demonstrated by detailed characterization. As a result, the surface of the catalyst Ph? Mn? HMS was more hydrophobic with a water droplet contact angle of 96°. In the oxidation of toluene to benzoic acid with dioxygen under solvent‐free conditions, this new catalyst showed higher activity and selectivity than non‐organomodified Mn? HMS, and the conversion and selectivity increased by a factor of 40% and 9%, respectively. CONCLUSION: Modification of the catalyst surface with phenyl groups was an effective strategy to increase activity in the oxidation of toluene. Both conversion and selectivity were improved and this is linked to the hydrophobic character of the surface. This organic modification strategy may also be extended for oxidation of other hydrocarbons. Copyright © 2009 Society of Chemical Industry     

Effect of pre‐treatments based on UV photocatalysis and photo‐oxidation on toluene biofiltration performance

BACKGROUND: The integration of UV photocatalysis and biofiltration seems to be a promising combination of technologies for the removal of hydrophobic and poorly biodegradable air pollutants. The influence of pre‐treatments based on UV_{254 nm} photocatalysis and photo‐oxidation on the biofiltration of toluene as a target compound was evaluated in a controlled long‐term experimental study using different system configurations: a standalone biofilter, a combined UV photocatalytic reactor‐biofilter, and a combined UV photo‐oxidation reactor (without catalyst)‐biofilter. RESULTS: Under the operational conditions used (residence time of 2.7 s and toluene concentrations 600–1200 mg C m^?3), relatively low removal efficiencies (6–3%) were reached in the photocatalytic reactor and no degradation of toluene was found when the photo‐oxidation reactor was operated without catalyst. A noticeable improvement in the performance of the biofilter combined with a photocatalytic reactor was observed, and the elimination capacity of the biological process increased by more than 12 g C h^?1 m^?3 at the inlet loads studied of 50–100 g C h^?1 m^?3. No positive effect on toluene removal was observed for the combination of UV photoreactor and biofilter. CONCLUSIONS: Biofilter pre‐treatment based on UV_{254 nm} photocatalysis showed promising results for the removal of hydrophobic and recalcitrant air pollutants, providing synergistic improvement in the removal of toluene. Copyright © 2011 Society of Chemical Industry     

Convenient synthesis of sulfonamides from amines and p‐toluene sulfonyl chloride mediated by crosslinked poly(4‐vinylpyridine)

A general, mild, and convenient method has been developed for the synthesis of various N‐substituted and N, N‐disubstituted sulfonamides, as a class of sulfa drugs, from the corresponding amines and p‐toluene sulfonyl chloride in the presence of readily available crosslinked poly(4‐vinylpyridine) as a catalyst, base or polymeric substrates. The use of polymeric catalyst simplifies routine sulfonylation of amines because it eliminates the traditional purification. The polymer can be removed quantitatively and it can be regenerated and reused for several cycles without losing its activity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

新型酸性离子液体催化下甲苯的选择性硝化

用HNIL-NO_3~-和HNIL·HSO_4~-新型酸性离子液体为Lewis酸催化剂,考察了催化剂种类、用量、硝化反应时间、温度、醋酐等因素对甲苯选择性硝化反应的影响,并研究了催化剂的循环使用效果.结果表明,醋酐存在条件下,以CCl_4为溶剂、95%发烟硝酸为硝化剂,温度控制在55℃,反应60 min,3.0 g HNIL·HSO_4~-新型酸性离子液体催化剂对甲苯硝化表现出较强的区域选择性,产物收率达到99.4%,硝化产物邻位和对位异构体的重量比达1.12,较硝硫混酸的1.67显著降低.该催化剂可循环使用5次,催化活性变化很小.     

Preliminary studies on the use of modified ALCELL lignin as a coupling agent in the biofiber composites

ALCELL lignin has been employed as a coupling agent in empty fruit bunch fiber (EFBF)–polypropylene (PP) composites. The lignin has been chemically modified with toluene diisocyanate (TDI) to various weight loadings. The evidence of the reaction between TDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on mechanical properties has been studied. The results show that the TDI‐modified lignin is able to impart greater compatibility between EFBF and PP. This is reflected in the greater mechanical properties shown by the composites with TDI‐modified lignin than in those with the unmodified lignin. Scanning electron microscopy (SEM) studies showed that TDI modification of lignin resulted in a better blending and compatibility between lignin and PP matrix. The glass‐transition temperature of the lignin increases as the WPG is increased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1333–1340, 2001     

Hydrotropic properties of some short-chain alkylbenzene- and alkylnaphthalene sulfonates

Alkylbenzene sulfonates based on toluene, xylene and cumene, and alkylnaphthalene sulfonates act as hydrotropes in surfactant systems. One measure of hydrotropicity is the amount of hydrotrope required to clear a cloudy detergent formulation; some hydrotropes are more effective than others, depending on the surfactant formulation. Another measure is the modification of the viscosity of surfactant formulations; the change in the viscosity depends on the amount and type of hydrotrope used and on the specific formulation involved. Additionally, alkylnaphthalene sulfonate hydrotropes change the solubility of nonionic surfactants in water, and both types of hydrotrope raise the cloud point of nonionic surfactant solutions; however, the naphthalene-based hydrotropes are more efficient. Ross-Miles foam test data are used to compare the foam characteristics of different alkylnaphthalene sulfonates. A critical micelle concentration (CMC) was determined for the alkylnaphthalene sulfonates, but although alkylbenzene sulfonates do show some surface activity, a CMC could not be found for these materials. Presented as a poster session at the AOCS Annual Meeting & Expo, May 1997, Seattle, Washington, and at Soaps, Detergents, and Oleochemicals: An AOCS International Conference, October 1997, Fort Lauderdale, Florida.