高压加氢环烷基橡胶油光氧化机理研究

以新疆克拉玛依高压加氢环烷基橡胶油KN4010为原料,采用碘量滴定法和红外光谱法分别监测高压加氢环烷基橡胶油中过氧化物、含氧化合物在光照条件下随时间的变化趋势,研究了其在紫外光照条件下氧化降解规律。研究表明其光氧化机理遵循自由基氧化机理,处于中等氧化程度阶段。过氧化值数据显示高压加氢环烷基橡胶油对光表现敏感。

光氧化及其对食品安全的影响

通过分析光氧化反应的诱发机理和氧化产物,来揭示光对食品的营养成分、色泽和风味产生的不良影响,从而进一步探讨光氧化对食品安全所产生的负面影响。从光氧化的机理和影响光氧化反应的因素出发,提出了相应的限制和避免食品光氧化的措施。并对光氧化的利用作了简要说明。

海洋石油光化学降解的研究

石油进入海水会发生各种物理、化学变化 ,以往的研究已证明光化学氧化在石油及其精炼产品风化过程中具有重要意义。光化学氧化机理主要在于接受日光照射的能量 ,以不同的方式与溶解氧结合 ,从而最终降解石油烃。生成的光氧化产物一般为羧酸、醇、醚、羰基化合物等几类 ,还有一些产物尚不能确定其结构。光氧化产物仍然存在毒性 ,对海洋生物等十分有害。在动力学方面 ,针对其某一组分已证实为一级反应动力学行为 ,并定量地得出了速率常数。光降解速率会受到光照条件、溶解氧、金属离子等因素的影响。目前的研究表明 ,对石油光化学进行深入探讨具有较高的研究价值和现实意义。

Au表面上SAMs的稳定性和抗腐蚀性

综述了单分子层自组装膜 (Self assembliedmonolayers,SAMs)结构形成的影响因素 ;探讨了SAMs的形成机理、组装分子间氢键作用形成的超分子结构及其SAMs的光氧化机理 。

Xanthophyll Cycle and Its Molecular Mechanism in Photoprotection

When plants absorb more light than that can be used for photosynthesis, the excessive energy can cause photoinhibition and even photooxidation of photosynthetic apparatus. Xanthophyll cycle-dependent photo-protection is believed to be the main mechanism for plants to deal with excessive light energy. This review focuses on molecular biological aspects and regulations of violaxanthin de-epoxidase and zeaxanthin epoxidase involved in xanthophyll cycle. We will summarize the functions of xanthophyll cycle, especially recent advances in its thermal dissipation mechanism of photoprotection. Some interesting issues deserving further study will be discussed.

Synergistic integration of metallic Bi and defects on BiOI: Enhanced photocatalytic NO removal and conversion pathway

Surface plasmon resonance(SPR)of metals may provide a way to improve light absorption and utilization of semiconductors,achieving better solar light conversion and photocatalysis efficiency.This study uses the advantages of SPR in metallic Bi and artificial defects to cooperatively enhance the photocatalytic performance of BiOI.The catalysts were prepared by partial reduction of BiOI to form Bi@defective BiOI,which showed highly enhanced visible photocatalytic activity for NOx removal.The effects of reductant quantity on the photocatalytic performance of Bi@defective BiOI were investigated.The as-prepared photocatalyst(Bi/BiOI-2)using 2 mmol of reductant NaBH4 showed the most efficient visible light photocatalytic activity.This enhanced activity can be ascribed to the synergistic effects of metallic Bi and oxygen vacancies.The electrons from the valence band tend to accumulate at vacancy states;therefore,the increased charge density would cause the adsorbed oxygen to transform more easily into superoxide radicals and,further,into hydroxyl radicals.These radicals are the main active species that oxidize NO into final products.The SPR effect of elemental Bi enables the improvement of visible light absorption efficiency and the promotion of charge carrier separation,which are crucial factors in boosting photocatalysis.NO adsorption and reaction processes on Bi/BiOI-2 were dynamically monitored by in situ infrared spectroscopy(FT-IR).The Bi/BiOI photocatalysis mechanism co-mediated by elemental Bi and oxygen vacancies was proposed based on the analysis of intermediate products and DFT calculations.This present work could provide new insights into the design of high-performance photocatalysts and understanding of the photocatalysis reaction mechanism for air-purification applications.

The pivotal effects of oxygen vacancy on Bi_2MoO_6:Promoted visible light photocatalytic activity and reaction mechanism

Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,such as limited photo-response and low charge separation efficiency.In this work,we developed a facile method to introduce artificial oxygen vacancy into Bi2MoO6 microspheres,which could effectively address these problems and realize highly efficient visible light photocatalysis.The experimental and theoretical methods were combined to explore the effects of oxygen vacancy on the electronic structure,photocatalytic activity and the reaction mechanism toward NO removal.The results showed that the addition of NaBH4 during catalyst preparation induced the formation of oxygen vacancy in Bi2MoO6,which plays a significant role in extending the visible light absorption of Bi2MoO6.The visible light photocatalytic activity of Bi2MoO6 with oxygen vacancy was obviously enhanced with a NO removal ratio of 43.5%,in contrast to that of 25.0%with the pristine Bi2MoO6.This can be attributed to the oxygen vacancy that creates a defect energy level in the band gap of Bi2MoO6,thus facilitating the charge separation and transfer processes.Hence,more reactive radicals were generated and participated in the photocatalytic NO oxidation reaction.The in situ FT-IR was used to dynamically monitor the photocatalytic NO oxidation process.The reaction intermediates were observed and the adsorption-reaction mechanism was proposed.It was found that the reaction mechanism was unchanged by introducing the oxygen vacancy in Bi2MoO6.This work could provide new insights into the understanding of the oxygen vacancy in photocatalysis and gas-phase photocatalytic reaction mechanism.

Recent progress in production and usage of hydrogen peroxide

Hydrogen peroxide has attracted increasing interest as an environmentally benign and green oxidant that can also be used as a solar fuel in fuel cells.This review focuses on recent progress in production of hydrogen peroxide by solar-light-driven oxidation of water by dioxygen and its usage as a green oxidant and fuel.The photocatalytic production of hydrogen peroxide is made possible by combining the e^(-)and 4e-oxidation of water with the e^(-)reduction of dioxygen using solar energy.The catalytic control of the selectivity of the e^(-)vs.4e-oxidation of water is discussed together with the selectivity of the e^(-)vs.4e-reduction of dioxygen.The combination of the photocatalytic e^(-)oxidation of water and the e^(-)reduction of dioxygen provides the best efficiency because both processes afford hydrogen peroxide.The solar-light-driven hydrogen peroxide production by oxidation of water and by reduction of dioxygen is combined with the catalytic oxidation of substrates with hydrogen peroxides,in which dioxygen is used as the greenest oxidant.

Influence of PEG 6000 on gallium oxide(Ga_2O_3) polymorphs and photocatalytic properties

Three different nanorod-like gallium oxides with mono/poly-crystalline nature(α, β, and α/β-Ga2O3) were prepared by regulating the amount of polyethylene glycol(PEG) 6000 in the range of 0.2–0.8 g proportionally via a hydrothermal method combined with further calcination. The bandgap of the products, given by UV-Vis diffuse reflectance spectra(UV-Vis DRS), was in the order of α-Ga2O3 > α/β-Ga2O3 > β-Ga2O3. To further investigate the photocatalysis performance of the catalysts, the decomposition of rhodamine B(Rh B) by Ga2O3 under UV light illumination(λ < 387 nm) was presented and complete degradation could be achieved within 30 min, a result that showed the highest efficiency. The photocatalytic oxidation mechanism is further discussed and prominently related to the active species: hydroxyl radical(·OH) and superoxide radical(O·-2), which were confirmed by electron paramagnetic resonance(EPR).