在腐植酸上二氧化氮光敏还原制备亚硝酸

研究结果表明,土壤和其他含有腐植酸的表面,具有一种能产生还原表面物质的有机表面光化学,而这种还原表面物质可以选择性地与二氧化氮反应。亚硝酸形成的表观速率可以解释最近观察到的白天在边界层中亚硝酸高浓度现象,亚硝酸的光分解占整个羟基自由基源的60%。我们认为这种在腐植酸上的光诱导亚硝酸产物对最低对流层的化学过程有潜在的重要影响。     

香兰素对甲苯胺西夫碱及其轻,重络合物的Raman光谱研究

本文用独特的实验方法得到西夫碱稀土络合物的表面增强喇曼光谱（ＳＥＲＳ）、表面增强共振喇曼光谱（ＳＥＲＲＳ）。通过对样品的常规喇曼光谱的分析．指认了Ｌｎ－Ｃｌ、Ｌｎ－Ｎ、　Ｌｎ－Ｕ等键的伸缩振动谱带及Ｌｎ－（ＯＨ２）的面外摇摆振动谱带。讨论了西夫碱与它的不同原子序数的稀土元素的络合物光谱之间的差异     

Synthesis and Photocatalytic Application of Stable Lead‐Free Cs2AgBiBr6 Perovskite Nanocrystals

Lead halide perovskite nanocrystals (NCs) have demonstrated great potential as appealing candidates for advanced optoelectronic applications. However, the toxicity of lead and the intrinsic instability toward moisture hinder their mass production and commercialization. Herein, to solve such thorny problems, novel lead‐free Cs₂AgBiBr₆ double perovskite NCs fabricated via a simple hot‐injection method are reported, which exhibit impressive stability in moisture, light, and temperature. Such materials are then applied into photocatalytic CO₂ reduction, achieving a total electron consumption of 105 µmol g^?1 under AM 1.5G illumination for 6 h. This study offers a reliable avenue for Cs₂AgBiBr₆ perovskite nanocrystals preparation, which holds a great potential in the further photochemical applications.     

Photochromic films prepared by solid state processing of disentangled ultrahigh molecular weight polyethylene and photochromic dyes composites

Disentangled ultrahigh molecular weight polyethylene (DPE) is a special grade of polyethylene (molecular weight, >10⁶ Da) which can be processed by an environment friendly solid state process on counter rotating two roll mill (TRM) below the melt temperature of the polymer. This unique processing property of DPE was utilized to develop smart DPE photochromic films. Photochromic dye like 'Spirooxazine' or 'Spiropyran' has been mixed with DPE resin powder prior to film formation without altering the DPE properties. These films could change their optical appearances on exposure to UV-light of wavelength 365 nm and the color change phenomenon of the films could also be replicated by sunlight. The color change observed is found to be reversible, that is, films could return to colorless form either spontaneously in dark or by thermal stimuli. Such smart property was imparted to DPE even at very low concentration (2,000 ppm) of photochromic dyes. Spectrophotometric studies were used to measure the rate of forward reaction with UV radiation and the rate of backward reaction in dark. In fact, DPE powder and photochromic dye composite was used to produce the compression molded disc to understand the color change phenomena. Moreover, it was observed that the photo-degradation rate of dye, could be retarded ~30% by using amphoteric Zinc phthalate salt. TGA and DSC studies confirmed that the characteristics of DPE film remained almost unaltered even after with preparation of film photochromic dyes.     

Polyoxometalates/polymer composites for the photodegradation of bisphenol-A

Nowadays water scarcity represents a threat for human and living beings. Therefore, to satisfy the demands of people for clean and safe water, new technologies for wastewater treatment have been developed. Thus, photocatalysis has emerged as a green chemical approach for such treatment. In this context, new polyoxometalate (POM)/polymer composites with relevant photocatalytic properties have been developed via an easy and cheap photopolymerization process upon mild visible light irradiation at 405 nm. This fruitful association between POM and polymer allowed the obtention of shaped materials facile to collect and reuse at the end of the photocatalytic treatment avoiding then the usual time-consuming regeneration methods. The prepared photocomposites displayed excellent photocatalytic performance for the removal of bisphenol-A from water under different sources of irradiation. Hence, 100%, 88%, and 50% of this model compound were decomposed by the phosphomolybdic composite under just 90 min of UV lamp, solar and LED@375 nm irradiations, respectively. The effectiveness of these developed photocatalysts towards the degradation of other organic compounds, as well as the degradation mechanism based on the generation of highly reactive chemicals such as ^•OH radicals promoting the degradation were already reported. Bisphenol-A degradation pathway and the identification of the photoproducts were discussed using mass spectroscopy technique. Therefore, this paper highlighted the photocatalytic efficiency of the new manufactured materials for the photodegradation of the bisphenol-A, thus expanding their application fields, under different sources of irradiation and under pure solar irradiation which make their applications more interesting and less energy consuming.     

高级氧化技术降解卤乙酸效果及动力学研究

为降低预氯化过程中产生的消毒副产物带来的饮用水不安全性,探讨高级氧化技术降解消毒副产物中的卤乙酸的效果并进行反应动力学分析.结果表明,当紫外光强为1048μW/cm2,双氧水投加量为70 mg/L,UV/H2O2工艺对二氯乙酸去除率为84.58%,紫外光强为183μW/cm2,双氧水投加量为141.51 mg/L,O3累计投加量为5 mg/L,UV/H2O2/O3工艺对二氯乙酸的去除率为80.37%,分析两种工艺的反应动力学规律,试验拟合反应速率k与双氧水投加量的反应动力学方程模型分别为:k=0.0002[H2O2]和k=0.0008[H2O2]0.5403.     

数学建模与仿真在光动力疗法研究中的应用

采用建模和仿真方法,建立光动力疗法（Photodynamic Therapy,PDT）微血管效应的系统模型,可以分析出光动力疗法对组织的损伤机制及各个因素的作用关系和作用规律,辅助医生进行临床治疗和决策。本文综述了在建立光动力疗法微血管效应数学模型研究中所涉及到的组织光学、药代动力学、光化学等研究领域的研究方法和研究结果及其在模型中的作用。     

羟基自由基(·OH)的特性及其在光化学氧化中的反应机理

概述了羟基自由基(·OH)区别于普通化学氧化剂的一系列特性,并通过对UV/H2O2、UV/O3、UV/H2O2/O3 3种不同系统光化学氧化技术中羟基自由基反应机理的分析以及三者之间的相互比较,阐明了羟基自由基在光化学氧化技术领域的重要性.     

光催化环己烷选择氧化合成环己酮/环己醇催化研究进展

环己烷选择性氧化合成环己醇/酮具有重要工业价值,工业上热氧化路线反应温度高、副反应多、转化率低、选择性不高,亟需条件更温和、更环保的替代路线。以太阳光为驱动的光催化环己烷氧化路线可在常温常压下实现环己烷的选择性氧化,受到极大关注。本文综述了近10年来光催化环己烷选择性氧化催化体系、反应机理和反应影响因素的研究情况,对光催化环己烷选择性氧化催化循环中环己烷分子活化、环己酮/醇形成、活性自由基再生的基元过程和催化剂失活机理进行总结和分析;对影响光催化环己烷选择性氧化的反应参数进行深入分析和讨论;指出·OH为主要的活性自由基,环己基过氧化氢是重要的中间产物,环己酮/醇主要通过环己基过氧化氢的光催化分解形成,光辐射条件（光强和波长）、溶剂、催化剂结构和表面性质都是光催化环己烷选择性氧化的重要影响因素。最后指出光催化环己烷选择性氧化规模化应用的关键是进一步提高光催化剂的寿命和稳定性以及设计结构合理、高效利用光能的光催化反应装置。     

Study on in situ synthesis of konjac glucomannan/silver nanocomposites via photochemical reduction

Konjac glucomannan (KGM)/Silver nanocomposites have been prepared directly in the dilute hydrosol of KGM using photochemical reduction of Ag⁺. The KGM/Ag nanocomposites have been characterized by means of Fourier transform infrared (FTIR) spectra, transmission electron microscopy (TEM), and thermalgravimetry (TG). The results of FTIR showed that the wavenumbers and the strengths of some characteristic peaks of KGM treated by silver nanoparticles were changed obviously, the characteristic peaks of the O? H stretching and the C? O? (H) stretching became wider with increasing concentrations of the reactants, and the characteristic peaks of the O? H stretching and the C? O? (H) stretching shifted to high wavenumbers with increasing time of photochemical reduction. The images of TEM indicated that Ag nanoparticles were finely dispersed inside the KGM films with different shapes, such as sphere‐like (average diameters of 9 ± 4 nm) and star‐like (edge lengths of about 20 nm), respectively. These suggested that the morphology and the agglomerated state of Ag nanoparticles in the composites changed with the conditions of the preparation, especially with the concentrations of Ag⁺ and KGM as well as the time of photochemical reduction. The KGM and KGM/Ag films had remarkably different thermal properties from the TG curves. The mechanism of interaction between the polysaccharide and the silver nanoparticles has also been generally discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1323–1327, 2006