十二烷基苯磺酸钠的超声降解研究

采用频率为１．８ＭＨｚ,声强近似为５Ｗ·ｃｍ~－２的超声波,在固定式声化学的应器内研究了初始浓度为２００ｍｇ／Ｌ－４００ｍｇ／Ｌ的十二烷基苯磺酸钠（ＤＢＳ）溶液的声化学降解情况．实验表明,浓度的改变对ＴＯＣ的削减率无明显的影响,溶液的ＰＨ值对降解率则有显著影响,碱性条件下（ＰＨ＝１３）,ＤＢＳ几乎无降解,酸性条件下（ＰＨ＝３）ＴＯＣ削减率≤１０％．通过分析降解过程中溶液的紫外光谱（１９０－３４０ｎｍ）,发现降解过程中有复杂的中间产物生成,包括小分子烃类碎片及硝基化合物。我们认为,能使溶液表面张力。降低的表面活性剂,其声化学降解率低的原因在于,溶液表面张力下降后影响了溶液中空化效应的产生,从而降低了溶液中声化学反应的强度,致使ＴＯＣ削减率不高。     

Enhancement of the photocatalytic activity of TiO2 nanoparticles by surface-capping DBS groups

TiO₂ nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) are synthesized by a sol-hydrothermal process using tetrabutyl titanate and DBS as raw materials. The effects of surface-capping DBS on the surface photovoltage spectroscopy (SPS), photoluminescence (PL) and photocatalytic performance of TiO₂ nanoparticles are principally investigated together with their relationships. The results show that the surface of TiO₂ nanoparticles can be well capped by DBS groups while the pH value and added DBS amount are controlled at 5.0 and 2% of TiO₂ mass weight, respectively, and the linkage between DBS groups and TiO₂ surfaces is mainly by means of quasi-sulphonate bond. The intensities of SPS and PL spectra of TiO₂ obviously decrease after DBS-capping, while the activity can greatly increase during the photocatalytic degradation of Rhodamine B (RhB) solution, which are mainly attributed to the electron-withdrawing character of the DBS groups. Moreover, the enhancement of photocatalytic activity of DBS-capped TiO₂ is also related to the increase in the capability for adsorbing RhB.     

NMR investigation of hydrophobe molecule solubility in a DBS micelle solution

The distribution of hydrophobe molecules in the volume of a micelle of sodium dodecylbenzene sulfonate was examined by high resolution NMR spectra. The supposition of an arrangement of the hydrocarbon chains in the micelle volume of a large density in the center and small density in the periphery was confirmed.     

纳米颗粒DBS/TiO_2的拉曼光谱

采用水热法制得表面包覆有十二烷基苯磺酸的二氧化钛纳米粒子 ,并应用拉曼光谱对其进行了检测。结果表明 :样品为表面包覆有十二烷基苯磺酸的二氧化钛纳米粒子的集合体。其拉曼峰与未包裹的二氧化钛拉曼峰相比 ,出现了蓝移现象 ,从纳米粒子的表面结构及包裹层的压力出发对此现象进行了定性解释和讨论     

DBS包覆TiO2纳米粒子的表面光伏及光致发光性能

采用溶胶-水热法合成了十二烷基苯磺酸钠(DBS)包覆的TiO2纳米粒子,并利用X射线衍射仪、透射电镜、表面光电压谱(SPS)和光致发光光谱(PL)等对样品进行表征.重点探讨了DBS包覆的适宜条件及DBS包覆对TiO2光伏和发光等性质的影响.结果表明,进釜前pH值在4.5~5.5,DBS用量为TiO2质量的1.0%~3.0%时,能够获得理想包覆.在水热过程中,DBS的引入对锐钛矿型TiO2微晶的生长有抑制作用.由于DBS的包覆,使TiO2的SPS和PL信号强度显著下降,这可能与磺酸基的吸电子性以及表面缺陷等的减少有关.     

The transmission performance degradation of the optical millimeter-wave signals by fiber chromatic dispersion

The influence of the fiber chromatic dispersion on double sideband (DSB), optical carrier suppression (OCS), and single sideband (SSB) optical mm-wave signals is investigated based on the Taylor expansion of the propagation constant and is verified by simulation. According to our theoretical results, the fading effect suppresses the signal power of the DSB optical mm-wave periodically in a cosine-like pattern, and it can be described by the zero-order Taylor expansion of the propagation constant. For the optical mm-wave with the signal modulated on two or more tones, the bit pulses of the mm-wave signal are distorted by the dispersion-inducing bit walk-off effect between tones, which is expressed by the first-order Taylor expansion of the propagation constant. Moreover, as the signal rate and the transmission distance are increased further, higher-order Taylor expansion of the propagation constant still degrades the optical mm-wave signal even if both the fading effect and the bit walk-off effect are eliminated completely. The distortion of the signal pulses of SSB optical mm-wave is derived based on the second-order Taylor expansion of the propagation constant. This degradation is verified by the simulation with the eye diagram evolution of the SSB optical mm-wave signal.     

Millimeter- and submillimeter-wave spectroscopy of HBS and DBS in vibrationally excited states

Normal and deuterated isotopic variants of thioborine have been produced in the gas phase by a high temperature reaction between crystalline boron and hydrogen sulfide. Millimeter- and submillimeter-wave rotational spectra have been recorded in the frequency range from 75 to 730 GHz for vibrational ground and excited states of the H^10/11B³²S and D^10/11B³²S isotopic species. The spectra of all the excited states which lie below 1500 cm⁻¹, that are 01¹0, 00⁰1, 02⁰0, and 02²0, have been observed and analyzed for each of the four isotopologues investigated. High-order Fermi resonance parameters were found important to analyze properly the spectra of the 00⁰1 and 02⁰0 interacting states. The improved rotational data in conjunction with earlier infrared spectroscopy results have been employed to calculate more precise anharmonic force constants and equilibrium bond lengths.     

Study on the Nonisothermal Melt Crystallization Kinetics of DBS/PBT Blends

The modified Avrami, Mo, and Kissinger models were applied to investigate the nonisothermal melt crystallization process of dibenzylidene sorbitol (DBS)/poly(butylene terephthalate) (PBT) blends by differential scanning colorimetry (DSC) measurements. The modified Avrami model can describe the nonisothermal melt crystallization processes of DBS/PBT blends fairly well. The cooling rates and the blend composition affect the crystallization of the blends according to Mo crystallization kinetics parameters. The Mo model shows that F(T) increases with increasing crystallinity, indicating that the needed cooling rate when it reached a certain crystallinity increased in unit time, the crystallization rate of DBS/PBT blends is faster than the crystallization rate of pure PBT, and the crystallization rate of the DBS/PBT blends with 0.5% DBS is fastest. The Kissinger model showed that the crystallization activation energy of DBS/PBT blends is lower than the activation energy of pure PBT; the crystallization activation energy of the DBS/PBT blends with 0.5% DBS is the lowest.     

Fast degradation of fullerenes by ultraviolet laser radiation

The first observation of fullerene C₆₀ ultraviolet photolysis in hexane solution was published two years ago [1]. Similar further experiments realized with an ultraviolet lamp and solar light gave inconsistent results with ambiguous interpretations. We report the unexpectedly fast and efficient degradation of the fullerenes in n-hexane solutions, induced by an XeCl-excimer laser. Well-defined experimental conditions and good reproducibility in these experiments allow us to estimate the minimal value of the quantum yield of fullerene photolysis.     

Enhanced sonochemical degradation of bisphenol-A by bicarbonate ions

Sonochemical elimination of organic pollutants can take place through two degradation pathways. Molecules with relatively large Henry’s law constants will be incinerated inside the cavitation bubble, while nonvolatile molecules with low Henry’s law constants will be oxidised by the OH ejected from the bubble of cavitation. Taking bisphenol-A as a model pollutant, this study points out an alternate degradation route, mediated by bicarbonate ions, which is significant for the elimination of micro-pollutants at concentrations present in natural waters. In this process, OH radicals react with bicarbonate ions to produce the carbonate radical, which, unlike the OH radical, can migrate towards the bulk of the solution and therefore induce the degradation of the micro-pollutants present in the bulk solution. As a consequence, initial degradation rate is increased by a factor 3.2 at low concentration of bisphenol-A (0.022 μmol l⁻¹) in presence of bicarbonate in water.     

噻吩类含硫模型化合物的降解机理研究

为了探究煤中噻吩类有机硫化合物降解规律,采用密度泛函理论搜索过渡态提出了两条反应路径。通过对反应路径中各物种的原子电荷、热力学、动力学参数和噻吩降解的势能剖面图分析得出：各路径发生的难易程度是不同的,噻吩降解的最有利的反应路径为Path1,即首先是H9转移到S5上,接着H8从C3转移到C4上伴随着C4-S5键的断裂,然后H6转移到S5上,最后随着H7从C2转移到C1上,H2S离开原来的结构,丁二炔形成。利用密度泛函理论对煤中噻吩类含硫模型化合物在不同降解路径中的变化规律进行研究,可以有助于理解煤中噻吩硫的脱除机理,为煤中噻吩类有机硫的脱除实验及工业处理过程提供理论指导。     

The use of ultrasound to enhance the degradation of the Basic Green by cast iron

The effect of pH, amount of cast iron and initial concentration on the removal ratio of Basic Green by cast iron combined with ultrasound was investigated. It was shown that the reduction of Basic Green was enhanced by ultrasound. In all combined systems, the decolorization efficiency is more than 95%, but removal ratio of CODcr decreased with the increasing pH or initial dye concentration and increased with the increase of the amount of cast iron.     

The effect of surface modification by nitrogen plasma on photocatalytic degradation of polyvinyl chloride films

The solid-phase photocatalytic degradation of poly(vinyl chloride) (PVC) films was investigated under the ambient air in order to assess the feasibility of developing photodegradable polymers. Nitrogen plasma was used to modify PVC films to enhance the photocatalytic degradation of PVC with nano-sized anatase TiO₂. The plasma parameter varied in this study is discharge power from 30 to 120 W for a constant treatment time of 60 s and a constant gas pressure of 10 Pa. The photodegradation of the plasma-treated PVC-TiO₂ films was compared with that of pure PVC films and PVC-TiO₂ films performing weight loss monitoring, scanning electron microscopy (SEM) analysis, contact angle measurements, electron spin resonance (ESR), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The wettability of the plasma-treated PVC is improved significantly. ESR revealed that the signal of radicals on the surface of the plasma-treated PVC film was enhanced after the treatment. Furthermore, the weight loss indicated that TiO₂ speeds up the photocatalytic degradation of PVC chains. The SEM image of the plasma-treated PVC-TiO₂ film showed a lot of crack on the film surface after irradiation. XPS indicated that the C and Cl atomic concentration reached minimum values on the surface of plasma-treated PVC-TiO₂ under identical photocatalytic condition. The experimental results reveal that plasma treatment can obviously enhance the photocatalytic degradation of PVC.     

电芬顿降解苯乙酮过程中有机物三维荧光特征的变化规律

采用荧光光谱技术检测分析了苯乙酮在电芬顿处理过程中的三维荧光光谱特征变化规律,研究了苯乙酮的三维荧光特征及其指纹特征,对苯乙酮去除率和荧光峰强度变化进行线性拟合研究.结果表明,苯乙酮具有两个荧光峰,分别在λEx/Em=270/305 nm(Peak A)和λEx/Em=215/305 nm(Peak B)处,且荧光指纹...     

Degradation of methyl orange by atmospheric DBD plasma: Analysis of the degradation effects and degradation path

The degradation process of methyl orange solution by dielectric barrier discharge (DBD) plasma using a board-DBD reactor was studied. The percentage destruction reached 99% after 35 min treatment. The pH value of the methyl orange solution decreased with the treatment time and it reached a constant value when discharged for 20 min. The COD value of the methyl orange solution decreased by 57.9% for 30 min treatment. The degradation path was suggested based on the analysis of the molecular structure of methyl orange, intermediate products and the molecular bond energies.     

Fast degradation of azo dye by nanocrystallized Fe-based alloys

Exploring new alloys with high efficiency in degrading organic pollutants in aqueous solutions is of wide interests. Here, we report that the nanocrystallized Fe_(82.65)Si_4B_(12)Cu_(1.35) alloy exhibits higher efficiency in decolorizing azo dye solutions compared to its amorphous counterpart. The increased efficiency is attributed to the formation of numerous microbatteries between the α-Fe(Si)and Fe_2 B nanocrystalline phases, which exhibit different corrosion potentials. These results suggest that nanocrystallized Fe-based amorphous composites hold promising application potential in degrading azo dyes solutions.     

Photocatalytic degradation of methylene blue solution by diphenylanthrazoline compounds

The photocatalytic degradation of methylene blue solution by 8 photocatalytic diphenylanthrazoline compounds was investigated. All diphenylanthrazoline compounds exhibited a good photocatalytic activity towards the methylene blue solution. The removal rate for chemical oxygen demand (COD_Cr) in the methylene blue solution at 12 hours was ~54.1% to 96.3%. 2,8‐Bis(4‐triphenylamino)‐4,6‐diphenyl‐1,9‐anthrazoline ( TM‐2‐d ) was selected for further investigation because of its better photocatalytic activity. To study the optimal reaction conditions for the photocatalytic degradation of dye wastewater, photocatalyst was applied to degrade methylene blue solution. The decolorization rate for simulated dye solutions can exceed 99% in 10 hours, and the COD_Cr removal rate exceeded 91%. These organic semiconductor materials, diphenylanthrazoline compounds, displayed comparative photocatalytic properties to the inorganic semiconductor materials, which can be used in the photocatalytic degradation of organic pollutants.     

Enhanced sonochemical degradation of perfluorooctanoic acid by sulfate ions

This study investigated the effects of sulfate ions on the decomposition of perfluorooctanoic acid (PFOA) by ultrasonic (US) irradiation at various pHs, sulfate doses, powers and temperatures. The removal of PFOA was augmented with an increased sulfate ion concentration, with PFOA being almost completely decomposed in 90 min at 25 °C with a sulfate dose of 117 mM. The two major mechanisms in the sulfate-assisted sonochemical system are the direct destruction of PFOA by cavitation and the indirect destruction of PFOA by sulfate free radicals. The decomposition of PFOA followed pseudo-first-order kinetics and was not influenced by pH. The reaction rate constants decreased with increases in temperature due to decreases in the surface tension of the solution.