Measurement of total OH reactivity by laser-induced pump and probe technique—comprehensive observations in the urban atmosphere of Tokyo

Total OH reactivity was observed by use of the laser-induced pump and probe technique, and the urban air quality in Tokyo was diagnosed comprehensively. The concentrations of NO_x, CO, O₃, non-methane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (OVOCs) were observed simultaneously. The observations were conducted in July and August 2003, and in January, February, May, and November 2004. Generally, the observed OH reactivity was higher than the calculated values derived using the observed concentrations of the trace species. The differences between the observed and calculated values in summer, spring, and autumn were approximately 30%. However, the difference in winter was smaller than those in the other seasons. In addition, while the differences observed in summer, spring, and autumn correlated with the total reactivity of the OVOCs (Σ_i k_OVOCi[OVOC_i](s⁻¹), k_i is rate constant of its compounds with OH), the correlations were not confirmed in the case of winter because atmospheric oxidation was less active and OVOCs levels were low in winter. These results suggest that the secondary products of the photochemical reactions in the atmosphere would be a missing sink for the OH loss process in the urban area.     

F-SnO2/GAC粒子电极的制备及其电催化性能

以颗粒活性炭（GAC）为载体,通过溶胶-凝胶法制备了经F^-掺杂改性的F-SnO₂/GAC粒子电极.采用扫描电子显微镜（SEM）、X射线能谱（EDS）、X射线衍射（XRD）、X射线光电子能谱（XPS）、循环伏安曲线（CV）对粒子电极进行了表征.并以罗丹明B（RhB）为目标污染物,考察该粒子电极的电催化性能.结果表明：F-SnO₂纳米颗粒均匀分布在GAC的内外表面,且结晶完整;经F^-掺杂改性后的SnO₂活性组分能够增加反应体系中的转变电荷量,提高电催化活性.当RhB质量浓度为300mg/L、初始pH 3、槽电压为9V、处理30min时,在500℃下煅烧2h的10% F-SnO₂/GAC粒子电极对RhB的脱色率和COD去除率达到了97.6%和89.0%.运用电子自旋共振技术（ESR）确定了电催化过程主要是以羟基自由基（·OH）的间接氧化来实现对污染物的去除.     

A hydroxyl radical detection system using gas expansion and fast gating laser-induced fluorescence techniques

An OH radical measurement instrument based on Fluorescence Assay by Gas Expansion(FAGE)has been developed in our laboratory.Ambient air is introduced into a low-pressure fluorescence cell through a pinhole aperture and irradiated by a dye laser at a high repetition rate of 8.5 k Hz.The OH radical is both excited and detected at 308 nm using A-X(0,0)band.To satisfy the high efficiency needs of fluorescence collection and detection,a 4-lens optical system and a self-designed gated photomultiplier(PMT)is used,and gating is actualized by switching the voltage applied on the PMT dynodes.A micro channel photomultiplier(MCP)is also prepared for fluorescence detection.Then the weak signal is accumulated by a photon counter in a specific timing.The OH radical excitation spectrum range in the wavelength of 307.82–308.2 nm is detected and the excited line for OH detection is determined to be Q_1(2)line.The calibration of the FAGE system is researched by using simultaneous photolysis of H_2O and O_2.The minimum detection limit of the instrument using gated PMT is determined to be 9.4×10~5molecules/cm~3,and the sensitivity is 9.5×10~(-7)cps/(OH·cm~(-3)),with a signal-to-noise ratio of 2 and an integration time of 60 sec,while OH detection limit and the detection sensitivity using MCP is calculated to be 1.6×10~5molecules/cm~3and 2.3×10~(-6)cps/(OH·cm~(-3)).The laboratory OH radical measurement is carried out and results show that the proposed system can be used for atmospheric OH radical measurement.     

纳米Fe3O4/H2O2降解诺氟沙星

采用纳米Fe3O4催化H2O2氧化降解水环境中的诺氟沙星.考察了溶液酸度、温度、催化剂和H2O2浓度对诺氟沙星降解的影响,对比不同底物在Fe3O4/H2O2体系中的降解情况,并进一步探讨了其反应机制.结果表明,溶液酸度显著影响诺氟沙星的降解率,在酸性条件下（pH=3.5）诺氟沙星的降解效率最高.诺氟沙星的降解率随纳米F...     

生物铁膜生物反应器（SMBR）处理生活污水的试验研究

试验研究了在SMBR中投加不同量氢氧化铁对出水水质以及膜污染的影响。结果表明,生物铁SMBR中随氢氧化铁投加量的增加,CODrr,NH3-N去除率略有提高;当氢氧化铁投加量为混合液中污泥浓度的0～5％时,TP去除率逐渐提高,在7％时急剧下降。试验条件下氢氧化铁最佳投加量为混合液污泥浓度的5％．此时半透膜压增长最慢,膜污染程度最轻。在3％～5％的投加量下生物铁具有良好的絮状结构,有效地降低了膜表面滤饼层阻力,并且缓解了膜孔堵塞的影响,然而当投加量增大到7％时,生物铁结构变得密实,削弱了生物铁对溶解性有机物和磷的吸附,加剧了膜污染．     

Electro-assisted regeneration of ion exchange resins

Electro-assisted regeneration (EAR) for the mixed bed of strongly acidic cation and weakly basic anion exchange resins with the Al(OH)3 suspension in a three-compartment cell was investigated. The desalination experiments were carried out to evaluate the characteristic of the regenerated mixed resins. Experimental results showed that the efficiency of resin regeneration was strictly dependent on the voltage, regeneration time, and feed regenerant flow rate. The amount of the effluent reached 50 times the volume of the resins bed, and the conductivity was less than 1.0 μs/cm. Compared to the conventional ER, the total effluent volume of EAR was about 1000 mL more than that of ER under the same conditions, and the outlet conductivity was significantly lower. The desalination and regeneration reaction mechanisms of the mixed resins indicated the regeneration efficiency of resin with Al(OH)₃ as the regenerant was much higher than that with H₂O.     

用于CO2捕集的Mg(OH)2粉末溶解速率

氢氧化镁是一种正在研究的用于脱除烟气中低浓度CO2的化学吸收剂。为了掌握工业用氢氧化镁粉末的溶解速率,利用缓冲溶液,在不改变溶液体积的情况下对不同悬浊液浓度、溶液温度、溶液pH值和搅拌速率情况下的氢氧化镁粉末溶解速率进行了研究。提高悬浊液浓度、提高溶液温度、降低溶液pH值和提高搅拌速率均能增大氢氧化镁的溶解速率。悬浊液浓度从0.1 mol/L增加到1 mol/L时,溶解速率增大了2.2倍;温度从23℃增加到52℃时,溶解速率增大了4.3～9.5倍;pH值从9.8降低到6.6时,溶解速率增大了78～225倍;搅拌速率从350 r/min增加到700 r/min时,溶解速率增大了1～2倍。     

Dissolution of beryllium in artificial lung alveolar macrophage phagolysosomal fluid

Dissolution of a lung burden of poorly soluble beryllium particles is hypothesized to be necessary for development of chronic beryllium lung disease (CBD) in humans. As such, particle dissolution rate must be sufficient to activate the lung immune response and dissolution lifetime sufficient to maintain chronic inflammation for months to years to support development of disease. The purpose of this research was to investigate the hypothesis that poorly soluble beryllium compounds release ions via dissolution in lung fluid. Dissolution kinetics of 17 poorly soluble particulate beryllium materials that span extraction through ceramics machining (ores, hydroxide, metal, copper-beryllium [CuBe] fume, oxides) and three CuBe alloy reference materials (chips, solid block) were measured over 31 d using artificial lung alveolar macrophage phagolysosomal fluid (pH 4.5). Differences in beryllium-containing particle physicochemical properties translated into differences in dissolution rates and lifetimes in artificial phagolysosomal fluid. Among all materials, dissolution rate constant values ranged from 10⁻⁵ to 10⁻¹⁰ g cm⁻² d⁻¹ and half-times ranged from tens to thousands of days. The presence of magnesium trisilicate in some beryllium oxide materials may have slowed dissolution rates. Materials associated with elevated prevalence of CBD had faster beryllium dissolution rates [10⁻⁷-10⁻⁸ g cm⁻² d⁻¹] than materials not associated with elevated prevalence (p < 0.05).     

Automobile exhaust gas as a source of aqueous phase OH radical in the atmosphere and its effects on physiological status of pine trees

Free radical generation potential of automobile exhaust gas was examined by measuring hydroxyl (OH) radical photo-formation rates in exhaust gas-scrubbing water. Effects of automobile exhausts on physiological status of Japanese red pine trees (Pinus densiflora Sieb. et Zucc.) were also investigated to elucidate the mechanism how the free radicals derived from exhaust gas damage higher plants. Gasoline and diesel exhaust gases were scrubbed into pure water. Potential photo-formation rates of OH radical in aqueous phase (normalized to sun light intensity of clear sky midday on May 1 at 34°N) for gasoline and diesel cars were ave. 51 and 107 μM h⁻¹ m⁻³ of exhaust gas, respectively. Nitrite was a dominant source (ca. 70-90%) of photochemical formation of OH radical in both gasoline and diesel car exhausts. The scrubbed solution of diesel car exhaust gas was sprayed for six times per week to needles of pine tree seedlings in open top chambers. Control, exhaust + mannitol (added as OH radical scavenger), and nitrite + nitrate standard solution (equivalent levels existed in the exhaust gas) were also sprayed. Two months sprays indicated that the sprayed solutions of diesel exhaust and nitrite + nitrate caused a decrease of maximum photosynthetic rate and stomata conductance in pine needles while the control and exhaust + mannitol solution showed no effects on photosynthetic activities of pine needles. These results indicated that OH radicals generated mainly from photolysis of nitrite occurring in the scrubbing solution of exhaust gas are responsible for the decrease of photosynthetic activities of pine needles.     

催化湿式过氧化（CWPO）偶氮染料反应机理及降解历程研究

采用浸渍法制备出具有较高催化活性的催化剂CuO/γ-Al2O3,通过XRD、电镜等手段对催化剂进行了表征。降解了几种不同结构的偶氮染料,并通过改变CWPO的反应条件推断了其催化反应机理。采用紫外/可见分光光度计（UV-Vis）和傅里叶红外光谱仪（IR）等手段对染料降解过程进行跟踪和分析,对比染料处理前后紫外可见光谱与红...