紫外光照下锐钛型Fe-TiO2粉末对甲基蓝的催化降解

采用水热法自制的锐钛型Fe-Ti O2粉末在紫外光(λ=254 nm)照射下,对有机污染物甲基蓝进行光催化降解,研究了甲基蓝溶液的初始浓度、溶液的p H、Ti O2掺杂量、Ti O2用量、反应时间等因素对甲基蓝降解率的影响。结果表明:在甲基蓝溶液初始浓度为50 mg/L(p H=6)、Ti O2掺铁量3%(摩尔分数)、Ti O2粉末用量为1.00 g/L、室温18℃下经紫外光照射反应105 min,甲基蓝的降解率达到97.3%。     

分光光度法同时测定岩盐中微量Fe2+和Fe3+的研究

研究了在酸性条件下,邻-菲啉分光光度法测定岩盐中微量Fe2+、Fe3+。实验结果表明,铁的质量浓度在0~5μg/mL范围内测得吸光度值与质量浓度之间的关系遵守朗伯—比耳定律,摩尔吸光系数ε=1.1×104L.moL-1.cm-1。Fe2+、Fe3+平均回收率分别为102.47%、100.93%,相对标准偏差分别为2.82%、2.68%(RSD,N=6)。该方法操作简单、灵敏度高、稳定性好、选择性好,用于岩盐中微量Fe2+、Fe3+的测定,结果令人满意。     

微乳液介质—DBH-PF光度法测定食品中微量锗的研究

以阳离子型 O/ W CTMAB/ n- C5H11OH/ n- C7H16/ H2 O微乳液为介质 ,进行 Ge( IV) - DBH- PF的分光光度法测定 ,ε510 nm=2 .18× 10 5L· mol-1.cm-1,建立了高灵敏测定食品中微量锗的新方法 ,锗量在每 2 5m L 0～ 7.0μg范围内符合比尔定律 ,方法选择性好 ,试样无需萃取分离 ,可快速测定     

Modifications of the curcumin method enabling precise and accurate measurement of seawater boron concentration

To achieve greater precision and accuracy in the measurement of seawater boron concentrations, we propose a series of modifications to an established (curcumin) method based on the reaction of boric acid with curcumin. The modifications were derived from a series of experiments evaluating the stability of the curcumin–acetic acid reagent, the dependence of the reaction on temperature and duration, the effect of evaporation during the dehydration process, the interference of water, and the effect of sea salts. Application of the modified method to analysis of seawater samples collected from the Pacific Ocean indicated that it yielded considerably better precision and accuracy for boron concentration measurements than both the conventional curcumin method and other analytical techniques.     

The interstellar 217 nm band: a third catalogue of equivalent widths

Using the data obtained with the ultraviolet photometer in the Astronomical Netherlands Satellite the equivalent widths of the interstellar 217 nm band as well as other parameters characterizing the behaviour of the continuous interstellar extinction in the wavelength region of the band have been derived for 790 O, B stars with colour excesses E(B - V) ≥ 0·4 mag.     

不同粒径镁铝水滑石的合成及其紫外阻隔性能研究

采用水热合成法,以六水氯化镁为镁源,六水氯化铝为铝源,通过改变沉淀剂种类、水热温度和水热时间等条件,实现了不同粒径镁铝水滑石的可控制备。多晶X射线衍射、扫描电子显微镜、红外光谱和原子发射光谱测试表明合成了具有相同化学组成、不同粒径的片状镁铝水滑石,产物平均横向尺寸的可控范围在63 nm～5μm之间。紫外光屏蔽实验显示,横向尺寸为136～270 nm的镁铝水滑石具有最佳的紫外阻隔性能,这一结果可以用光散射理论进行解释。     

Spectrophotometric Determination of Gold (III) after Liquid–Liquid Extraction and Selective Pre‐concentration with a Novel Dibenzo‐18‐Crown‐6 Derivative

A selective and sensitive method for the extraction and spectrophotometric determination of gold with N,N′‐6,7,9,10,17,18,20,21‐octahydrodibenzo[b,k][1,4,7,10,13,16] hexaoxacyclo‐octadecine‐2,13–diylbis(2‐chloroacetamide) (ODBOCA) is described. The ODBOCA–Au(III) complex was extracted from a slightly acidic aqueous solution (pH 5) into a chloroform layer and then the absorbance of the extract was measured using a UV–Vis spectrophotometer with 1.0 cm quartz cells at 540 nm. An enrichment factor of 200 was achieved. In the chloroform medium at 540 nm, the molar absorptivity and Sandell’s sensitivity were 4.12 × 10³ l mol^?1 cm^?1 and 0.048 μg cm^?2, respectively. Beer’s law was obeyed in the range of 0.5–15 μg ml^?1 in the measured solution. The relative standard deviation for ten replicate samples at the 1.0 μg ml^?1 level was 3.0%. The limit of detection, based on 3s, was 0.5 μg l^?1 in the original sample. The effects of pH, ligand concentration and shaking time were studied. The ratio of the metal ion to ligand molecules in the complex was found to be 1:2 according to the Job Method. The effects of interference by a number of metal ions were investigated. The method was verified with certified reference materials and spiked tests, and quantitative recovery values were obtained. The method was fast, accurate, selective and precise, and was applied to the determination of gold in water and ore with good results.     

热水解-催化分光光度法测定海相碳酸盐岩中的溴

目前衡量古海洋生产力的指标都存在一定的局限性,本文提出将溴元素作为研究古海洋生产力的新指标,建立了海相碳酸盐岩的分解方法以及其中溴元素的测定方法,即热水解-分光光度法。采用热水解方法对海相碳酸盐岩样品进行分解,吸收液充分吸收其释放出的溴,分光光度法检测样品中溴元素的含量。试验确定了热水解的最佳条件和分光光度检测的最佳波长,实际样品加标回收率为97.5%～101.6%,相对标准偏差为1.2%～3.6%(n=10)。本方法的样品分解时间较短,能很好地实现溴与基体组分分离,且所需仪器均为比较常见的仪器,操作简单,成本低廉,适合于海相碳酸盐岩样品的批量分解和元素测定。     

纬度和海拔高度对云南地面紫外线强度影响的数值试验

依据已经建立起来的昆明地区紫外辐射传输方案，计算并讨论了大气中中低云、气溶胶粒子以及不同地理纬度和海拔高度对UV辐照度的影响。研究结果表明，在考虑了大气层中臭氧的吸收和空气分子散射的情况下，UV辐照度随地理纬度的增高和海拔高度的降低均有明显而强烈的改变。云对紫外辐照度有很大的影响。而且低云对UV辐照度的削弱作用大于中云的削弱作用。大气中气溶胶粒子对紫外辐射的影响在UV—A波段和UV—B波段具有不同的表现。