BUNSEKI KAGAKU Abstracts

Radioactive nuclides in the incinerator fly ash of municipal solid waste was determined and monitored. For leaching radioactive Cs from incinerating fly ash in reclaimed land, a modified No. 13 elution test and adsorption with stable Cs onto andosol were performed. The activity concentration of radioactive nuclides in incinerator fly ash was constant within the range of the activity concentration before the accident at Fukushima Daiichi Nuclear Power Station. The ¹³⁴Cs/¹³⁷Cs activity concentration ratio was almost equal to 1, corresponding to ¹³⁷Cs existing in environment before the accident. 40% of ¹³⁷Cs in incinerator fly ash eluted with the modified No. 13 elution test, and adsorption ratio of Cs⁺ onto the andosol showed 90% as being the primary concentration was equal to or more than 5000 μg L⁻¹. In addition, the desorption results used for 5 types of solvent showed that desorption ratio of adsorbed Cs⁺ from the soil was 3.6% at the maximum. Hence, it is anticipated that using a soil that is similar in composition to the andosol suppresses the leaching out of radioactive Cs from reclaimed land.

A conventional analytical apparatus for simultaneous determination of oxygen and nitrogen was modified by inserting a by-pass column filled with an appropriate amount of molecular sieve 5A into the gas flowing path. The extraction curve of oxygen could be fully separated from that of nitrogen when the measuring conditions were optimized. When high-purity potassium nitrate was employed as a certified material for the calibration, a linear relationship of the signal response was obtained up to the upper limit of nitrogen that the equipment could quantify. Using these optimized parameters for the measurement, analytical results of nitrogen in steel standard samples agreed to the corresponding guaranteed values.

A highly sensitive and selective analysis of alkali metal and ammonium ions was investigated on the basis of a Förster-type excitation energy transfer between two quantum dots (QDs) with different sizes. QDs are semiconductor nanoparticles and their emission wavelengths depend on their sizes. For the molecular recognition of potassium ion, mercaptoalkanoic 15-crown-5 ether was introduced onto the surface of QDs with their diameter of 2.1 (15C5-QDs2.1) and 2.6 nm (15C5-QDs2.6). When K⁺ is added to a mixed suspension of 15C5-QDs2.1 and 15C5-QDs2.6, the efficiency of the excitation energy transfer will be enhanced since the recognition of K⁺ brings a 1:2 sandwich-type complexation between the different size of QDs. As the concentration of K⁺ was increased, actually, the fluorescence intensity at longer wavelength derived from 15C5-QDs2.6 was increased. Thus, the signal transduction can be accomplished through the energy transfer resulting in a ratiometric change in the emission intensity. The limit of detection (LOD) of K⁺ was evaluated to be 0.50 μM, so that the sensitive detection of K⁺ was successful. When Na⁺ was added to the mixed suspension, the change in the fluorescence spectrum was not observed. Therefore, it was found that 15C5-QDs was K⁺ selective fluorescent probe. We also prepared Na⁺ or NH₄⁺ selective QDs probes by inducing mercaptoalkanoic 12-crown-4 ether or 18-crown-6 ether on QDs, respectively. The obtained LODs for Na⁺ and NH₄⁺ were 1.3 μM and 0.31 μM, respectively.

A microsyringe-based capillary LC–GC interface with GC carrier gas flow switching for GC injection was developed. The carrier gas flow to GC was divided into two ways: one way was connected to a general carrier gas port of GC and the other to a syringe interface inserted into an injection port of GC. The solution from capillary LC was stored in the syringe and successfully injected by switching the carrier gas flow-pass. The repeatability of the injection amount was sufficient (<5.5% in %RSD for the peak area, <1.5% for the relative peak area, n = 8). LC–GC analyses of the test mixture (alkylbenzenes and phthalates) were successfully demonstrated.

The primary contributors to the acidification of rainfall are the oxides of sulfur and nitrogen, which originate from both human activity and natural sources, the latter of which includes volcanic emissions. Two active volcanoes, Mt. Sakurajima and Mt. Shinmoe, are located equidistant from Satsumasendai City, Kagoshima, Japan, and large eruptions of Mt. Shinmoe occurred several times during 2010–2011. The present study examines the effects of these volcanoes on the acidification of rainfall in Satsumasendai City by analyzing the electrical conductivity (EC), pH, and SO₄²⁻ and NO₃⁻ contents of rain water. It was observed that the values of EC, SO₄²⁻, and NO₃⁻ were high, and the pH was low, during the eruption of both volcanoes. These results indicate that the volcanic activity of Mt. Sakurajima and Mt. Shinmoe influenced the acidity of rain water in the vicinity of Satsumasendai City. In particular, the ratio of SO₄²⁻/NO₃⁻ was low compared to the values for rain water in other areas of Japan, suggesting that rain water acidity in Satsumasendai City is influenced primarily by SO₄²⁻ rather than by NO₃⁻.

Gold was regarded as an inactive element for longer than a century. However, it exhibited unique catalytic properties when deposited on base metal oxides as nanoparticles with mean diameters smaller than 10 nm. Especially, gold nanoparticles catalysts with 2 to 6 nm diameters are active for many reactions, such as CO oxidation at a temperature as low as −70°C. Some typical reactions in liquid and gas phases are listed. A new area is clusters that are smaller than 2 nm and less than 200 atoms. Unique catalytic performances of gold clusters have recently been found. This paper summarizes the characteristic features of gold nanoparticles and clusters catalysts as well as their applications.

Novel cellulose functionalized with polyallylamine based on wood powder was synthesized. It was applied to the collection of gold in gold-plating waste. The synthesized adsorbent, cellulose-pentaerythritol polyglycidyl ether-polyallylamine-glutaraldehyde-polyvinyl alcohol (CPP-GP), showed good adsorption behavior toward gold and palladium compared to other anions. The pH range for the adsorption of gold was about 4–6, and this maximum adsorption capacity was 8.4% in gold-plating waste. By X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS) of CPP-GP adsorbent, which adsorbed gold in plating waste, the adsorbent was found to be combined in form of gold(I) cyanide. A column method with CPP-GP adsorbent was successfully applied to the collection of gold in 90 L of gold-plating waste with satisfactory results, which this recovery of gold could obtain about 87%.