Synthesis of Tobermorite from the Ash after Treatment of Asbesto-Containing Disaster Waste, and Its Removal Ability of Cs(I) from Aqueous Solution

Tobermorite was synthesized successfully from the ash, which was produced and detoxified from asbesto-containing disaster waste in great east Japan earth quake, by alkali hydrothermal treatment. Tobermorite synthesis was examined as a function of reaction temperature and NaOH concentration. The formation of tobermorite was identified in the product treated with 1 - 4 M NaOH solution at 130 and 180oC, while no product phases was identified at 80oC. With increasing reaction temperature, intensity of tobermorite phase in the product and Cs+ removal ability of the product increase. The product, which was treated with 4 M NaOH at 180oC for 20 h, revealed the high selective uptake for Cs+ in saline water. The Cs+ uptake of the product was extrapolated using Langmuir and Freundlich isotherm models, experimental data are found to fit Langmuir than Freundlich, and the calculated uptake amount was 0.51 mmol/g. The kinetics for Cs+ uptake was tested for pseudo-second order reactions, and the rate constants of uptake were calculated. With increasing temperature of aqueous solution, the kinetics of uptake is almost same and the uptake amount of Cs+ decreases. The product is expected to be used for Cs+ removal from wastewater

A novel adsorbent formed from blast furnace slag by alkali fusion for phosphate ions removal / Takaaki Wajima

Blast furnace slag (BF slag) was converted using alkali fusion method into a novel adsorbent to remove phosphate from aqueous solutions. The slag was mixed with NaOH powder (NaOH / Slag = 1.6) and then heated at 600 °C for 6 h to prepare the fused precursor. The precursor was stirred in distilled water at room temperature to synthesize the adsorbent and its ability to remove phosphate from aqueous solution was investigated. Fand PO43- removal efficiencies by the adsorbent were higher than those of raw BF slag, with the removal of PO43- being particularly excellent (99%), while Cl-, SO42-, NO3- and Brwere barely adsorbed. With increasing pH of the solution to around pH 7, phosphate removal of the product increases, and then becomes almost constant. The equilibrium adsorption capacity of the product for PO43- was found to fit the Freundlich isotherm better than the Langmuir isotherm, and the calculated maximum PO43- adsorption capacity of the product was 7.67 mmol/g. Phosphate removal corresponded better to a pseudo second-order kinetic model than a pseudo first-order model. The high affinity of the adsorbent for PO43- in aqueous solution was caused by the formation of hydroxyapatite [Ca5(PO4)3(OH)] and brushite [CaHPO4•2H2O

What Kinds of Accretion Disks Are There in the Nuclei of Radio Galaxies?

It seems to be a widely accepted opinion that the types of accretion disks (or flows) generally realized in the nuclei of radio galaxies and in further lower mass-accretion rate nuclei are inner, hot, optically thin, radiatively inefficient accretion flows (RIAFs) surrounded by outer, cool, optically thick, standard type accretion disks. However, observational evidence for the existence of such outer cool disks in these nuclei is rather poor. Instead, recent observations sometimes suggest the existence of inner cool disks of non-standard type, which develop in the region very close to their central black holes. Taking NGC 4261 as a typical example of such light eating nuclei, for which both flux data ranging from radio to X-ray and data for the counterjet occultation are available, we examine the plausibility of such a picture for the accretion states as mentioned above, based on model predictions. It is shown that the explanation of the gap seen in the counterjet emission in terms of the free-free absorption by an outer standard disk is unrealistic, and moreover, the existence itself of such an outer standard disk seems very implausible. Instead, the model of RIAF in an ordered magnetic field (so called resistive RIAF model) can well serve to explain the emission gap in terms of the synchrotron absorption, as well as to reproduce the observed features of the overall spectral energy distribution (SED). This model also predicts that the RIAF state starts directly from an interstellar hot gas phase at around the Bondi radius and terminates at the inner edge whose radius is about 100 times the Schwartzschild radii. Therefore, there is a good possibility for a cool disk to develop within this innermost region.Comment: 8 pages, 3 figures, to appear in PASJ, Vol.62, No.

Desalination of seawater using calcined hydrotalcite with different MG/AL ratio / Daiki Tsutsui and Takaaki Wajima

Salt damaged farmland increases in the world, and a novel method to capture salt in soil for avaiable use of agriculture is desired. In this study, we focused on calcined hydrotalcite as a desalination agent, and desalination properties of calcined hydrotalcite with different Mg/Al ratio from seawater was estimated. Calcined hydrotalcite with Mg/Al ratio of 1 – 6 was prepared, and the desalination ability were investigated using seawater collected from an Imari bay in Saga prefecture, Japan. In comparison, commercial hydrotalcite was done as the same procedure. As a resalt, the decrease of salinity was confirmed using all calcined hydrotalcites and the decreasing rates were almost same. The calcined hydrotalcite with approximately Mg/Al = 3.0 indicated the highest desalination property, due to the decrease of Na+ , Mg2+, Cl- and SO4 2- with addition of calcined hydrotalcite. The structure of calcined hydrotalcite returned to that of hydrotalcite by reconstruction reactio

Internal Motion of 6.7-GHz Methanol Masers in H II Region S269

We present the first internal motion measurement of the 6.7-GHz methanol maser within S269, a small HII region in the outer Galaxy, which was carried out in 2006 and 2011 using the Japanese VLBI Network (JVN). Several maser groups and weak isolated spots were detected in an area spanning by ~200 mas (1000 AU). Three remarkable maser groups are aligned at a position angle of 80 degree. Two of three maser groups were also detected by a previous observation in 1998, which allowed us to study a long-term position variation of maser spots from 1998 to 2011. The angular separation between the two groups increased ~10 mas, which corresponds to an expansion velocity of ~10 km s^{-1}. Some velocity gradient (~10^{-2} km s^{-1} mas^{-1}) in the overall distribution was found. The internal motion between the maser groups support the hypothesis that the methanol masers in S269 could trace a bipolar outflow.Comment: 8 pages, 6 figures, accepted for publication in PAS

The Dense Plasma Torus Around the Nucleus of an Active Galaxy NGC 1052

A subparsec-scale dense plasma torus around an active galactic nucleus (AGN) is unveiled. We report on very-long-baseline interferometry (VLBI) observations at 2.3, 8.4, and 15.4 GHz towards the active galaxy NGC 1052. The convex spectra of the double-sided jets and the nucleus imply that synchrotron emission is obscured through free--free absorption (FFA) by the foreground cold dense plasma. A trichromatic image was produced to illustrate the distribution of the FFA opacity. We found a central condensation of the plasma which covers about 0.1 pc and 0.7 pc of the approaching and receding jets, respectively. A simple explanation for the asymmetric distribution is the existence of a thick plasma torus perpendicular to the jets. We also found an ambient FFA absorber, whose density profile can be ascribed to a spherical distribution of the isothermal King model. The coexistence of torus-like and spherical distributions of the plasma suggests a transition from radial accretion to rotational accretion around the nucleus.Comment: 10 pages, to appear in Publ. Astron. Soc. Japan, vol.53, No.2 (2001

VLBI observations of the most radio-loud, narrow-line quasar SDSS J094857.3+002225

We observed the narrow-line quasar SDSS J094857.3+002225, which has the highest known radio loudness for a narrow-line Seyfert~1 galaxy (NLS1), at 1.7--15.4 GHz with the Very Long Baseline Array (VLBA). This is the first very-long-baseline interferometry (VLBI) investigation for a radio-loud NLS1. We independently found very high brightness temperatures from (1) its compactness in a VLBA image and (2) flux variation among the VLBA observation, our other observations with the VLBA, and the Very Large Array (VLA). A Doppler factor larger than 2.7--5.5 was required to meet an intrinsic limit of brightness temperature in the rest frame. This is evidence for highly relativistic nonthermal jets in an NLS1. We suggest that the Doppler factor is one of the most crucial parameters determining the radio loudness of NLS1s. The accretion disk of SDSS J094857.3+002225 is probably in the very high state, rather than the high/soft state, by analogy with X-ray binaries with strong radio outbursts and superluminal jets such as GRS 1915+105.Comment: 6 pages, 2 figures, accepted for publication in PAS