天野 佳正

The effects of surface properties of activated carbon (AC), pH and temperature of solution on Cr(VI) removal and reduction were investigated. AC oxidized by HNO₃ could possess large amount of surface functional groups and showed a higher Cr(VI) removal than AC with little amount of surface functional groups prepared by outgassing at 1000°C under neutral conditions. This result indicates that AC possessing the acidic functional groups had a reduction ability of Cr(VI). In contrast, under highly acidic conditions Cr(VI) was more easily reduced to Cr(III). The decrease amount of both adsorbents consequently showed the same value. The decrease amount increased with the increase in temperature. From the difference in reduction amount of Cr(VI) on AC which had different surface conditions, the carboxylic and/or carboxylate groups would be involved in the reduction process.

In this study, the collection of extracellular polymeric substances (EPS) as a powder form from unicellular Microcystis aeruginosa and water bloom was attempted to control the EPS concentration in the culture medium and to promote the colonyformation of unicellular M. aeruginosa. Then, the effects of EPS and divalent cation such as iron ion on the colony formation of M. aeruginosa were examined through the unialgal culture experiment. The results showed that EPS collected from unicellular M. aeruginosa possessed the hydroxyl groups and carboxyl groups on EPS, indicating the similar trend to other cyanobacterial species. The unialgal culture experiment showed that, at the iron ion concentration of 0.68 mg-Fe/L, EPS itself would not act as a binder for M. aeruginosa cells. However, the colony of M. aeruginosa was observed when EPS as well as high amount of iron ion (6.8 mg-Fe/L) were added into culture medium, and the colony density tended to be higher for culture medium with the EPS concentrations of 10 mg/L or less than that with the higher condition (EPS = 25 mg/L).

Ultra-wideband (UWB) technology finds new application in sensing systems as a result of its high spatial resolution and extremely low spectral density. Impulse radio (IR) UBW radars are highly attractive as sensing devices, with applications such as through-the-wall detection [1], surveillance [2], human health monitoring [3, 4] and automotive radars used in active safety systems [5]. This paper presents the design and fundamental properties of an 8-channel 26-GHz impulse radio ultra-wideband (IR-UWB) beam steering radar transceiver IC implemented in a 90-nm CMOS for use in short-range automotive radars. Experimental data demonstrated the feasibility of single-chip ICs, which are expected to improve the performance and reduce the cost of automotive radars.

Several activated carbons (ACs) were prepared from bamboo chips (BCs) with ZnCl2 activation. The influences of the specific surface area and pore size distribution on the adsorption of dyes, such as 2-naphthol (2-N, MW: 144), methylene blue (MB, MW: 320), and congo red (CR, MW: 697) were investigated using each prepared AC. AC with different mesopore volumes and same surface chemistry could be prepared by ZnCl2 activation. In particular, the sample activated with the ZnCl2/BC mass ratio of 6 (Z6) showed a remarkable increase in the specific surface area and mesopore volume to values as high as 2050 m(2)/g and 1.1 cm(3)/g, respectively. The results of all adsorption experiments revealed that MB and CR were adsorbed on mesoporous AC more efficiently than on microporous AC, and no CR adsorption onto microporous AC was observed. Further, the adsorbed amount of 2-N, with small molecule size, was dependent on the specific surface area rather than mesopore volume.

Adsorption of heavy metal ions onto activated carbon is explained as a consequence of ion exchange with acidic functional groups such as the carboxyl group. In this study, bead-shaped activated carbon (BAC) was oxidized with nitric acid or ammonium persulfate to introduce surface acidic functional groups. Cadmium ions (Cd(II)) were employed to evaluate the heavy metal adsorption capacity of the oxidized BAC. The amount of surface functional groups was determined by Boehm titration. Surface area and pore volume were measured from N2adsorption/desorption isotherms. The results showed that, although similar amounts of surface carboxyl groups were introduced by nitric acid and ammonium persulfate oxidation, BAC oxidized by ammonium persulfate adsorbed a larger amount of Cd(II) (0.76 mmol/g) than that oxidized by nitric acid (0.61 mmol/g) at an initial pH of around 5.0. The amount of Cd(II) adsorbed increased with increasing equilibrium solution pH, and the maximum Cd(II) adsorption for BAC oxidized by ammonium persulfate reached as much as 1.8 mmol/g in the solution equilibrium pH range of 7.1-7.6. The surface area and pore volume were decreased in each oxidized BAC. Since N2is not adsorbed onto macropores, this implies that the oxidation process increases pore radius, causing the expansion of micro and mesopores into macropores. © 2013 The Society of Chemical Engineers, Japan.

The improvement of water quality in Lake Tega, Japan, has been carried out by dilution, causing the shift of dominant species from Microcystis aeruginosa to Cyclotella sp. in summer. The disappearance of Microcystis blooms would be related to dilution, but the detail effect has not been understood yet. In this study, the effect of nitrate concentration on the competition between M. aeruginosa and Cyclotella sp. was investigated through the single-species and the competitive culture experiments. The single-species culture experiment indicated that the half saturation constants for M. aeruginosa and Cyclotella sp. were 0.016 and 0.234 mg N L-1, representing that M. aeruginosa would possess a higher affinity to nitrate. On the other hand, the maximum growth rate for Cyclotella sp. was obtained as 0.418 day(-1), which did not represent a significant difference with 0.366 day(-1) obtained for M. aeruginosa. The competitive culture experiment revealed that Cyclotella sp. completely dominated over M. aeruginosa at the nitrate concentrations of 0.5 and 2.5 mg N L-1. The dominance of Cyclotella sp. could be attributed to the difference in the abilities of nitrate storage as well as nitrate uptake. One of the possibilities for the disappearance of Microcystis blooms caused by dilution as observed in Lake Tega could be due to the decrease in nitrate concentration, and the lower N:P ratio seemed not to relate to Microcystis blooms.

An investigation of food web structures in the northwestern soft-bottom area, including the intertidal and subtidal zones, of inner Ariake Bay, suggests that resuspended BM are substantial for offshore secondary production, and the main source of BM would be outwelling from the intertidal mudflat. Carbon and nitrogen stable isotope ratios were measured for macrobenthos samples from the intertidal mudflats, subtidal fringe and offshore subtidal zones, together with their potential food sources. Carbon and nitrogen signatures indicated that most macrobenthos assimilated offshore particulate organic matters (POM) (delta C-13: -23.9 +/- 0.1 parts per thousand; delta N-15: 8.2 +/- 0.1 parts per thousand) and benthic microalgae (BM) (delta C-13: -16.8 +/- 1.5 parts per thousand; delta N-15: 8.0 +/- 0.4 parts per thousand) among other potential sources. The relative BM contribution to filter feeders significantly decreased seaward from about 50% in the mudflats to 25% in the offshore zone, and the 99% confidence intervals of the contribution did not include zero even in the offshore zone. (C) 2012 Elsevier Ltd. All rights reserved.

The high performance bamboo charcoal for humidity control was prepared by carbonization with an agent of potassium compound. The mixture of potassium carbonate and raw bamboo chip with the mass ratio (K<SUB>2</SUB>CO<SUB>3</SUB>/Bamboo ratio) of 0.05, 0.1 and 0.5 was carbonized at 500 °C with heating rate of 25 °C /min under nitrogen flow for 2 hours using a tubular furnace. The surface area and the pore volume were measured with BET, <I>α<SUB>s</SUB></I> -plot and <I>t</I>-plot method, and surface functional groups were determined by Boehm titration. The results showed that the surface area was varied according to the K<SUB>2</SUB>CO<SUB>3</SUB>/Bamboo ratio. The surface area of bamboo charcoal with the low K<SUB>2</SUB>CO<SUB>3</SUB>/Bamboo ratio was smaller than that of original bamboo charcoal of 250 m<SUP>2</SUP>/g. However, the high K<SUB>2</SUB>CO<SUB>3</SUB>/Bamboo ratio resulted in the increase in the surface area of 472 m<SUP>2</SUP>/g, which was much larger than original bamboo charcoal. The amount of surface functional groups increased with the existence of K<SUB>2</SUB>CO<SUB>3</SUB>, and especially the carboxyl group greatly increased. The result of water vapor adsorption-desorption experiment for each prepared bamboo charcoal revealed that the charcoal with high amount of functional groups could uptake water vapor at low humidity region, while high amount of water vapor adsorption was observed for the charcoals possessing high pore volume content at medium-high humidity region. The water vapor adsorption- desorption experiment as a function of temperature was also performed assuming the seasonal temperature variation. The amount of water vapor adsorption-desorption did not depend on the sorts of bamboo charcoals. Accordingly, the bamboo charcoal carbonized with an agent of potassium compound could be expected as a superior humidity control material, which was hardly affecterd by seasonal temperature variation.

In this study, the effect of coexisting aromatic compound such as pyridine, aniline, indole, benzonitrile, phenol and benzoic acid on the Cd(II) adsorption onto activated carbon fibers (ACFs) was examined to identify which functional groups were effective for the adsorption. The results showed that the coexisting benzoic acid and pyridine were effective and increased the amount of Cd(II) adsorption at the pH of around 7 in the solution. On the other hand, the coexisting indole, aniline, phenol and benzonitrile caused the decrease in the amount of adsorbed Cd(II).These results suggest that carboxyl group (benzoic acid) and pyridine-N (pyridine) are more effective than pyrrole-N (indole), amino group (aniline), phenolic hydroxyl (phenol) and cyano group (benzonitrile) for the removal of Cd(II).

有明海干潟底泥から回収した水溶性細胞外多糖類様物質（EPS）を有機物分解処理した底泥の懸濁液に添加した．回転粘度計のスリーブの中で人工海水懸濁液では非ニュートン挙動を示して，ずり速度に比例してずり応力が増加した．底泥の粒子径は約1.3倍に増加した．これは底泥に吸着したEPSが海水中のカチオンにより，底泥間にネットワークを形成するためと考えられた．

A 95% confidence interval was estimated from 2-methylisoborneol (2-MIB) numbers, as an index of adsorption capacity described in this article, for 31 different powdered activated carbons (PACs) used for drinking water purification. The seven PACs selected in this study were chosen as five of them were within the 95% confidence interval and the other two PACs were not. The PACs were assessed based on previous studies, which represented the relationships between 2-MIB adsorption capacity and surface area, pore distribution, bulk oxygen content and surface oxygen functional groups. From the results, we assumed the 2-MIB adsorption mechanism and studied relationships between 2-MIB number and ash content of PAC or pH value of PAC slurry. It was shown that the 2-MIB number correlated with the ash content and the pH value. Easily measurable ash content and pH values would help a water supplier briefly screen PACs for removing 2-MIB at a water purification facility.

This study demonstrated the modification of commercially available activated carbons (CS and R1) by de-ashing (DA), oxidation (Ox) and outgassing (OG) treatment to possess different surface area, pore volume, and the amount of surface functional groups, and these parameters were related to the efficiency of phosphate removal. The results showed that positively charged carbon surface due to the adsorption of protons to the basic sites resulted in the promotion of phosphate adsorption, that is, the extent of the surface area with the basic sites such as Cp electrons and/or basic oxygen groups would enable to enhance the efficiency of phosphate adsorption.

Heavy metal removal from aqueous solution onto activated carbons (ACs) by adsorption is briefly reviewed from the aspects of the structure, surface chemistry of ACs, and temperature and pH of aqueous solutions based on our previous studies. Oxygen and nitrogen atoms on the AC surface play an important role as well as solution pH for the adsorption of the heavy metal ions on ACs. In spite of the small uptake amounts of heavy metals indicated so far by ACs, there seems to be much room to study for increasing the adsorption capacity. ACs would still have a high potential for the removal of ionic pollutants in aqueous solution due to their availability and easy regeneration.

The chemical activation with ZnCl₂ was conducted to prepare mesoporous activated carbons (ACs) from bamboo chips (BC), and the optimization as well as mechanism of ZnCl₂ activation was examined. The pore properties of the prepared ACs were evaluated through N₂ adsorption/desorption isotherms. The results showed that both surface area and mesopore volume were significantly developed up to as much as 1900 m²/g and 1.6 cm³/g, respectively, by ZnCl₂ activation at the impregnation ratio (ZnCl₂/BC) of 9 g/g. The mesopore volume of the ACs could be controlled by varying the amount of ZnCl₂ in the impregnation process. The development of porosity was observed around a 400–500 °C activation temperature, and was attributed to the expansion of the carbon microstructure by fusion and vaporization of ZnCl₂. The increase in activation temperature to above 500 °C, however, caused a significant reduction of porosity for ACs. This was due to the rapid progression of organization of the graphite structure. Adsorption of Pb(II) ions revealed that it strongly depended on the number of total basic sites on the carbon surface rather than the mesopore volume, while the Pb(II) ion adsorption kinetics was much higher for ACs with a larger mesopore content.

近年，再生可能なバイオマスエネルギー資源への注目の高まりから，廃材や間伐材など木質系バイオマス由来の炭化物を用いた水質浄化や湿度調整，有機化合物除去等に関する研究が広く行われている。竹は主にアジア圏内において安価で豊富な木質バイオマスであり，また樫や杉などに比べ成長が速いため安定的に原料の供給が出来る持続可能な資源であるといえる。近年，竹を原料とした活性炭の細孔構造特性，ガスや薬品賦活による竹炭の調製や賦活法の効果などの研究が多数報告されている。一般的な活性炭の製造方法である薬品賦活法とガス賦活法は、装置への負荷や賦活後の洗浄処理，あるいは高温度条件を必要とするなど種々の問題点がある。本研究では豊富で安価であり，原料として安定供給が可能な竹に着目し，一般的な木炭の炭化温度より低温だが十分な炭化が進む500°Cでの炭化を試みた。また一般の賦活に用いられる温度よりも低い180，280および380°Cでの温度条件下，空気雰囲気中で賦活を試み，空気酸化温度が表面・細孔特性に与える影響について検討した。

In the sediment of the estuary of the Chikugo River where inflow load quantity to Ariake Sea was bigger ,the carbohydrate was measured. The carbohydrate in the sediment surface of the estuary of the Chikugo River quantity was around 10 times higher than Ariake Sea sediment. Carbohydrate quantity to the time of edd tide is increased and to the times of a high-tide was decrease, it based on dissolubility carbohydrate caused by an adhesion alga. The dissolubility carbohydrates have chesion effect, and stabilization of sediment increased.

Polyacrylonitrile (PAN)-based activated carbon fiber (PAN-ACF) was prepared with various temperatures of both air treatment (350, 400, 425 and 450 °C) and activation (850 and 900 °C). The observation for the surface nitrogen with X-ray photoelectron spectroscopy (XPS) showed the presence of quaternary-N and pyridinic-N on PAN-ACF. The rise in both the air treatment and the activation temperature increased the nitrogen content in PAN-ACF and also extended the specific surface area. The resultant PAN-ACF prepared at the higher temperature preferably adsorbed Cd(II). The amounts of Cd(II) adsorption were much greater for PAN-ACF than the commercial coal pitch-based ACF containing less amount of nitrogen despite that specific surface area for the coal pitch ACF was twice as great as that for PAN-ACF. The activated carbon fiber possessing greater nitrogen content in the peripheral of the graphite sheet was considered to be effective for the Cd(II) adsorption.