Freeze-concentrated layers as a unique field for the formation of hydrogels

Sekine, Yurina; Nankawa, Takuya

Bulletin of the Chemical Society of Japan, 96(10), p.1150 - 1155, 2023/10

https://doi.org/10.1246/bcsj.20230146

The phase separation of ice crystals and solutes and bound water that occurs during freezing can be used as a reaction field to control a hierarchical structure of hydrogels. Here, we present a study of carboxymethyl cellulose nanofiber (CMCF) hydrogels formed using the solid-quasi liquid phase separation. CMCF hydrogels were formed simply by adding citric acid to frozen CMCF and thawing the mixture. It was found that rearrangement of CMCF structures via hydrogen bonding proceeds in the freeze concentration layer before the ice crystals melt. Under freeze concentration, CMCF and bound water are confined at high concentrations. The crosslinking reaction in such a unique space contributed to the formation of CMCF hydrogel with high mechanical strength. We discuss the gelation behavior and properties of freeze crosslinked CMCF hydrogels and their applications.

Ion-selective adsorption of lead by a two-dimensional terbium oxalate framework

Nankawa, Takuya; Sekine, Yurina; Yamada, Teppei*

Bulletin of the Chemical Society of Japan, 95(5), p.825 - 829, 2022/05

https://doi.org/10.1246/bcsj.20220055

Advances in hazardous metal ion removal are essential for wastewater clean-up to tackle the global water shortage crisis. Here, we report a Pb-selective adsorbent using a Tb oxalate framework (TOF) synthesized by a one-pot hydrothermal method. The TOF has a two-dimensional sheet structure, in which the interlayer space functions as an ion exchangeable site. Sorption tests using a mixed-ion solution containing Pb, Cd, Mn, Co, Ni, Cu, Na, K, Mg, and Ca showed that the TOF has high selectivity for Pb among other metal ions. The saturated adsorption capacity of the TOF for Pb was 276 mg g, which is higher than that of conventional adsorbents. Furthermore, the TOF exhibited reversible Pb adsorption/desorption and could be used for at least three cycles. The results showed that TOF has excellent potential as an adsorbent for removing Pb, and because of its reusability, it is also a promising material for wastewater clean-up.

Mechanisms responsible for adsorption of molybdate ions on alumina for the production of medical radioisotopes

Fujita, Yoshitaka; Niizeki, Tomotake*; Fukumitsu, Nobuyoshi*; Ariga, Katsuhiko*; Yamauchi, Yusuke*; Malgras, V.*; Kaneti, Y. V.*; Liu, C.-H.*; Hatano, Kentaro*; Suematsu, Hisayuki*; et al.

Bulletin of the Chemical Society of Japan, 95(1), p.129 - 137, 2022/01

https://doi.org/10.1246/bcsj.20210249

In this work, the mechanisms responsible for the adsorption of molybdate ions on alumina are investigated using in-depth surface analyses carried out on alumina specimens immersed in solutions containing different molybdate ions at different pH values. The obtained results reveal that when alumina is immersed in an acidic solution containing molybdate ions, the hydroxyl groups present on the surface are removed to generate positively charged sites, and molybdate ions (MoO or AlMoOH) are adsorbed by electrostatic interaction. Alumina dissolves slightly in an acidic solution to form AlMoOH, which is more easily desorbed than MoO. Furthermore, the enhancement in the Mo adsorption or desorption property may be achieved by enriching the surface of the alumina adsorbent with many -OH groups and optimizing Mo solution to adsorb molybdate ions on alumina as MoO ions. These findings will assist researchers in engineering more efficient and stable alumina-based adsorbents for molybdenum adsorption used in medical radioisotope (Mo/Tc) generators.

Effect of the headgroup structure on counterion binding in adsorbed surfactant films investigated by total reflection X-ray absorption fine structure spectroscopy

Imai, Yosuke*; Tokiwa, Yuhei*; Ueno, Shusaku*; Tanida, Hajime; Watanabe, Iwao*; Matsubara, Hiroki*; Takiue, Takanori*; Aratono, Makoto*

Bulletin of the Chemical Society of Japan, 91(10), p.1487 - 1494, 2018/10

https://doi.org/10.1246/bcsj.20180167

Competitive binding of binary mixed counterions to the headgroups of adsorbed surfactant films has been investigated at solution surfaces by total reflection X-ray absorption fine structure (XAFS) spectroscopy. The obtained extended XAFS spectra for bromide counterions are linear combinations of the spectra of fully hydrated bromide ions (free Br) and partially dehydrated bromide ions bound to the headgroups of the surfactant ions (bound Br). From the fraction of bound Br in counterion mixed systems, two series of the relative strengths of counterion binding are proposed for the trimethylammonium (TA) and 3-methylimidazolium (MIM) headgroups: (a) TA-SO TA-Cl TA-Br TA-BF and (b) MIM-Br TA-Br TA-BF MIM-BF. For the TA headgroup, matching the hydration of the headgroups and counterions gives series (a) according to Collins' law, which states that the tendency of contact ion pair formation becomes larger when the absolute values of the hydration enthalpies of the ions match. For the MIM headgroup, the number of binding sites of hydrogen bonds between the MIM headgroup and counterion is essential, which leads to series (b) because of competition between the counterion and water for interaction with the MIM headgroup.

Molybdenum adsorption properties of alumina-embedded mesoporous silica for medical radioisotope production

Saptiama, I.*; Kaneti, Y. V.*; Oveisi, H.*; Suzuki, Yoshitaka; Tsuchiya, Kunihiko; Takai, Kimiko*; Sakae, Takeji*; Pradhan, S.*; Hossain, M. S. A.*; Fukumitsu, Nobuyoshi*; et al.

Bulletin of the Chemical Society of Japan, 91(2), p.195 - 200, 2018/02

https://doi.org/10.1246/bcsj.20170295

no abstracts in English

Bithiophene with winding vine-shaped molecular asymmetry; Preparation, structural characterization, and enantioselective synthesis

Toyomori, Yuka*; Tsuji, Satoru*; Mitsuda, Shinobu*; Okayama, Yoichi*; Ashida, Shiomi*; Mori, Atsunori*; Kobayashi, Toru; Miyazaki, Yuji; Yaita, Tsuyoshi; Arae, Sachie*; et al.

Bulletin of the Chemical Society of Japan, 89(12), p.1480 - 1486, 2016/09

https://doi.org/10.1246/bcsj.20160265

Development of nondestructive and quantitative elemental analysis method using calibration curve between muonic X-ray intensity and elemental composition in bronze

Ninomiya, Kazuhiko; Nagatomo, Takashi*; Kubo, Kenya*; Ito, Takashi; Higemoto, Wataru; Kita, Makoto*; Shinohara, Atsushi*; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; et al.

Bulletin of the Chemical Society of Japan, 85(2), p.228 - 230, 2012/02

https://doi.org/10.1246/bcsj.20110151

Elemental analysis of bulk materials can be performed by detecting the high-energy X-rays emitted from muonic atoms. Muon irradiation of standard bronze samples was performed to determine the muon capture probabilities for the elemental components from muonic X-ray spectra. Nondestructive elemental analysis of an ancient Chinese coin was also performed.

Chloride complexation of Zr and Hf in HCl investigated by extended X-ray absorption fine structure spectroscopy; Toward characterization of chloride complexation of element 104, rutherfordium (Rf)

Haba, Hiromitsu*; Akiyama, Kazuhiko*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Yaita, Tsuyoshi; Hirata, Masaru; Sueki, Keisuke*; Nagame, Yuichiro

Bulletin of the Chemical Society of Japan, 82(6), p.698 - 703, 2009/06

https://doi.org/10.1246/bcsj.82.698

Chloride complexation of the group-4 elements Zr and Hf in 8.0-11.9 M HCl is investigated by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy to characterize chloro complexes of the transactinide element, rutherfordium (Rf). The complexes of Zr and Hf successively vary with the concentration of HCl from a hydrated complex [M(HO) ] at 8.0 M to a hexachloro complex [MCl] at 11.9 M (M = Zr and Hf). The present structural changes of the Zr and Hf complexes well reflect the previously studied anion-exchange behavior of Zr and Hf in HCl. From both the EXAFS and anion-exchange results, we suggest that Rf forms the same complexes as those of Zr and Hf in HCl, and that the complexation strength of the hexachloro complexes of the group-4 elements, [MCl] (M = Zr, Hf, and Rf), is in the sequence of Rf Zr Hf.

Component analysis of particulate products in electron beam-irradiated Xylene/air mixtures using an atmospheric pressure ionizing mass spectrometer

Hakoda, Teruyuki; Sako, Toshihiro*; Shimada, Akihiko; Ishida, Tsuneo*; Kojima, Takuji

Bulletin of the Chemical Society of Japan, 79(5), p.731 - 737, 2006/05

https://doi.org/10.1246/bcsj.79.731

no abstracts in English

Decomposition of phenolic endocrine disrupting chemicals by potassium permanganate and -ray irradiation

Abe, Yasuhiro*; Takigami, Machiko; Sugino, Koji*; Taguchi, Mitsumasa; Kojima, Takuji; Umemura, Tomonari*; Tsunoda, Kinichi*

Bulletin of the Chemical Society of Japan, 76(8), p.1681 - 1685, 2003/08

https://doi.org/10.1246/bcsj.76.1681

The decomposition of phenolic endocrine disrupting chemicals (P-EDCs), such as phenol, 4-butylphenol (BuP), and bisphenol A (BPA), in aqueous solutions by potassium permanganate (KMnO) was studied and its efficiency was compared with that of hydroxyl radicals (OH) generated by Co -ray irradiation. Various organic acids and inorganic carbon were formed in the decomposition of P-EDCs due to either KMnO or OH. They were formed via direct aromatic ring cleavage in the case of KMnO and OH addition-substitution reactions followed by aromatic ring cleavage in the case of OH. Comparing the decrease in the P-EDCs based on the number of electrons, the amount of KMnO spent to completely eliminate BuP and BPA was comparable to the amount of OH. Although three times more KMnO was needed for phenol than OH, the complete conversion of phenol into organic acids and inorganic carbon was achieved with 720M of electrons in both cases.