BACKGROUND: The large Itaya zeolite deposit in Yonezawa, Japan produces good quality, natural zeolite. Its properties as an adsorbent and a functional carrier were assessed and the ion exchange characteristics examined. Natural zeolite has a useful high cation exchange capacity, but has a disadvantage in scattering of the powder. In this study a nonwoven fabric containing zeolite was tested for the removal of cesium. RESULTS:The X-ray diffraction (XRD) peak pattern confirmed that Itaya zeolite is mainly clinoptilolite and contains some mordenite. Ion exchange selectivity of the natural zeolite was Ag + > Pb 2+ > Cu 2+ > Zn 2+ > Cd 2+ > Cr 3+ > Ni 2+ with almost 100% removal of Ag + and Pb 2+ ions.The cation exchange capacity (CEC) of Itaya zeolite was 131 cmol kg -1 . Low concentrations of Cs + were removed effectively from the solution with natural zeolite. Cesium ions were removed by ion exchange with potassium and sodium. Cs + was desorbed from the zeolite with ammonium salt solutions. Elution of Cs + was influenced by the coordination ability of counter anions. CONCLUSION: Satisfactory results were obtained using zeolite-containing nonwoven fabric for the removal of cesium ions.

The intramolecular dehydration of biomass-derived sugar alcohols d-sorbitol, d-mannitol, galactitol, xylitol, ribitol, l-arabitol, erythritol, l-threitol, and dl-threitol was investigated in high-temperature water at 523-573 K without the addition of any acid catalysts. d-Sorbitol and d-mannitol were dehydrated into isosorbide and isomannide, respectively, as dianhydrohexitol products. Galactitol was dehydrated into anhydrogalactitols; however, the anhydrogalactitols could not be dehydrated into dianhydrogalactitol products because of the orientation of the hydroxyl groups at the C-3 and C-6 positions. Pentitols such as xylitol, ribitol, and l-arabitol were dehydrated into anhydropentitols. The dehydration rates of the pentitols containing hydroxyl groups in the trans form, which remained as hydroxyl groups in the product tetrahydrofuran, were larger than those containing hydroxyl groups in the cis form because of the structural hindrance caused by the hydroxyl groups in the cis form during the dehydration process. In the case of the tetritols, the dehydration of erythritol was slower than that of threitol, which could also be explained by the structural hindrance of the hydroxyl groups. The dehydration of l-threitol was faster than that of dl-threitol, which implies that molecular clusters were formed by hydrogen bonding between the sugar alcohols in water, which could be an important factor that affects the dehydration process.

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Here, we report the development of catalysts comprising highly dispersed Au on an alumina (Al 2 O 3 ) support for the oxidation of glycerol to high-value carboxylic acids in a liquid-phase flow reactor. The catalysts were prepared by means of a deposition–precipitation method. To ensure that the catalysts could be used for long-term catalytic conversions in a liquid-phase flow reactor, we chose an alumina support with high temperature stability and a particle size (50–200 μm) large enough to prevent leakage of the catalyst from the reactor. One of the five catalysts had a high catalytic activity for the conversion of glycerol to the high-value carboxylic acids, glyceric acid and tartronic acid (conversion of glycerol >70%), and the catalyst retained its catalytic activity over long-term use (up to 1770 min). Pretreatment of the catalyst with fructose, a mild reductant, increased the activity of the catalyst. Scanning transmission electron microscopy revealed three Au species highly dispersed on the surface of the alumina support—Au nanoparticles (mode = 7.5–10 nm), Au clusters (1–2 nm), and atomic Au.