Author
Keiko Sasaki
Other affiliations: Otaru University of Commerce, Hokkaido University, Gadjah Mada University
Bio: Keiko Sasaki is an academic researcher from Kyushu University. The author has contributed to research in topics: Adsorption & Sorption. The author has an hindex of 36, co-authored 319 publications receiving 5341 citations. Previous affiliations of Keiko Sasaki include Otaru University of Commerce & Hokkaido University.
Topics: Adsorption, Sorption, Arsenate, Aqueous solution, Chalcopyrite
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the La 0.1 -PC composite was used as a multifunctional sorbent for the remediation of phosphate along with alkaline metal ions (Ca 2+ and Mg 2+ ) as well as the removal of humic substances in wastewaters.
181 citations
TL;DR: In this article, the authors evaluated the performance of raw tropical peat derived from Pontianak, West Kalimantan-Indonesia, at temperatures ranging from 150 to 380°C, a maximum final pressure of 25.1 MPa and a residence time of 30 min.
135 citations
Journal Article•
TL;DR: The Raman spectra of jarosite-group compounds are characterized by a tendency for the wavenumbers assigned to two vibrational modes of S042-, VI(SOi-) and V,(S042-) to decrease with an increase in the c unit-cell parameter as discussed by the authors.
Abstract: Raman spectra (200-1300 cm-I) were measured for synthesized jarosite-group compounds [MFe,(S04h(OH)r" M+ = K+, NH4+,Na+, Ag+, and Y2Pb2+).The Raman spectra of jarosite-group compounds are characterized by a tendency for the wavenumbersassigned to two vibrational modes of S042-, VI(SOi-) and vj(SOi-), and three vibrational modes of Fe-O bonds, to decrease with increase in the c unit-cell parameter. The wavenumbers assigned to the v2(SOi-) and v4(SOi-) vibrational modes'are independent of the.value.of c. For plumbojarosite, thc peaks corresponding to the VI(S042-) and V,(S042-) vibrational modesare broad owing to two overlapping peaks assigned to two types of sulfate groups, S042- ions adjacent and not adjacent to Pb2+ ions. Raman spectra can serve to identify the specific type of jarosite-group compound in poorly crystalline or low-concentration geochemical samples.
107 citations
TL;DR: In this article, the morphological features of jarosite-group phases formed by the biological method were rendered distinguishable by the effect of extracellular substances, and the order of formation was confirmed to be argentojarosite > jarosite > ammoniojarosite at 30°C where Fe 3+ ions are present in the system from the beginning.
Abstract: Jarosite-group compounds [ M Fe 3 (SO 4 ) 2 (OH) 6 : argentojarosite ( M + = Ag + ), jarosite ( M + = K + ), ammoniojarosite ( M + = NH 4 + )] were synthesized by supplying Fe 3+ ions in three different ways: biological oxidation of Fe 2+ ions by T. ferrooxidans (biological products), chemical oxidation of Fe 2+ ions by slow addition of H 2 O 2 (chemical products 1), and chemical oxidation by rapid addition of H 2 O 2 (chemical products 2). These were characterized by XRD, FTIR, chemical analysis and SEM; as well, the morphological features were compared with those formed by the hydrothermal method (standard substances). The jarosite-group compounds so synthesized do not contain crystalline by-products, as revealed by XRD, but the order of purity inferred from IR spectra, which is determined by the intensity of specific peaks, was found to be dependent on the method of preparation and is independent of the jarosite species; the order was found to be standard substances > chemical products 2 > chemical products 1 > biological products. Two main factors were found to affect the morphology, the method and rate of supply of Fe 3+ ions to the system and the nature of the monovalent cations, which determine the intrinsic rate of formation under given conditions. Where Fe 3+ ions are present in the system from the beginning, the order of rate of formation is confirmed to be argentojarosite > jarosite > ammoniojarosite at 30°C. Morphological features of jarosite-group phases formed by the biological method were rendered distinguishable by the effect of extracellular substances. Morphological information is useful to distinguish the mode of occurrence of jarosite-group phases in natural samples, since it may be difficult to do so by other analytical techniques, such as XRD, FTIR, Raman spectroscopy and chemical analysis.
106 citations
TL;DR: In this article, the stoichiometry of pyrite dissolution by Fe(II) ions was studied in a chloride media around pH 2, and the major constituent of the layer was elemental S, identified by X-ray photoelectron spectroscopy (XPS) and Raman Spectroscopy.
100 citations
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TL;DR: The state of the art in preprocessing of End-of-life materials containing rare-earth elements (REEs) and the final recovery is discussed in detail in this article, where the relevance of Life Cycle Assessment (LCA) for REE recycling is emphasized.
1,718 citations
1,571 citations
01 Jan 2011
TL;DR: The wet pyrolysis process, also known as hydrothermal carbonization, opens up the field of potential feedstocks for char production to a range of nontraditional renewable and plentiful wet agricultural residues and municipal wastes as discussed by the authors.
Abstract: The carbonization of biomass residuals to char has strong potential to become an environmentally sound conversion process for the production of a wide variety of products. In addition to its traditional use for the production of charcoal and other energy vectors, pyrolysis can produce products for environmental, catalytic, electronic and agricultural applications. As an alternative to dry pyrolysis, the wet pyrolysis process, also known as hydrothermal carbonization, opens up the field of potential feedstocks for char production to a range of nontraditional renewable and plentiful wet agricultural residues and municipal wastes. Its chemistry offers huge potential to influence product characteristics on demand, and produce designer carbon materials. Future uses of these hydrochars may range from innovative materials to soil amelioration, nutrient conservation via intelligent waste stream management and the increase of carbon stock in degraded soils.
1,360 citations
TL;DR: In this paper, the authors present a review of coal fly ash at the global level, focusing on its current and potential applications, including use in the soil amelioration, construction industry, ceramic industry, catalysis, depth separation, zeolite synthesis, etc.
1,167 citations
TL;DR: In this paper, the potential applications for coal fly ash as a raw material were reviewed. And the authors found that there is significant potential for the increased utilisation of coal fly-ash both in its raw and refined state.
879 citations