Hiroyasu Ichikawa

National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan

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Publications (13)47.01 Total impact

  • Hiroyasu Ichikawa · Ronald R Navarro · Yosuke Iimura · Kenji Tatsumi
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    ABSTRACT: The nature of bioavailability of DNA-intercalated PAHs in aqueous solution was investigated. The degradability of different PAHs including anthracene, phenanthrene and pyrene by Sphingomonas sp. was not inhibited even at a high DNA concentration of 2%. The DNA was stable against the PAH-degrader as indicated by the unchanged electrophoresis gel chromatograms after treatment. This shows that a structural change in the polymer is not necessary for the release of PAHs. Partitioning experiments using phenanthrene as a model PAH illustrated the presence of an initial passive uptake by autoclaved cells. Subsequent intracellular degradation became apparent from parallel data with live cells. Phenanthrene transfer from the DNA was diffusion-controlled and the exit of this molecule from their intercalation sites is favored in lieu of the presence of stronger hydrophobic binding sites in the cell membrane.
    No preview · Article · Aug 2010 · Chemosphere
  • Ronald R Navarro · Hiroyasu Ichikawa · Kenji Tatsumi
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    ABSTRACT: Photo-Fenton oxidation followed by ferrite formation was applied for the degradation of a representative organic compound, phenol, and the subsequent removal of the Fe ions. At a phenol:Fe(II):H(2)O(2) molar ratio of 1:0.5:15, TOC analysis showed almost complete mineralization of 10.6mM phenol after 2h at a controlled pH of 3. Recalcitrant low molecular weight organic acid by-products particularly oxalic acid were destroyed. A ferrous-rich solution was generated so that alkalinization at pH 10.5 generated a pitch black sludge of lower volume and moisture content than a ferric hydroxide control of the same Fe concentration. The flocs exhibited a strong affinity for a magnet and its X-ray diffraction pattern showed a close similarity to a standard spinel magnetite. With proper monitoring of Fe(II) and dissolved oxygen, the reaction was successfully controlled to generate flocs with more than 30% magnetite content. When photo-Fenton was employed as a pre-treatment step so that residual oxalic acid remained, ferrite formation was not inhibited. The presence of oxalates even allowed ferrites to form in a solution containing Ca(2+) ions, which is well-known to be deterrent to the process.
    No preview · Article · Jun 2010 · Chemosphere
  • Ronald R Navarro · Hiroyasu Ichikawa · Kengo Morimoto · Kenji Tatsumi
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    ABSTRACT: The effect of a common plant alkaloid, caffeine, on the release and plant uptake of some polycyclic aromatic hydrocarbons (PAHs) in soils was investigated. Cucurbita pepo (ssp. pepo cv. Gold Rush) was grown in PAH-spiked media in the presence and absence of caffeine. Solubility tests initially confirmed the ability of caffeine to dissolve PAHs mixtures of anthracene, phenanthrene, pyrene, benzo[a]pyrene and benzo[ghi]perylene. Extraction experiments also highlighted its potential as a PAH-releasing agent from an aged soil. Phytoextraction from a low organic sand medium (f(OC)=0.056+/-0.03%) indicated a significant enhancement of pyrene uptake with three weeks daily watering with 500mgL(-1) caffeine solution. The average pyrene content of roots was 35.3 and 16.0microgg(-1), in caffeine and non-caffeine set-ups, respectively. In the shoots, the corresponding values were 3.60 and 1.67microgg(-1). Both showed more than twofold increase with caffeine. Caffeine also accumulated mainly in the leaves of the treated samples at 2800mgkg(-1) dry weight. Further tests with a 1-year aged soil (f(OC)=5.2+/-1%) containing a mixture of phenanthrene and pyrene yielded parallel results. However, lower PAH content in these samples were observed due to the stronger PAHs partitioning in aged-soil matrix. After four weeks of caffeine, phenanthrene in shoots and roots increased by one and a half and four times, respectively. The corresponding enhancements for pyrene were two and a half and three and a half times.
    No preview · Article · Jun 2009 · Chemosphere
  • Ronald R Navarro · Yosuke Iimura · Hiroyasu Ichikawa · Kenji Tatsumi
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    ABSTRACT: The biodegradation of polycyclic aromatic hydrocarbons (PAHs) in aqueous deoxyribonucleic acid (DNA) solution from contaminated soil washing was investigated. Initial data with a model effluent consisting of anthracene, phenanthrene, pyrene and benzo[a]pyrene that were individually dissolved in 1% aqueous DNA solution confirmed their positive degradation by Sphingomonas sp. at around 10(8)CFU mL(-1) initial cell loading. For anthracene and phenanthrene, complete removal was achieved within 1h treatment. Degradation of pyrene and benzo[a]pyrene took a relatively longer time of a few days and weeks, respectively. DNA-dissolved PAHs were also degraded relatively faster than PAH crystals in aqueous medium to suggest that the binding of the PAHs in the polymer does not pose serious constraint to bacterial uptake. The DNA was stable against the PAH-degrading bacteria. Parallel experiments with actual DNA solutions obtained during pyrene extraction from an artificially spiked soil also showed similar results. Close to 100% pyrene degradation was achieved after 1d treatment. With its chemical stability, the cell-treated DNA was re-used up to four cycles without a considerable decline in extraction performance.
    No preview · Article · Oct 2008 · Chemosphere
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    Ronald R Navarro · Hiroyasu Ichikawa · Yosuke Iimura · Kenji Tatsumi
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    ABSTRACT: An aqueous DNA solution was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from a spiked soil. Solubilities of 0.56, 11.78, and 11.24 mg L(-1) for anthracene, phenanthrene, and pyrene, respectively, were achieved after 1 day equilibration in 1% DNA. Using a spiked soil that contained 72 mg kg(-1) anthracene, 102 mg kg(-1) phenanthrene, and 99 mg kg(-1) pyrene, extractions of close to 88, 78, and 94%, respectively, were attained with 5% DNA at a 1:50 soil/extractant ratio. Maximum PAH dissolution occurred after 4-6 h. Comparative tests showed the main advantage of DNA over methyl-beta- and gamma-cyclodextrins and Tween 80 for pyrene removal. An ionic strength of 0.1 M NaCl was found necessary for maximum PAH dissolution and extraction. The performance of hexane regenerated DNA also remained stable after three stages of recycling. These results show the huge potential of DNA as an aqueous washing agent for PAH-contaminated soil.
    Preview · Article · Jul 2007 · Environmental Science and Technology
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    ABSTRACT: To elucidate the role of a soil humic acid (HA) in the transport of polychlorinated organic pollutants (PCOPs), such as polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and coplanar-polychlorinated biphenyls, their partition coefficients (Kdoc) into an HA were compared with their adsorption coefficients (KOC) for a soil with a higher organic carbon (OC) content. The soil sample (ando soil) used in the present study was collected in the same location as the HA. The log Kdoc values were positively correlated with logarithm of octanol-water partition coefficients (log KOW) of the PCOPs, indicating that the partitioning of PCOPs into the HA was mainly due to hydrophobic interactions. However, the correlation between log Kdoc and log KOC was negative. This can be attributed to the enhanced water solubility of the PCOPs as the result of the dissolved organic matter from the soil. That is, when the more hydrophobic PCOPs with higher log KOW values are partitioned into the HA, then the larger quantities of PCOPs that are partitioned into the HA are able to dissolve in the aqueous phase. These results suggest that, in a soil with a higher OC content, the HA can serve as more effective carrier of PCOPs from the soil to an aquatic environment.
    No preview · Article · Feb 2006 · Journal of Environmental Science and Health Part A
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    ABSTRACT: The partition coefficients (Koc) of 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) with respect to a variety of humic substances (HSs) were evaluated by a method involving solid-phase microextraction and gas chromatography-electron capture detection. The log Koc values for each of the HS samples were in the range of 6.4-7.7. The log Koc values for HAs from tropical peat, brown forest and ando soils were in the range of 7.3-7.6, similar to the calculated value for the octanol-water partition coefficient (log Koc=7.56). In contrast, the log Koc values for FAs and peat HAs were 0.5-1 unit lower than the calculated value. The parameters for the polarity of HSs, as calculated from (N+O)/C, O/C atomic ratios and the carboxyl group content, were numerically similar related to the log Koc for HpCDD. These results show that the Koc values for HpCDD are significantly influenced by the polarity of HSs.
    No preview · Article · Apr 2005 · Chemosphere
  • Sinta Rismayani · Masami Fukushima · Hiroyasu Ichikawa · Kenji Tatsumi
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    ABSTRACT: Orange II, C.I. Acid Orange 7 (AO7), is oxidatively decolorized via catalytic oxidation by iron(III) phthalocyanine-tetrasulfonic acid (Fe(III)-PcTS) as a biomimetic catalyst and KHSO(5) as an oxygen donor. The nature of the decolorization of AO7 was investigated in the catalyst concentration range of 10-50 microM, in which the initial concentration of AO7 was 417 mg l(-1). A 99.6% decolorization was observed at [KHSO(5)] = 2.5 mM and [Fe(III)-PcTS] = 20 microM after a 3-h reaction period. However, the fact that only 4.9% of the TOC was removed indicated that the conversion to CO(2) was incomplete. The results of a total organic nitrogen analysis of the reaction mixture showed that the nitrogen in the azo chain was mainly converted to N(2) gas. In addition, 38.6% of the AO7 was converted to 1,2-dihydroxynaphthalene, and 21.4% to p-phenolsulfonic acid. These results indicate that the degradation via this catalytic system involves the conversion of AO7 to phenolic compounds, followed by N(2) production. In addition, a Microtox test showed that toxicity of the solution increased as a result of AO7 oxidation using this catalytic system.
    No preview · Article · Oct 2004 · Journal of Hazardous Materials
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    ABSTRACT: Iron(III)-tetra(p-sulfophenyl)porphine (Fe(III)-TPPS), manganese(III)-5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (Mn(III)-TPyP), iron(III)-phthalocyanine-tetrasulfonic acid (Fe(III)-PcTS) and copper(II)-phthalocyanine-tetrasulfonic acid (Cu(II)-PcTS) were evaluated in terms of the catalytic activity for the oxidation of pentachlorophenol (PCP). Although Cu(II)-PcTS had no activity, 40–70% of the PCP was oxidized in the Fe(III)-TPPS, Fe(III)-PcTS and Mn(III)-TPyP systems. In addition, the effects of the addition of peat humic acids (HAs) on PCP oxidation were also investigated. In the presence of HAs, 65–85% of the PCP was oxidized in the Mn(III)-TPyP system, and approximately 100% of the PCP was oxidized in the Fe(III)-TPPS and Fe(III)-PcTS systems. These results show that the addition of peat HAs is effective in enhancing the PCP oxidation. The effects of peat HAs were investigated using hydroxypropyl-β-cyclodextrin (HP-β-CD) as a model for the hydrophobic portions in HAs, because peat HA contains a hydrophobic core similar to that of cyclodextrin. The conversion of PCP increased with increasing concentrations of HP-β-CD. This suggests that structural moieties analogous to cyclodextrins in peat HAs contribute to the enhanced PCP oxidation via the catalytic system with Fe(III)- and Mn(III)-complexes.
    No preview · Article · Aug 2004 · Journal of Molecular Catalysis A Chemical
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    ABSTRACT: We developed a method for the evaluation of the partition coefficients (K(oc)) of hexachlorobenzene (HCB) and 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) into humic substances (HSs) by using solid-phase microextraction (SPME). In the aqueous solution containing HCB or HpCDD and HS, the unbound species of HCB or HpCDD were accumulated on the SPME fiber. Subsequently, HCB or HpCDD on the SPME fiber was directly analyzed by GC-ECD. When the concentration of organic carbon in HS ([OC]) was plotted against the ratio of [HCB] or [HpCDD] in the absence of HS to that in the presence of HS, linear relationships were observed. The slope of the line corresponded to the K(oc) value. The log K(oc) values for HCB and HpCDD evaluated were in the ranges of 3.9 - 4.9 and 5.9 - 7.2, respectively. These values were the same order as those in the literature, which were evaluated by other methods (e.g., solubility enhancement, solid-phase extraction and dialysis). The relative standard deviations of the log K(oc) values evaluated in this study were within 5%.
    No preview · Article · Jun 2004 · Analytical Sciences
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    ABSTRACT: To investigate some basic aspects of soil remediation using biomimetic catalysts, the effects of humic substances (HSs) on the removal of xenobiotics, such as pentachlorophenol (PCP), were investigated. The use of a biomimetic catalytic system using tetra(p-sulfophenyl)porphine-iron(III) (Fe(III)-TPPS) and potassium monopersulfate (KHSO5) resulted in the disappearance of PCP, accompanied by dechlorination. In addition, this process was enhanced by the presence of several types of HSs. The degrees of enhancement (% delta(PCP)60) achieved by the presence of HSs from peat and compost soils were larger than those in the presence of other types of HSs (tropical peat, brown forest, and ando soils). In control experiments, no PCP disappearance and dechlorination were observed in the presence of only KHSO5, only Fe(III)-TPPS, or combinations of HSs and either KHSO5 or Fe(III)-TPPS. To better understand the role of added HS in enhancing or inhibiting PCP disappearance, correlations between the chemical parameters of the HSs and % delta(PCP)60 were investigated. The most effective HSs had lower carboxylic acid contents and lower degrees of unsaturation. The carboxylic acid content and degree of unsaturation increase with the extent of humification. Therefore, HSs of a lower degree of humification would be predicted to be more useful in enhancing the disappearance of PCP in an Fe(III)-TPPS/KHSO5 system.
    No preview · Article · Apr 2003 · Environmental Science and Technology
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    ABSTRACT: In the presence of humic substances (HSs), the oxidative conversion of pentachlorophenol (PCP) was found to be efficiently catalyzed by tetra(p-sulfophenyl)porphineiron(III) (Fe(III)-TPPS) using KHSO5 as an oxygen donor. Ortho-tetrachloroquinone (o-TeCQ), 2-hydroxyl-nonachlorodiphenyl ether (2H-NCDE), 4-hydroxyl-nonachlorodiphenyl ether (4H-NCDE), and octachlorodibenzo-p-dioxin (OCDD) were identified as the major byproducts of the reaction. Decreased amounts of these byproducts were produced in the presence of HS. In particular, the addition of HSs with a lower degree of humification resulted in a large decrease in the formation of dimers, such as 2H-NCDE, 4H-NCDE, and OCDD. More than 60% of the chlorine, which was released from PCP, was found in the HS fractions after the reaction. This suggests that chlorinated intermediates from PCP were incorporated into the HS. Pyrolysis-GC/MS and 13C NMR studies confirmed that the binding of the chlorinated intermediates was covalent in nature and that the intermediates were copolymerized with HS via oxidative coupling reactions. A Microtox test demonstrated that the toxicity of the HS fraction containing PCP-derived intermediates was much lower than that of the mixture of PCP and HS in the absence of a catalytic reaction.
    No preview · Article · Feb 2003 · Environmental Science and Technology
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    ABSTRACT: Pentachlorophenol (PCP) was degraded in an aqueous mixture of tetrakis(sulfonatophenyl)porphyrin (TPPS) and Fe(II) at pH 6. The degradation was enhanced by the addition of ascorbic acid (ASC), and PCP was largely degraded to tetrachlorohydroquinone (TeCHQ) and tetrachlorocatechol (TeCC). Chloride ions were released during the reaction in molar amounts that were approximately 2–3 times larger than those of PCP degraded. This suggests that further oxidative products are also produced. The percentage of PCP degraded decreased with increasing concentrations of 2-propanol, a hydroxyl radical (OH) scavenger. This supports the hypothesis that HO is involved in PCP degradation. When an aqueous solution, which contained only TPPS, was shaken under aerobic conditions, H2O2 was generated at mM level after a 24h reaction period. Thus, TPPS appears to be involved in the reduction of dissolved oxygen to O2−, leading to the generation of H2O2. However, in the presence of both TPPS and ASC, >100μM-levels of H2O2 were generated. This shows that the addition of ASC to TPPS enhances the generation of H2O2. These results lead to the conclusion that the degradation of PCP in the present systems can be attributed to a Fenton-like process.
    Full-text · Article · Sep 2002 · Journal of Molecular Catalysis A Chemical