A new method for the removal of arsenite [As(III)] and selenate [Se(VI)], which are difficult to remove by conventional water treatment methods from aqueous media, was investigated. This method involves the use of photocatalytic oxidation of As(III) and photocatalytic reduction of Se(VI). Also, a novel TiO2-adsorbent hybrid (HYB) which has photocatalyst sites and adsorbent sites on the same particle was developed. When the removal of As(III) by use of photocatalyst adsorbent system and the HYB system was carried out, As(III) was effectively removed from aqueous phase. Moreover, with the removal of Se(VI) by using photocatalytic reduction, Se(VI) could also be removed from aqueous phase under the photocatalyst-adsorbent system and the HYB system, even if the concentration of a hole scavenger formic acid was reduced.
Water Science & Technology Water Supply 02/2012; 12(1):24. DOI:10.2166/ws.2011.090
The mutagens produced through chemical reaction between chlorine and the insecticide fenitrothion were studied by using a quadrupole GC-MS. The mutagenicity and the mutagen formation potential (MFP) of the identified by-products were evaluated by the Ames assay (preincubation method) using Salmonella typhimurium TA100 without exogenous activation by S9 mix (TA100-S9). Before conducting GC/MS analyses, six compounds were presumed to be produced in chlorinated fenitrothion. These compounds were confirmed to be produced by the GC/MS analyses, but none of them were mutagenic. One of the chlorination by-products, 3-methyl-4-nitrophenol, has 19 times greater MFP than that of fenitrothion. This result suggests that a major mutagen in chlorinated fenitrothion will be produced via a chemical reaction between chlorine and 3-methyl-4-nitrophenol.
Water Science & Technology 07/2010; 62(1):85-91. DOI:10.2166/wst.2010.264 · 1.21 Impact Factor
A case of large cell neuroendocrine carcinoma (LCNEC) of the tongue base is described. It was characterized by solid tumor nests with central necrosis and rosette formation resembling basaloid squamous cell carcinoma. Immunohistochemical examination revealed that this tumor had neuroendocrine differentiation. It was diagnosed as LCNEC of the tongue base. Pulmonary LCNEC is a well-established entity, but LCNEC also occurs in other organs. This is the first report of mucosal LCNEC in the oral cavity. Basal cells in the normal squamous epithelium around the tumor indicated positivity for neural cell adhesion molecule and N-cadherin. These cells were considered neuroendocrine-related cells in the lingual squamous epithelium, which are related to the tumorigenesis of mucosal LCNEC in the tongue base.
International Journal of Oral and Maxillofacial Surgery 02/2009; 38(3):296-9. DOI:10.1016/j.ijom.2008.12.012 · 1.36 Impact Factor
Journal of Water and Environment Technology 01/2008; 6(1):19-33. DOI:10.2965/jwet.2008.19
Two low-rank coals, a sub-bituminous coal (BA) and a lignite (LY), were treated
by hot water extraction (HWE) and hydrothermal treatment (HTT), and the
environmental impacts of water-soluble matters eluted from coal by the HWE
and HTT processes were evaluated in terms of TOC, mutagenicity, and the acute
toxicity against freshwater organisms. When HWE was performed at 80°C, the
degree of TOC for LY was much higher than that for BA. However, for HTT,
the two coals gave comparable TOC values in L/S ratio of both 100 and 3. The
HWE and HTT eluents of two coals were assessed by the Ames mutagenicity
assay with Salmonella typhimurium TA100 and TA98 strains, and no notable
mutagenicity was observed in the presence or absence of metabolic activation.
When the mutagenicity of the 300ºC-HTT eluent of LY was analyzed, no notable
mutagenicity was also observed. For the HWE and HTT eluents of LY, the acute
toxicity test was carried out by use of Daphnia magna and Oryzias latipes. When
the 80°C-HWE eluent was tested, almost no toxicity was observed for D. magna
and O. latipes. However, when the HTT eluents were examined, the toxicity
increased as the elevation of the HTT temperature, and the toxicity of organic
matters dissolved in the 350°C-HTT eluent was comparable to that of reference
phenolic compounds. From the FTIR analysis of organic matters eluted in the
HTT eluents, it is found that the toxicity is caused by the presence of aromatic
compounds with hydrophilic substituents, such as carboxyl and hydroxyl groups.
Keywords: low-rank coal, wastewater, water-soluble organic matters,
mutagenicity, ames assay, acute toxicity.
ENVIRONMENTAL HEALTH RISK 2007; 06/2007
The mutagen formation potential (MFP) was measured for the river water, the
raw sewage and the effluent of the sewage works by means of the Ames
Salmonella mutagenicity assay. MFP of the river water samples ranged from
1,200 to 22,000 net revertant colonies per liter of sample water. MFP of the
effluent was from 5,300 to 22,000 net revertant colonies per liter. This survey
showed that the removal percentages of dissolved organic carbon (DOC) at the
sewage works were 62.0-79.3%. It also showed that MFP reductions at the same
sewage works were 37.5-62.9%. There was no significant correlation observed
between MFP and organic matter concentration for the river water samples.
However, a weak correlation between ammonia nitrogen and MFP was observed
for the same river water samples. These results indicate that MFP cannot be
accurately estimated by use of the conventional water quality indices. When the
samples contain a high concentration of ammonia nitrogen, it is difficult to
control the amount of free chlorine dosages stoichiometrically, possibly resulting
in the overdose of chlorine. An overdose of chlorine may cause further formation
of mutagens. The isotherm of mutagen precursors adsorption onto the activated
carbon (OL 20x50), which was purchased from Calgon Mitsubishi Chemical
Corporation, was studied using river water in order to explore the means of
removing mutagen precursors from raw water used for the water supply. The
adsorption isotherm attained fit well into the Freundlich model.
Keywords: Ames Salmonella assay, chlorination, mutagenicity, mutagen
formation potential, river water, sewage, activated carbon, adsorption isotherm.
RIVER BASIN MANAGEMENT 2007; 05/2007
A novel adsorbent, which had been developed for phosphate adsorption, was adopted for arsenic removal from groundwater. Adsorption isotherm, pH dependence of the isotherm and adsorption rate were studied by batch method. Furthermore, by using a granular adsorbent of 1.8 mm diameter which is commercially available, lab-scale experiments of continuous adsorption treatment of actual groundwater containing arsenic at 50 mg m(-3) were conducted to examine the performance of the adsorbent. A large amount of arsenic, i.e., 10 g As kg(-1), was adsorbed at pH 7.0 and 10 mg As m(-3) in equilibrium concentration. It was only a 5% higher amount compared to conventional activated alumina. However, twice the bed volume, i.e., total volume of effluent divided by empty column volume, was achieved till breakthrough by using this novel adsorbent. This may be because the pH decrease, which enlarges apparent adsorption capacity of the adsorbent, is caused by a self-pH decrease function of the adsorbent. The self-pH decrease function must be delivered by dissociation of Al (III) aquoion. The proton release was clearly observed in batch experiments.
Water Science & Technology 02/2004; 50(8):23-32. · 1.21 Impact Factor