Noriko Hata

Behavior of di(2-ethylhexyl) phthalate discharged from domestic waste water into aquatic environment

The behavior of di(2-ethylhexyl) phthalate (DEHP) discharged from domestic waste water into river water, sediment and submerged aquatic vegetation was investigated. The concentrations of DEHP were found to be between 8-25 microg L(-1) in river water, 1,000-2,000 microg kg(-1) in sediment and less than 20-2,000 microg kg(-1) in submerged aquatic vegetation. The experiments performed in laboratory were on the biodegradation of DEHP in water and sediment, and also adsorption equilibrium of DEHP between water and sediment. The results obtained from the investigations made it clear that the high enrichment of DEHP from water to sediment was caused from not only its high adsorptive potential but also slow degradation in sediment.

Bis[2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulpho propylamino)phenolato]cobaltate(III) as a counter ion for the extraction and spectrophotometric determination of long-chain quaternary ammonium salts and tertiary alkylamines in the presence of each other

Abstract The singly charged complex anion bis[2-(5-bromo-2-pyridylazo)-5-( N -propyl- N -sulphopropylamino)phenolato]cobaltate(III) is intensely purple-violet and is stable over the pH range 1–13. Its absorption spectrum remains the same over this pH range. At pH2, it forms extractable ion pairs with long-chain quaternary ammonium ions and protonated alkylamines. Only the quaternary ammonium ions are extracted into chloroform at pH 11, hence separate extractions allow both types to be determined. The absorbance of the organic phase is measured at 594 nm. The apparent molar absorptivity is 7.0 × 10 4 l mol −1 cm −1 . Calibration graphs for zephiramine, benzethonium and hexadecylpyridinium ions are linear over the range 0.1–2 × 10 −6 M. The only interference found was from anionic surfactants. The method is applied to hair and fabric conditioners.

Transportation and fate of cationic surfactant in river water.

The degradation, sorption, transportation and material balance of cationic surfactants discharged from domestic waste into river water was studied. Ion-pair solid-phase extraction behavior showed that the sorption of cationic surfactants as an ion-pair with anionic surfactant onto river sediment was so strong that little cationic surfactant was found in the bulk water. Cationic surfactant was found in river sediment at more than 500 times higher concentration than that in the bulk water. The degradation of the cationic surfactant was very slow in river water and much slower in the sediment. A material balance of cationic surfactant was estimated for a river running through Toyama City by measuring the flow rate and the concentration of cationic surfactant in the water at several points. It was found that more than 30% of cationic surfactant introduced to the river was lost during the river running through ca. 3 km in 3 h. This reduction probably comes from a quick transfer of the cationic surfactant from river water to sediment and water weed by means of adsorption or precipitation with suspending solids.

Spectrophotometric determination of anionic surfactants in sea-water based on ion-pair extraction with bis[2-(5-trifluoromethyl-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) as counter ion

A simple and sensitive spectrophotometric method was developed for the extraction and spectrophotometric determination of low levels of anionic surfactants in sea-water. Anionic surfactants are extracted into toluene as an ion-pair with bis[2-(5-trifluoromethyl-2-pyridylazo)-5-diethylaminophenolato]cobalt(III){[Co(CF3-PADAP)2]+} and the absorbance of the organic phase is measured at 560nm. The cobalt complex cation is inert and stable over a wide pH range, and has a large molar absorption coefficient (Iµ= 1.06 × 104 m2 mol–1 at 573 nm in water and Iµ= 5.83 × 103 m2 mol–1 at 560 nm in toluene). The Beer–Lambert law was obeyed over the concentration range 0.01–0.4 mg dm–3 of sodium dodecyl sulfate (SDS) and the detection limit was 0.005 mg dm–3 on a 3σb basis. The relative standard deviations for artificial sea-water spiked SDS were about 2%. Electrolytes in sea-water do not interfere. The proposed method is simpler and more sensitive than the conventional Methylene Blue method even when the degradation products of anionic surfactants are present. The method was applied to the determination of anionic surfactants in sea-water samples without interference from matrix substances.

Membrane solubilization with tetramethylammonium hydroxide for the preconcentration and electrothermal atomic absorption spectrometric determination of trace amounts of arsenic in water

Solubilization of a mixed cellulose ester membrane filter (MF) with tetramethylammonium hydroxide (TMAH) is proposed for the preconcentration and electrothermal atomic absorption spectrometric (ETAAS) determination of trace amounts of arsenic in water. Arsenic at not more than 0.4 µg in 100 ml of sample solution was retained on the MF by filtration as an ion associate of arsenomolybdate and tetraphenylphosphonium ions.The ion associate was dissolved in a small volume of TMAH together with the MF. After being made up to 2 ml with water, the arsenic in the concentrate was determined by ETAAS in the presence of zirconyl nitrate as a chemical modifier. This method is very simple and rapid. The detection limit, defined as three times the standard deviation of the blank, was 0.04 µg l–1. Inorganic matrix components in river waters, Na+, K+, Ca2+, Mg2+, SO42–, NO3– and silicate at high concentrations did not interfere with the determination. Trace components, phosphate at 0.3 mg l–1, dodecyl sulfate at 14 mg l–1 and aluminium at 5 mg l–1, also did not interfere with the determination. The proposed method was applied to the analysis of river water samples.

The evaluation for alterations of DOM components from upstream to downstream flow of rivers in Toyama (Japan) using three-dimensional excitation-emission matrix fluorescence spectroscopy.

The dissolved organic matter (DOM) is one of the important factors for controlling water quality. The behavior and constitutions of DOM is related to the risk of human health because it is able to directly or indirectly affect the behavior, speciation and toxicity of various environmental pollutants. However, it is not easy to know the contents of DOM components without using various complicated and time consuming analytical methods because DOM is a complex mixture and usually exists at low concentration. Here, we describe the fluorescence properties of DOM components in water samples collected from four rivers in Toyama, Japan by means of the three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy. In order to evaluate the alterations of DOM components in each of the river during the flow from upstream to downstream, the patterns of relative fluorescence intensity (RFI) at six peaks which are originated from fluorophores including humic-like and protein-like components were investigated. The changes in the patterns of RFI values at each of the peak and the concentration of dissolved organic carbon (DOC) for each river water sample were discussed in connection with the differences of land use managements and basic water quality parameters, such as pH, EC, turbidity, Fe3+, T-N, NO3-N, T-P, PO4-P, chlorophyll a, DOC and N/P ratio. The DOC concentrations in the water samples collected from these rivers were relatively low (0.63–1.16 mg/L). Two main peaks which have a strong RFI value expressed a positive correlation with the DOC concentration (r = 0.557, 0.535). However, the correlations between the RFI values for other four peaks and the DOC concentration were below 0.287. The alterations of DOM components during the flow of a river from upstream to downstream were investigated from the changes in the patterns of RFI values for six fluorescent peaks. It was clarified that the great increase of RFI values in peak A and peak T from river water located in urban area showed high concentration of PO4-P and Fe3+, and low N/P ratio due to the high biological activities. The values of fluorescence index (FIX) and biological index (BIX) were as high as 1.60 and 0.72, respectively.

Simultaneous multiselective spectroelectrochemical fiber-optic sensor: demonstration of the concept using methylene blue and ferrocyanide.

Herein, we present a novel spectroelectrochemical fiber-optic sensor that combines electrochemistry, spectroscopy, and electrostatic adsorption in three modes of selectivity. The proposed sensor is simple and consists of a gold mesh cover on a multimode fiber optic that uses attenuated total reflection as the optical detection mode. The sensing is based on changes in the attenuation of the light that passes through the fiber-optic core accompanying the electrochemical oxidation-reduction of an analyte at the electrode. Methylene blue and ferrocyanide were used as model analytes to evaluate the performance of the proposed sensor. The optical transmission changes generated by electrochemical manipulation showed a good linear relationship with the concentration and the limits of detection (3σ) for methylene blue and ferrocyanide at 2.0 × 10(-7) and 1.6 × 10(-3) M, respectively. The sensor responses were successfully enhanced with an additional level of selectivity via an electrostatically adsorbed, self-assembled monolayer (SAM), which consisted of a silane coupling layer, a polyanion, and a polycation. The improvement observed in the sensitivity of a SAM-modified fiber-optic sensor was rather encouraging. The optimized sensor had detection limits (3σ) of 8.3 × 10(-9) M for methylene blue and 7.1 × 10(-4) M for ferrocyanide. The developed sensor was successfully applied to the detection of ferrocyanide in simulated nuclear waste.

The evaluation of forest fire severity and effect on soil organic matter based on the L*, a*, b* color reading system

The evaluation of forest fire severity and effect on soil is very important when discussing the damage to the environment. The purpose of this study is to evaluate the effect forest fires have on the soil color using the CIE Lab system. The color changes in four kinds of soil samples caused by heating at different temperatures were investigated. It was found that the Δa* and Δb* values drastically decrease when samples were heated over the temperature range from 200 to 250 °C, that is above the ignition temperature of volatile matter. The Δa* and Δb* values show a good linear negative correlation with the atomic ratios of H/C and O/C. The results obtained from this study indicate that the proposed method is able to evaluate the dehydration and decarboxylation of soil caused by forest fires. We demonstrated this method using soil samples collected from unburned and burned areas in Kalimantan, Indonesia.

Membrane filters for the concentration of trace elements in water: distribution of ion pairs between membrane filter and aqueous phases

The sorption of ion pairs on membrane filters (MFs) has been studied by taking the membrane filter as one of the homogeneous phases. The sorbability of some ionic species and the sorption abilities of different types of MF were evaluated in terms of the sorption constant defined by Ksor,CA = [(C+,A-)f]/[C+][A-], where C+, A- and (C+,A-) refer to the cation, anion and the ion pair, respectively, and f refers to the filter phase. The values of Ksor,CA were determined for many combinations of ionic complexes of cobalt(III) with pyridylazophenols, either as cations or anions, and oppositely charged organic ions having different alkyl chain lengths, with MFs made of different materials: nitrocellulose (NC; Toyo Advantec), acetylcellulose (AC; Fuji Film), regenerated cellulose (RC; Toyo Advantec) and polyethersulphone (PS; Toyo Advantec). For a given cobalt complex ion, the value of log Ksor,CA increased linearly with the increasing number of carbons in the counter ion. Membrane filters made of different materials showed different sorption abilities, the order being NC greater than PS greater than RC greater than AC. It was shown that the surface area of the MF is of greater significance than the volume of the matrix of the MF in determining the sorption constant.

Determination of arsenic by inductively coupled plasma atomic emission spectrometry after pre-concentration on an acid-soluble membrane filter as arsenomolybdate in the presence of a quaternary ammonium salt

A simple pre-concentration technique, based on collecting trace analytes on a membrane filter and dissolving the filter and the analytes in a suitable solvent, has been applied to the determination of arsenic in water by inductively coupled plasma atomic emission spectrometry. Arsenic, in the range 1–50 µg in a 100–500-ml sample, is collected on a nitrocellulose membrane filter as an ion associate of arsenomolybdate with tetrapentylammonium ion. The membrane filter and the arsenomolybdate are dissolved in a small volume of concentrated sulphuric acid, diluted to 2–10 ml and aspirated into the nebuliser. Arsenic is determined from the emission intensity at 228.812 nm. Moderate concentrations of silicate, phosphate and cadmium and high concentrations of sodium chloride do not interfere. Enrichment factors as high as 250 can be easily attained by the proposed pre-concentration technique. The detection limit, defined as three times the standard deviation of the blank, is 0.3 µg l–1 with 250-fold pre-concentration.