Correlation of low-volatile organic chlorine (LVOCl) and PCDD/Fs in various municipal waste incinerators (MWIs)

Medium- and low-volatile organic chlorine (M/LVOCl) and PCDD/Fs in flue gas from various municipal waste incinerators (MWIs) were monitored. The sample for M/LVOCl was collected in an adsorption tube which was thermally desorbed and the amount of chlorine was measured by atomic emission spectrometry (AES) detection using radiofrequency helium plasma. The helium plasma excited chlorine having an optical emission line of 837.6 nm was monitored. The MVOCl and LVOCl were organic chlorine groups whose boiling points (bp) ranged from 70-120 degrees C and 170-270 degrees C, respectively. The compounds having bp 120-170 degrees C were distributed in two tubes. LVOCl correlated well with PCDD/Fs (ng/Nm3, r=0.81) in a wide range of 0.01-100 ng/Nm3 of PCDD/Fs, while the correlation of LVOCl vs. TEQ was less related (r=0.69). These results agreed with the fact that LVOCl monitored the amount of organic chlorine without molecular structure information, which is critical to toxicity. Since the bp of LVOCl was not identical with that of PCDD/Fs, the regression was effected by the conditions of the gas treatment devices. Because most data of 2001 were collected just after the installation of PCDD/Fs in MWIs, the regression of 2001 was slightly different from that of 2002-2003. Eliminating these initial unsteady data, the regression of LVOCl vs. PCDD/Fs became better, giving r= 0.86. Besides having PCDD/Fs as surrogates, M/LVOCl is valuable as a versatile element-selective organic chlorine monitor to improve thermal process control.     

Ozone Injection into an Activated Carbon Bed to Remove Hydrogen Sulfide in the Presence of Concurrent Substances

ABSTRACT

Adsorption using activated carbon is one of the most reliable techniques for preventing odor by substances such as H₂S. Concurrent substances in effluent gas often reduce the removal capacity of activated carbon for H₂S. As a means of restoring capacity under such conditions, ozone injection into an activated carbon column was examined. When activated carbon was saturated with substances such as toluene, ethanol, n-butanol, or iso-butanol, its capacity to remove H₂S decreased in proportion to the amount of the saturating substance. Under such conditions, ozone injection greatly increased capacity. Toluene, which is not easily decomposed by ozone, was displaced by ozone and by oxidized products of H₂S. Ethanol, which is adsorbed in small amounts by activated carbon and easily decomposed by ozone, was removed by ozone injection. Butanols, which are also decomposed by ozone and adsorbed in large quantities by activated carbon, showed intermediate behavior between that of toluene and ethanol.     

Partitioning of polar and non-polar neutral organic chemicals into human and cow milk

The aim of this work was to develop a predictive model for milk/water partition coefficients of neutral organic compounds. Batch experiments were performed for 119 diverse organic chemicals in human milk and raw and processed cow milk at 37°C. No differences (<0.3 log units) in the partition coefficients of these types of milk were observed. The polyparameter linear free energy relationship model fit the calibration data well (SD=0.22 log units). An experimental validation data set including hormones and hormone active compounds was predicted satisfactorily by the model. An alternative modelling approach based on log K(ow) revealed a poorer performance. The model presented here provides a significant improvement in predicting enrichment of potentially hazardous chemicals in milk. In combination with physiologically based pharmacokinetic modelling this improvement in the estimation of milk/water partitioning coefficients may allow a better risk assessment for a wide range of neutral organic chemicals.     

Sorption of alkylphenols on Ebro River sediments: comparing isotherms with field observations in river water and sediments

This study reports sorption isotherms of the endocrine disruptors nonylphenol (NP) and octylphenol (OP) in three sediment samples from the Ebro River basin (NE Spain), with organic carbon fractions (f_OC) ranging from 0.0035 to 0.082 g_OC g⁻¹. All isotherms were fitted to the Freundlich model with slightly nonlinear exponents ranging from 0.80 to 0.94. The solubility of the compounds as well as the organic carbon (OC) content had the strongest influences on the sorption behavior of these compounds. Comparison of the laboratory-spiked samples with the native contamination of NP of 45 water and concurrent sediment samples resulted in reasonable matches between both data sets, even though the lowest concentrations in the field were not completely reached in laboratory tests. This good agreement indicates that sorption laboratory data can be extrapolated to environmental levels and therefore the distribution of nonylphenol between sediments and water can be predicted with a precision of one order of magnitude. Furthermore, laboratory experiments with simultaneous loading of NP and OP revealed negligible competition for sorption sites at low concentrations.     

Japan’s waste management policies for dioxins and polychlorinated biphenyls

We summarize the measures taken by the Japanese government to prevent the emission of dioxins and polychlorinated biphenyls (PCBs) into the environment. Because incineration is the main method of waste management in Japan, reducing the amount of dioxins emitted from waste incinerators is an essential aspect of proper waste treatment. Intensive measures to prevent the formation of dioxins at the source have been implemented, with a focus on waste treatment methods and improving comprehensive management. The efforts have been very successful, with a 95% reduction in the amount of dioxins emitted between 1997 and 2003. The toxicity of PCBs has been monitored with keen interest since the Yusho incident. Unfortunately, treatment facilities for PCB wastes were not built until long after PCBs had been removed from use, and PCB wastes remained in storage in an untreated state. The Japanese government has promoted the construction of facilities for treating PCB wastes, and five such facilities have commenced operations. To more completely eradicate dioxins, a future challenge will be to reduce the amount of PCB-derived dioxins, which are persistent in the environment and have a long exposure pathway from the environment media to the organism and the human body.     

Spectroscopic analysis of NIR-dye sensitization in bulk heterojunction polymer solar cells

The photovoltaic conversion efficiency for near-infrared (NIR) sunlight is improved successfully by dye sensitization of bulk heterojunction polymer solar cells, in which the active layer was prepared by a ternary blend of poly(3-hexylthiophene), a fullerene derivative (1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene), and an NIR dye, silicon phthalocyanine bis(trihexylsilyl oxide). The mechanism of the NIR-dye sensitization is studied by femtosecond transient absorption spectroscopy.     

Spectroscopic Analysis of NIR-Dye Sensitization in Bulk Heterojunction Polymer Solar Cells

The photovoltaic conversion efficiency for near-infrared (NIR) sunlight is improved successfully by dye sensitization of bulk heterojunction polymer solar cells, in which the active layer was prepared by a ternary blend of poly(3-hexylthiophene), a fullerene derivative (1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene), and an NIR dye, silicon phthalocyanine bis(trihexylsilyl oxide). The mechanism of the NIR-dye sensitization is studied by femtosecond transient absorption spectroscopy.     

Measurements of surface contamination of spray equipment with pesticides after various methods of application

Abstract

A traditional method to determine operator dermal exposure is to quantify the amount of pesticide coming into contact with specific body regions and then to integrate the deposition density values with the total body surface. It is known that extremely high deposition values may occur in the hand region; however, the source of contamination is generally assumed to be direct splash or contact with the pesticide container. One of the parameters affecting operator/pilot exposure could be the transfer of pesticide residue, particularly in the case of pesticides with a longer half‐life, from contaminated surfaces of spray equipment by direct contact over extended periods. If the rate of skin absorption of pesticide is readily known, the expected values of daily dose for an operator or pilot may significantly rise due to the extended contact period. This study produced field data on the surface contamination of spray equipment used for ground and aerial applications. If field data on precise work practice (time‐motion) observations are incorporated, it may be possible to estimate the potential exposure of operator/pilot due to hand contact with contaminated surfaces.     

Removal of thiobencarb in aqueous solution by zero valent iron

A cost-effective method with zero valent iron (ZVI) powder was developed for the purification of thiobencarb (TB)-contaminated water. The removal treatment was performed in the batch system. A sample solution of 10 ml containing 10 microg ml(-1) of TB could be almost completely treated by 100mg of ZVI at 25 degrees C for 12h of treatment time. Since the formation of chloride ion in the aqueous solution during the treatment of TB was observed, the removal of TB with ZVI may contain two processes: reduction (degradation) and adsorption. Because the present treatment for TB is simple, easy handling and cheap, the developed technology with ZVI can contribute to the treatment of agricultural wastewaters.     

Separation and characterization of the colored material from sugarcane molasses

The colored material (X) was effectively separated from sugarcane molasses using reversed-phase chromatography. Characterization of the molecular structure of sample X was performed using infrared absorption (IR) spectrometry, mass spectrometry (MS), and dynamic light scattering (DLS). The IR spectrum was similar to that of commercial humic acid, and the MS analysis showed that the sample possessed relatively small heterogeneous molecules with molecular masses around 234, 446, 657, 868, and 1079 Da. On the other hand, X sample showed an inhibitory activity toward the cysteine proteinase papain. Furthermore, the inhibitory (G-1) and weak inhibitory (G-2) fractions were separated from sample X using gel permeation chromatography. Samples G-1 and G-2 inhibited papain partial-noncompetitively and had the inhibition constants of 5.01 x 10(-5) and 1.08 x 10(-3)M, respectively. Interestingly, in the DLS experiment, the Stokes radius of sample G-1 was approximately 2 nm, about twice one of sample G-2.