Development of an environmentally acceptable volatile organic compounds recovery and reuse system based on vacuum spray flash with dibasic acid esters as absorbents

We used dibasic acid esters as the absorbent for a volatile organic compounds (VOC) recovery and reuse system geared mainly toward VOCs from painting and presswork. The system consists of three elements: absorption using dibasic acid esters, separation by vacuum spray flash method, and recovery by condensation. The concentration of both ethyl acetate (EtAc) and isopropyl alcohol (IPA) decreased around 90% at room temperature. Vacuum spray flash was found as a useful process for cost-effective and energy-effective VOC removal system. The difference in the dissolubility parameters (Hansen constant) between dibasic acid esters and VOCs and the boiling point of VOCs was the main contributor to the separation behavior.     

Properties of Poly(Vinyl Alcohol)/Chitosan Nanocomposite Films Reinforced with Oil Palm Empty Fruit Bunch Amorphous Lignocellulose Nanofibers

The objective of this study was to investigate the properties of poly(vinyl alcohol)/chitosan nanocomposite films reinforced with different concentration of amorphous LCNFs. The properties analyzed were morphological, physical, chemical, thermal, biological, and mechanical characteristics. Oil palm empty fruit bunch LCNFs obtained from multi-mechanical stages were more dominated by amorphous region than crystalline part. Varied film thickness, swelling degree, and transparency of PVA/chitosan nanocomposite films reinforced with amorphous part were produced. Aggregated LCNFs, which reinforced PVA/chitosan polymer blends, resulted in irregular, rough, and uneven external surfaces as well as protrusions. Based on XRD analysis, there were two or three imperative peaks that indicated the presence of crystalline states. The increase in LCNFs concentration above 0.5% to PVA/chitosan polymer blends led to the decrease in crystallinity index of the films. A noticeable alteration of FTIR spectra, which included wavenumber and intensity, was obviously observed along with the inclusion of amorphous LCNFs. That indicated that a good miscibility between amorphous LCNFs and PVA/chitosan polymer blend generated chemical interaction of those polymers during physical blending. Reinforcement of PVA/chitosan polymer blends with amorphous LCNFs influenced the changes of T_g (glass transition temperature), T_m (melting point temperature), and T_max (maximum degradation temperature). Three thermal phases of PVA/chitosan/LCNFs nanocomposite films were also observed, including absorbed moisture evaporation, PVA and chitosan polymer backbone structural degradation and LCNFs pyrolysis, and by-products degradation of these polymers. The addition of LCNFs 0.5% had the highest tensile strength and the addition of LCNFs above 0.5% decreased the strength. The incorporation of OPEFB LCNFs did not show anti-microbial and anti-fungal properties of the films. The addition of amorphous LCNFs 0.5% into PVA/chitosan polymer blends resulted in regular and smooth external surfaces, enhanced tensile strength, increased crystallinity index, and enhanced thermal stability of the films.     

Process analysis of ozone formation under different weather conditions over the Kanto region of Japan using the MM5/CMAQ modelling system

We have assessed the contributions of individual physical and chemical atmospheric processes on ozone formation under different weather conditions during a typical summer month (August 2005) using the MM5/CMAQ modelling system. We found that the ozone episodes in the Kanto region are dominated by three major patterns, of which Patterns I and II are regular summertime pressure patterns with a 26% and 16% frequency of occurrence, respectively. A process analysis at two typical sites in the Kanto region – one located in the central region of Tokyo and the other located in the rural areas of Kanto – indicates that ozone formation is mainly controlled by advection, vertical diffusion, dry deposition, and chemical processes. The ground-level ozone concentrations are enhanced mainly by the vertical mixing of ozone-rich air from aloft, whereas the dry deposition and chemical processes mainly deplete ozone. By investigating the effects of each process under different weather conditions, we found that the significant decrease in ozone removal due to the chemical and advection processes under conditions of high stagnation is the most important cause of the enhanced levels of ozone in the central region of Tokyo. The results of this study can contribute to a better understanding of ozone formation in the Kanto region, and they may be valuable for local policy makers for further development planning.     

Photodecomposition of humic acid and natural organic matter in swamp water using a TiO2-coated ceramic foam filter: Potential for the formation of disinfection byproducts

This paper reports on the photodecomposition of aqueous humic acid (HA) by a TiO₂-coated ceramic foam filter (TCF) reactor and on the potential for the formation of disinfection byproducts (DBPs) upon chlorination of the photocatalytically treated solutions. This photocatalytic reactor can also be applied to the removal of natural organic matter (NOM) in swamp waters. The proposed photocatalytic reaction system was operated as per standardized methodologies. First, the ability of the TCF to decompose HA (a representative compound of NOM) was evaluated from the changes in the total organic carbon (TOC) and UV₂₅₄ with the reaction time. Remarkably, TOC removal and UV₂₅₄ values ranging from 44% to 61% and from 60% to 83%, respectively, were achieved. The potential for the formation of DBPs (total trihalomethane and total haloacetic acid) by chlorination of the phototreated solution was strongly dependent on the TOC removal and UV₂₅₄ values in the solution. The degree of photodecomposition of NOMs in the swamp water samples and the DBP formation potential showed similar trends as in the case of the standard solutions containing HA. The method used in this study could be effectively used to evaluate the efficiency of TCF for reducing HA and NOM, while suppressing the formation of DBP products.     

Direct assessment of international consistency of standards for ground-level ozone: strategy and implementation toward metrological traceability network in Asia

An international exercise to directly assess consistency of standards for ground-level ozone in East Asia was conducted as part of the East Asian Regional Experiment 2005 (EAREX 2005) in the framework of the Atmospheric Brown Clouds (ABC) project. Ten organizations collaboratively participated in the intercomparison. Four groups representing Japan, Korea, Hong Kong, and Taiwan made comparisons at the Gosan super observatory, Jeju Island, Korea, in March 2005, with ozone instruments calibrated to their national standards, and four Japanese groups made off-site comparisons with laboratory-level standards. All comparisons generally indicated good agreement with the standard reference photometer (SRP) 35, built by the National Institute of Standards and Technology (USA) and maintained by the National Institute for Environmental Studies (Japan). The assessment was expanded to measurement networks contributing to the World Meteorological Organization's Global Atmospheric Watch (WMO/GAW) program as part of off-site comparisons, and excellent agreement was achieved. These efforts contribute to propagating traceability of the national metrology standards among the atmospheric science community, to ensuring comparability of the existing ozone measurements, and to establishing an integrated network of air quality monitoring in Asia.     

Postembryonic development of the bone-eating worm Osedax japonicus

Bone-eating worms of the genus Osedax exclusively inhabit sunken vertebrate bones on the seafloor. The unique lifestyle and morphology of Osedax spp. have received much scientific attention, but the whole process of their development has not been observed. We herein report the postembryonic development and settlement of Osedax japonicus Fujikura et al. (Zool Sci 23:733–740, 2006). Fertilised eggs were spawned into the mucus of a female, and the larvae swam out from the mucus at the trochophore stage. Larvae survived for 10 days under laboratory conditions. The larvae settled on bones, elongated their bodies and crawled around on the bones. Then they secreted mucus to create a tube and the palps started to develop. The palps of O. japonicus arose from the prostomium, whereas the anterior appendages of other siboglinids arose from the peristomium. The recruitment of dwarf males was induced by rearing larvae with adult females. Females started to spawn eggs 6 weeks after settlement.     

Effects of humic substances on the decomposition of 2,4-dichlorophenol by ozone after extraction from water into acetic acid through activated carbon

The objectives of this study are to clarify the behavior of humic substances throughout the processes of 2,4-dichlorophenol (2,4-DCP) adsorption on granular activated carbon (GAC) from water and extraction into acetic acid, and the influence of the extracted humic substances on the decomposition of 2,4-DCP by ozone in the acetic acid. The adsorption capacity of GAC for 2,4-DCP was not influenced by the humic substances preloaded to have equilibrium concentration of 24.9mg Cl(-1) (14.5mg Cg(-1)). The adsorption capacity of GAC for 2,4-DCP decreased to one tenth of new GAC after the first adsorption-extraction step because of only 16% desorption in the first step. However, 2,4-DCP adsorbed on GAC was completely extracted after the second step suggesting that GAC can be used as adsorbent to transfer 2,4-DCP from water to acetic acid. The concentration ratio of 2,4-DCP from water into acetic acid was around 2x10(5), whereas the concentration ratio of humic substances was about 3.5, indicating that 2,4-DCP was selectively adsorbed and extracted by this system. The first order degradation rate constant for 2,4-DCP by ozone in acetic acid increased with the addition of humic substances. The rate constant with 16mg Cl(-1) of humic substances was 2.6 times as high as that without humic substances. Humic substances behaved as a promoter for the degradation of 2,4-DCP by ozone.     

Syntheses of Biodegradable Functional Polymers by Radical Ring-Opening Polymerization of 2-Methylene-1,3,6-trioxocane

2-Methylene-1,3,6-trioxocane (MTC) was polymerized via ring-opening in the presence of a radical initiator and the obtained polyester was biodegradable. MTC could also copolymerize with various vinyl monomers such as styrene, vinyl acetate, methyl vinyl ketone, N-vinyl-2-pyrrolidone, N-isopropyl acrylamide, and maleic anhydride. By copolymerizing MTC with these vinyl monomers in the presence of a radical initiator, we could obtain various biodegradable polymers with ester group introduced into the backbone. In addition the obtained copolymers exhibit certain functionalities such as photolysis, water-solubility, thermosensitivity, detergent builder, and water-absorbability.     

Comparative study of microbial dechlorination of chlorinated ethenes in an aquifer and a clayey aquitard

In order to determine whether natural attenuation of chlorinated ethenes by microbial activity occurs in aquitards, sediments at a site contaminated with tetrachloroethene were vertically studied by drilling. The distribution of microbes (Dehalococcoides group and anaerobic hydrogen producers) and the ability of the sediments to sustain microbial dechlorination were determined in an aquitard as well as in an aquifer. Close-spaced sampling revealed the existence of large populations of Dehalococcoides and H(2)-producing bacteria, especially in the organic-rich clayey aquitard rather than in the aquifer. The vinyl chloride reductase gene was also detected in the clay layer. Furthermore, incubation experiments indicated that the clay sediment could sustain transformations of tetrachloroethene at least to vinyl chloride. In contrast, no significant transformation was observed in the aquifer sand. Our results indicate that dechlorination of tetrachloroethene by bacteria can take place in an organic-rich clayey aquitard, and that organic-rich clay may also be important in the natural attenuation in an adjacent aquifer, possibly supplying a carbon source or an electron donor.     

Principal components derived from soil physicochemical data explained a land degradation gradient,and suggested the applicability of new indexes for estimation of soil productivity in the Sakaerat Environmental Research Station,Thailand

To find a principal component (PC) that quantifies the degree of soil degradation, we analyzed various physicochemical characteristics of soils over a land degradation gradient related to aboveground vegetation in the Sakacrat Environmental Research Station (SERS), Thailand. The aboveground vegetative types representing the degradation gradient were bare ground (BG, highly degraded), dry dipterocarp forest (DDF, moderately disturbed) and dry evergreen forest (DEF, the original vegetation). Soils under these vegetative types were sampled in February (dry season). March just after temporal precipitation) and June (rainy season) 2001. Through the period of this research, the degradation was consistently explained by sandy texture, high bulk density, lower pH, high exchangeable acidity, poor mineral and organic nutrients and dryness. Principal component analysis (PCA) was applied to determine significant principal components (PCs) that clarify the differences in soil properties between the vegetative types and between the timing of soil sampling. The PC loadings suggested that the first PC was the component that indicates total fertility of soil in the site, while the fifth PC indicates the dry to wet seasonal transition. The first PC was named the total fertility component (TFC). The linear regression between the TFC score and recently proposed indexes, the soil fertility index (SFI) or the soil evaluation factor (SEF), was highly significant (p < 0.001), indicating that the SFI and the SEF are applicable to measuring total fertility of soils in the SERS.