Recovery of benzene-rich oil from the degradation of metal- and metal oxide-containing poly(ethylene terephthalate) composites

Pure poly(ethylene terephthalate) (PET) resin and metal-/metal oxide-containing PET composites were thermally decomposed in the presence of Ca(OH)₂ using a tube reactor. The effects of batch and continuous processing, the presence of Ca(OH)₂, and PET size on benzene production were investigated. A maximum benzene yield and purity of 82.9 % and 78.8 wt%, respectively, were obtained at 700 °C in the presence of Ca(OH)₂ when using small PET particles; further, a continuous feed reactor was favored over a batch reactor. Effective contact between PET and Ca(OH)₂ was important in the PET degradation, which promoted hydrolysis of PET and decarboxylation of terephthalic acid, whereas pyrolysis was suppressed. Furthermore, the results of thermal decomposition of PET-based waste—PET-based X-ray films, magnetic tape, and prepaid cards—indicated that the metal and metal oxides contained in the waste had no significant catalytic effect on PET degradation or on the recovery of benzene-rich oil in the presence of Ca(OH)₂.     

Crystallization Behavior and Dynamic Mechanical Properties of Poly(l-Lactic Acid) with Poly(Ethylene Glycol) Terminated by Benzoate

Effect of the addition of poly(ethylene glycol) terminated by benzoate (PEG-BA) on the crystallization behavior and dynamic mechanical properties of poly(l-lactic acid) PLLA is studied as compared with poly(ethylene glycol) (PEG-OH). It is found that PEG-BA is miscible with PLLA and shows good plasticizing effect. Because PEG-OH having the same degree of polymerization is immiscible with PLLA, the end group in PEG-BA, i.e., benzoate, plays an important role in the miscibility. Furthermore, PEG-BA does not induce the PLLA degradation at melt-processing, whereas PEG-OH leads to the hydrolysis degradation. Finally, the addition of PEG-BA pronounces the crystallization rate of PLLA at low crystallization temperatures and thus enhances the degree of crystallinity at conventional processing. Consequently, the temperature dependence of dynamic mechanical properties are similar to that for isotactic polypropylene.     

Understanding productivity declines of resource accumulation in the prefectures of Japan

Environmental Economics and Policy Studies - This study employs a data envelopment analysis (DEA) framework using long-term panel data of the physical stocks of buildings and infrastructure...     

Formation of mutagens by photolysis of amino acids in neutral aqueous solution containing nitrite or nitrate ion

Nine amino acids, i.e., alanine, threonine, cysteine, glutamic acid, arginine, proline, tryptophan, phenylalanine and tyrosine, were irradiated with UV light in water containing nitrite or nitrate ion under neutral conditions. The mutagenicities of the ether extracts and the residual water layers of the reaction mixtures were assayed with and without S-9 mix using $\text{Salmonella typhimurium}$ TA98 and TA100. Three aromatic amino acids, tryptophan, phenylalanine and tyrosine, were found to give direct-acting and frameshift mutagens by irradiation in aqueous nitrite solution. Among them, the ether extract of tryptophan exhibited the strongest mutagenicity toward TA98. In the case of irradiation in aqueous nitrate solution, only the ether extract of tryptophan exhibited weak mutagenicity toward TA98 without S-9 mix. The effects of nitrite concentration, irradiation time and pH on mutagen formation from tryptophan and some characteristics of the produced mutagens were examined.     

Biogeochemical model (BGC-ES) and its basin-level application for evaluating ecosystem services under forest management practices

It is important for humans to live in harmony with ecosystems. Evaluation of ecosystem services (ES) may be helpful in achieving this objective. In Japan, forest ecosystems need to be re-evaluated to prevent their degradation due to lack of forest management.In order to evaluate the effects of forest management on forest ES, we developed a process-based biogeochemical model to estimate water, carbon, and nitrogen cycles in forest ecosystems (BGC-ES). This model consists of four submodels: biomass, water cycle, carbon-nitrogen (CN) cycles, and forest management. The biomass submodel can calculate growth of forest biomass under forest managements.Several parameters of the model were calibrated using data from observations of evapotranspiration flux and quality of stream flow in forests. The model results were compared with observations of runoff water from a dam catchment site and with carbon flux observations.Our model was coupled with a basin-level GIS database of forests. Evaluations under various forest management scenarios were carried out for forests in a basin contained in the Ise Bay basin (Chubu region, Japan), where plantations (artificial forests) seemed to have degraded from poor forest management.Comparing our simulation results with those of forests without management in the basin, we found that the amounts of absorbed carbon and runoff were larger in managed forests. In addition, the volume of harvested timber was larger and its quality (diameter) was better in managed forests. Changes of ES within the various scenarios were estimated for their economic value and were compared with the cost of forest management.     

Divergence of the sustaining and marginalizing communities in the process of rural aging: a case study of Yurihonjo-shi, Akita, Japan

This study examines the marginalization process of rural communities, which is caused by the decline of community-based autonomy and various activities in relation to the decline and aging of their populations, based on the frameworks that describe the process in three stages. A field survey was conducted in five rural communities in Yurihonjo-shi in Akita Prefecture, Japan. These communities were selected based on their locations, population decline and aging rates, and population sizes and were categorized into two groups, the remote and the central communities. This survey was composed of two sections: (1) a questionnaire-based survey to households and (2) an interview survey with the chairperson of each community. In order to capture the multidimensionality of residents’ daily lives, sustainable development indicators, which are originally designed to capture the well-being of nations, were utilized to develop the questionnaire. The results demonstrated significant differences between the two groups of communities mainly on four aspects: (1) farming type, (2) visits and roles of out-migrated family, (3) self-evaluation of living conditions, and (4) residents’ future concerns. These findings suggest the current state of the remote community can be seen as that of the “marginalizing” community, for which a welfare-based approach is recommended to secure the living conditions of the residents. On the other hand, the current state of the central community is considered as that of the “sustaining” community for which a revitalization approach is recommended in order to rejuvenate the diminishing community functions.     

Physical containment of municipal solid waste incineration bottom ash by accelerated carbonation

Accelerated carbonation of municipal solid waste incineration residues is effective for immobilizing heavy metals. In this study, the contribution of the physical containment by carbonation to immobilization of some heavy metals was examined by some leaching tests and SEM–EDS analysis of untreated, carbonated, and milled bottom ash after carbonation that was crushed with a mortar to a mean particle size of approximately 1 μm. The surface of carbonated bottom ash particles on SEM images seemed mostly coated, while there were uneven micro-spaces on the surface of the untreated bottom ash. Results of Japan Leaching Test No. 18 (JLT18) for soil pollution showed that milling carbonated bottom ash increased the pH and EC. The leaching concentration of each element tended to be high for untreated samples, and was decreased by carbonation. However, after the milling of carbonated samples, the leaching concentration became high again. The immobilization effect of each element was weakened by milling. The ratio of physical containment effect to immobilization effects by accelerated carbonation was calculated using the results of JLT18. The ratio for each element was as follows: Pb: 13.9–69.0 %, Cu: 12.0–49.1 %, Cr: 24.1–99.7 %, Zn: 20.0–33.3 %, and Ca: 28.9–63.4 %.     

High immobilization of soil cesium using ball milling with nano-metallic Ca/CaO/NaH2PO4: implications for the remediation of radioactive soils

This report shows that cesium can be immobilized in soils with an efficiency of 96.4% by ball milling with nano-metallic Ca/PO₄. In Japan, the major concern on ¹³⁷Cs deposition and soil contamination due to the emission from the Fukushima Daiichi nuclear power plant showed up after a massive quake on March 11, 2011. The accident rated 7, the highest possible on the international nuclear event scale, released 160 petabecquerels (PBq) of iodine ¹³¹I and 15 PBq of ¹³⁷Cs according to the Japanese Nuclear and Industrial Safety Agency. Both ¹³⁷Cs and ¹³¹I radioactive nuclides are increasing cancer risk. Nonetheless, ¹³⁷Cs, with a half-life of about 30 years compared with 8 days for ¹³¹I, is a major threat for agriculture and stock farming and, in turn, human life for decades. Therefore, in Japan, the ¹³⁷Cs fixation and immobilization in contaminated soil is the most important problem, which should be solved by suitable technologies. Ball milling treatment is a promising treatment for the remediation of cesium-contaminated soil in dry conditions. Here, we studied the effect, factors and mechanisms of soil Cs immobilization by ball milling with the addition of nano-metallic Ca/CaO/NaH₂PO₄, termed “nano-metallic Ca/PO₄.” We used scanning electron microscopy combined with electron dispersive spectroscopy (SEM/EDS) and X-ray diffraction. Results show that immobilization efficiency increases from 56.4% in the absence of treatment to 89.9, 91.5, and 97.7 when the soil is ball-milled for 30, 60 and 120 min, respectively. The addition of nano-metallic Ca/PO₄ increased the immobilization efficiency to about 96.4% and decreased the ball milling time. SEM/EDS analysis allows us to observe that the amount of Cs decreased on soil particle surface. Use of nano-metallic Ca/PO₄ over a short milling time also decreases Cs leaching. Therefore, ball milling with nano-metallic Ca/PO₄ treatment may be potentially applicable for the remediation of radioactive Cs-contaminated soil in dry conditions.