摘要 :
Recent years have seen upsurge in plastic manufacturing and its utilization in various fields, such as, packaging, household goods, medical applications, and beauty products. Due to various adverse impacts imposed by synthetic pla...
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Recent years have seen upsurge in plastic manufacturing and its utilization in various fields, such as, packaging, household goods, medical applications, and beauty products. Due to various adverse impacts imposed by synthetic plastics on the health of living well-being and the environment, the biopolymers have been emerged out an alternative. Although, the biopolymers such as polyhydroxyalkanoates (PHA) are entirely degradable. However, the other polymers, such as poly (lactic acid) (PLA) are only partially degradable and often not biosynthesized. Biodegradation of the polymers using microorganisms is considered an effective bioremediation approach. Biodegradation can be performed in aerobic and anaerobic environments. In this context, the present review discusses the biopolymer production, their persistence in the environment, aerobic biodegradation, anaerobic biodegradation, challenges associated with biodegradation and future perspectives. In addition, this review discusses the advancement in the technologies associated with biopolymer production, biodegradation, and their biodegradation standard in different environmental settings. Furthermore, differences in the degradation condition in the laboratory as well as on-site are discussed.
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Synthetic polymers are important in many branches of industry, for example in the packaging industry. However, they have an undesirable influence on the environment and cause problems with waste deposition and utilization. Thus, t...
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Synthetic polymers are important in many branches of industry, for example in the packaging industry. However, they have an undesirable influence on the environment and cause problems with waste deposition and utilization. Thus, there is a tendency to substitute such polymers with polymers that undergo biodegradable processes. Increasing interest in applying polymers based on natural materials such as starch has been observed.
This review describes biodegradation processes of xenobiotics such as aromatic compounds, plastics (PVA, polyesters, polyethylene, and nylon), and polymer blends (Starch/Polyethylene, Starch/Polyester, and Starch/PVA). Moreover, this review includes information about biodegradable polymers such as mixtures of synthetic polymers and substances that are easy digestible by microorganisms (chemically modified starch, starch-polymer composites, thermoplastic starch, and biodegradable packing materials), synthetic materials with groups susceptible to hydrolytic microbial attack (polycaprolactone), and biopolyesters (poly-β-hydrox-yalkanoates). Production of this kind of material and introducing it to the market is important for the natural environmental. It may result in decreasing the volume of waste dumps.
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Biodegradable materials are used to make compostable products that are expected to be collected and recovered in specialist waste treatment plants. The appropriate targeting of their distribution and marketing can bring systemic b...
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Biodegradable materials are used to make compostable products that are expected to be collected and recovered in specialist waste treatment plants. The appropriate targeting of their distribution and marketing can bring systemic benefits by enabling improved organic recycling. At the same time, there is growing interest in knowing the environmental impacts of solid waste that has leaked into the environment, including the littering of compostable packaging waste. International Standard (ISO) test methods have been developed to determine the "ultimate" biodegradation of plastic materials exposed to environmental matrices (e.g., soil, marine sediments). High levels of conversion to CO2, comparable to those achieved by generally recognized as biodegradable (GRAB) substances, indicate that the plastic is intrinsically biodegradable. The term "intrinsic" refers to an inherent quality dependent on the chemical composition and structure of the material, prior to consideration of any "extrinsic" properties. Residence time, which has an effect on biota's exposure to the litter, is a relevant factor in the assessment of ecological risk of littering. Residence time is affected by the litter's persistence, which in part is determined by the litter's intrinsic biodegradability. Thus, the intrinsic biodegradability is key information in this assessment. The need for a comprehensive approach based on the assessment of the ecological risk of solid waste littering, including an assessment of biodegradability, is established.
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Biodegradable elastomer poly[(1,4-butylene terephthalate)-co-(1,4-butylene adipate)] foam was successfully prepared using supercritical CO2. The elastomer foam has closed and uniform cell structure with density about 90 g/L. Narro...
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Biodegradable elastomer poly[(1,4-butylene terephthalate)-co-(1,4-butylene adipate)] foam was successfully prepared using supercritical CO2. The elastomer foam has closed and uniform cell structure with density about 90 g/L. Narrow size distribution with average cell diameter 32 m were obtained. The foamed balls show rubbery properties and can recover well (>90%) to their original shape quickly after releasing press stress. Cell growth needs to take place at melting state where the migration and orientation of polymer chains are permanently kept without remained force of springback. Some unique phenomena were observed during foaming the elastomer: post-expansion (about 40%) was obtained after removing the foamed samples from a cylinder mold, which results in forming a ball rather than a cylinder like the mold. This phenomenon was explained by the lower glass transition temperature of the elastomer, in which residual CO2 foam continuously in the room temperature; and memory of internal strength. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44354.
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This work presents a kinetic analysis of the aerobic biodegradation of anaerobically digested sewage sludge and dried reed mixtures at different temperatures. Batch experiments were conducted in laboratory-scale reactors with temp...
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This work presents a kinetic analysis of the aerobic biodegradation of anaerobically digested sewage sludge and dried reed mixtures at different temperatures. Batch experiments were conducted in laboratory-scale reactors with temperature (T) control and forced aeration of the solid mixture. The biowaste mixture was treated at four different temperatures: 25, 40, 50 and 60 ℃, with moisture controlled and samples taken weekly for carbon (C) and volatile solids (VS) measurements. The duration of experiments was either 90 d (at 25 ℃) or 60 d (at 40,50 and 60 ℃). Two different kinetic models were used to fit the carbon mineralisation curves: the 2C model, which considers two organic fractions (biodegradable and non-biodegradable) and the 3C model, which considers three fractions (easily biodegradable, slowly biodegradable and non-biodegradable). In both cases, the kinetic rate constants were calculated by mathematical fitting and were compared with previously reported values. The temperature influence on the rate constants was studied for both models using a T-dependent equation. The calculated kinetic rate constants were in agreement with previously published values, and good fitting of the experimental data was obtained with both models. Similar rate constant values were obtained for mineralisation of the biodegradable fraction (2C model) and the easily biodegradable fraction (3C model). The rate constants for the slowly biodegradable fraction (3C model) were much lower. A good correlation between rate constants and T was observed. Different optimum temperature values were obtained for each rate constant depending on which carbon fraction was degraded. The T-dependent rate constant values obtained could be used for modelling the C mineralisation of real variable-temperature composting processes.
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Most materials currently used for food packaging are nondegradable, generating environmental problems. Several biopolymers have been exploited to develop materials for ecofriendly food packaging. However, the use of biopolymers ha...
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Most materials currently used for food packaging are nondegradable, generating environmental problems. Several biopolymers have been exploited to develop materials for ecofriendly food packaging. However, the use of biopolymers has been limited because of their usually poor mechanical and barrier properties, which may be improved by adding reinforcing compounds (fillers), forming composites. Most reinforced materials present poor matrix-filler interactions, which tend to improve with decreasing filler dimensions. The use of fillers with at least one nanoscale dimension (nanoparticles) produces nanocomposites. Nanoparticles have proportionally larger surface area than their microscale counterparts, which favors the filler-matrix interactions and the performance of the resulting material. Besides nanoreinforcements, nanoparticles can have other functions when added to a polymer, such as antimicrobial activity, etc. in this review paper, the structure and properties of main kinds of nanostructured materials which have been studied to use as nanofiller in biopolymer matrices are overviewed, as well as their effects and applications.
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A series of biodegradable polymeric nanocomposite films based on poly(lactic acid) (PLA) and magnesium-aluminum layered double hydroxide (Mg-Al LDH) nano-particles was prepared by solution casting method. Two different Mg-Al LDH n...
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A series of biodegradable polymeric nanocomposite films based on poly(lactic acid) (PLA) and magnesium-aluminum layered double hydroxide (Mg-Al LDH) nano-particles was prepared by solution casting method. Two different Mg-Al LDH nano-fillers at Mg:Al mol ratios of 2:1 and 3:1 were synthesized by co-precipitation technique and to improve the interfacial interaction, the nanoparticles were modified by intercalating sodium dodecyl sulfate (SDS) surfactant into the LDH galleries. The PLA nanocomposite films, prepared using unmodified (Mg-Al LDH) and modified (SDS-Mg-Al LDH) nano fillers. Both XRD and TEM analyses showed an increasing dispersion and improved exfoliation of SDS-Mg-Al LDH into the PLA matrix. DMA analysis indicated that, at each composition, filler modification resulted in higher storage modulus and T-g. The composite films showed increasing oxygen barrier property up to 23.5 %, compared to PLA. The films containing 5 % of SDS-Mg-Al LDH at Mg:Al ratio of 3:1 exhibited significant increase in oxygen barrier property.
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Bio-based, biodegradable polymers can dramatically reduce the carbon dioxide released into the environment by substituting fossil-derived polymers in some applications. In this work, prototypes of trays for aquaculture application...
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Bio-based, biodegradable polymers can dramatically reduce the carbon dioxide released into the environment by substituting fossil-derived polymers in some applications. In this work, prototypes of trays for aquaculture applications were produced via injection molding by using a biodegradable polymer, Mater-Bi?. A characterization carried out via calorimetric, rheological and mechanical tests revealed that the polymer employed shows properties suitable for the production of tools to be used in aquaculture applications. Moreover, the samples were subjected to a biodegradation test in conditions that simulate the marine environment. The as-treated samples were characterized from gravimetrical, morphological and calorimetric point of views. The obtained data showed a relatively low biodegradation rate of the thick molded samples. This behavior is of crucial importance since it implies a long life in marine water for these manufacts before their disappearing.
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We determined that polyamide 4 (PA4), which is easily degraded in the environment, is also degraded in vivo. We previously reported that PA4 was degraded by activated sludge. However, the potential biodegradability of PA4 in vivo ...
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We determined that polyamide 4 (PA4), which is easily degraded in the environment, is also degraded in vivo. We previously reported that PA4 was degraded by activated sludge. However, the potential biodegradability of PA4 in vivo has not been evaluated. In the present study, we subcutaneously implanted various PA4 samples in the backs of rats, including non-woven fabric as well as film and mold. The weights of implanted and recovered non-woven cloth composed of the PA4 polymer started to decrease at 3 months. At 8.5 months, weights decreased by 90%. For the non-woven PA4 cloth with a fine structure, there was no significant decrease in weight until 8.5 months. These results showed that PA4 was degraded in vivo and that polymer structure was important in determining the degradation rates. Copolymers composed of PA4 and polycaprolactone were also degraded in vivo. Homopolymers of PA4 were not hydrolyzed in phosphate buffer at 37 ℃ after one year. These results suggested the possibility that biochemical reactions were implicated in the degradation of PA4 in vivo. Based on tissue sample observations, implanted PA4 did not modify surrounding tissues. Safety evaluation, mutagenicity testing using bacteria (Ames test), and in vitro cytotoxicity testing using Chinese hamster V79 cells suggested that PA4 had no mutagenicity or cytotoxicity. Our study demonstrates that PA4 has potential as a bio-absorbable polymer material for biomedical applications.
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В результате исследования установлено, что бактерии Rhodococcuspyridinivorans 5Ар дикого типа являются высокоэффективными деструкторами...
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В результате исследования установлено, что бактерии Rhodococcuspyridinivorans 5Ар дикого типа являются высокоэффективными деструкторами нафталинаи полностью утилизируют данное соединение в концентрации 500 мг/л в течение трех суток, что может быть использовано для очистки загрязненных нафталином водных экосистем. Инактивация генов биодеградации пагАа (кодирует большую субъединицу нафталиндиоксигеназы) и пагВ (кодирует гмс-нафталиндигидродиолдегид-рогеназу) приводит к потере бактериями R. pyridinivorans 5Ар способности утилизировать нафталин в качестве единственного источника углерода. Это указывает на отсутствие в геноме исследуемых бактерий детерминант, обеспечивающих окисление нафталина по альтернативным путям. Помимо этого, инактивация гена пагВ приводит к накоплению в культуральной среде полярного окрашенного соединения(вероятно, продукта первичного окисления нафталина).
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