Waste Polymeric Materials Research Articles

Waste paper recycling and its application in modification of the green biodegradable material

Waste paper is a significant waste resource that is part of waste polymer materials in vast quantities, and there is now a lot of focus on the development of high-value conversion and use technologies for waste paper. High-quality waste paper fibers (WF) were extracted in this work from the deinked waste paper pulp by mechanical process. Then, waste paper fiber/polylactic acid (WF/PLA) composites were synthesized using hybrid forming technique to investigate the modification impact of WF on WF/PLA composites. The results showed that a certain additive amount of WF could improve barrier property of WF/PLA composites. When WF was added of 3.5 %, a water vapor transport rate was only of 59 g/(m2d), and the barrier property was increased by 82.8 %. Besides, WF/PLA composites also possessed good thermal stability. With the additive WF ranging from 3 % to 4 %, the initial decomposing temperature of WF/PLA composites increased by 19℃. Importantly, the transparency of PLA was slightly improved with a certain addition of WF. Hence, this work realized the performance enhancement of WF/PLA composites by a small addition of WF, and reduced the production cost of PLA to some extent, which had a good application prospect.

Synthesis and properties of biodegradable PBAT prepared from PBT chemically recycled resources

The production of synthetic polymer materials has engendered substantial environmental hazards stemming from waste generation. Employing chemical recycling methods constitutes a viable approach for attaining sustained recycling of synthetic raw materials. In the present study, bishydroxybutyl terephthalate (BHBT), a precursor for the synthesis of poly(butylene adipate-co-terephthalate) (PBAT), was created by chemically alcoholyzing polybutylene terephthalate (PBT). Further, bis(4-hydroxybutyl) adipate (BHAT), which was produced via esterification with adipic acid (AA) and 1,4-butanediol (BDO), and BHBT condensation polymerization were combined to create biodegradable PBAT. Additionally, the effects of the recycled BHBT and BHAT segment ratio on the structures and properties of biodegradable PBAT were investigated. The results indicate that the synthesis of repolymerized PBAT was accomplished successfully. As the proportion of butylene terephthalate (BT) segments increased, several notable improvements were observed: an increase in melting temperature, enhanced thermal stability, elevated tensile strength, and a reduction in the rate of biodegradation. The melting point was 139.51 °C, the tensile strength was 22.62 MPa, and the 30-day biodegradation rate was 23.32 % when the percentage of BT segments was 60 %. In the present study, a method for producing biodegradable polyesters through the process of alcoholysis and repolymerization of recalcitrant polyester waste was proposed. It provides a new solution for the efficient recycling of waste polymer materials.

Analysis of Selected Properties of Polymer Mixtures Derived from Virgin and Re-Granulated PP with Glass Fibers.

The problem of the growing amount of waste polymer materials currently affects virtually every area of the global economy. New actions taken by the E.U. and member states could lead to a reduction in the burden on the natural environment, as well as the reuse of thermoplastic waste. The aim of this study was to analyze the possibility of reusing post-industrial waste (recycled polypropylene-rPP) in order to produce mixtures with original polypropylene (PP) and glass fibers. The research undertaken is characterized by a high level of innovation and was carried out on an industrial scale from industrial waste. The primary goal of the analyses was to determine changes in the properties of the polymer mixtures depending on the amount of recycled polymers. For this purpose, four types of mixtures were prepared, characterized by different degrees of filling with recycled material obtained from big-bag packaging (the filling levels were 0 wt.%, 20 wt.%, 30 wt.%, and 70 wt.%). A detailed analysis of the physical properties of the obtained mixtures was carried out to determine changes in the densities depending on the amount of rPP material. In addition, changes in the MFIs (melt flow indexes), characterizing viscosity changes, were analyzed depending on the amount of secondary raw material used. An analysis of the mechanical properties was also carried out based on static tensile testing, the impact strength (the Charpy method), and the Rockwell hardness test (the M method). The analysis of the thermal changes was performed using the DSC method. The results showed that the composites made of virgin polypropylene (PP GF30) and those made from re-granulates and glass fibers (rPP GF30) are characterized by similar mechanical properties and significantly different processing properties, determined by MFI. This means that the addition of re-granulates significantly affects the processability of the obtained materials, while the addition of glass fibers maintains the basic mechanical properties.

Polyethylene terephthalate waste derived nanomaterials (WDNMs) and its utilization in electrochemical devices

Plastics are a vital component of our daily lives in the contemporary globalization period; they are present in all facets of modern life. Because the bulk of synthetic plastics utilized in the market are non-biodegradable by nature, the issues associated with their contamination are unavoidable in an era dominated by polymers. Polyethylene terephthalate (PET), which is extensively used in industries such as automotive, packaging, textile, food, and beverages production represents a major share of these non-biodegradable polymer productions. Given its extensive application across various sectors, PET usage results in a considerable amount of post-consumer waste, majority of which require disposal after a certain period. However, the recycling of polymeric waste materials has emerged as a prominent topic in research, driven by growing environmental consciousness. Numerous studies indicate that products derived from polymeric waste can be converted into a new polymeric resource in diverse sectors, including organic coatings and regenerative medicine. This review aims to consolidate significant scientific literatures on the recycling PET waste for electrochemical device applications. It also highlights the current challenges in scaling up these processes for industrial application.

Solvent-Promoted Catalyst-Free Recycling of Waste Polyester and Polycarbonate Materials.

Polymeric materials are indispensable in our daily lives. However, the generation of vast amounts of waste polymers poses significant environmental and ecological challenges. Instead of resorting to landfilling or incineration, strategies for polymer recycling offer a promising approach to mitigate environmental pollution. Pioneering studies have demonstrated the alcoholysis of waste polyesters and polycarbonates; however, these processes typically require the use of catalysts. Moreover, the development of strategies for catalyst removal and recycling is crucial, particularly in some industrial applications. In contrast, we present a catalyst-free method for the alcoholysis of common polyester and polycarbonate materials into small organic molecules. Certain polar organic solvents exhibit remarkable efficiency in polymer degradation under catalyst-free conditions. Employing these polar solvents, both polymer resins and commercially available products could be effectively degraded via alcoholysis. Our design contributes a straightforward route for recycling waste polymeric materials.

Developing a new sustainable eco-adsorbent film from flexographic printing plate waste to remove cationic organic and inorganic pollutants.

Although climate change poses a threat to the future of the world, we still have time to adapt and lessen its effects. However, the incineration of polymeric waste materials has increased the release of carbon-containing gases called greenhouse gases (GHGs) and tiny particles called 'black carbon', leading to global warming, which is the cause of the worst environmental crisis in history. Flexography is an advanced printing technique and is widely used in the packaging industry as well as in the printing of various functional films and coatings. In general, the polymeric waste produced from this industry poses a grave environmentally sustainable problem; thus, due to the fact that this waste's primary component is carbon, it has attracted our attention towards converting it into carbon-based value-added products such as graphene, which can be used in water treatment processes. The prepared material was tested as a potential coated film in a batch adsorption system for the removal of lead (Pb) and methylene blue (MB) after being supported on poly(vinyl alcohol) (PVA) film. Furthermore, contact time, solution pH, and starting pollutant concentrations were studied and used in the response surface methodology (RSM) model for optimization. The adsorption kinetics were more clearly depicted by the pseudo-second-order kinetic model. To meet the objectives of waste management and water treatment, waste-derived materials can be used in wastewater treatment, based on the "wastes-treat-wastes" approach.

Sunflower and Watermelon Seeds and Their Hybrids with Pineapple Leaf Fibers as New Novel Thermal Insulation and Sound-Absorbing Materials.

Pineapple leaf fiber (PALF), striped sunflower seed fiber (SFSF), and watermelon seed (WMS) are considered natural waste polymer materials, which are biodegradable and sustainable. This study presents new novel thermal insulation and sound absorption materials using such waste as raw materials. PALF, SFSF, and WMS were used as loose, bound, and hybrid samples with different compositions to develop promising thermal insulation and sound-absorbing materials. Eleven sample boards were prepared: three were loose, three were bound, and five were hybrid between PALF with either SFSF or WMS. Wood adhesive was used as a binder for both the bound and hybrid sample boards. Laboratory scale sample boards of size 30 cm × 30 cm with variable thicknesses were prepared. The results show that the average thermal conductivity coefficient for the loose samples at the temperature range 20-80 °C is 0.04694 W/(m.K), 0.05611 W/(m.K), and 0.05976 W/m.K for PALF, SFSF, and WMS, respectively. Those for bound sample boards are 0.06344 W/(m.K), 0.07113 W/(m.K), and 0.08344 W/m.K for PALF, SFSF, and WMS, respectively. The hybrid ones between PALF and SFSF have 0.05921 W/m.K and 0.06845 W/(m.K) for two different compositions. The other hybrid between PALF and WMS has 0.06577 W/(m.K) and 0.07007 for two different compassions. The sound absorption coefficient for most of the bound and hybrid boards is above 0.5 and reaches higher values at some different frequencies. The thermogravimetric analysis for both SFSF and WMS shows that they are thermally stable up to 261 °C and 270 °C, respectively. The three-point bending moment test was also performed to test the mechanical properties of the bound and hybrid sample boards. It should be mentioned that using such waste materials as new sources of thermal insulation and sound absorption materials in buildings and other applications would lead the world to utilize the waste until zero agrowaste is reached, which will lower the environmental impact.

DEVELOPMENT OF THE METHOD OF DESIGNING THE MICRO SCREW EXTRUDER OF A 3D PRINTER

The article deals with the development of a design method for a 3D printer extruder screw. The key aspects that must be applied during design are described. The main mechanical properties that should be taken into account when designing the screw element of the extruder are given. Various designs of screws, their advantages and disadvantages are considered. A single-screw extruder was selected for a 3D printer, which uses granules, crushed waste polymer materials as raw materials. It is proposed to use a three-zone cylindrical one-way screw with a constant pitch and without a degassing zone of the screw for processing granules or crushed polymer particles. Recommended for screw extruders that do not require high dosing pressure of molten polymer material and that process non-porous homogeneous polymer materials, single-zone screws with a constant pitch and depth of screw cutting. Their use in the processing of cut strips from plastic waste is proposed. The main geometric parameters of the screw with a constant pitch and a variable depth of the screw channel were determined for designing. The diameter for the 3D printer extruder has been selected. Dependencies are given for determining the length of the screw, the pitch of the screw thread, the width of the crest of the turn, the angle of elevation of the screw line of the screw thread, and the depth of the screw channel of the screw. Dependencies are given for determining the boundaries of feeding, plasticizing, and dosing zones. The degree of screw compression was determined for the main polymer materials used in 3D printing. The geometry of screws depending on the degree of compression for different materials is given. A formula is presented for determining the volume performance of a 3D printer extruder depending on the design of the dosing zone and nozzle resistance. The formulas for determining the forward flow constant, the reverse flow constant and the flow constant of the flowing material and the dependence of the coefficients characterizing the design of the auger with a variable cutting depth are presented. The geometric parameters of screws with a constant pitch and depth of screw cutting and expressions for their determination are described.

Enhancing thermal efficiency and durability of sintered clay bricks through incorporation of polymeric waste materials

This pioneering study investigates the use of expanded polystyrene (EPS) and waste rubber tyre powder (WRTP) in sintered clay bricks for eco-friendly and cleaner buildings. Different ratios of EPS and WRTP were mixed with clay and sintered at 1000 °C. Advanced material characterization techniques were used to evaluate the materials, and physical, mechanical, and durability tests were performed on the bricks. The findings show that higher doses of EPS and WRTP increased the bricks' thermal efficiency and reduced their weight. Brick specimens with 0.5% EPS dosage met the weathering resistance requirements, and those with 0.5% EPS dosage and 5% WRTP dosage met the minimum compressive strength standards. The study offers valuable insights into the potential applications of EPS and WRTP in producing clean and sustainable polymer waste bricks to improve brick performance and efficient waste management in the construction industry.

INVESTIGATION OF THE MECHANICAL PERFORMANCE OF STONE MASTIC ASPHALT MIXTURES MODIFIED BY RECYCLED WASTE POLYMERS

The usage of polymer-modified asphalt binders has increased as a result of the significant increase in the number of conventional cars operating on Iraqi roads in recent years. This has resulted in increased strains being placed on pavement structures and materials. Global exploration has focused on the development of stabilizing Stone Mastic Asphalt mixtures for improved pavement behavior. Numerous effective efforts were made to stabilize stone mastic asphalt mixes with polymers and fibers. Iraq produces a considerable amount of waste polymer materials each year. Usually, they are sent to landfills for disposal. These wastes are dumped, occupying a sizable portion of landfill space and creating various serious environmental issues. The study focuses on how waste polymer additions, such as recycled plastic bottles, shopping boxes, and tire crumb rubber, affect the mechanical performance and durability of stone mastic asphalt mixtures. The mechanical performance attributes were assessed. It is evident from the findings that the drain-down amounts were within the permissible requirement range. The findings also showed that the indirect tensile strength, Marshall Stability, moisture damage resistance, and resistance for permanent deformation of stone mastic asphalt mixtures have all increased as a result of the use of waste polymer components. The recycled polymer-modified mixes are the combinations that are most resistant to rutting, according to the results of the repeated load axial creep tests. Iraq may have new options to employ the significant volumes of recycled polymers that are becoming accessible as a result of recycling waste polymers.

Bioplastics: Environment-friendly materials and their production technologies

Objective: To analyze the recent contributions of bioplastics in addressing environmental problems caused by plastic pollution. Design/Methodology/Approach: A literature review was carried out on the definitions of plastics and bioplastics, the sources of raw materials, processing technologies and methods to assess biodegradation. Current practices for final disposal and/or reuse were also examined. Special emphasis was placed on polylactic acid (PLA), one of the most widely used biodegradable materials today. Results: Over the years, there have been significant developments in the definitions of plastics and bioplastics, as well as in the sources of raw materials and processing technologies used to create final plastic products. By using bioplastics instead of conventional plastics, it is possible to reduce the dependence on petroleum and mitigate the pollution associated with plastic production and disposal. Furthermore, the enhanced biodegradability of bioplastics ensures that they break down more readily in natural environments, reducing the accumulation of plastic waste and its detrimental impact on ecosystems. The production of bioplastics using plant fibers, biological materials, and polymeric waste materials presents an opportunity for integration into the productive activities of the agro-industrial sector. This integration brings several benefits and synergies between agriculture and industry. Study limitations/Implications: We provide a report based on the literature. Findings/Conclusions: there is a notable current trend in the utilization of bioplastics as a viable substitute for conventional plastics. In order to assess the biodegradability and compostability of these materials, specific testing and certification standards have been established by reputable organizations. These standards serve as a reliable framework for evaluating the environmental impact and degradation characteristics of bioplastics. By adhering to these guidelines, manufacturers can ensure that their bioplastic products meet the necessary criteria for sustainable use.

Upcycling of textile and footwear wastes for synergistical reinforcement of cement mortar

The utilization of waste polymeric materials from textile, clothing and footwear (TCF) industry as aggregates in the cement is a valuable approach to reduce plastic pollution. However, the low modulus of polymers and poor interfacial interactions with the cement deteriorate their applications. Herein, we report an upcycling strategy for the recovery of waste fabrics and footwear sole materials from TCF industry as cement mortar reinforcement. The exfoliation of fabrics and pulverization of footwear soles enable them to expose the reactive groups which can absorb Ca2+ dissolved in water, thus helping the formation of C–H–S gel at the organic–inorganic interfacial transition zones between polymers and cement. It was determined by laser confocal Raman spectra. Hence, the exfoliated polyester fibers can prevent the crack expansion of cement and the devulcanized sole elastomers can dissipate energy while subjected to the external force, synergistically enhancing the mechanical properties. The flexural and compressive strengths of cement containing 0.5 wt% PFW and 5 wt% EPW are 48.9% and 59.6% higher than the neat cement. This work suggests a new strategy to realize value-added utilization of waste polymers which are difficult to be classified and separated.

Conventional properties, rheological properties, and storage stability of crumb rubber modified asphalt with WCO and ABS

To enhance the performance of asphalt and conserve resources, there is growing interest in the use of diverse waste polymer materials to modify asphalt. In this study, waste cooking oil (WCO) was used to activate crumb rubber (CR) and acrylonitrile–butadienestyrene (ABS) to obtain crumb rubber modified asphalt (CRMA) with low temperature sensitivity, excellent storage stability, and improved working performance. The physical properties of the modified asphalt were evaluated by conventional tests and rheological tests. The cohesive properties and compatibility of modified asphalt were investigated by the 60℃ dynamic viscosity, cigar tube test, and fluorescence microscope. The test results showed that WCO activated ABS/CR reduced the penetration of CRMA but increased its softening point and low temperature fracture work. In addition, the WCO activated ABS/CR could reduce the rotational viscosity of CRMA, and the viscosity-temperature curves prove that WCO activation of ABS/CR reduced the mixing and compaction temperature. Besides, the dynamic viscosity value of CRMA at 60℃ was also improved. The addition of ABS has a higher complex modulus and a lower phase angle, thus reducing the temperature sensitivity of asphalt. The zero shear viscosity (ZSV) value of the compound CRMA was six times higher than that of single CRMA. Additionally, proper proportions of ABS and WCO reduced the separation index (SI) of CRMA and enhanced its storage stability. Notably, group “AWCRMA1” exhibits a much higher ZSV than other asphalts while exhibiting lesser temperature sensitivity.

Reinforcing mechanically reclaimed polyurethane foam wastes‐based elastomer with modified recycled polyester fibers

AbstractPolyurethane foams are widely used in daily life due to their superior performance. However, it is very challenging to recycle and reuse waste polyurethane foams since the three‐dimensional crosslinking network structure makes them non‐melting and insoluble. In this work, a low‐cost, green, room‐temperature solid‐state shear milling method is proposed to break the cross‐linking bonds of waste polyurethane foam (crosslinking density decreases from 0.768 to 0.489 mol dm−3). The recycled polyurethane (RPU) powders regain their thermoplastic processability. Recycled waste polyester (PET) fibers are modified through plasma treatment and used as reinforcing fillers for the reprocessed RPU elastomer. Compared to original PET fibers, modified polyester (m‐PET) fibers construct strong interfacial interactions and physical interlocks with RPU matrix, leading to significantly enhanced mechanical properties. Molecular dynamics studies demonstrate that RPU/m‐PET composites have higher cohesive energy density and lower free volume, and significantly improved compatibility, which greatly promotes stress dissipation upon stretching. This study provides a feasible strategy for the high‐value recycling of waste polymer materials.

Waste Plastic and Rubber in Concrete and Cement Mortar: A Tertiary Literature Review

In recent years, the addition of plastic and rubber waste to construction materials has been widely studied by the research community. This great interest can mainly be attributed to the achievable potential environmental and economic benefits, mainly deriving from the reduction of incinerated or landfilled wastes and the decrease of used raw materials. Several reviews have been published on the addition of polymeric waste materials in concrete and cement mortar mixtures, discussing properties, environmental and cost implications. However, there are not available studies that organize and analyses the knowledge presented in this review. For the scope, in this paper we present a tertiary study of previous relevant review articles from peer-reviewed journals, with the aim to provide an overview of the state of the evidence related to this topic and to highlight the main critical aspects and open issues. The overview provides conclusions drawn from the 33 included reviews finding different open issues on the theme regarding environmental performance, cost savings and impacts on the supply chain as well as long term health problem related to the use of waste plastic and rubber in concrete and cement mortar. For each open issue further research proposals are also suggested.

Co-pyrolysis of low-rank coal and waste truck-tire: A comprehensive study on product distributions, product properties, and synergistic effects

Co-pyrolysis of low-rank coal and waste polymer materials is thought to be a promising way for solid waste disposal and recovering value-added chemicals. In our study, the co-pyrolysis of waste truck-tire (WTT) and Hongliulin low-rank coal (HLL) was carried out in a bench scale fixed-bed reactor to further investigate the synergistic effects during the co-pyrolysis process. The results showed that WTT volatiles inhibited the crosslinking and polycondensation reactions of HLL volatiles to a degree, showing an increase in tar yields. Volatiles-volatiles interactions improved the quality of tar products by enhancing the conversion of heavy components into more light tar, effectively lowering the average molecular weight of tars. The co-pyrolysis produced more chain hydrocarbons and aromatics while producing fewer terpenoids compared with individual pyrolysis, which was attributed mostly to the catalytic effects of char. Volatiles-char interactions increased the graphitization degree and ordered structure of the co-pyrolysis chars, and the pore structure of the co-pyrolysis chars became more developed. The large number of hydrogen-rich radicals produced by WTT pyrolysis consumed the reactive functional groups on the surface of HLL char, resulting in a decrease in the volatiles and cross-linking degree of co-pyrolysis chars. Finally, the potential synergistic mechanism for co-pyrolysis of WTT and HLL was summarized and depicted based on the analysis results.

COMPOSITES BASED ON SECONDARY POLYVINYL CHLORIDE RAW AND WOOD WASTE

A solution to the problem of rational use of secondary polymeric raw materials and wood waste is presented by creating composite materials for structural and decorative purposes on their basis. Wood-polymer composites (WPC) are modern materials made from a mixture of an organic thermoplastic polymer and a plant-based filler. To obtain WPC, various fillers and thermoplastic binders are used. Work in this direction is being actively carried out and the production of WPC (molded, sheet, complex profile) is widely mastered in the world. In order to significantly reduce the cost of composites while maintaining their physical, mechanical and operational characteristics, studies were carried out on the use of secondary raw materials as the main raw material. The object of the study was the most large-tonnage types of waste polymeric thermoplastic materials, in particular, polyvinyl chloride, which is formed both in the process of its industrial production, and in the field of industrial and domestic consumption, as well as soft waste from sawmilling and woodworking (sawdust, shavings). In the studies, the direct extrusion method was used. Based on the results of a complex of studies, the optimal technological parameters of the extrusion processing mode of the developed press compositions were determined, which have sufficient manufacturability and ensure high physical, mechanical and operational performance of the created composites at their minimum cost. The optimal content of the modified polymer component in the press composition should be in the range of 40–50% wt., depending on the purpose of products from this composite. From a wide range of additives, only the most, in our opinion, significant and affordable additives were used: calcium stearate (stabilizer and lubricant), dioctyl phthalate (plasticizer). These additives provide the necessary thermal stability and fluidity of the press composition during extrusion, as well as a certain light and thermal stability during product operation. The best performance is for a composite based on wood particles of medium fraction (l = 2.0…8.0 mm), which is characterized by an optimal structure of reinforcing particles and uniform distribution of the binder. Comprehensive evaluation tests (physical-mechanical, technological, operational, sanitary and hygienic) of WPC based on polyvinyl chloride waste and soft wood waste showed the practical possibility and expediency of creating and mastering the production of structural and decorative and finishing profile elements that are not inferior in basic properties to coniferous wood products rocks or polymers. On an industrial scale, on the basis of domestic equipment, in particular, the WP 90×25 extruder with modified working bodies, a wide range of products has been launched (for example: flooring profiles for civil and industrial construction, finishing boards, platbands, plinths, etc.).

Hypercrosslinked waste polymers as adsorbents for O2/N2 separation

Waste polymer materials offer a lot of promise for recycling or enhancement in terms of the environment. HCPs (hypercrosslinked polymers) are an excellent contender for recycling polymers in environmental applications. We employed waste-expanded polystyrene and waste polycarbonate as precursors to make HCPs adsorbents for O2/N2 adsorption. Characterization analysis were performed to determine the adsorbents' morphology and structure. The fine adsorbent was waste-expended polystyrene which had been synthesized at 45 °C for 12 h and had a surface area of 802.84 (m2/g), an average pore diameter of 2.86 nm, and a micropore volume of roughly 184.46 (cm3/g). The Sips isotherm and Elovich kinetic models provided the best agreement (R2 = 0.9994), according to experimental data. At 5 °C and 10 bar, the fine adsorbent had the highest O2 and N2 adsorption, with 12.78 and 7.67 (mmol/g), respectively. Eventually, the kinetic evidence demonstrated that the process physically occurred. Over nine cycles, the sorbent's ability for adsorption decreased by about 5%, indicating a high degree of reusability for air separation. The method described in this study can be considered a promising approach to air separation and purification by eco-friendly hypercrosslinked polymers.

Biodegradation of polyester polyurethane by the marine fungus Cladosporium halotolerans 6UPA1

Lack of degradability and the accumulation of polymeric wastes increase the risk for the health of the environment. Recently, recycling of polymeric waste materials becomes increasingly important as raw materials for polymer synthesis are in short supply due to the rise in price and supply chain disruptions. As an important polymer, polyurethane (PU) is widely used in modern life, therefore, PU biodegradation is desirable to avoid its accumulation in the environment. In this study, we isolated a fungal strain Cladosporium halotolerans from the deep sea which can grow in mineral medium with a polyester PU (Impranil DLN) as a sole carbon source. Further, we demonstrate that it can degrade up to 80% of Impranil PU after 3 days of incubation at 28 ℃ by breaking the carbonyl groups (1732 cm-1) and C-N-H bonds (1532 cm-1 and 1247 cm-1) as confirmed by Fourier-transform infrared (FTIR) spectroscopy analysis. Gas chromatography-mass spectrometry (GC-MS) analysis revealed polyols and alkanes as PU degradation intermediates, indicating the hydrolysis of ester and urethane bonds. Esterase and urease activities were detected in 7 days-old cultures with PU as a carbon source. Transcriptome analysis showed a number of extracellular protein genes coding for enzymes such as cutinase, lipase, peroxidase and hydrophobic surface binding proteins A (HsbA) were expressed when cultivated on Impranil PU. The yeast two-hybrid assay revealed that the hydrophobic surface binding protein ChHsbA1 directly interacts with inducible esterases, ChLip1 (lipase) and ChCut1 (cutinase). Further, the KEGG pathway for “fatty acid degradation” was significantly enriched in Impranil PU inducible genes, indicating that the fungus may use the degradation intermediates to generate energy via this pathway. Taken together, our data indicates secretion of both esterase and hydrophobic surface binding proteins by C. halotolerans plays an important role in Impranil PU absorption and subsequent degradation. Our study provides a mechanistic insight into Impranil PU biodegradation by deep sea fungi and provides the basis for future development of biotechnological PU recycling.

Application of Optimization and Modeling for the Composting Process Enhancement

Composting is a more environmentally friendly and cost-effective alternative to digesting organic waste and turning it into organic fertilizer. It is a biological process in which polymeric waste materials contained in organic waste are biodegraded by fungi and bacteria. Temperature, pH, moisture content, C/N ratio, particle size, nutrient content and oxygen supply all have an impact on the efficiency of the composting process. To achieve optimal composting efficiency, all of these variables and their interactions must be considered. To this end, statistical optimization techniques and mathematical modeling approaches have been developed over the years. In this paper, an overview of optimization and mathematical modeling approaches in the field of composting processes is presented. The advantages and limitations of optimization and mathematical modeling for improving composting processes are also addressed.