Photolytic Model of Six Degradable Mulch Plastic Films

[Objective] This study aimed to solve the mulch plastic film pollution problems in Xinjiang, in order to provide reliable theoretical basis for the research on the degradation mechanism of biodegradable plastic films. [Method] The effect of illumination intensity on the decomposition of decomposable mulching films was investigated through simulating the field condition in laboratory. Regression analysis was employed to fit the processes of film decompositions. [Result] The weight loss ratios of different types of plastic films were closely related with the illumination. There was no sundry produced during the degradation process, but the weight was reduced, indicating that degradation produced gas, thus, ultraviolet rays had destructive effect on mulch plastic films. Different types of plastic films showed significant differences in the degradation speeds, and under the same conditions, the degradation speed of S4# with the induction period of 30 d was the fastest. With the extension of uv illumination time, the degradation became cumulative degradation process. [Conclusion] Under the uv rays, the weight loss ratio and illumination hours is regarded as a positive correlation relationship. The significant inspection shows that the data fitted degradation model can be described by the logistic model of Y = a/（1＋b×e -ct）, and all the parameters show significant differences （P0.01）.

Multi-Component Resource Recycling from Waste Light-Emitting Diode Under Hydrothermal Condition:Plastic Package Degradation,Speciation of Nano-TiO_(2),and Environmental Impact Assessment

Light emitting diodes(LEDs)have accounted for most of the lighting market as the technology matures and costs continue to reduce.As a new type of e-waste,LED is a double-edged sword,as it contains not only precious and rare metals but also organic packaging materials.In previous studies,LED recycling focused on recovering precious and strategic metals while ignoring harmful substances such as organic packaging materials.Unlike crushing and other traditional methods,hydrothermal treatment can provide an environment-friendly process for decomposing packaging materials.This work developed a closed reaction vessel,where the degradation rate of plastic polyphthalamide(PPA)was close to 100%,with nano-TiO_(2)encapsulated in plastic PPA being efficiently recovered,while metals contained in LED were also recycled efficiently.Besides,the role of water in plastic PPA degradation that has been overlooked in current studies was explored and speculated in detail in this work.Environmental impact assessment revealed that the proposed recycling route for waste LED could significantly reduce the overall environmental impact compared to the currently published processes.Especially the developed method could reduce more than half the impact of global warming.Furthermore,this research provides a theoretical basis and a promising method for recycling other plastic-packaged e-waste devices,such as integrated circuits.

High-efficiency Ce-modified ZSM-5 nanosheets for waste plastic upgrading

Zeolite-based catalyst hydrocracking of plastics is a potential strategy for mitigating the environmental impacts of plastic wastes and recycling valuable resources,but difficult mass transfer,low concentration of acid sites,and high cost are still barriers to their practical applications.In this paper,we report an excellent hydrocracking catalyst of ZSM-5 nanosheets(Ce/b-ZSM-5)modified by Ce species with high conversion up to 96.3%,C_(3)−C_(5)selectivity up to 80.9%,and good stability during the hydrogenation of low-density polyethylene.Through comprehensive studies,b-ZSM-5 shows higher molecular diffusion efficiency and acid site concentrations compared with normal ZSM-5(n-ZSM-5)and hollow ZSM-5(h-ZSM-5).The introduction of Ce species into b-ZSM-5 further increases the density of Brønsted(B)and Lewis(L)acid sites as active sites,which enhances the adsorption of substrates and facilitates the formation of intermediates and desorption of products.As a result,the hydrocracking activity of Ce/b-ZSM-5 is significantly improved.

Base-or acid-assisted polystyrene plastic degradation in supercritical CO_(2)

Plastic has caused serious"white pollution"to the environment,and the highly inert characteristics of plastic bring a major challenge for degradation.Supercritical fluids have unique physical properties and have been widely used in various fields.In this work,supercritical CO_(2)(Sc-CO_(2))with mild conditions was selected and assisted by NaOH/HCl solution to degrade polystyrene(PS)plastic,and the reaction model was designed using response surface methodology(RSM).It was found that,regardless of the types of assistance solutions,the factors affecting PS degradation efficiencies were reaction temperature,reaction time,and NaOH/HCl concentration.At the temperature of 400℃,time of 120 min,and base/acid concentration of 5%(in weight),0.15 g PS produced 126.88/116.99±5 mL of gases with 74.18/62.78±5 mL of H2,and consumed 81.2/71.5±5 mL of CO_(2).Sc-CO_(2)created a homogeneous environment,which made PS highly dispersed and uniformly heated,thus promoting the degradation of PS.Moreover,Sc-CO_(2)also reacted with the degradation products to produce new CO and more CH_(4)and C_(2)H_(x)(x=4,6).Adding NaOH/HCl solution not only improved the solubility of PS in Sc-CO_(2),but also provided a base/acid environment that reduced the activation energy of the reaction,and effectively improved the degradation efficiencies of PS.In short,degrading PS in Sc-CO_(2)is feasible,and better results are obtained with the assistance of base/acid solution,which can provide a reference for the disposal of waste plastics in the future.

Plastic materials and water sources actively select and shape wastewater plastispheres over time

The daily use of plastics presents a serious pollution issue due to their extremely slow degradation.Microplastics and the biofilm that grows on plastics(i.e.,the plastisphere)are important subsets of plastic wastes.Many studies have been conducted to reveal the structures of the plastispheres,the driving factors for the formation of the plastisphere,and the ability of the plastispheres to degrade plastics in a variety of water bodies.However,the plastispheres related to wastewater are understudied.In this study,we used a microcosmic strategy to study the evolution of the plastispheres associated with microplastics(MPs)over time in wastewater.We found that plastic materials and water sources did not actively select and shape the plastispheres at an early stage,but the active selection for a unique niche of the plastisphere occurred after 14 d of growth.In addition,we confirmed that the alkB gene was densely present,and metagenomics showed some additional chemical reactions,which suggests that MPs are consumed by the microbes in the plastispheres.Additionally,metagenomics identified some metagenome-assembled genomes(MAGs)associated with high-density polyethylene(HDPE)and polyethylene terephthalate(PET).The identification of HDPE-associated MAGs and PET-associated MAGs further supports the notion that the selection for a unique niche of the plastisphere is driven by plastic materials and water sources(in this study,after 14 d of growth).Our discoveries bring new views on the behavior of the wastewater-associated plastisphere,especially how long it takes a wastewater plastisphere to form.

Ten decadal advances in fungal biology leading towards human well‑being

Fungi are an understudied resource possessing huge potential for developing products that can greatly improve human well-being.In the current paper,we highlight some important discoveries and developments in applied mycology and interdisciplinary Life Science research.These examples concern recently introduced drugs for the treatment of infections and neurological diseases;application of–OMICS techniques and genetic tools in medical mycology and the regulation of mycotoxin production;as well as some highlights of mushroom cultivaton in Asia.Examples for new diagnostic tools in medical mycology and the exploitation of new candidates for therapeutic drugs,are also given.In addition,two entries illustrating the latest developments in the use of fungi for biodegradation and fungal biomaterial production are provided.Some other areas where there have been and/or will be significant developments are also included.It is our hope that this paper will help realise the importance of fungi as a potential industrial resource and see the next two decades bring forward many new fungal and fungus-derived products.

Assessment of plastic degradation by indigenous bacteria from waste disposal sites

The present study focuses on the isolation of bacterial pathogens from waste disposal sites,and examination of their efficiencies for degrading various plastics.Seven bacterial isolates such as E.coli,Corynebacterium spp.,Micrococcus spp.,Azotobacter spp.,Pseudomonas spp.,Staphylococcus spp.,and Bacillus spp.were identified.Bacillus spp.exhibited the highest percentage reduction in black plastic weight(47.46%),while Corynebacterium spp.,and E.coli achieved a maximum reduction of 45.76 and 46.42%for pink plastic respectively.Pseudomonas spp.and Micrococcus spp.demonstrated notable reductions of 46.43%and 56.60%in white and Canteen Stores Department(CSD)biodegradable plastics,respectively.Optical density(OD)measurements revealed that bacterial isolates achieved maximum OD values with CSD plastics,emphasizing their proficiency in plastic degradation.Fourier Transform Infrared Spectroscopy(FTIR)confirmed the degradation process,with a decrease in the peak value from 2916 to 2914 cm^(-1) for pink plastic,signifying alkane,and alkene presence.Three new peaks at 1398,1371,and 1361 cm^(-1) in the FTIR spectrum of CSD plastic indicated presence of alcohol.Scanning Electron Microscopic(SEM)micrographs illustrated bacterial colonization,cracks,and spots on plastic surfaces,while Xray Diffraction(XRD)spectra showed peaks at 4.083,3.705,3.020,and 1.909,suggesting plastic degradation.In conclusion,soil of waste disposal site harbored diverse microbial species,and have highlighted their effectiveness in mitigating environmental pollution by degrading hazardous plastic waste.