Identification of Commercial Oxo-Biodegradable Plastics: Study of UV Induced Degradation in an Effort 1 to Combat Plastic Waste Accumulation

About 50% of plastics is discarded after only single use which creates major environmental burdens. End of life 14 single-use items such as carrier bags constitute a large proportion of the litter found in marine and terrestrial 15 environments alike. The main objective of the current work was to investigate the response of an oxo-16 biodegradable commercial plastic film product to photo-degradation using accelerated weathering, verifying the 17 claim of its biodegradability and suitability as an eco-friendly product. The test specimens used were white to 18 transparent commercial grade plastic bags of PE origin acquired from an international franchise of household 19 goods, which were claimed to be of oxo-biodegradable nature. This study is also geared towards the 20 appropriateness of such products to reduce plastic waste accumulation in urban environments. The film samples 21 were exposed to weathering up to 20 continuous days to determine their degradability and assess their thermal 22 properties as a means to determine impact of UV induced oxo-biodegradation. Haze (%), light transmission (%) 23 and the total change in colour (ΔE) were measured as indicators to the degradation profile of the polymeric 24 materials, in addition to tensile pull mechanical properties and thermal stability. The melting peak indicates the 25 melting point (Tm) of the polymer and with exposure to weathering it showed a slight decrease from 105 to 26 102oC indicating that biodegradation mechanism was triggered. The reduction is strain at rupture was also 27 indicative of a loss in crystalline structure, coupled with Young’s modulus increase throughout weathering 28 exposure tests

A critical review of multi-hole drilling path optimization

Hole drilling is one of the major basic operations in part manufacturing. It follows without surprise then that the optimization of this process is of great importance when trying to minimize the total financial and environmental cost of part manufacturing. In multi-hole drilling, 70% of the total process time is spent in tool movement and tool switching. Therefore, toolpath optimization in particular has attracted significant attention in cost minimization. This paper critically reviews research publications on drilling path optimization. In particular, this review focuses on three aspects; problem modeling, objective functions, and optimization algorithms. We conclude that most papers being published on hole drilling are simply basic Traveling Salesman Problems (TSP) for which extremely powerful heuristics exist and for which source code is readily available. Therefore, it is remarkable that many researchers continue developing novel metaheuristics for hole drilling without properly situating those approaches in the larger TSP literature. Consequently, more challenging hole drilling applications that are modeled by the Precedence Constrained TSP or hole drilling with sequence dependent drilling times do not receivemuch research focus. Sadly, these many low quality hole drilling research publications drown out the occasional high quality papers that describe specific problematic problem constraints or objective functions. It is our hope through this review paper that researchers' efforts can be refocused on these problem aspects in order to minimize production costs in the general sense

Scientometric analysis and scientific trends on biochar application as soil amendment

This manuscript presents a scientometric analysis on the studies performed on the application of biochar for soil amendment in order to investigate the research and developments in this field and to identify the existing gaps to provide recommendations for future studies. A total of 2982 bibliographic records were retrieved from the Web of Science (WoS) database using appropriate sets of keywords, and these were analyzed based on the criteria of authors, publishing journals, citations received, contributing countries, institution, and categories in research and development. Based on these data, progress of research was mapped to identify the scientific status, such as current scientific and technological trends as well as the knowledge gaps. The majority of scientific developments started in the early 2000′s and accelerated considerably after 2014. China and USA are the leading countries in the application of biochar for the treatment of soils. Among the active journals, “Plant and Soil” has received the highest number of citations. This study attempts for a comprehensive discussion and understanding on scientific advances as well as the progress made, especially in recent years.publishe

Bioethanol from Lignocellulosic Biomass: Current Findings Determine Research Priorities

“Second generation” bioethanol, with lignocellulose material as feedstock, is a promising alternative for first generation bioethanol. This paper provides an overview of the current status and reveals the bottlenecks that hamper its implementation. The current literature specifies a conversion of biomass to bioethanol of 30 to ~50% only. Novel processes increase the conversion yield to about 92% of the theoretical yield. New combined processes reduce both the number of operational steps and the production of inhibitors. Recent advances in genetically engineered microorganisms are promising for higher alcohol tolerance and conversion efficiency. By combining advanced systems and by intensive additional research to eliminate current bottlenecks, second generation bioethanol could surpass the traditional first generation processes

Reviewing the thermo-chemical recycling of waste polyurethane foam

The worldwide production of polymeric foam materials is growing due to their advantageous properties of light weight, high thermal insulation, good strength, resistance and rigidity. Society creates ever increasing amounts of poly-urethane (PU) waste. A major part of this waste can be recycled or recovered in order to be put into further use. The PU industry is committed to assist and play its part in the process. The recycling and recovery of PU foam cover a range of mechanical, physical, chemical and thermo-chemical processes. In addition to the well- documented mechanical and chemical processing options, thermo-chemical treatments are important either as ultimate disposal (incineration) or towards feedstock recovery, leading to different products according to the thermal conditions of the treatment. The review focuses on these thermo-chemical and thermal processes. As far as pyrolysis is concerned, TDI and mostly polyol can be recovered. The highest recovery yields of TDI and polyols occur at low temperatures (150–200 ◦C). It is however clear from literature that pure feedstock will not be produced, and that a further upgrading of the condensate will be needed, together with a thermal or alternative treatment of the non-condensables. Gasification towards syngas has been studied on a larger and industrial scale. Its application would need the location of the PU treatment plant close to a chemical plant, if the syngas is to be valorized or considered in conjunction with a gas-fired CHP plant. Incineration has been studied mostly in a co- firing scheme. Potentially toxic emissions from PU combustion can be catered for by the common flue gas cleaning behind the incineration itself, making this solution less evident as a stand-alone option: the combination with other wastes (such as municipal solid waste) in MSWI′s seems the indicated route to go

Bio-energy Carriers as Back-up Fuel in Hybrid Solar Power Plants

Electricity from concentrated solar power (CSP) plants, gains an increasing interest and importance. To fully match the supply-demand principle, CSP processes include a thermal energy storage and back-up fuel supply. Novel CSP concepts are needed with specific targets of increased efficiency and reliability, and of reduced CAPEX and OPEX. The use of particle suspensions offers significant advantages since applicable in all sub-sections of the complete CSP as heat carrier from the receiver, to the heat storage, and ultimately to the power block. The use of particles in the steam generation (power block) is a common fluidized bed boiler technology. This paper will present the entire particle-based concept, while also discussing the potential to use biomass-based energy carriers as back-up heat supply. Process data and expected effects on the process economy of the system will be discussed