Pyro-gas analysis of fixed bed reactor end of life tyres (ELTs) pyrolysis: A comparative study

Pyrolysis of end of life tyres (ELTs) present a promising alternative to their incineration or classical product recovery using mechanical means. It can produce light hydrocarbons (HCs) and other valuable chemicals as part of the pyro-gas stream it generates. In this work, two grades of tyres namely a fresh (virgin) one and a waste disposed ELTs, were used as a feedstock to analyse their pyro-gas constituents. There wasn't much difference in the maximum conversion rate between both tyre grades where the fresh tyres had an estimated 15.17% conversion and the ELTs was 13.45% conversion (both at 800 °C). The difference herein was attributed to release of free radicals prior to subjecting the samples to pyrolysis due to their history. The analysis of the pyro-gas samples showed a large make of light hydrocarbon (HC) products, namely methane (CH₄/C₁), ethane (C₂H₆/C₂), ethylene (C₂H₄), propane (C₃H₈/C₃), propylene (C₃H₆), n-butane (C₄H₁₀), butadiene compounds, carbon mono and dioxide (CO,CO₂). Light HCs mimciking natural gas were more abundant in the case of ELTs were C₁ was estimated as 14.53% at 500 °C and 16.73% at 800 °C. C₂ was also estimated higher than the fresh tyres where a 11.78% at 500 °C was noted and 7.67% at 800 °C. It can be recommended that future integration plans in oil and gas ventures, namely refinery and petrochemical complexes, are to start taking responsible measures towards the environment by substituting part of their operations with sustainable feedstock such as ELTs.

Insights into the evaluation of the abiotic and biotic degradation rate of commercial pro-oxidant filled polyethylene (PE) thin films

In this study, commercial products formulated from polyethylene (PE) with pro-oxidant additives, were subjected to abiotic and biotic environments. The materials were presumed to be oxo-biodegradable plastics with thicknesses varying between 30 and 70 μm, and calcium carbonate (CaCO₃) filler content reaching up to 11 wt%. Accelerated (aging) weathering tests conducted revealed that UV radiation triggered the biodegradation mechanism. Weight loss reached 50% after exposure to weathering which was attributed to triggering the fragmentation of the plastic films. Furthermore, some 83% of weight loss was estimated after 12 months of soil burial. Fluctuation of weight in mid exposure time spans was related to the cross-linking reaction within the polymeric matrix. The mechanical properties investigated along with the thermal stability profile determined for the materials showed that weathering was more severe than soil burial. Thermogravimetry revealed that onset temperature (T_os) was lower than conventional PO products by 25 °C. This could be attributed to the thermal response of the materials due to presence of ion salts and sterates within their composition. The claims by the manufacturing companies which provided the original specimens under an environmentally friendly pretence is disputed due to the fact that none of the products actually showed evidence of major fragmentation or deterioration after exposure to harsh environments. The work also paves the way in standardising assessment methodology for examining biodegradable plastics.

A review of the valorization and management of industrial spent catalyst waste in the context of sustainable practice: The case of the State of Kuwait in parallel to European industry

Industrial solid waste management encompasses a vital part of developed and developing countries strategies alike. It manages waste generated from vital industries and governs the hazardous waste generated as a major component of integrated waste management strategies. This article reviews the practices that govern the management approaches utilized in the developed world for industrial spent catalysts. It critically assesses the current situation of waste management within the developing world region focusing on the industrial waste component, in a novel attempt to crucially develop a strategy for a way forward based on best practices and future directions with major European industries. The review also draws parallels with European countries to compare their practices with those of the State of Kuwait, which rely solely on landfilling for the management of its industrial waste. Spent catalysts recovery methods are discussed at length covering conventional methods of valuable metals and chemicals recovery (e.g., hydrometallurgical, solid-liquid and liquid-liquid extraction) as well as biological recovery methods. A major gap exists within regulations that govern the practice of managing industrial waste in Kuwait, where it is essential to start regulating industries that generate spent catalysts in-view of encouraging the establishment of valorization industries for metal and chemical recovery. This will also create a sustainable practice within state borders, and can reduce the environmental impact of landfilling such waste in Kuwait.

On the Kinetics of Degradation Reaction Determined Post Accelerated Weathering of Polyolefin Plastic Waste Blends

Polyolefin (PO) polymers constitute the majority of consumer plastic commodities. The reliance on such materials make it near imposable to avoid touching one in any given day. Therefore, the accumulation of plastic solid waste (PSW) in developed and developing societies alike requires immediate attention to manage and valorize this type of waste. In this work, PSW originating from real life sources and virgin linear low-density polyethylene (LLDPE) films were compounded in a mechanical recycling effort. The recycled blends constituted up to 100% (by weight) of the waste material. Accelerated weathering (aging) was conducted on the blends, reaching threshold limit of exposure to study the major changes occurring on the recycled blends. Thermogravimetry and differential scanning calorimetry (DSC) were used to determine their characteristics and applicability for future recycling using thermo-chemical treatment (TCT) methods. Analytical solution methods following the international committee of thermal analysis and calorimetry (ICTAC) were followed in conducting the measurements and kinetic calculations alike. A novel analytical mathematical solution model is also introduced to determine both the pre-exponential factor (A_o) and apparent activation energy (E_a) of the degradation reaction. The model proved to be a more accurate analysis tool, and the work in whole enabled the determination of future plans for using such waste components as a feedstock to thermal units.