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Landfilling is viewed nowadays as a serious threat associated with various burdens and stressors on the urban environment. To date, there is little information available on actual value of landfilled waste namely plastic solid waste (PSW) resulting from mining operations. In this work, PSW reclaimed from an active unsanitary landfill site (MAB) has been studied with the aim of determining its thermal profile and degradation behaviour for future utilisation in thermo-chemical conversion (TCC) processes. The materials were characterised by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) in accordance with internationally approved test methods in a simulated pyrolytic environment. In addition, chemical analysis using Fourier Transform Infrared Spectroscopy (FTIR) was applied to study the nature of the materials reclaimed. The degradation kinetics of the reclaimed PSW were studied with the aim of determining the apparent activation energy (Ea) of the pyrolytic reactions. The Ea values determined ranged from 199 to 266 kJ mol−1 which is in-line with pyrolytic reactions applicable for future use in fuel recovery units. TGA showed a clear shift in thermograms indicating a clear change in the degradation mechanism. The physico-chemical studies conducted on the materials also favours TCC treatment over other conventional end of life options such as physical (mechanical) recycling or incineration. The degradation mechanism was also determined from the Criado method showing that Avarami-Erofeve was the model that best represents PSW degradation. Overall, this work points towards future intervention schemes for reclaimed municipal solid waste (MSW) and in particular PSW favouring TCC technologies.

Plastics are abundant and have a high energy content making their use in energy applications attractive. This article presents a review on plastic waste (PW) management by pyrolysis and gasification, which are two types of thermochemical conversion (TCC) techniques. The conversion of PW and the application of its converted products are important steps toward reducing reliance on fossil fuels, enhancing closed-loop recycling of materials and the circular economy. The review presented herein also focuses on product distribution and yields with emphasis on the energy content and potential integration to energy systems and grids. It is found that pyro-oils have properties similar to conventional fuels such as diesel and can partially substitute for fossil fuels. In fact, the energy content of PW pyro-oils obtained by various researchers range from 41.10−46.16 MJ kg−1 , which is close to the heating values of conventional fuels and thus are potential candidates for fuel applications. Typical treatment post-conversion is also conducted to maintain the quality of the oil produced and the removal of sulfur content to conform with market standards. On the other hand, syngas produced during gasification possesses a lower potential for fuel applications as its energy content may reach values as low as 20 MJ kg−1 in comparison to pyro-oil. However, depending on the process conditions, it is possible to increase the energy content to values of over 40 MJ kg−1 . Additionally, syngas is the building block for many valuable chemicals. With appropriate treatment, the syngas obtained from the gasification of PW can be used in gas engines and can be converted to commercial products such as liquid fuels via the Fischer−Tropsch synthesis. This review also highlights some available commercial-scale plants for the TCC of PW and real-life application of their obtained products. It is noted that the integration of the processes to energy systems is technically and economically feasible. Real-life applications of products obtained from the pyrolysis and gasification of PW in different parts of the world are also discussed. The produced fuels have been used in cooking stoves and burned in a gas turbine, internal combustion engine, and direct injection diesel engine.

With fossil fuel being the major source of energy, CO2 emission levels need to be reduced to a minimal amount namely from anthropogenic sources. Energy consumption is expected to rise by 48% in the next 30 years, and global warming is becoming an alarming issue which needs to be addressed on a thorough technical basis. Nonetheless, exploring CO2 capture using membrane contactor technology has shown great potential to be applied and utilised by industry to deal with post- and pre-combustion of CO2. A systematic review of the literature has been conducted to analyse and assess CO2 removal using membrane contactors for capturing techniques in industrial processes. The review began with a total of 2650 papers, which were obtained from three major databases, and then were excluded down to a final number of 525 papers following a defined set of criteria. The results showed that the use of hollow fibre membranes have demonstrated popularity, as well as the use of amine solvents for CO2 removal. This current systematic review in CO2 removal and capture is an important milestone in the synthesis of up to date research with the potential to serve as a benchmark databank for further research in similar areas of work. This study provides the first systematic enquiry in the evidence to research further sustainable methods to capture and separate CO2.

End of life single-use items such as carrier bags constitute a large proportion of the litter found in marine and terrestrial environments. The main objective of the current work was to investigate the response of an oxo-biodegradable commercial plastic film product to photo-degradation using accelerated weathering, verifying the claim of its biodegradability and suitability as an eco-friendly product. This study is also geared towards the appropriateness of such products to reduce plastic waste accumulation in urban environments. The film samples were exposed to weathering as a means to determine the impact of UV induced oxo-biodegradation. Haze (%), light transmission (%) and the total change in colour (ΔE) were measured as indicators to the degradation profile of the polymeric materials, in addition to tensile pull mechanical properties and thermal stability. The melting peak indicates the melting point (Tm) of the polymer and with exposure to weathering it showed a slight decrease from 105 to 102 °C indicating that biodegradation mechanisms were triggered to a certain extent. The reduction in strain at rupture was also indicative for a loss in crystalline structure, coupled with Young’s modulus increase throughout the weathering exposure tests. Therefore, the material studied could be a candidate to mitigate the accumulation of plastic waste in open environments based on the results of this study whilst regulating controlled substances.

Landfilling is Kuwait’s only waste disposal method. It presents an economical and a reliable solution in waste management but can pose a threat to human health and environment, making rehabilitation and restoration of these areas critical for future developments. Moreover, improper handling and management of waste in landfill sites could result in release of toxic gases and leachate contamination and might have a long-term impact on the environment. Thus, the objective of this study was to establish a baseline soil characterisation for the planning of landfill restoration based on the contamination of heavy metals and organic pollutants in these sites. The contamination and soil permeability of three of Kuwait’s active landfills, namely the South Seven Ring Road, Mina Abdullah, and A-Jahra, were quantified. These landfills are under consideration by the government for restoration and future developments. The granulometric distribution and waste handling for these landfills were quantified. Hydraulic conductivity (k) of the soil samples was estimated to determine the nature of the soil. A series of heavy metals and organic pollutants were also quantified in laboratory and compared to the Canadian and Australian guidelines. Though these contaminants were mostly within the level of threshold of their toxicity, the sites should be handled properly and carefully for restoration and future uses as the bioavailability may change with alterations and should be tested in future.

This article shows a preliminary study of an end of life tyres (ELTs) use as a feedstock in a newly developed and patented reactor system that utilises a three zone heating element set-up along its fixed bed. The pyrolysis reaction was conducted between 500 to 700 °C and has yielded a maximum pyrolysis oil at 500 °C which was attributed to the promotion of secondary cracking of the oil into permanent (non-condensable) gaseous products. The oil yield and properties including estimated mass balance, sulphur content and higher heating value (HHV) shows that the pyro-oil is within fuel standards of the market making it a green and renewable resource off of waste. In addition, The hydrocarbon (HC) range of the products obtained from the oil shows that it is within the diesel range of typical fuels. The analysis of the gaseous products from the pyrolysis showed that an increase in the average reactor bed temperature promotes the decomposition of primary HC and pyrolysis oil into secondary products. This results in the detection of tetradecanoic acid, limonene and eicosane, among other major chemical groups at temperatures above 550 °C which is the end-set temperature of feedstock examined. It can be concluded that by using such a reactor set-up and upgrading the fuels extracted from its downstream stigmatic features of fixed bed reactors might be overcome with a lucrative economical value and rate of return in a circular economy perspective.

In this article, supercritical water gasification of biocrude at different conditions was performed and compared to each other. Three scenarios were considered while treating biocrude originating from cattle manure (CM) and corn husk (CH), namely, uncatalyzed feedstock, catalyzed with 10% Ni–0.08% Ru/Al2O3 and finally catalyzed with 10% Ni–0.08% Ru/Al2O3–ZrO2. It was found that 10% Ni–0.08% Ru/Al2O3–ZrO2 has performed significantly better than the other two scenarios over the 5 hour run time with a 193 and 187% higher hydrogen yield compared to the uncatalyzed and 10% Ni–0.08% Ru/Al2O3 catalyzed scenarios, respectively. Compared to CM gasification in the presence of a 10% Ni–0.08% Ru/Al2O3–ZrO2 catalyst, the catalyst got deactivated because of the high phenol and furan content in the corn husk biocrude, therefore hydrogen yield performance fell significantly. It was observed that the carbon gasification efficiency of the biocrude was independent of temperature. In terms of carbon conversion, the equilibrium conditions for the biocrude considered were attained at lower temperature. A mechanistic model based on the Eley–Rideal method was devised and tested against the obtained data. The dissociation of adsorbed oxygenated hydrocarbon is found to be the rate-determining step with an average absolute deviation of 3.55%.

A process simulation and techno-economic evaluation of using molten solar salt as the heating medium for pyrolysis of mixed plastic waste (MPW) containing poly(vinyl chloride) (PVC) was performed. ...

The present study investigates the steam gasification of biomass with an in-process CO2 capture. The work is aimed at achieving hydrogen enrichment while reducing the carbon dioxide (CO2) concentra...

A computational fluid dynamics (CFD) model was derived and validated in order to investigate the hydrodeoxygenation reaction of 4-propylguaiacol, which is a lignin-derived compound present in bio-oil. A 2-D packed bed microreactor was simulated using a pre-sulphided NiMo/Al2O3 solid catalyst in isothermal operation. A pseudo-homogeneous model was first created to validate the experimental results from the literature. Various operational parameters were investigated and validated with experimental data, such as temperature, pressure and liquid flow rate, and it was found that the CFD findings were in very good agreement with the results from the literature. The model was then upgraded to that of a detailed multiphase configuration, and phenomena such as internal and external mass transfer limitations were investigated, as well as reactant concentrations on the rate of 4-propylguaiacol. Both models were in agreement with the experimental data, and therefore confirm their ability for applications related to the prediction of the behaviour of bio-oil compound hydrodeoxygenation.

In this work, end of life tyres (ELTs) samples were subjected to pyrolysis in a dynamic thermogravimetry set-up under various heating rates between 5°C and 25°C min−1. The experimental design involved dried and non-dried sample results in an isothermal step within the heating program, to be able to compare the data against non-dried samples, to further investigate the effect of drying on the results obtained. The drying of the samples resulted in an increase in the onset temperature by some 30°C. However, cryomilling the ELTs samples showed a great effect in reducing the onset of the degradation curve by about 10°C amongst the same set of experiments. The type of sample, in terms of size and processing/milling condition, had a significant impact on the heat flow properties and calorimetry reported. The exothermic region for the original shavings resulted in an enthalpy of −48 J g−1, whilst the cutting mill samples exhibited an enthalpy increase to −184 J g−1. However, the cryomilled samples showed an enthalpy increase estimated at 139 J g−1.

The aim of this study is to assess the effect of leached pollutants from solid waste landfills on shallow utilized aquifers within the State of Kuwait. The objectives of the work were achieved through developing a 3D-VMF Flex numerical flow and solute transport model. The results of the study of Kuwait show that the pollutants longitudinal dispersivity should be less than or equal to 420 m coupled with a ratio of horizontal transverse to longitudinal dispersivity equal to 0.1 and a vertical transverse dispersivity to longitudinal dispersivity ratio equal to 0.01. The novelty of this research is that the developed model was for the first time simulating concurrently the three processes that control the movement of pollutants in the porous media under landfills in Kuwait: advection, dispersion and adsorption. The dispersion and adsorption model parameters were calibrated against measured pollutants concentration in the field. This study shows that the adsorption process plays an important role in controlling the migrantion of heavy metals and inorganic pollutions into shallow aquifers. This study calibrates adsorption coefficient (kd) for conservative pollutants such as Cl to be 1 × 10–7 (mg/l)−1, for nitrogen compound such as NO3 to be 1.2 × 10–7 (mg/l)−1 and for heavy metals such as Pb and Cr to be 1 × 10–5 (mg/l)−1. It was also concluded that conservative pollutants take about one year to leach to the closets observational point (2.57 km). It took the conservative pollutant plume about 16.5 years (6000 days) to reach the furthest observation point, which is 5.26 km away. These conclusions combined draw a priority action-plan for interested parties to take into considerations future works for land and environmental rehabilitation strategies including natural underground water resources management.

The use of hydrogen as a renewable fuel has attracted great attention in recent years. The decomposition of formic acid under mild conditions was investigated using a 2%Pd6Zn4 catalyst in a batch reactor. The results showed that the conversion of formic acid increases with reaction temperature and with the formic acid concentration. A process-simulation model was developed to predict the decomposition of formic acid using 2%Pd6Zn4 in a batch reactor. The model demonstrated very good validation with the experimental work. Further comparisons between the 2%Pd6Zn4 catalyst and a commercial Pd/C catalyst were carried out. It was found that the 2%Pd6Zn4 demonstrated significantly higher conversions when compared with the commercial catalyst., The authors thank London South Bank University; School of Engineering for the PhD fund that supports the work of Sanaa Hafeez.

With increases in population and industrialization, global energy demand is increasing rapidly and resulting in various environmental challenges related to fossil fuel consumption. These challenges have made it imperative to look for alternative means of environmentally sustainable energy production, such as the thermal degradation of biomass. Biofuels obtained from pyrolysis have the potential to be substituted for fossil fuels, but one of the major barriers to utilization of pyrolysis oil is the presence of oxygenated compounds. An approach to overcome this is to co-pyrolyze the biomass with hydrogen-rich feedstocks such as plastic and tire wastes. Studies have shown that exists a synergistic relationship between plastics/tires and biomass as well as resulting products from co-pyrolysis have higher heating value along with improved bio-oil properties. This paper discusses the current progress on the co-pyrolysis of biomass with waste plastics/tires and their synergistic interactions for high grade fuel production. Co-pyrolysis studies done on pilot-scale have also been discussed in this review.

A process simulation model was created using Aspen Plus to investigate the hydrodeoxygenation of 4-propylguaiacol, a model component in lignin-derived pyrolysis oil, over a presulphided NiMo/Al2O3 solid catalyst. Process simulation modelling methods were used to develop the pseudo-homogeneous packed bed microreactor. The reaction was conducted at 400 °C and an operating pressure of 300 psig with a 4-propylguaiacol liquid flow rate of 0.03 mL·min−1 and a hydrogen gas flow rate of 0.09 mL·min−1. Various operational parameters were investigated and compared to the experimental results in order to establish their effect on the conversion of 4-propylguaiacol. The parameters studied included reaction temperature, pressure, and residence time. Further changes to the simulation were made to study additional effects. In doing so, the operation of the same reactor was studied adiabatically, rather than isothermally. Moreover, different equations of state were used. It was observed that the conversion was enhanced with increasing temperature, pressure, and residence time. The results obtained demonstrated a good model validation when compared to the experimental results, thereby confirming that the model is suitable to predict the hydrodeoxygenation of pyrolysis oil.

The year 2020 has been noted to be one of major calamity the world over, in which the majority of efforts in research and development have been dedicated towards combating the threat of the novel Coronavirus (COVID-19). Ever since the announcement of COVID-19 as a pandemic, such efforts were dedicated towards the research of its spread and vaccination. Yet still, the world might reach a resolution via an environmental solution that various entities have overlooked, with a plethora of environmental benefits vis-à-vis waste management. In this short communication, the possibility of using plastic solid waste as a substrate to employ copper, and copper alloys and their nanocomposite nanopowders to be used as permanent surface protective coats, is presented. The fact that we present such materials to be of waste origin, is an added value advantage to their beneficial advantage of developing various commodities and products that could be used in our daily lives. Furthermore, the fact that such recyclable materials are susceptible to antiviral properties and chemicals, is an added value that we should not neglect.

Pyrolysis is a promising thermolysis technique to recover valuable oils and light hydrocarbons (HC) with high yields from plastic solid waste (PSW). In this work, thermal pyrolysis of high density polyethylene (HDPE) with the aim of producing gasoline range hydrocarbon oils, has been carried out in a novel fixed bed (batch) reactor. The pyrolysis of HDPE has been conducted between 500 to 800 °C in the presence of nitrogen as an inert carrier gas media to produce liquid fuel oil, gaseous products and solid char. The optimum temperature of obtaining maximum oil product yield (70%) was 550° C. A comprehensive gas chromatography (GC) analysis of the liquid and gaseous products was conducted to quantify high molecular weight individual HC components. Moreover, light molecular weight HC constituting the gaseous fraction were identified. A chemical kinetic analysis of the cracking reactions, was performed to investigate the reaction mechanism of yielding the maximum oil product. The oil product recovered had a high proportion of aliphatic HC especially in the range of C8 to C12, whilst aromatic HC were of lower proportion. The carbon number of the pyrolysis oil was noted to increase proportionally with the increasing operating temperature. The gaseous product had a high percentage (> 70%) of C2 to C4 HC, which was attributed to the high activity of carbon/carbon (C-C) chain scission reaction.

In this study, the properties of virgin linear low-density polyethylene (LLDPE) and its blends with reclaimed plastic solid waste (PSW) are investigated by thermogravimetry, differential scanning calorimetry (DSC), infrared spectroscopy and scanning electron microscopy (SEM). The PSW constituted polyolefin (PO) polymers recycled mechanically via extrusion/blown-film and exposed to accelerated weathering tests to determine the change in their degradation behaviour. The oxidation products determined using the FTIR analysis and thermal stability studies points toward the blend constituting 25% of waste by weight as the most stable. Changes in crystallinity of the polymers were attributed to the crystal size change as a consequence of the weathering mechanism. The DSC results revealed that both oxidation induction temperature (OIT) and crystallinity were affected by the PO waste content. This points towards the impact of polymers immiscibility and polydispersity within the matrix of the blends due to chain scission reaction and oxidation with the UV exposure.

This study investigates the calcination and carbonation reaction kinetics of eggshell. Nonisothermal (dynamic) thermogravimetry using multiple heating rates was conducted to study the calcination process. On the other hand, isothermal conditions were applied to report on the carbonation process in a carbon dioxide (CO2) atmosphere. Several model-based and isoconversional kinetic methods were used to evaluate the calcination kinetic parameters. The methods include the Friedman, Coats and Redfern, modified Coats and Redfern, Kissinger, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose methods. Furthermore, an analytical solution method was developed to evaluate the kinetic parameters and to predict the experimental conversion. The carbonation reaction was modeled with a modified form of the shrinking core model. Both the rapid surface reaction-controlled and the slow diffusion-limited stages of carbonation were analyzed. The results showed that the kinetic parameters obtained with the various methods are in go...

In this work, real life reclaimed plastic solid waste (PSW) secured from the municipal sector was mechanically recycled and compounded with virgin linear low density polyethylene (LLDPE). The compounding of the plastic film samples utilised the means of extrusion and blown filming to produce various formulations of the blends containing up to 100% (by weight) of the PSW in the examined specimens. The film samples were compared to market products used in the State of Kuwait where PSW accumulation presents a major obstacle. Natural weathering under arid and harsh climatic conditions was also performed to determine the degradation extent of the film samples. Haze (%), light transmission (%) and the total change in colour (ΔE) were measured as indicators to the degradation profile of the polymeric materials, in addition to tensile pull mechanical properties. Properties were noted to deteriorate as a function of weathering time and waste content. Statistical analysis was also performed on the properties measured and climatic conditions including airborne pollutants levels. The abundance of the secondary airborne pollutant (ozone) was determined to be a significant variable on the studied properties. This can be attributed to induced photo-oxidation the polymeric matrix is subjected to under such climatic conditions which increases oxygen diffusion throughout the polymeric matrix. Future development of the recycled blends studied in this work can be a route for the decrease of associated environmental stressors with virgin plastic resin conversion.

For the first time, a fully comprehensive heterogeneous computational fluid dynamic (CFD) model has been developed to predict the selective catalytic deoxygenation of palm oil to produce green diesel over an Ni/ZrO2 catalyst. The modelling results were compared to experimental data, and a very good validation was obtained. It was found that for the Ni/ZrO2 catalyst, the paraffin conversion increased with temperature, reaching a maximum value (&gt, 95%) at 300 °C. However, temperatures greater than 300 °C resulted in a loss of conversion due to the fact of catalyst deactivation. In addition, at longer times, the model predicted that the catalyst activity would decline faster at temperatures higher than 250 °C. The CFD model was able to predict this deactivation by relating the catalytic activity with the reaction temperature.

It is imperative to have soil guidelines that consider commodities on the market especially biodegradable plastics that are increasing in popularity nowadays. In this short communication, heavy metal in soil was investigated after degrading plastics commonly used on the market. The plastic materials included virgin linear low-density polyethylene, plastic waste of polyolefin origin, and biodegradables of oxo- and hydro-based types. Soil/water matrix that simulates arid land conditions was used. Metals including cobalt, chromium, cadmium, and nickel, among others, were studied after exposure of three continuous months. It was noted that background concentrations reduced with water indicating that leachate might contain the majority of the transferred metals from plastics. In particular, the concentration of nickel in soil was detected to be 84 ppm after exposure to type I of the oxo-biodegradable commercial plastics. Furthermore, the material of similar source started to retain nickel by day 74 of exposure. This surpasses both Canadian and Australian guidelines discussed herein. Furthermore, nickel concentrations exceeded international guidelines and point towards the need for remediation. Mean values of chromium exceeded soil control results and the USA remediation values in the case of single screw compounded plastics. It should also be noted that the work conducted points towards metal trace detection limits that are tied to waste and sludge disposal in an improper manner with time.

Polymer waste was subjected to biodegradation evaluation after compounding specimens with an oxo-prodegradant chemical (PDQ-M) and thermoplastic starch, to determine its susceptibility to degrade with time in contact with soil simulating an arid environment. The ASTM D 5988–18 test method was followed to evaluate the biodegradation extent of the materials under investigation, whilst using linear low density polyethylene (LLDPE), polycaprolactone (PCL) and TPS alongside the starch (positive control) as reference materials. The samples were also subjected to thermal characterisation using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), in addition to studying their infrared spectra (IR). It was noted that the LLPDE and the oxo-prodegradant induced polymer waste had a similar degradation extent evaluated after rigorous testing and monitoring, which was 23% after 180 days of experimental time. Furthermore, a plateau was reached for the biodegradation (%) as a function of time after some 50 days, which indicate that the additives in the samples act as a source of nutrient to sustain the biodegradation by enriching the microorganisms in the soil to produce carbon. The work in this study points towards a new method for treating polymer waste using physical blending with additives to biodegrade it with time as promising alternative for plastic waste accumulation.

The use of hydrogen as a renewable fuel has gained increasing attention in recent years due to its abundance and efficiency. The decomposition of formic acid for hydrogen production under mild conditions of 30 °C has been investigated using a 5 wt.% Pd/C catalyst and a fixed bed microreactor. Furthermore, a comprehensive heterogeneous computational fluid dynamic (CFD) model has been developed to validate the experimental data. The results showed a very good agreement between the CFD studies and experimental work. Catalyst reusability studies have shown that after 10 reactivation processes, the activity of the catalyst can be restored to offer the same level of activity as the fresh sample of the catalyst. The CFD model was able to simulate the catalyst deactivation based on the production of the poisoning species CO, and a sound validation was obtained with the experimental data. Further studies demonstrated that the conversion of formic acid enhances with increasing temperature and decreasing liquid flow rate. Moreover, the CFD model established that the reaction system was devoid of any internal and external mass transfer limitations. The model developed can be used to successfully predict the decomposition of formic acid in microreactors for potential fuel cell applications.

Plastic production and use are currently widespread. However, plastic wastes are non-biodegradable and leave a high carbon footprint, posing challenges to ecosystems and the environment. Therefore, innovative recycling technologies should be geared towards waste-to-energy conversion solutions. Chemical recycling technologies that convert plastic wastes into feedstocks for liquid hydrocarbon fuels and chemical production are highly desirable. This chapter provides a detailed discussion of the possible plastic reuses such as for (a) hydrogen production, (b) production of gasoline and diesel fuel, (c) production of chemicals or chemical building materials, and (d) co-processing with other feedstocks. Because of the high carbon and energy content of plastics, environmentally friendly and cost-effective production of carbon nanomaterials can also be achieved by using plastic waste conversion technologies. The technical challenges and future potential of plastic waste recycling are also discussed.

The rapid growth and urbanization rate, coupled with hot climate and scarce rainfall, makes it essential for a country like Kuwait to have several power and desalination plants with high-generating capacity. These plants are entirely reliant on burning fossil fuels as a source of thermal energy. These plants are also universally accepted to be the largest CO2 emitters; hence, they present a potential for carbon capture and storage (CCS). Having established the suitability of the existing conditions for post-combustion CCS, a techno-economic-based feasibility study, which took into consideration local power generation technologies and economic conditions, was performed. Relying on fifteen case study models and utilizing the concept of levelized cost of electricity (LCOE), the statistical average method (SAM) was used to assess CCS based on realistic and reliable economic indicators. Zour power station, offering the highest potential CO2 stream, was selected as a good candidate for the analysis at hand. Heavy fuel oil (HFO) was assumed to be the only fuel type used at this station with affixed price of USD 20/barrel. The analysis shows that the internal rate of return (IRR) was about 7%, which could be attributed to fuel prices in Kuwait and governmental support, i.e., waived construction tax and subsidized workforce salaries. Furthermore, the net present value (NPV) was also estimated as USD 47,928 million with a 13-year payback period (PBP). Moreover, 1–3% reductions in the annual operational cost were reflected in increasing the IRR and the NPV to 9–11% and USD 104,085–193,945 million, respectively, and decreasing the PBP to 12–11 years. On the contrary, increasing the annual operational cost by 1% made the project economically unfeasible, while an increase of 3% resulted in negative IRR (−1%), NVP (−USD 185,458 million) and increased PBP to 30 years. Similarly, increasing the HFO barrel price by USD 5 resulted in negative IRR (−10%) and NVP (−USD 590,409); hence, a CCS project was deemed economically unfeasible. While the study considered the conditions in Kuwait, it is expected that similar results could be obtained for other countries with an oil-driven economy. Considering that around 62% of the fossil fuel blend in Kuwait is consumed by electricity and water generation, it is inevitable to consider the possibility and practicality of having a carbon network with neighboring countries where other oil-driven economies, such as Kingdom of Saudi Arabia and Iraq, can utilize a CCS-based mega infrastructure in Kuwait. The choice of Kuwait is also logical due to being a mid-point between both countries and can initiate a trading scheme in oil derivatives with both countries.

Marine plastic litter has been a major concern over the past decade particularly in semi-enclosed seas such as the Arabian/Persian Gulf, which are likely to impose a relatively higher threat to ecosystem and human health. In this work, we have focused our efforts on the transport features of marine surface microplastics (MPs) in the Gulf. The assessment utilizes a 3D hydrodynamic model of the northern Gulf which was coupled with a particle tracking model. We have considered five release locations and investigated two dominant wind conditions by applying different numerical scenarios. The results revealed that the northerly winds result in high dispersion and seaward transport of MPs in the open coastal zones, while in semi-enclosed regions they result in high trapping and beaching verified by visual investigation. The study shows that further detailed field investigations are warranted to enable the models to better parameterize the fate and distributions of MPs.

Transition metal nitrides possess superior mechanical, physical, and chemical properties that make them desirable materials for a broad range of applications. A prime example is zirconium nitride (ZrN), which can be obtained through different fabrication methods that require the applications of high temperature and pressure. The present work reports an interesting procedure for synthesizing disordered face centered cubic (fcc)-ZrN nanoparticles through the reactive ball milling (RBM) technique. One attractive point of this study is utilizing inexpensive solid-waste (SW) zirconium (Zr) rods as feedstock materials to fabricate ZrN nanopowders. The as-received SW Zr rods were chemically cleaned and activated, arc-melted, and then disintegrated into powders to obtain the starting Zr metal powders. The powders were charged and sealed under nitrogen gas using a pressurized milling steel vial. After 86 ks of milling, a single fcc-ZrN phase was obtained. This phase transformed into a metastable fcc-phase upon RBM for 259 ks. The disordered ZrN powders revealed good morphological characteristics of spherical shapes and ultrafine nanosize (3.5 nm). The synthetic ZrN nanopowders were consolidated through a spark plasma sintering (SPS) technique into nearly full-density (99.3% of the theoretical density for ZrN) pellets. SPS has proven to be an integral step in leading to desirable and controlled grain growth. Moreover, the sintered materials were not transformed into any other phase(s) upon consolidation at 1673 K. The results indicated that increasing the RBM time led to a significant decrease in the grain size of the ZrN powders. As a result, the microhardness of the consolidated samples was consequently improved with increasing RBM time.

Hydrogen, which is a new clean energy option for future energy systems possesses pioneering characteristics making it a desirable carbon-free energy carrier. Hydrogen storage plays a crucial role in initiating a hydrogen economy. Due to its low density, the storage of hydrogen in the gaseous and liquids states had several technical and economic challenges. Despite these traditional approaches, magnesium hydride (MgH2), which has high gravimetric and volumetric hydrogen density, offers an excellent potential option for utilizing hydrogen in automobiles and other electrical systems. In contrast to its attractive properties, MgH2 should be mechanically and chemically treated to reduce its high activation energy and enhance its modest hydrogen sorption/desorption kinetics. The present study aims to investigate the influence of doping mechanically-treated Mg metal with 5 wt% amorphous Zr2Cu abrasive nanopowders in improving its kinetics and cyclability behaviors. For the first time, solid-waste Mg, Zr, and Cu metals were utilized for preparing MgH2 and amorphous Zr2Cu alloy (catalytic agent), using hydrogen gas-reactive ball milling, and arc melting techniques, respectively. This new nanocomposite system revealed high-capacity hydrogen storage (6.6 wt%) with superior kinetics and extraordinary long cycle-life-time (1100 h) at 250 °C.

Recycling of metallic solid-waste (SW) components has recently become one of the most attractive topics for scientific research and applications on a global scale. A considerable number of applications are proposed for utilizing metallic SW products in different applications. Utilization of SW magnesium (Mg) metal for tailoring high-hydrogen storage capacity nanoparticles has never been reported as yet. The present study demonstrates the ability to produce pure Mg ingots through a melting and casting approach from Mg-machining chips. The ingots were used as a feedstock material to produce high-quality Mg-ribbons, using a melting/casting and spinning approaches. The ribbons were then subjected to severe plastic deformation through the cold rolling technique. The as-cold roll Mg strips were then snipped into small shots before charging them into reactive ball milling. The milling process was undertaken under high-pressure of pure hydrogen gas (H2), where titanium balls were used as milling media. The final product obtained after 100 h of milling showcased excellent nanocrystalline structure and revealed high hydro/dehydrogenation kinetics at moderate temperature (275&deg, C). The present study shows that primer cold rolling of Mg-strips before reactive ball milling is a necessary step to prepare ultrafine magnesium hydride (MgH2) nanopowders with advanced absorption/desorption kinetics behavior. These ultrafine powders with their nanocrystalline structure are believed to play an important role in effective gas diffusion process. Moreover, the fine titanium particles came from the ball-powder-ball collisions and introduced to the Mg matrix have not only acted as micro-scaled milling media, but they played a vital catalyzation role for the process.

Microplastics are recognised as a (persistent) pollutant and are believed to be ubiquitous in the marine environment. The importance of this issue is evident from the large number of technical publications and research efforts within the past decade. However, the Arabian (Persian) Gulf region has few reported datasets in spite of being an area with excessive plastic use and a hefty generation rate of plastic solid waste. This communication aims at stimulating a discussion on this topic focusing on the available regional and international datasets, along with the environmental conditions that are likely to contribute to the disintegration and transport of the plastic debris rendering it as microplastic. This work also highlights some of the constraints in sampling techniques, identification methods, and the reported units of microplastics. Most studies employ neuston nets of variable dimensions that samples different thicknesses of surface water, which also posses a major constraint in standardising field sample collection. Extrapolation of a trawl to units such as particles.km-2 without considering the fact that neuston nets collect three-dimensional samples, is also another aspect discussed in this communication. This study also intends to initiate a discussion on standardising the practices across the region to enable an intercomparison of the reported data. In addition, it calls for a comprehensive assessment using the standardized methodology for putting a mitigation plan for microplastics as a potential threat detected in environmental sinks.

Population growth has led to higher consumption of fossil fuel, and subsequently to a major increase of greenhouse gases emissions to the atmosphere, thus inducing global warming. Fossil fuel supplies are depleting, and the price of these fuels is increasing. Moreover, there are concerns about related emissions of toxic pollutants such as sulphur dioxide and aromatic hydrocarbons. Here, we review alternative fuel technologies. We focus on how membrane reactors improve the existing production processes of renewable fuels. Advantages and environmental benefits of membrane reactors are compared to the conventional techniques. Membrane reactors have been applied successfully to improve biodiesel, hydrogen and Fischer–Tropsch synthesis. Membranes help the conversion of products, whilst shifting the equilibrium of the reaction and reducing undesired by-products. Membrane reactors also overcome immiscibility issues that hinder conventional reactor processes. Overall, membrane reactors reduce cost and energy needed for the treatment of wastewater from fuel production. Funding text The authors would like to thank London South Bank University, School of Engineering, for the PhD funding support.

In this communication, we discuss various production methods as potential venues targeted towards alternative fuel generation. These will revolve around the Fischer–Tropsch (FT) process and biodiesel and hydrogen generation techniques. The implementation of membrane reactors in the production of fuels will be shown and discussed; and their advantages will be detailed. The main routes of hydrogen production are also detailed, which include autothermal reforming and biological process. This was done to compare the main advantages of various techniques for the production of hydrogen, as it is noted to be the most desired utility fuel that can serve various purposes. The application of membranes also facilitates an increase in the conversion of desired products while shifting the equilibrium of the reaction and reducing undesired by-products. Membrane reactors also overcome immiscibility issues that hinder conventional reactor processes. Membrane reactors are also demonstrated to reduce the difficulty in separating and purifying impurities, as they couple separation and reaction in one process. This shows drastic economic and energy requirement reductions in the amount of wastewater treatment associated with conventional fuel production reactor. Emphasis is also paid to catalytic membranes used for the production of biodiesel, which can also remove glycerol from the product line as an added advantage.

This study presents the thermo-chemical conversion by means of pyrolysis as a route to valorise end of life tyres (ELTs) in a sustainable manner whilst targeting produced pyrolysis oil (pyro-oil) to replace conventional fossil fuels. The work presented here compares the results of pyro-oil extracted from the pyrolysis of three tyre grades, namely fresh (new) tyres, car and lorry truck ELTs; and investigates the pyro-oil extracted for fuel properties and common fuel hydrocarbon range. A fixed bed reactor system was used to conduct the experimental runs between 500 and 800 °C. The results show that fresh tyres and car ELTs yield some 45% of pyro-oil at an average reactor bed temperature equal to 600 °C which promotes evolution of liquid hydrocarbons via primary route of tyres cracking, hence pyro-oil production to a maximum. Furthermore, and at a similar operating temperature; the diesel range hydrocarbons (C10–C19) were around 66% of the total fuel like chromatograph studied for the pyrolysis oils. The work in this study and based on properties of fuel investigated point towards blending the oil extracted with conventional fuels that could result in lowering dependency on fossil based ones. Further upgrading is also possible whereby desulphurisation could lead to renewable and sustainable fuel source utilising a solid waste feedstock such as ELTs.

Biochar has recently proven to be effective in various applications including soil amendment for crop production and removal of pollutants from the contaminated water and soil environments. However, major studies on the alterations in bulk density, porosity, water holding capacity, acidity and mineral content of the soils due to the addition of biochar have been carried out in lab-scales. Innumerable studies have investigated the properties of the biochar prepared from various feedstocks under various pyrolysis conditions to examine the effect of peak operating temperature, heating rate and residence time. To promote the commercialization of biochar for large-scale applications, there is a need for critical discussion on the advantages and disadvantages of the biochar for various soil applications (e.g., soil amendment and/or decontamination) in terms of technical, environmental, economic and social considerations. To address this urgent need, the present review attempts to evaluate the application of biochar for soil amendment within the framework of sustainability and recommendations for the future research and applications of biochar for soil treatment.