AhMed Ibrahim | Queen's University, Belfast (original) (raw)

Papers by AhMed Ibrahim

The rising amount of waste generated worldwide is inducing issues of pollution, waste management,... more The rising amount of waste generated worldwide is inducing issues of pollution, waste management, and recycling, calling for new strategies to improve the waste ecosystem, such as the use of artificial intelligence. Here, we review the application of artificial intelligence in waste-to-energy, smart bins, waste-sorting robots, waste generation models, waste monitoring and tracking, plastic pyrolysis, distinguishing fossil and modern materials, logistics, disposal, illegal dumping, resource recovery, smart cities, process efficiency, cost savings, and improving public health. Using artificial intelligence in waste logistics can reduce transportation distance by up to 36.8%, cost savings by up to 13.35%, and time savings by up to 28.22%. Artificial intelligence allows for identifying and sorting waste with an accuracy ranging from 72.8 to 99.95%. Artificial intelligence combined with chemical analysis improves waste pyrolysis, carbon emission estimation, and energy conversion. We also explain how efficiency can be increased and costs can be reduced by artificial intelligence in waste management systems for smart cities.

Environmental Chemistry Letters, 2023

Access to drinkable water is becoming more and more challenging due to worldwide pollution and th... more Access to drinkable water is becoming more and more challenging due to worldwide pollution and the cost of water treatments. Water and wastewater treatment by adsorption on solid materials is usually cheap and effective in removing contaminants, yet classical adsorbents are not sustainable because they are derived from fossil fuels, and they can induce secondary pollution. Therefore, biological sorbents made of modern biomass are increasingly studied as promising alternatives. Indeed, such biosorbents utilize biological waste that would otherwise pollute water systems, and they promote the circular economy. Here we review biosorbents, magnetic sorbents, and other cost-effective sorbents with emphasis on preparation methods, adsorbents types, adsorption mechanisms, and regeneration of spent adsorbents. Biosorbents are prepared from a wide range of materials, including wood, bacteria, algae, herbaceous materials, agricultural waste, and animal waste. Commonly removed contaminants comprise dyes, heavy metals, radionuclides, pharmaceuticals, and personal care products. Preparation methods include coprecipitation, thermal decomposition, microwave irradiation, chemical reduction, micro-emulsion, and arc discharge. Adsorbents can be classified into activated carbon, biochar, lignocellulosic waste, clays, zeolites, peat, and humic soils. We detail adsorption isotherms and kinetics. Regeneration methods comprise thermal and chemical regeneration and supercritical fluid desorption. We also discuss exhausted adsorbent management and disposal. We found that agro-waste biosorbents can remove up to 68-100% of dyes, while wooden, herbaceous, bacterial, and marinebased biosorbents can remove up to 55-99% of heavy metals. Animal waste-based biosorbents can remove 1-99% of heavy metals. The average removal efficiency of modified biosorbents is around 90-95%, but some treatments, such as cross-linked beads, may negatively affect their efficiency.

The global shift from a fossil fuel-based to an electrical-based society is commonly viewed as an... more The global shift from a fossil fuel-based to an electrical-based society is commonly viewed as an ecological improvement. However, the electrical power industry is a major source of carbon dioxide emissions, and incorporating renewable energy can still negatively impact the environment. Despite rising research in renewable energy, the impact of renewable energy consumption on the environment is poorly known. Here, we review the integration of renewable energies into the electricity sector from social, environmental, and economic perspectives. We found that implementing solar photovoltaic, battery storage, wind, hydropower, and bioenergy can provide 504,000 jobs in 2030 and 4.18 million jobs in 2050. For desalinization, photovoltaic/wind/battery storage systems supported by a diesel generator can reduce the cost of water production by 69% and adverse environmental effects by 90%, compared to full fossil fuel systems. The potential of carbon emission reduction increases with the percentage of renewable energy sources utilized. The photovoltaic/wind/hydroelectric system is the most effective in addressing climate change, producing a 2.11-5.46% increase in power generation and a 3.74-71.61% guarantee in share ratios. Compared to single energy systems, hybrid energy systems are more reliable and better equipped to withstand the impacts of climate change on the power supply.

New technologies, systems, societal organization and policies for energy saving are urgently need... more New technologies, systems, societal organization and policies for energy saving are urgently needed in the context of accelerated climate change, the Ukraine conflict and the past coronavirus disease 2019 pandemic. For instance, concerns about market and policy responses that could lead to new lock-ins, such as investing in liquefied natural gas infrastructure and using all available fossil fuels to compensate for Russian gas supply cuts, may hinder decarbonization efforts. Here we review energy-saving solutions with a focus on the actual energy crisis, green alternatives to fossil fuel heating, energy saving in buildings and transportation, artificial intelligence for sustainable energy, and implications for the environment and society. Green alternatives include biomass boilers and stoves, hybrid heat pumps, geothermal heating, solar thermal systems, solar photovoltaics systems into electric boilers, compressed natural gas and hydrogen. We also detail case studies in Germany which is planning a 100% renewable energy switch by 2050 and developing the storage of compressed air in China, with emphasis on technical and economic aspects. The global energy consumption in 2020 was 30.01% for the industry, 26.18% for transport, and 22.08% for residential sectors. 10-40% of energy consumption can be reduced using renewable energy sources, passive design strategies, smart grid analytics, energy-efficient building systems, and intelligent energy monitoring. Electric vehicles offer the highest cost-per-kilometer reduction of 75% and the lowest energy loss of 33%, yet battery-related issues, cost, and weight are challenging. 5-30% of energy can be saved using automated and networked vehicles. Artificial intelligence shows a huge potential in energy saving by improving weather forecasting and machine maintenance and enabling connectivity across homes, workplaces, and transportation. For instance, 18.97-42.60% of energy consumption can be reduced in buildings through deep neural networking. In the electricity sector, artificial intelligence can automate power generation, distribution, and transmission operations, balance the grid without human intervention, enable lightning-speed trading and arbitrage decisions at scale, and eliminate the need for manual adjustments by end-users.

Hydrogen is an energy carrier that can be utilized in various applications, including power plant... more Hydrogen is an energy carrier that can be utilized in various applications, including power plants, the synthesis of high-value products, and clean transportation fuels without emissions. Hence, hydrogen is a potential candidate that can replace fossil fuels and reduce environmental pollution. The high demand for plastics is driving the plastics production rate to increase yearly, leading to a great accumulation of plastic waste materials resulting in a severe burden on the environment. Thermo-catalytic conversion of plastic waste materials to hydrogen and other high-value fuels is a promising route that can efficiently provide an ideal long-term solution necessary to overcome this environmental challenge. Developing durable and high-efficiency catalysts that can immerge hydrogen production from plastic wastes on the industrial scale is still a potential challenge for researchers. This study comprehensively summarizes and discusses the recently published literature for hydrogen production from plastic waste materials using different thermo-catalytic processes, including pyrolysis, pyrolysisair gasification, pyrolysis-steam reforming, pyrolysis-(CO 2) dry reforming, and pyrolysis-plasma catalysis. The scope of this review is to focus on the influence of catalysts and supports, catalysts synthesis method on the production yield of hydrogen, and the impact of several crucial reaction parameters like pyrolysis temperature, catalytic temperature, a catalyst to plastic, and steam to plastic ratios is inclusive in this review as well. The conclusions of this review study will be extremely valuable for researchers interested in the sustainable generation of H 2 from plastic waste materials.

Barium doping effect on the activity and stability of nickel-based catalysts, supported on yttria... more Barium doping effect on the activity and stability of nickel-based catalysts, supported on yttria-stabilized zirconia (Ni-YZr), was investigated in dry reforming of methane. Catalysts were characterized by several techniques (nitrogen sorption, X-ray diffraction [XRD], scanning electron microscopy with energy dispersive X-ray, transmission electron microscopy [TEM], thermogravimetric analysis [TGA], temperature programmed oxidation, CO 2-TPD, H 2-TPR) and were tested in a fixed-bed reactor at 800°C and 42,000 mL/h g cat. Barium played a crucial role in enhancing catalyst reducibility and CO 2 adsorption at high temperatures, as indicated by the activity and stability of the Ni-YZr catalyst. The addition of 4.0 wt% of barium appeared to be the optimal loading, allowing for CH 4 conversion of 82%, which remained constant for 7 h of reaction, compared with 72% of bariumunpromoted Ni-YZr at 800°C. TEM images of the spent catalysts revealed the formation of multiwalled carbon nanotubes on all samples. The TGA analysis showed, however, that an increase in baria loading significantly reduced the coke formation amount, indicating the inhibition of coke formation and the enhancement of the catalytic activity. Such improvement in activity and stability was attributed to the incorporation of barium into

Environmental Chemistry Letters, 2020

The extensive use of petroleum-based synthetic and non-biodegradable materials for packaging appl... more The extensive use of petroleum-based synthetic and non-biodegradable materials for packaging applications has caused severe environmental damage. The rising demand for sustainable packaging materials has encouraged scientists to explore abundant unconventional materials. For instance, cellulose, extracted from lignocellulosic biomass, has gained attention owing to its ecological and biodegradable nature. This article reviews the extraction of cellulose nanoparticles from conventional and non-conventional lignocellulosic biomass, and the preparation of cellulosic nanocomposites for food packaging. Cellulosic nanocomposites exhibit exceptional mechanical, biodegradation, optical and barrier properties, which are attributed to the nanoscale structure and the high specific surface area, of 533 m2 g−1, of cellulose. The mechanical properties of composites improve with the content of cellulose nanoparticles, yet an excessive amount induces agglomeration and, in turn, poor mechanical prope...

Environmental Chemistry Letters

Global industrialization and excessive dependence on nonrenewable energy sources have led to an i... more Global industrialization and excessive dependence on nonrenewable energy sources have led to an increase in solid waste and climate change, calling for strategies to implement a circular economy in all sectors to reduce carbon emissions by 45% by 2030, and to achieve carbon neutrality by 2050. Here we review circular economy strategies with focus on waste management, climate change, energy, air and water quality, land use, industry, food production, life cycle assessment, and cost-effective routes. We observed that increasing the use of bio-based materials is a challenge in terms of land use and land cover. Carbon removal technologies are actually prohibitively expensive, ranging from 100 to 1200 dollars per ton of carbon dioxide. Politically, only few companies worldwide have set climate change goals. While circular economy strategies can be implemented in various sectors such as industry, waste, energy, buildings, and transportation, life cycle assessment is required to optimize n...

Environmental Chemistry Letters

In the context of climate change and the circular economy, biochar has recently found many applic... more In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and e...

The removal of heavy metals combined with biodiesel production by microalgae in a cost-effective ... more The removal of heavy metals combined with biodiesel production by microalgae in a cost-effective way is a promising approach. Herein, we grew two green microalgal species, Chlorella sorokiniana and Scenedesmus acuminatus, in media contaminated with Cu 2+ (3.2 ppm) or Zn 2+ (65.4 ppm) to investigate their growth and full metabolic profile. Furthermore, to integrate the potential economic impact of biodiesel production with heavy metals removal efficiencies. Although acute exposure to heavy metals, on the other hand, reduced growth and increased removal efficiencies of Cu 2+ (59.4, 98.1%) and Zn 2+ (72.4, 98.2%) in C. sorokiniana and S. acuminatus, respectively. Besides, Cu 2+ and Zn 2+ increased primary metabolites, particularly lipids (49, 47% in S. acuminatus, 27, 26% in C. sorokiniana), with a significant induction in the unsaturation levels. Indicating that C. sorokiniana and S. acuminatus are excellent phycoremediators for industrial drainage and future sustainable algal-biofuels platform. Economic assessment of daily 1000-tonne biodiesel production from S. acuminatus grown on highly polluted wastewater via Na 4 SiO 4 transesterification catalysis has all been assessed with an accuracy of ± 10% for the price of the diesel of US$ 1000/tonne and for the cost of the evaluated algal biomass of US$ 430/tonne. The daily 1000 T algal diesel business was viable, with a return on high investment (16.4%) and a payback period of 5 years. According to break-even and sensitivity analyses, the algal diesel cost that makes this business viable should be greater than US$ 147/barrel, while the biomass cost should not exceed US$ 462/tonne. Brent Crude Oil Spot exceeds US$ 95/barrel indicating promising prospects for algal fuel industrialization. Furthermore, the protein and amino acids-based waste biomass may serve as a sustainable biorefienry platform for various biofuel industries through biomass conversion technologies.

The utilization of Mg−O−F prepared from Mg(OH) 2 mixed with different wt % of F in the form of (N... more The utilization of Mg−O−F prepared from Mg(OH) 2 mixed with different wt % of F in the form of (NH 4 F•HF), calcined at 400 and 500°C, for efficient capture of CO 2 is studied herein in a dynamic mode. Two different temperatures were applied using a slow rate of 20 mL•min −1 (100%) of CO 2 passing through each sample for only 1 h. Using the thermogravimetry (TG)-temperature-programed desorption (TPD) technique, the captured amounts of CO 2 at 5°C were determined to be in the range of (39.6−103.9) and (28.9−82.1) mg COd 2 •g −1 for samples of Mg(OH) 2 mixed with 20−50% F and calcined at 400 and 500°C, respectively, whereas, at 30°C, the capacity of CO 2 captured is slightly decreased to be in the range of (32.2−89.4) and (20.9− 55.5) mg COd 2 •g −1 , respectively. The thermal decomposition of all prepared mixtures herein was examined by TG analysis. The obtained samples calcined at 400 and 500°C were characterized by X-ray diffraction and surface area and porosity measurements. The total number of surface basic sites and their distribution over all samples was demonstrated using TG-and differential scanning calorimetry-TPD techniques using pyrrole as a probe molecule. Values of (ΔH) enthalpy changes corresponding to the desorption steps of CO 2 were calculated for the most active adsorbent in this study, that is, Mg(OH) 2 + 20% F, at 400 and 500°C. This study's findings will inspire the simple preparation and economical design of nanocomposite CO 2 sorbents for climate change mitigation under ambient conditions.

The development and recycling of biomass production can partly solve issues of energy, climate ch... more The development and recycling of biomass production can partly solve issues of energy, climate change, population growth, food and feed shortages, and environmental pollution. For instance, the use of seaweeds as feedstocks can reduce our reliance on fossil fuel resources, ensure the synthesis of cost-effective and eco-friendly products and biofuels, and develop sustainable biorefinery processes. Nonetheless, seaweeds use in several biorefineries is still in the infancy stage compared to terrestrial plants-based lignocellulosic biomass. Therefore, here we review seaweed biorefineries with focus on seaweed production, economical benefits, and seaweed use as feedstock for anaerobic digestion, biochar, bioplastics, crop health, food, livestock feed, pharmaceuticals and cosmetics. Globally, seaweeds could sequester between 61 and 268 megatonnes of carbon per year, with an average of 173 megatonnes. Nearly 90% of carbon is sequestered by exporting biomass to deep water, while the remaining 10% is buried in coastal sediments. 500 gigatonnes of seaweeds could replace nearly 40% of the current soy protein production. Seaweeds contain valuable bioactive molecules that could be applied as antimicrobial, antioxidant, antiviral, antifungal, anticancer, contraceptive, anti-inflammatory, anti-coagulants, and in other cosmetics and skincare products.

Climate change and the unsustainability of fossil fuels are calling for cleaner energies such as ... more Climate change and the unsustainability of fossil fuels are calling for cleaner energies such as methanol as a fuel. Methanol is one of the simplest molecules for energy storage and is utilized to generate a wide range of products. Since methanol can be produced from biomass, numerous countries could produce and utilize biomethanol. Here, we review methanol production processes, techno-economy, and environmental viability. Lignocellulosic biomass with a high cellulose and hemicellulose content is highly suitable for gasification-based biomethanol production. Compared to fossil fuels, the combustion of biomethanol reduces nitrogen oxide emissions by up to 80%, carbon dioxide emissions by up to 95%, and eliminates sulphur oxide emission. The cost and yield of biomethanol largely depend on feedstock characteristics, initial investment, and plant location. The use of biomethanol as complementary fuel with diesel, natural gas, and dimethyl ether is beneficial in terms of fuel economy, thermal efficiency, and reduction in greenhouse gas emissions.

The Ukraine conflict has put critical pressure on gas supplies and increased the price of fertili... more The Ukraine conflict has put critical pressure on gas supplies and increased the price of fertilisers. As a consequence, biogas has gained remarkable attention as a local source of both gas for energy and biofertiliser for agriculture. Moreover, climate change-related damage incentivises all sectors to decarbonise and integrate sustainable practices. For instance, anaerobic digestion allows decarbonisation and optimal waste management. Incorporating a biogas system in each country would limit global warming to 2 °C. If suitable policies mechanisms are implemented, the biogas industry could reduce global greenhouse gas emissions by 3.29-4.36 gigatonnes carbon dioxide equivalent, which represent about 10-13% of global emissions. Here, we review the role of the biogas sector in capturing methane and mitigating carbon emissions associated with biogas outputs. Since biogas impurities can cause severe practical difficulties in biogas storing and gas grid delivering systems, we present upgrading technologies that remove or consume the carbon dioxide in raw biogas, to achieve a minimum of 95% methane content. We discuss the role of hydrogen-assisted biological biogas upgrading in carbon sequestration by converting carbon dioxide to biomethane via utilising hydrogen generated primarily through other renewable energy sources such as water electrolysis and photovoltaic solar facilities or wind turbines. This conceptual shift of 'power to gas' allows storing and utilising the excess of energy generated in grids. By converting carbon dioxide produced during anaerobic digestion into additional biomethane, biogas has the potential to meet 53% of the demand for fossil natural gas. We also evaluate the role of digestate from biogas systems in producing biochar, which can be used directly as a biofertiliser or indirectly as a biomethanation enhancement, upgrading, and cleaning material.

Energy Science & Engineering, 2022

Herein we demonstrate the preparation and characterization of nanocrystalline ZnO, either pure or... more Herein we demonstrate the preparation and characterization of nanocrystalline ZnO, either pure or promoted with 1-10 wt.% K 2 O. All catalysts calcined at 400°C were in the nano-crystallite scale as confirmed by X-ray powder diffraction analysis in the 22.9-28.0 nm range. According to the CO 2-temperature-programmed desorption study using thermogravimetric analysis and differential scanning calorimetry techniques, they have a broad spectrum of surface basic sites. Because of the significance of methyl ethyl ketone (MEK) as a next-generation biofuel candidate with high-octane, low boiling point, and relatively high vapor pressure. The prepared catalysts were examined during the direct production of MEK via 2-butanol (2B) dehydrogenation. Among catalysts tested, ZnO promoted with 1% K 2 O showed a superior catalytic activity towards the conversion of 2B to MEK, that is, 71.7% at a reaction temperature of 275°C. The selectivity for the production of

Environmental Chemistry Letters, 2021

Dihydrogen (H 2), commonly named 'hydrogen', is increasingly recognised as a clean and reliable e... more Dihydrogen (H 2), commonly named 'hydrogen', is increasingly recognised as a clean and reliable energy vector for decarbonisation and defossilisation by various sectors. The global hydrogen demand is projected to increase from 70 million tonnes in 2019 to 120 million tonnes by 2024. Hydrogen development should also meet the seventh goal of 'affordable and clean energy' of the United Nations. Here we review hydrogen production and life cycle analysis, hydrogen geological storage and hydrogen utilisation. Hydrogen is produced by water electrolysis, steam methane reforming, methane pyrolysis and coal gasification. We compare the environmental impact of hydrogen production routes by life cycle analysis. Hydrogen is used in power systems, transportation, hydrocarbon and ammonia production, and metallugical industries. Overall, combining electrolysis-generated hydrogen with hydrogen storage in underground porous media such as geological reservoirs and salt caverns is well suited for shifting excess off-peak energy to meet dispatchable on-peak demand.

Renewable and Sustainable Energy Reviews, 2021

Rising demand for energy resources alongside climate emergency concerns has attracted the urgent ... more Rising demand for energy resources alongside climate emergency concerns has attracted the urgent attention of researchers towards the preparation and utilization of biofuels. This review will investigate the different generations of biofuels and more particularly, the developmental and production processes for creating liquid biofuels. Initially, the first-generation biofuel was dependent on edible resources, which has caused controversy and arguments on whether to fulfil the "food or fuel requirement" for civilization. Second-generation biofuels employed inedible resources, however, the cost of production at a commercial scale has restricted its expansion. Recently, third and fourth-generation use microorganisms and genetically modified microorganisms, respectively, to produce biofuels and create an efficient synthetic fuel switch route. Although the last two generations are still in the developmental phase, thorough research is required before commercial-scale production. In conclusion, this review has found that first-and second-generation biofuel production approaches will soon be inadequate to satisfy the exponentially rising demand for biofuels. Therefore, substantial research efforts currently and in the future should focus on the production of third and fourth-generation biofuels, especially on engineered microorganisms. Ultimately, the structure of this review is to outline the current state of the art research regarding biofuels, their production processes and limitations/challenges. This was done through critically reviewing the most up-to-date literature and utilizing bibliometric analysis tools to put forward the guidelines for the future routes of the four generations of biofuels.

As the global cumulative installation of solar photovoltaic (PV) devices grows every year, a prop... more As the global cumulative installation of solar photovoltaic (PV) devices grows every year, a proportionate number of waste PV modules arises because of their limited lifespan. It is estimated that by 2050, there will be approximately 60−78 million tonnes of PV waste (Farrell, C.; Osman, A. I.; Zhang, X. et al. Sci Rep. 2019, 9, 5267). These modules are bound in a strong encapsulated laminate that is prone to imminent degradation. Subsequently, a form of treatment is required to remove a problematic polymeric material such as the encapsulant poly(ethylene-co-vinyl acetate) (EVA) in order to recycle. Pyrolysis is an ideal option that facilitates clean delamination by removing the polymer fraction, and it does not promote chemical oxidation to any of the constituents left behind after pyrolysis. To date, there are limited studies on the pyrolysis of EVA found in PV modules, resulting in significant gaps in the knowledge of pyrolysis kinetic parameters. This work aims to investigate the pyrolysis reaction kinetics concerning the EVA encapsulant found in end-of-life (EoL) crystalline silicon (c-Si) PV modules. The thermoanalytical technique employed was thermogravimetric analysis, which was carried out at 0.5, 1, 2, 4, and 5°C min −1 to ensure accuracy and high resolution while analyzing the kinetics. The kinetic triplet was determined and reported for the first time using the Advanced Kinetics and Technology Solutions (AKTS) Thermokinetics software. The main kinetic modeling method employed was the Friedman differential isoconversional method. Other conventional kinetic modeling approaches were also used, such as the integral (Ozawa) and ASTM-E698 methods for comparison of apparent activation energy. It was observed that the activation energy values for each method were 167.66−260.00, 259.70, and 167.00−252.65 kJ mol −1 for EVA pyrolysis. Additionally, isothermal, nonisothermal, and step-based predictions were reported for the first time using the thermokinetics package. Furthermore, pyrolysis of EVA can have a triple role in the successful delamination of PV modules, recovery of additional constituents, and aiding of waste management of this problematic polymer.

Environmental Chemistry Letters, 2021

The global energy demand is projected to rise by almost 28% by 2040 compared to current levels. B... more The global energy demand is projected to rise by almost 28% by 2040 compared to current levels. Biomass is a promising energy source for producing either solid or liquid fuels. Biofuels are alternatives to fossil fuels to reduce anthropogenic greenhouse gas emissions. Nonetheless, policy decisions for biofuels should be based on evidence that biofuels are produced in a sustainable manner. To this end, life cycle assessment (LCA) provides information on environmental impacts associated with biofuel production chains. Here, we review advances in biomass conversion to biofuels and their environmental impact by life cycle assessment. Processes are gasification, combustion, pyrolysis, enzymatic hydrolysis routes and fermentation. Thermochemical processes are classified into low temperature, below 300 °C, and high temperature, higher than 300 °C, i.e. gasification, combustion and pyrolysis. Pyrolysis is promising because it operates at a relatively lower temperature of up to 500 °C, compared to gasification, which operates at 800-1300 °C. We focus on 1) the drawbacks and advantages of the thermochemical and biochemical conversion routes of biomass into various fuels and the possibility of integrating these routes for better process efficiency; 2) methodological approaches and key findings from 40 LCA studies on biomass to biofuel conversion pathways published from 2019 to 2021; and 3) bibliometric trends and knowledge gaps in biomass conversion into biofuels using thermochemical and biochemical routes. The integration of hydrothermal and biochemical routes is promising for the circular economy.

Environmental Chemistry Letters, 2021

In the context of climate change, there is an urgent need for rapid and efficient methods to capt... more In the context of climate change, there is an urgent need for rapid and efficient methods to capture and sequester carbon from the atmosphere. For instance, production, use and storage of biochar are highly carbon negative, resulting in an estimated sequestration of 0.3-2 Gt CO 2 year −1 by 2050. Yet, biochar production requires more knowledge on feedstocks, thermochemi-cal conversion and end applications. Herein, we review the design and development of biochar systems, and we investigate the carbon removal industry. Carbon removal efforts are currently promoted via the voluntary market. The major commercialized technologies for offering atmospheric carbon removal are forestation, direct air carbon capture utilization and storage, soil carbon sequestration, wooden building elements and biochar, with corresponding fees ranging from 10 to 895 GBP (British pounds) per ton CO 2. Biochar fees range from 52 to 131 GBP per ton CO 2 , which indicates that biochar production is a realistic strategy that can be deployed at large scale. Carbon removal services via biochar are currently offered through robust marketplaces that require extensive certification, verification and monitoring, which adds an element of credibility and authenticity. Biochar eligibility is highly dependent on the type of feedstock utilized and processing conditions employed. Process optimization is imperative to produce an end product that meets application-specific requirements, environmental regulations and achieve ultimate stability for carbon sequestration purposes.

The rising amount of waste generated worldwide is inducing issues of pollution, waste management,... more The rising amount of waste generated worldwide is inducing issues of pollution, waste management, and recycling, calling for new strategies to improve the waste ecosystem, such as the use of artificial intelligence. Here, we review the application of artificial intelligence in waste-to-energy, smart bins, waste-sorting robots, waste generation models, waste monitoring and tracking, plastic pyrolysis, distinguishing fossil and modern materials, logistics, disposal, illegal dumping, resource recovery, smart cities, process efficiency, cost savings, and improving public health. Using artificial intelligence in waste logistics can reduce transportation distance by up to 36.8%, cost savings by up to 13.35%, and time savings by up to 28.22%. Artificial intelligence allows for identifying and sorting waste with an accuracy ranging from 72.8 to 99.95%. Artificial intelligence combined with chemical analysis improves waste pyrolysis, carbon emission estimation, and energy conversion. We also explain how efficiency can be increased and costs can be reduced by artificial intelligence in waste management systems for smart cities.

Environmental Chemistry Letters, 2023

Access to drinkable water is becoming more and more challenging due to worldwide pollution and th... more Access to drinkable water is becoming more and more challenging due to worldwide pollution and the cost of water treatments. Water and wastewater treatment by adsorption on solid materials is usually cheap and effective in removing contaminants, yet classical adsorbents are not sustainable because they are derived from fossil fuels, and they can induce secondary pollution. Therefore, biological sorbents made of modern biomass are increasingly studied as promising alternatives. Indeed, such biosorbents utilize biological waste that would otherwise pollute water systems, and they promote the circular economy. Here we review biosorbents, magnetic sorbents, and other cost-effective sorbents with emphasis on preparation methods, adsorbents types, adsorption mechanisms, and regeneration of spent adsorbents. Biosorbents are prepared from a wide range of materials, including wood, bacteria, algae, herbaceous materials, agricultural waste, and animal waste. Commonly removed contaminants comprise dyes, heavy metals, radionuclides, pharmaceuticals, and personal care products. Preparation methods include coprecipitation, thermal decomposition, microwave irradiation, chemical reduction, micro-emulsion, and arc discharge. Adsorbents can be classified into activated carbon, biochar, lignocellulosic waste, clays, zeolites, peat, and humic soils. We detail adsorption isotherms and kinetics. Regeneration methods comprise thermal and chemical regeneration and supercritical fluid desorption. We also discuss exhausted adsorbent management and disposal. We found that agro-waste biosorbents can remove up to 68-100% of dyes, while wooden, herbaceous, bacterial, and marinebased biosorbents can remove up to 55-99% of heavy metals. Animal waste-based biosorbents can remove 1-99% of heavy metals. The average removal efficiency of modified biosorbents is around 90-95%, but some treatments, such as cross-linked beads, may negatively affect their efficiency.

The global shift from a fossil fuel-based to an electrical-based society is commonly viewed as an... more The global shift from a fossil fuel-based to an electrical-based society is commonly viewed as an ecological improvement. However, the electrical power industry is a major source of carbon dioxide emissions, and incorporating renewable energy can still negatively impact the environment. Despite rising research in renewable energy, the impact of renewable energy consumption on the environment is poorly known. Here, we review the integration of renewable energies into the electricity sector from social, environmental, and economic perspectives. We found that implementing solar photovoltaic, battery storage, wind, hydropower, and bioenergy can provide 504,000 jobs in 2030 and 4.18 million jobs in 2050. For desalinization, photovoltaic/wind/battery storage systems supported by a diesel generator can reduce the cost of water production by 69% and adverse environmental effects by 90%, compared to full fossil fuel systems. The potential of carbon emission reduction increases with the percentage of renewable energy sources utilized. The photovoltaic/wind/hydroelectric system is the most effective in addressing climate change, producing a 2.11-5.46% increase in power generation and a 3.74-71.61% guarantee in share ratios. Compared to single energy systems, hybrid energy systems are more reliable and better equipped to withstand the impacts of climate change on the power supply.

New technologies, systems, societal organization and policies for energy saving are urgently need... more New technologies, systems, societal organization and policies for energy saving are urgently needed in the context of accelerated climate change, the Ukraine conflict and the past coronavirus disease 2019 pandemic. For instance, concerns about market and policy responses that could lead to new lock-ins, such as investing in liquefied natural gas infrastructure and using all available fossil fuels to compensate for Russian gas supply cuts, may hinder decarbonization efforts. Here we review energy-saving solutions with a focus on the actual energy crisis, green alternatives to fossil fuel heating, energy saving in buildings and transportation, artificial intelligence for sustainable energy, and implications for the environment and society. Green alternatives include biomass boilers and stoves, hybrid heat pumps, geothermal heating, solar thermal systems, solar photovoltaics systems into electric boilers, compressed natural gas and hydrogen. We also detail case studies in Germany which is planning a 100% renewable energy switch by 2050 and developing the storage of compressed air in China, with emphasis on technical and economic aspects. The global energy consumption in 2020 was 30.01% for the industry, 26.18% for transport, and 22.08% for residential sectors. 10-40% of energy consumption can be reduced using renewable energy sources, passive design strategies, smart grid analytics, energy-efficient building systems, and intelligent energy monitoring. Electric vehicles offer the highest cost-per-kilometer reduction of 75% and the lowest energy loss of 33%, yet battery-related issues, cost, and weight are challenging. 5-30% of energy can be saved using automated and networked vehicles. Artificial intelligence shows a huge potential in energy saving by improving weather forecasting and machine maintenance and enabling connectivity across homes, workplaces, and transportation. For instance, 18.97-42.60% of energy consumption can be reduced in buildings through deep neural networking. In the electricity sector, artificial intelligence can automate power generation, distribution, and transmission operations, balance the grid without human intervention, enable lightning-speed trading and arbitrage decisions at scale, and eliminate the need for manual adjustments by end-users.

Hydrogen is an energy carrier that can be utilized in various applications, including power plant... more Hydrogen is an energy carrier that can be utilized in various applications, including power plants, the synthesis of high-value products, and clean transportation fuels without emissions. Hence, hydrogen is a potential candidate that can replace fossil fuels and reduce environmental pollution. The high demand for plastics is driving the plastics production rate to increase yearly, leading to a great accumulation of plastic waste materials resulting in a severe burden on the environment. Thermo-catalytic conversion of plastic waste materials to hydrogen and other high-value fuels is a promising route that can efficiently provide an ideal long-term solution necessary to overcome this environmental challenge. Developing durable and high-efficiency catalysts that can immerge hydrogen production from plastic wastes on the industrial scale is still a potential challenge for researchers. This study comprehensively summarizes and discusses the recently published literature for hydrogen production from plastic waste materials using different thermo-catalytic processes, including pyrolysis, pyrolysisair gasification, pyrolysis-steam reforming, pyrolysis-(CO 2) dry reforming, and pyrolysis-plasma catalysis. The scope of this review is to focus on the influence of catalysts and supports, catalysts synthesis method on the production yield of hydrogen, and the impact of several crucial reaction parameters like pyrolysis temperature, catalytic temperature, a catalyst to plastic, and steam to plastic ratios is inclusive in this review as well. The conclusions of this review study will be extremely valuable for researchers interested in the sustainable generation of H 2 from plastic waste materials.

Barium doping effect on the activity and stability of nickel-based catalysts, supported on yttria... more Barium doping effect on the activity and stability of nickel-based catalysts, supported on yttria-stabilized zirconia (Ni-YZr), was investigated in dry reforming of methane. Catalysts were characterized by several techniques (nitrogen sorption, X-ray diffraction [XRD], scanning electron microscopy with energy dispersive X-ray, transmission electron microscopy [TEM], thermogravimetric analysis [TGA], temperature programmed oxidation, CO 2-TPD, H 2-TPR) and were tested in a fixed-bed reactor at 800°C and 42,000 mL/h g cat. Barium played a crucial role in enhancing catalyst reducibility and CO 2 adsorption at high temperatures, as indicated by the activity and stability of the Ni-YZr catalyst. The addition of 4.0 wt% of barium appeared to be the optimal loading, allowing for CH 4 conversion of 82%, which remained constant for 7 h of reaction, compared with 72% of bariumunpromoted Ni-YZr at 800°C. TEM images of the spent catalysts revealed the formation of multiwalled carbon nanotubes on all samples. The TGA analysis showed, however, that an increase in baria loading significantly reduced the coke formation amount, indicating the inhibition of coke formation and the enhancement of the catalytic activity. Such improvement in activity and stability was attributed to the incorporation of barium into

Environmental Chemistry Letters, 2020

The extensive use of petroleum-based synthetic and non-biodegradable materials for packaging appl... more The extensive use of petroleum-based synthetic and non-biodegradable materials for packaging applications has caused severe environmental damage. The rising demand for sustainable packaging materials has encouraged scientists to explore abundant unconventional materials. For instance, cellulose, extracted from lignocellulosic biomass, has gained attention owing to its ecological and biodegradable nature. This article reviews the extraction of cellulose nanoparticles from conventional and non-conventional lignocellulosic biomass, and the preparation of cellulosic nanocomposites for food packaging. Cellulosic nanocomposites exhibit exceptional mechanical, biodegradation, optical and barrier properties, which are attributed to the nanoscale structure and the high specific surface area, of 533 m2 g−1, of cellulose. The mechanical properties of composites improve with the content of cellulose nanoparticles, yet an excessive amount induces agglomeration and, in turn, poor mechanical prope...

Environmental Chemistry Letters

Global industrialization and excessive dependence on nonrenewable energy sources have led to an i... more Global industrialization and excessive dependence on nonrenewable energy sources have led to an increase in solid waste and climate change, calling for strategies to implement a circular economy in all sectors to reduce carbon emissions by 45% by 2030, and to achieve carbon neutrality by 2050. Here we review circular economy strategies with focus on waste management, climate change, energy, air and water quality, land use, industry, food production, life cycle assessment, and cost-effective routes. We observed that increasing the use of bio-based materials is a challenge in terms of land use and land cover. Carbon removal technologies are actually prohibitively expensive, ranging from 100 to 1200 dollars per ton of carbon dioxide. Politically, only few companies worldwide have set climate change goals. While circular economy strategies can be implemented in various sectors such as industry, waste, energy, buildings, and transportation, life cycle assessment is required to optimize n...

Environmental Chemistry Letters

In the context of climate change and the circular economy, biochar has recently found many applic... more In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and e...

The removal of heavy metals combined with biodiesel production by microalgae in a cost-effective ... more The removal of heavy metals combined with biodiesel production by microalgae in a cost-effective way is a promising approach. Herein, we grew two green microalgal species, Chlorella sorokiniana and Scenedesmus acuminatus, in media contaminated with Cu 2+ (3.2 ppm) or Zn 2+ (65.4 ppm) to investigate their growth and full metabolic profile. Furthermore, to integrate the potential economic impact of biodiesel production with heavy metals removal efficiencies. Although acute exposure to heavy metals, on the other hand, reduced growth and increased removal efficiencies of Cu 2+ (59.4, 98.1%) and Zn 2+ (72.4, 98.2%) in C. sorokiniana and S. acuminatus, respectively. Besides, Cu 2+ and Zn 2+ increased primary metabolites, particularly lipids (49, 47% in S. acuminatus, 27, 26% in C. sorokiniana), with a significant induction in the unsaturation levels. Indicating that C. sorokiniana and S. acuminatus are excellent phycoremediators for industrial drainage and future sustainable algal-biofuels platform. Economic assessment of daily 1000-tonne biodiesel production from S. acuminatus grown on highly polluted wastewater via Na 4 SiO 4 transesterification catalysis has all been assessed with an accuracy of ± 10% for the price of the diesel of US$ 1000/tonne and for the cost of the evaluated algal biomass of US$ 430/tonne. The daily 1000 T algal diesel business was viable, with a return on high investment (16.4%) and a payback period of 5 years. According to break-even and sensitivity analyses, the algal diesel cost that makes this business viable should be greater than US$ 147/barrel, while the biomass cost should not exceed US$ 462/tonne. Brent Crude Oil Spot exceeds US$ 95/barrel indicating promising prospects for algal fuel industrialization. Furthermore, the protein and amino acids-based waste biomass may serve as a sustainable biorefienry platform for various biofuel industries through biomass conversion technologies.

The utilization of Mg−O−F prepared from Mg(OH) 2 mixed with different wt % of F in the form of (N... more The utilization of Mg−O−F prepared from Mg(OH) 2 mixed with different wt % of F in the form of (NH 4 F•HF), calcined at 400 and 500°C, for efficient capture of CO 2 is studied herein in a dynamic mode. Two different temperatures were applied using a slow rate of 20 mL•min −1 (100%) of CO 2 passing through each sample for only 1 h. Using the thermogravimetry (TG)-temperature-programed desorption (TPD) technique, the captured amounts of CO 2 at 5°C were determined to be in the range of (39.6−103.9) and (28.9−82.1) mg COd 2 •g −1 for samples of Mg(OH) 2 mixed with 20−50% F and calcined at 400 and 500°C, respectively, whereas, at 30°C, the capacity of CO 2 captured is slightly decreased to be in the range of (32.2−89.4) and (20.9− 55.5) mg COd 2 •g −1 , respectively. The thermal decomposition of all prepared mixtures herein was examined by TG analysis. The obtained samples calcined at 400 and 500°C were characterized by X-ray diffraction and surface area and porosity measurements. The total number of surface basic sites and their distribution over all samples was demonstrated using TG-and differential scanning calorimetry-TPD techniques using pyrrole as a probe molecule. Values of (ΔH) enthalpy changes corresponding to the desorption steps of CO 2 were calculated for the most active adsorbent in this study, that is, Mg(OH) 2 + 20% F, at 400 and 500°C. This study's findings will inspire the simple preparation and economical design of nanocomposite CO 2 sorbents for climate change mitigation under ambient conditions.

The development and recycling of biomass production can partly solve issues of energy, climate ch... more The development and recycling of biomass production can partly solve issues of energy, climate change, population growth, food and feed shortages, and environmental pollution. For instance, the use of seaweeds as feedstocks can reduce our reliance on fossil fuel resources, ensure the synthesis of cost-effective and eco-friendly products and biofuels, and develop sustainable biorefinery processes. Nonetheless, seaweeds use in several biorefineries is still in the infancy stage compared to terrestrial plants-based lignocellulosic biomass. Therefore, here we review seaweed biorefineries with focus on seaweed production, economical benefits, and seaweed use as feedstock for anaerobic digestion, biochar, bioplastics, crop health, food, livestock feed, pharmaceuticals and cosmetics. Globally, seaweeds could sequester between 61 and 268 megatonnes of carbon per year, with an average of 173 megatonnes. Nearly 90% of carbon is sequestered by exporting biomass to deep water, while the remaining 10% is buried in coastal sediments. 500 gigatonnes of seaweeds could replace nearly 40% of the current soy protein production. Seaweeds contain valuable bioactive molecules that could be applied as antimicrobial, antioxidant, antiviral, antifungal, anticancer, contraceptive, anti-inflammatory, anti-coagulants, and in other cosmetics and skincare products.

Climate change and the unsustainability of fossil fuels are calling for cleaner energies such as ... more Climate change and the unsustainability of fossil fuels are calling for cleaner energies such as methanol as a fuel. Methanol is one of the simplest molecules for energy storage and is utilized to generate a wide range of products. Since methanol can be produced from biomass, numerous countries could produce and utilize biomethanol. Here, we review methanol production processes, techno-economy, and environmental viability. Lignocellulosic biomass with a high cellulose and hemicellulose content is highly suitable for gasification-based biomethanol production. Compared to fossil fuels, the combustion of biomethanol reduces nitrogen oxide emissions by up to 80%, carbon dioxide emissions by up to 95%, and eliminates sulphur oxide emission. The cost and yield of biomethanol largely depend on feedstock characteristics, initial investment, and plant location. The use of biomethanol as complementary fuel with diesel, natural gas, and dimethyl ether is beneficial in terms of fuel economy, thermal efficiency, and reduction in greenhouse gas emissions.

The Ukraine conflict has put critical pressure on gas supplies and increased the price of fertili... more The Ukraine conflict has put critical pressure on gas supplies and increased the price of fertilisers. As a consequence, biogas has gained remarkable attention as a local source of both gas for energy and biofertiliser for agriculture. Moreover, climate change-related damage incentivises all sectors to decarbonise and integrate sustainable practices. For instance, anaerobic digestion allows decarbonisation and optimal waste management. Incorporating a biogas system in each country would limit global warming to 2 °C. If suitable policies mechanisms are implemented, the biogas industry could reduce global greenhouse gas emissions by 3.29-4.36 gigatonnes carbon dioxide equivalent, which represent about 10-13% of global emissions. Here, we review the role of the biogas sector in capturing methane and mitigating carbon emissions associated with biogas outputs. Since biogas impurities can cause severe practical difficulties in biogas storing and gas grid delivering systems, we present upgrading technologies that remove or consume the carbon dioxide in raw biogas, to achieve a minimum of 95% methane content. We discuss the role of hydrogen-assisted biological biogas upgrading in carbon sequestration by converting carbon dioxide to biomethane via utilising hydrogen generated primarily through other renewable energy sources such as water electrolysis and photovoltaic solar facilities or wind turbines. This conceptual shift of 'power to gas' allows storing and utilising the excess of energy generated in grids. By converting carbon dioxide produced during anaerobic digestion into additional biomethane, biogas has the potential to meet 53% of the demand for fossil natural gas. We also evaluate the role of digestate from biogas systems in producing biochar, which can be used directly as a biofertiliser or indirectly as a biomethanation enhancement, upgrading, and cleaning material.

Energy Science & Engineering, 2022

Herein we demonstrate the preparation and characterization of nanocrystalline ZnO, either pure or... more Herein we demonstrate the preparation and characterization of nanocrystalline ZnO, either pure or promoted with 1-10 wt.% K 2 O. All catalysts calcined at 400°C were in the nano-crystallite scale as confirmed by X-ray powder diffraction analysis in the 22.9-28.0 nm range. According to the CO 2-temperature-programmed desorption study using thermogravimetric analysis and differential scanning calorimetry techniques, they have a broad spectrum of surface basic sites. Because of the significance of methyl ethyl ketone (MEK) as a next-generation biofuel candidate with high-octane, low boiling point, and relatively high vapor pressure. The prepared catalysts were examined during the direct production of MEK via 2-butanol (2B) dehydrogenation. Among catalysts tested, ZnO promoted with 1% K 2 O showed a superior catalytic activity towards the conversion of 2B to MEK, that is, 71.7% at a reaction temperature of 275°C. The selectivity for the production of

Environmental Chemistry Letters, 2021

Dihydrogen (H 2), commonly named 'hydrogen', is increasingly recognised as a clean and reliable e... more Dihydrogen (H 2), commonly named 'hydrogen', is increasingly recognised as a clean and reliable energy vector for decarbonisation and defossilisation by various sectors. The global hydrogen demand is projected to increase from 70 million tonnes in 2019 to 120 million tonnes by 2024. Hydrogen development should also meet the seventh goal of 'affordable and clean energy' of the United Nations. Here we review hydrogen production and life cycle analysis, hydrogen geological storage and hydrogen utilisation. Hydrogen is produced by water electrolysis, steam methane reforming, methane pyrolysis and coal gasification. We compare the environmental impact of hydrogen production routes by life cycle analysis. Hydrogen is used in power systems, transportation, hydrocarbon and ammonia production, and metallugical industries. Overall, combining electrolysis-generated hydrogen with hydrogen storage in underground porous media such as geological reservoirs and salt caverns is well suited for shifting excess off-peak energy to meet dispatchable on-peak demand.

Renewable and Sustainable Energy Reviews, 2021

Rising demand for energy resources alongside climate emergency concerns has attracted the urgent ... more Rising demand for energy resources alongside climate emergency concerns has attracted the urgent attention of researchers towards the preparation and utilization of biofuels. This review will investigate the different generations of biofuels and more particularly, the developmental and production processes for creating liquid biofuels. Initially, the first-generation biofuel was dependent on edible resources, which has caused controversy and arguments on whether to fulfil the "food or fuel requirement" for civilization. Second-generation biofuels employed inedible resources, however, the cost of production at a commercial scale has restricted its expansion. Recently, third and fourth-generation use microorganisms and genetically modified microorganisms, respectively, to produce biofuels and create an efficient synthetic fuel switch route. Although the last two generations are still in the developmental phase, thorough research is required before commercial-scale production. In conclusion, this review has found that first-and second-generation biofuel production approaches will soon be inadequate to satisfy the exponentially rising demand for biofuels. Therefore, substantial research efforts currently and in the future should focus on the production of third and fourth-generation biofuels, especially on engineered microorganisms. Ultimately, the structure of this review is to outline the current state of the art research regarding biofuels, their production processes and limitations/challenges. This was done through critically reviewing the most up-to-date literature and utilizing bibliometric analysis tools to put forward the guidelines for the future routes of the four generations of biofuels.

As the global cumulative installation of solar photovoltaic (PV) devices grows every year, a prop... more As the global cumulative installation of solar photovoltaic (PV) devices grows every year, a proportionate number of waste PV modules arises because of their limited lifespan. It is estimated that by 2050, there will be approximately 60−78 million tonnes of PV waste (Farrell, C.; Osman, A. I.; Zhang, X. et al. Sci Rep. 2019, 9, 5267). These modules are bound in a strong encapsulated laminate that is prone to imminent degradation. Subsequently, a form of treatment is required to remove a problematic polymeric material such as the encapsulant poly(ethylene-co-vinyl acetate) (EVA) in order to recycle. Pyrolysis is an ideal option that facilitates clean delamination by removing the polymer fraction, and it does not promote chemical oxidation to any of the constituents left behind after pyrolysis. To date, there are limited studies on the pyrolysis of EVA found in PV modules, resulting in significant gaps in the knowledge of pyrolysis kinetic parameters. This work aims to investigate the pyrolysis reaction kinetics concerning the EVA encapsulant found in end-of-life (EoL) crystalline silicon (c-Si) PV modules. The thermoanalytical technique employed was thermogravimetric analysis, which was carried out at 0.5, 1, 2, 4, and 5°C min −1 to ensure accuracy and high resolution while analyzing the kinetics. The kinetic triplet was determined and reported for the first time using the Advanced Kinetics and Technology Solutions (AKTS) Thermokinetics software. The main kinetic modeling method employed was the Friedman differential isoconversional method. Other conventional kinetic modeling approaches were also used, such as the integral (Ozawa) and ASTM-E698 methods for comparison of apparent activation energy. It was observed that the activation energy values for each method were 167.66−260.00, 259.70, and 167.00−252.65 kJ mol −1 for EVA pyrolysis. Additionally, isothermal, nonisothermal, and step-based predictions were reported for the first time using the thermokinetics package. Furthermore, pyrolysis of EVA can have a triple role in the successful delamination of PV modules, recovery of additional constituents, and aiding of waste management of this problematic polymer.

Environmental Chemistry Letters, 2021

The global energy demand is projected to rise by almost 28% by 2040 compared to current levels. B... more The global energy demand is projected to rise by almost 28% by 2040 compared to current levels. Biomass is a promising energy source for producing either solid or liquid fuels. Biofuels are alternatives to fossil fuels to reduce anthropogenic greenhouse gas emissions. Nonetheless, policy decisions for biofuels should be based on evidence that biofuels are produced in a sustainable manner. To this end, life cycle assessment (LCA) provides information on environmental impacts associated with biofuel production chains. Here, we review advances in biomass conversion to biofuels and their environmental impact by life cycle assessment. Processes are gasification, combustion, pyrolysis, enzymatic hydrolysis routes and fermentation. Thermochemical processes are classified into low temperature, below 300 °C, and high temperature, higher than 300 °C, i.e. gasification, combustion and pyrolysis. Pyrolysis is promising because it operates at a relatively lower temperature of up to 500 °C, compared to gasification, which operates at 800-1300 °C. We focus on 1) the drawbacks and advantages of the thermochemical and biochemical conversion routes of biomass into various fuels and the possibility of integrating these routes for better process efficiency; 2) methodological approaches and key findings from 40 LCA studies on biomass to biofuel conversion pathways published from 2019 to 2021; and 3) bibliometric trends and knowledge gaps in biomass conversion into biofuels using thermochemical and biochemical routes. The integration of hydrothermal and biochemical routes is promising for the circular economy.

Environmental Chemistry Letters, 2021

In the context of climate change, there is an urgent need for rapid and efficient methods to capt... more In the context of climate change, there is an urgent need for rapid and efficient methods to capture and sequester carbon from the atmosphere. For instance, production, use and storage of biochar are highly carbon negative, resulting in an estimated sequestration of 0.3-2 Gt CO 2 year −1 by 2050. Yet, biochar production requires more knowledge on feedstocks, thermochemi-cal conversion and end applications. Herein, we review the design and development of biochar systems, and we investigate the carbon removal industry. Carbon removal efforts are currently promoted via the voluntary market. The major commercialized technologies for offering atmospheric carbon removal are forestation, direct air carbon capture utilization and storage, soil carbon sequestration, wooden building elements and biochar, with corresponding fees ranging from 10 to 895 GBP (British pounds) per ton CO 2. Biochar fees range from 52 to 131 GBP per ton CO 2 , which indicates that biochar production is a realistic strategy that can be deployed at large scale. Carbon removal services via biochar are currently offered through robust marketplaces that require extensive certification, verification and monitoring, which adds an element of credibility and authenticity. Biochar eligibility is highly dependent on the type of feedstock utilized and processing conditions employed. Process optimization is imperative to produce an end product that meets application-specific requirements, environmental regulations and achieve ultimate stability for carbon sequestration purposes.